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With the advancement of the supersonic aero propulsion system, optimizing the combined performance of inlet/engine integration has become increasingly crucial. To solve the coupling inlet/engine problem, a quasi-one-dimensional inlet modeling and drag calculation method are proposed, integrated performance seeking control (PSC) based on the neighborhood-based speciation differential evolution-grey wolf optimizer (NSDE-GWO) is presented and quantitatively analyses the influence of variable geometry inlet regulation on performance. The results reveal that the optimization effect of the ramp angle adjustment is generally better than that of the bleed adjustment, and the NSDE-GWO hybrid algorithm achieves remarkable optimization solutions in all three different modes. The PSC with variable geometry inlet adjustment provides more additional potential for optimization compared with fixed geometry inlet, and the performance can be maximized by adjusting both the bleed adjustment and the ramp angle. This study maximizes the exploitation of potential and has theoretical guidance and practical engineering significance. [ABSTRACT FROM AUTHOR]

To reveal the influence of distortion of S-duct on the flow field and performance of transonic fan, full annulus unsteady numerical simulation was carried out under S-duct/fan integrated condition. This study focuses on the coupling flow of S-duct/fan integrated condition under peak efficiency (PE) condition and near stall (NS) condition. Results show that, compared with the condition that S-duct or fan is investigated alone, the distortion of S-duct is suppressed under S-duct/fan integrated condition. The curved structure of S-duct is the important reason for the flow migration from undistorted region to distortion region. Higher inlet relative Mach number and more work input of the rotor are observed in the counter-swirl region. The flow separation in S-duct is weakened under NS condition compared with that of PE condition. Counter-swirl region of blade tip has larger region of blockage, and rotating stall inception is most likely to occur in this region. [ABSTRACT FROM AUTHOR]

Chemical ionisation inlets are fundamental instrument components in chemical ionisation mass spectrometry (CIMS). However, the sample gas and reagent ion trajectories are often understood only in a general and qualitative manner. Here we evaluate two atmospheric pressure chemical ionisation inlets (MION2 and Eisele type inlet) with computational fluid dynamics 3D physico-chemical models regarding the reagent ion and sample gas trajectories and estimate their efficiencies of reagent ion production, reagent ion delivery from the ion source volume into the ion–molecule mixing region, and the interaction between reagent ions and target molecules. The models are validated by laboratory measurements and quantitatively reproduce observed sensitivities to tuning parameters, including ion currents and changes in mass spectra. The study elucidates how the different transport and chemical reactions proceed within the studied inlets, that space charge can already be relevant at ion concentrations of as low as 107 cm−3, and compares the two investigated inlet models. The models provide insights into how to operate the inlets and will help in the development of future inlets that further enhance the capability of CIMS. [ABSTRACT FROM AUTHOR]

Culvert blockage is a recognized problem known to increase the risk of cross-drainage failure. Presently, the effects of bottom-up inlet blockage can be estimated using the theoretically derived energy loss method (ELM) and reduced area method (RAM). Both methods imply that hydraulically efficient inlets are more resilient to blockage effects but have not been verified experimentally for bottom-up blockages. In this study, a physical culvert model was used to determine the entrance loss coefficients and head-discharge relationships for commonly used pipe culvert inlets under different combinations of bottom-up blockage ratio, shape, and roughness. The experimental results confirm that hydraulically efficient inlets are more resilient to bottom-up blockage. Under submerged outlet control conditions, it was found that both blockage ratio and shape significantly influence the entrance loss coefficient and that ELM overestimated the entrance loss coefficient by up to 124%. Under inlet control conditions, it was found that only the blockage ratio significantly influenced the head-discharge relationship and that RAM underestimated the blockage discharge ratio by up to 38%. Comparisons to the experimental results show that ELM and RAM do not account for the increased efficiency of the unblocked part of the inlet under conditions of bottom-up blockage. Comparison to embedded inlets shows that they result in significantly lower entrance loss coefficients than partially blocked inlets under outlet control but yield similar discharge capacity ratios under inlet control. Uncertainties and estimation errors are given for the results, and validity for use in minimum performance design frameworks is evaluated for the different flow types used in hydraulic culvert design. The results show the importance of evaluating blockage effects as part of hydraulic culvert design and verify the general predictions of the energy loss method and reduced area method; that hydraulically efficient inlets are more resilient against blockage effects. The results are valid for type 1 and 5 (inlet control) and 4, 6, and 7 (outlet control) flows and can be used with existing design methods in the following ways: (1) informing the choice of inlet design, for both unblocked and blocked conditions; (2) including a blockage ratio in the design of culverts, based on registered blockage data or risk assessments; (3) evaluating necessary maintenance regimes based on acceptable blockage ratios; and (4) evaluating the effects of blockage on stream continuity. Given the large variation in in situ inlet blockage conditions, it is recommended to use the maximum values of entrance loss coefficients (keb) and the minimum discharge ratio (Qb/Q) as a conservative approach for bottom-up blockage effects. Recommended design blockage ratios given in design manuals should be supplemented with registered data on blockage history for specific locations. For data registration and monitoring, the blockage ratio (Ab/A) should be recorded. [ABSTRACT FROM AUTHOR]

The microclimate environment can be conveniently controlled with accuracy by plant incubators, in which the cuttings propagation method can efficiently enhance seedling production. To ensure air flow evenly throughout the incubator, the scientific design of the air inlet is crucial. This study utilized a computational fluid dynamics (CFD) model to simulate the airflow patterns in a culture layer under different air inlet conditions. Furthermore, the optimal design parameters were determined by way of response surface methodology (RSM) and the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). Adopting the optimal parameters, a prototype was manufactured, and a cuttings experiment was carried out with apple cuttings in the incubator. The results showed that the optimal air inlet radius is 90 mm, the optimal air inlet height is 188 mm, and the optimal uniform flow plate hole diameter is 13 mm. Meanwhile, the apple cuttings were able to root. Therefore, this incubator with optimal parameters can be used for cuttings. The study provides a methodological and theoretical basis for the future optimizing of air inlet parameters and promoting cuttings rooting. [ABSTRACT FROM AUTHOR]

Introduction: Gastric inlet patches are often incidental, but can also be a treatable cause of laryngo‐esophageal symptoms. Methods: We retrospectively reviewed all patients whose gastric inlet patches were diagnosed following assessment for laryngopharyngeal and swallowing symptoms. Improvement following Argon Plasma Coagulation (APC) was assessed using Minimum Clinically‐Important Difference methodology combining voice, throat, and swallowing domains. Correlations between APC response and measures of reflux and mucosal barrier integrity, measured during 24‐h pH‐impedance manometry, were obtained. Proximal and Distal Mean Nocturnal Baseline Impedance (MNBI) values were separately calculated and the novel variable of Mucosal Impedance Gradient was derived as [((Distal MNBI‐Proximal MNBI)/((Distal MNBI + Proximal MMBI)/2)) x 100]. Key Results: Inlet patches were detected in 57 of 651 patients who had Transnasal Panendoscopy (8.7 ± 2.2%). There were 34 males. Mean age was 58 years. Mean duration of symptoms was 2 years. The commonest symptoms were hoarseness (n = 33), throat symptoms (n = 24), and dysphagia (n = 21), respectively. APC was used to ablate patches in 34 patients. Treatment response was 71% at a mean followup of 5.5 months. MIG > − 25% predicted response to APC, with area under the receiver operating characteristic curve of 0.875 (Sensitivity = 81%; Specificity = 100%; p < 0.0001). Conclusions: Gastric inlet patches are common and under‐recognized. They can cause protracted pharyngo‐esophageal symptoms. Patch ablation is an effective treatment for carefully selected patients. Optimal patient selection requires multidisciplinary teamwork. Mucosal Impedance Gradient could further refine patient selection. [ABSTRACT FROM AUTHOR]

It is a major challenge for the airframe-inlet design of modern combat aircrafts, as the flow and electromagnetic wave propagation in the inlet of stealth aircraft are very complex. In this study, an aerodynamic/stealth optimization design method for an S-duct inlet is proposed. The upwind scheme is introduced to the aerodynamic adjoint equation to resolve the shock wave and flow separation. The multilevel fast multipole algorithm (MLFMA) is utilized for the stealth adjoint equation. A dorsal S-duct inlet of flying wing layout is optimized to improve the aerodynamic and stealth characteristics. Both the aerodynamic and stealth characteristics of the inlet are effectively improved. Finally, the optimization results are analyzed, and it shows that the main contradiction between aerodynamic characteristics and stealth characteristics is the centerline and cross-sectional area. The S-duct is smoothed, and the cross-sectional area is increased to improve the aerodynamic characteristics, while it is completely opposite for the stealth design. The radar cross section (RCS) is reduced by phase cancelation for low frequency conditions. The method is suitable for the aerodynamic/stealth design of the aircraft airframe-inlet system. [ABSTRACT FROM AUTHOR]

The integrated design of multibypass augmented/ramjet combustors can reduce the weight of turbine-based combined cycle (TBCC) engines and improve the thrust-to-weight ratio, but low-resistance mixing and efficient stable combustion of multiple airflows over short distances are necessary prerequisites. In this study, a novel structure for a TBCC multibypass integrated augmented/ramjet combustor is proposed. The influence of the inlet aerodynamic parameters on the flow field, mixing efficiency, flow loss, and combustion performance of the combustor under different working modes was obtained via experimental and numerical methods. The experimental results show that the outlet mixing efficiency is greater than 86% in the double-bypass mode (DB-mode). While the triple-bypass mode (TB-mode) has a larger decrease, the total pressure loss is slightly reduced (by approximately 0.5%). The opening of the ram duct has a significant impact on the flow field, resulting in different rules for the influence of the inlet temperature on the outlet mixing efficiency: in the DB-mode, the mixing efficiency decreases with increasing inlet temperature, while the rule is completely opposite after entering the TB-mode. Because the dominant role of the two mixing zones in the flow field changes with the velocity, the inlet velocity has a significant impact on the mixing efficiency in the flow direction. The combustion simulation results show that the combustion efficiency in the DB-mode is almost always above 90% and the high-temperature zone is mainly concentrated downstream of the integrated strut. The radial temperature gradient increases and the combustion efficiency decreases in the TB-mode. [ABSTRACT FROM AUTHOR]

Pressure swirl nozzles are widely applied in various heat and mass transfer applications due to advantages of reliable performance, simple structure, and easy processing. However, the complex design of the nozzle structure makes it difficult to miniaturize the pressure swirl nozzle, which restricts its use in limited spaces. In this study, a compact pressure swirl nozzle is proposed by merging a swirl chamber with the tangential inlet flow channel, addressing the issue of liquid atomization in limited spaces. The key geometric parameters are determined based on the internal flow properties by swirl chamber simulation. A spray test bench utilizing a phase Doppler particle analyzer and a high-speed camera was built to study the effect of pressure drop, geometric size, and nozzle inlet shape on spray characteristics. The simulation results show that the nozzle diameter and inlet shape are the main factors affecting flow in the swirl chamber. The experimental results further demonstrate that increasing nozzle diameter increases flow rate and spray cone angle, causing the droplets to move to the spray edge. The spray characteristics are affected by the inlet shape of the nozzle hole: radial velocity and particle size show a wider range of change with a funnel-shaped inlet. Axial velocity and pressure drop are obviously affected by a cylindrical-shaped inlet. This study provided a new design approach for pressure swirl nozzles and achieved flow rate of 5–35 l/h and Sauter mean diameter below 40 μm with an overall weight of 12 g. This compact nozzle construction is a reference for the design of atomizing nozzles in limited spaces. [ABSTRACT FROM AUTHOR]

This work sought to reveal the role of the inlet gas volume fraction (GVF) on the energy-conversion features of a multiphase pump. To this end, a self-developed single-stage multiphase pump was used as the research object, and a gas–liquid transport medium was examined based on the energy-transport theory. The role of the GVF in the pressure-gradient work, Lamb-vector divergence, and vortex pseudo-energy dissipation in the pressurization unit of the multiphase pump were analyzed, and the impact of the GVF on the energy-conversion features of the multiphase pump was also investigated. The results indicate that under various GVFs, increasing the tip clearance prevents the pressure gradient from exerting its intended function. Furthermore, as the GVF is increased, the scale of the tip-leakage vortex increases, the flow field in the pressurization unit is disturbed, and the vortex pseudo-energy dissipation in the impeller increases. As a result, the energy loss increases, the pressurization effect of the pump is weakened, and its work performance decreases. These results offer a reference for enhancing the efficiency of multiphase pumps. [ABSTRACT FROM AUTHOR]

Due to the high steam velocity and low thermal parameters at the turbine's final stage, steam generates non-equilibrium condensation and forms a large number of small droplets during the process of pressure expansion. The wet steam mixed with droplets impinges on the turbine blades, endangering turbine operation safety and reducing turbine work efficiency. This article modifies the non-equilibrium condensation control equation and embeds it into the numerical simulation software to make the numerical calculation results more accurate. By modifying the inlet steam superheat in the classical experiments, the condensation characteristics of wet steam in Moses–Stein nozzles and Dykas cascades are studied. The results show that increasing inlet superheat can effectively suppress the generation of non-equilibrium condensation and reduce outlet liquid mass fraction. The minimum supercooling temperature of non-equilibrium condensation is only related to the working fluid characteristics (the steam model used in this article is around 20 K). When the inlet superheat of the cascade is large, the rapid condensation region is mainly near the suction surface. In contrast, when the superheat is low, the rapid condensation zone is mainly near the pressure surface. The condensation location is mainly affected by the intensity of internal condensation shock waves in the cascade. Increasing inlet superheat not only increases the shock wave intensity but also decreases the shock wave angle in the passage. When the inlet temperature increases by 20 K, the heat efficiency of the cascade increases by about 1%. [ABSTRACT FROM AUTHOR]

For the roots hydrogen circulating pump (HCP), different rotor profiles result in variations in flow pulsation, pressure pulsation, and pressure-velocity distribution within the pump. In this study, unsteady numerical simulations were conducted on the HCP with variable trochoid ratio profiles to analyze its flow characteristics. The findings indicate that employing a variable trochoid ratio to design the rotor profile enhances the amplitude of the HCP's inlet and outlet flow rates, with a greater impact on the pulsation of the inlet flow rate. In comparison to an ordinary trochoid profile, the variable trochoid ratio profile exhibits reduced vortex in the suction chamber and is less affected by leakage flow between the rotor and casing. Furthermore, due to the lager area utilization rate of the variable trochoid ratio profile, the volume of the HCP's suction chamber increases, facilitating the full development of inlet flow and generating a high kinetic energy vortex, thereby further augmenting the inlet flow. [Display omitted] • Implementation of variable trochoid ratio profile enhances average flow rate. • Inlet flow pulsation varies in variable and ordinary trochoid profiles. • Inward-tapered profile expands suction chamber, generates high-energy vortex. [ABSTRACT FROM AUTHOR]

This study explores and analyzes the mixing efficiency of five innovative micromixers, each featuring serpentine microchannels, through comprehensive experimentation. The mixing experiments were conducted on micromixers with distinct shapes: backward arrow, loop, square, circular, and box waves, all equipped with backward arrow-shaped inlets, using the Villermaux–Dushman protocol. The assessment of mixing performance was carried out across a range of Reynolds numbers (Re) from 100 to 700, accompanied by varying pressure drop measurements. The efficiency of mixing was determined using ultraviolet spectrophotometry to measure the absorbance values and times for mixed fluids from the five micromixers. At Re values greater than 100, the mixing performance ranked as follows: Square-wave > Circular-wave > Box-wave > Loop-wave > Backward Arrow-shaped micromixers. Factors such as repeated perturbations, the presence of crests and troughs, the angle of the channels, and the split and recombination effects played significant roles in these outcomes. With increasing Re from 100 to 700, we observed progressive and consistent results across all microchannels. Remarkably, at a broad range of Reynolds numbers, the five micromixers demonstrated superior mixing performance compared to designs based on unbalanced split and collisions, achieving an impressive mixing efficiency of over 93 %, while keeping the pressure drop under 80 kPa. This pressure drop range is suitable for a variety of lab-on-a-chip and micro-total analysis systems. Furthermore, the experimental results show that the mixing performance of microfluidic systems can be improved by incorporating the presented design method of microchannel shapes, especially the Square-wave. [ABSTRACT FROM AUTHOR]

Swirling flow at vertical shaft spillways results in flow fluctuations, reduces hydraulic system efficiency, and causes structural damage. Optimizing the shape of the inlet is a practical means to decrease the swirling flow strength. In the present study a comprehensive experimental investigation was performed to examine the effects of a new type of inlet over vertical shaft spillways, namely the circular piano-key (CPK) inlet, for free, orifice and full-pipe or black water flow regimes. Head-discharge relationships, threshold and critical submergence depths and the effects of different geometrical parameters of the CPK inlets on the spillway flow discharge coefficient were assessed. Results reveal that increases in the height of the inlet and outlet keys increase the released capacity of the shaft spillway. Given its increased total crest length and the effects of the radially placed walls of a CPK against the swirling flow, angles of the inlet and outlet keys of the CPK are found to significantly affect the spillway flow discharge. The effect of inlet and outlet overhangs on the efficiency of CPK inlets is not noteworthy, being negligible. Considering the destructive effects of swirling flow, the CPK inlets significantly decrease the range of submergence for an unfavourable swirling flow regime condition, increasing the threshold submergence depth and decreasing the critical submergence depth. The flow discharge through the CPK inlets is higher than those of the other circular-type spillways. The present modified CPK inlets more effectively divert water, serving as an economical alternative to the conventional circular spillways. [ABSTRACT FROM AUTHOR]

Objective: Hatcheries are used to help supplement populations of Pacific salmon Oncorhynchus spp. for conservation and fisheries purposes and to provide stewardship opportunities. In British Columbia, small community-run hatcheries typically focus on the latter and generally do not know the efficacy of their release approaches, unlike larger production hatcheries. Methods: We used acoustic telemetry to track the survival and behavior of 90 hatchery-reared Coho Salmon O. kisutch smolts, released from a community hatchery, through Burrard Inlet and into the Strait of Georgia. This is the first study to track Coho Salmon smolts released directly into a marine environment and one of very few studies to track them in an oceanic setting. Result: Smolt survival was lowest through the first 3 km of the migration at 37%, and the estimated cumulative survival to the final array (~20 km from release) was 10-23%. The presence of numerous predators in the region suggests that predation is a possible explanation for poor survival over the relatively short migration distance. Travel rates ranged from ~4 to 18 km/day, depending on the migration segment, which is slower than the marine migration of smolts from other species, likely increasing exposure to predators. However, we found potential evidence of "predator swamping," as survival estimates across migration segments were highest for the final of our three release groups and poorest for the first release group, with intergroup survival estimates increasing by 7-12% in the final three migration segments. Releasing smolts at high densities and at night, as our partner hatchery currently does, likely improves smolt survival. Conclusion: Our work demonstrates how acoustic telemetry can be used to examine hatchery practices and propose potential improvements. Saltwater readiness and the release location are factors that our results suggest may warrant future attention to potentially improve marine survival of Coho Salmon smolts. [ABSTRACT FROM AUTHOR]

In nuclear-powered steam turbines, the aerodynamic performance of the inlet chamber tends to be contradictory to the compact design, which makes it difficult to achieve optimal efficiency and power in a nuclear-powered steam turbine. In this study, the quantitative correlation between compact design and aerodynamic performance was investigated to reveal the interaction mechanism between the aerodynamic performance of the inlet chamber of the steam turbine with its compactness. First, the effects of peripheral quantity and arrangement of inlets in the chamber inlet on its aerodynamic performance were studied. The results indicated that the proposed cross configuration exhibited optimized aerodynamic performance in multiple aspects. Then, the effects of two compactness indices (inlet/outlet area ratio and axial spacing at outlet) on the aerodynamic performance of the inlet chamber were investigated. The results indicated that the volume of the inlet chamber was proportional to the inlet/outlet area ratio, and an appropriate design of the inlet chamber can achieve compactness without significantly affecting its aerodynamic performance. In addition, the influencing mechanism of the compact optimization design on the aerodynamic performances of the inlet chamber was revealed. This study provides references for optimization designing an effective and compacted inlet chamber of steam turbines. [ABSTRACT FROM AUTHOR]

Tidal inlet structures are engineering projects with associated benefits related to flood control, water quality enhancement, and coastal protection. This study analyzes the performance of hydraulic gates on a stabilized inlet in estuarine systems by developing a simplified hydraulic model that considers inlet and outlet water levels. The proposed model was applied to the stabilized tidal inlet structure in Cartagena de Indias, Colombia. This model offers a practical tool for engineers and designers operating estuarine systems. The analysis focuses on the coastal lagoon of Ciénaga de la Virgen. The proposed model was successfully calibrated using two water sensors, with extreme input and outlet flow rates of approximately 260 m3/s and 110 m3/s, respectively. The average daily output volume in the system is 3,361,000 m3, while the average daily input volume is 3,200,000 m3. Consequently, the manipulation of the opening gates results in a decrease in the estuarine water level, potentially by as much as 25 cm, which local authorities can use to make decisions to reduce extreme water levels during flooding events. [ABSTRACT FROM AUTHOR]

When a sluice gate is arranged in parallel with pumping station units, biased flow occurs in the forebay when the units are operating. The transverse flow velocity in front of the channel inlet is relatively high, and, in severe cases, it may lead to the formation of suction vortices, impacting the stable operation of pump units. Taking the Liushan Pumping Station project of the Eastern Route of the South-to-North Water Diversion Project as a case study, this paper investigates the effect of the partition wall length on the inlet flow regime of pumping station units arranged in parallel with the sluice gate to reduce the transverse flow velocity in front of the channel inlet. Using numerical simulations, the inlet flow regimes for different partition wall lengths were compared. Moreover, the flow field distributions in the forebay under different operating conditions were analyzed alongside the transverse flow velocity in front of the channel inlet and the uniformity of flow velocity distribution in the section behind the channel inlet. Hydraulic model tests were then conducted to validate the simulation results. The results indicate that in the original design, there existed a vortex zone in the forebay in front of the inlet of the channel where the transverse flow was relatively high. However, the introduction of partition walls significantly reduced the transverse flow velocity in front of the inlet of the channel in the forebay. The optimal effect was achieved when the length of the partition wall was twice the width of the inlet channel. Furthermore, the uniformity of velocity distribution at the inlet of the channel increased by an average of 7.4%, leading to a substantial improvement in the inlet flow regime of the pumping station. The addition of partition walls in the forebay effectively resolved the issues related to the flow regime in the forebay, providing valuable references for similar engineering studies in the future. [ABSTRACT FROM AUTHOR]

The nozzle arrangement of internal spray cooling tool plays a crucial role in the efficiency of coolant flow into the cutting zone and has a significant impact on the cutting performance. This article designs three types of internal spray cooling turning tools based on the different arrangements of the upper nozzle on the tool rake face. Tool A has an upper nozzle near the main cutting edge, tool B is equipped with an upper nozzle near the minor cutting edge, and tool C possesses two upper nozzles near the main and minor cutting edges, respectively. The nozzle arrangement effect on the cooling performance of the internal spray cooling turning tool during the internal turning process was studied by the fluid–solid-thermal coupling simulation method. The simulation results showed that tool B with an upper nozzle arranged near the minor cutting edge had the best cooling performance because it is easy for air and coolant droplets to enter the tool-chip contact zone. On the contrary, tool C equipped with two upper nozzles near the main and minor cutting edges results in the worst cooling performance for the air and coolant droplets are difficult to flow into the tool-chip contact area. Internal turning experiments of QT500-7 workpieces were carried out. Results demonstrated that tool B performed best in reducing cutting temperature and improving machined surface quality. In addition, the number of small chips generated by all internal spray cooling turning tools increased at an inlet pressure of 0.6 MPa, especially for tool B. [ABSTRACT FROM AUTHOR]

The flow capacity of the intake port has a great influence on the charging efficiency of the internal combustion engine, affecting the engine's performance, so it is critical to improve the intake port flow capacity. In this paper, the intake port numerical model was established, and the influence of the inlet and outlet area ratio on intake port flow capacity was studied. The results show that, under the same condition of relative pressure difference, the intake port discharge coefficient increases sharply and then slowly with an increase in area ratio. Under the same condition of area ratio, the discharge coefficient is only determined by relative pressure difference and decreases with an increase of relative pressure difference when the inlet and outlet area ratio > 1. The optimal area ratio decreases and then converges with an increase in relative pressure difference. When the intake port is designed, the optimal area ratio under the working condition of a smaller relative pressure difference should be applied in order to ensure the discharge coefficient is optimal under all working conditions. [ABSTRACT FROM AUTHOR]

To improve the performance of hydrocyclones for in-situ natural gas hydrate recovery and desanding, this study analyzed the hydrocyclone's sensitivity factors, optimized the structural parameters, and investigated the adaptability to the reservoir and operating parameters through numerical simulations and experiments. Results showed that the optimal structural parameters were spiral pitch of 24 mm, vortex finder diameter of 36 mm, spigot diameter of 26 mm, number of spirals equals 5, and cone angle of 6°. Under the optimal parameter configuration, the efficiency of the hydrocyclone is exceeded 90%, and the pressure drop was within 0.5 MPa. When the inlet natural gas hydrate volume concentration, or the inlet sand volume concentration are increased, the separation efficiency and pressure drop changed only slightly. The natural gas hydrate hydrocyclone showed good adaptability to the reservoir and operating parameters. These findings provide theoretical guidance for the design and construction of natural gas hydrate in-situ separators. [ABSTRACT FROM AUTHOR]

The connection form of pipelines has an important impact on the comprehensive performance evaluation of fresh air systems. The most used PVC fresh air pipeline material in the market was selected for experimental research in this paper, and the deposition rates of particles of different pipeline connection form of 45°, 90° bend, and straight tee were all tested and compared. The purification effect of the pipeline connection form of the highest deposition rate is tested and studied. The results showed that the particle deposition rates were the highest in the connection form of straight tee, with deposition rates of 47.61%, 18.06%, and 8.13% for PM10, PM2.5, and PM1.0, respectively. As the particle size increases, the deposition rate of particles also gradually increases. The larger the inlet velocity, the greater the deposition rate. The particle concentration on the outlet of the pipeline in the connection forms of straight tee was significantly decreased after adding the purification equipment, and the deposition rates of PM10, PM2.5, and PM1.0 decreased by 45.01%, 68.89%, and 77.48%. Therefore, the use of pipeline elbows should be reduced, and purification equipment should be installed in the process of using, which will reduce the deposition of particles in the fresh air systems. [ABSTRACT FROM AUTHOR]

The article discusses a study on the seasonal occurrence of harbor seals near Oregon Inlet, North Carolina, USA, conducted by Britney E. Pepper et al., published in the journal. It highlights the recolonization of areas by harbor seals, expansion of their seasonal range southward, and potential impacts of human activities like bridge construction and demolition on their habitat and conservation.

Although there are many studies evaluating optimal inlet and outlet angles required for the correct placement of S1 iliosacral screws, there is no study evaluating reliability and feasibility of these angles for all individuals on three‐dimensional (3D) anatomical models. A total of 100 women and 100 men were selected randomly. A vertical line was created according to long axis of the tomography device on which patient was lying in supine position. The automatized best‐fit planes were created on superior and inferior endplates, anterior cortex including notch region and posterior cortex of first sacral vertebrae using 3D imaging software to measure mean inlet and outlet angles. We observed no statistically significant difference between gender groups in terms of inlet and outlet angles. Mean inlet view is obtained for anterior cortex of S1 in 22.5 ± 9.5° and for posterior cortex in 46.5 ± 9.3°. Mean fluoroscopic view angle of S1 for superior outlet is 40.3 ± 7.6 and for inferior outlet is 46.9 ± 8.8. Mean anterior and posterior S1 inlet view angles do not accurately visualize anterior cortex of 74 (37%) and posterior cortex of 66 (33%) individuals. Mean superior and inferior S1 outlet view angles do not accurately visualize superior endplate of 74 (37%) and inferior endplate of 56 (28%) individuals. Due to individual alterations of spatial position of sacrum, mean inlet and outlet view angles of S1 are not sufficient to visualize the iliosacral screws under fluoroscopy in many individuals. [ABSTRACT FROM AUTHOR]

To effectively reduce the dust pollution in the fully mechanized face, this study proposes a large-scale dust-droplet coupling model based on LES-VOF and the dust-droplet probabilistic collision algorithm. Subsequently, the dispersion of droplets and dust under various spray pressures was analyzed. The accuracy of the model was verified through experiments and measurements, with a relative error of less than 15.0%. The analysis results indicated that the airflow on the air inlet side generated a vortex field, resulting in the accumulation of dust and droplets within 0–9.8 m from the heading face. The airflow on the air outlet side moved backward along the tunnel floor, causing the droplets and dust to disperse in a larger area. As the spray pressure increased, the droplet coverage distance showed a bimodal pattern, while the dust diffusion distance initially increased and then decreased. If the spray pressure exceeded 5 MPa, the covering distance of droplets and dust reached 23.0 m and 4.2 m, respectively, and the dust concentration in the area going beyond 15.0 m was below 20.0 mg/m3. The dust concentration at the driver's location was measured at 5.35 mg/m3, achieving a significant dust reduction rate of 90.60%. More importantly, the on-site application analysis has presented well-aligned data with the simulation results. [Display omitted] [ABSTRACT FROM AUTHOR]

Aircraft-based measurements enable large-scale characterization of gas-phase atmospheric composition, but these measurements are complicated by the challenges of sampling from high-speed flow. Under such sampling conditions, the sample flow will likely experience turbulence, accelerating and mixing of potential contamination of the gas-phase from the condensed-phase components on walls, and reduced vapor transmission due to losses to the inner walls of the sampling line. While a significant amount of research has gone into understanding aerosol sampling efficiency for aircraft inlets, a similar research investment has not been made for gas sampling. Here, we analyze the performance of a forward-facing laminar flow gas inlet to establish its performance as a function of operating conditions, including ambient pressure, freestream velocities, and sampling conditions. Using computational fluid dynamics (CFD) modeling we simulate flow inside and outside the inlet to determine the extent of freestream turbulent interaction with the sample flow and its implication for gas sample transport. The CFD results of flow features in the inlet are compared against measurements of air speed and turbulent intensity from full-sized high-speed wind tunnel experiments. These comparisons suggest that the Reynolds-averaged Navier–Stokes (RANS) CFD simulations using the shear stress transport (SST) modeling approach provide the most reasonable prediction of the turbulence characteristics of the inlet. [ABSTRACT FROM AUTHOR]

Purpose: Thoracic inlet angle (TIA) is a sagittal radiographic parameter with a constant value regardless of posture and is significantly correlated with the sagittal balance of the cervical spine. However, the practical use of TIA has not been studied. This study aimed to investigate the usefulness of the preoperative TIA for predicting the development of kyphotic deformity after cervical laminoplasty in comparison to the preoperative T1 slope (T1S). Methods: A total of 98 patients who underwent cervical laminoplasty without preoperative kyphotic alignment were included (mean age, 73.7 years; 41.8% female). Radiography was evaluated before surgery and at the 2-year follow-up examination. The cervical sagittal parameters were measured on standing radiographs, and the TIA was measured on T2-weighted MRI in a supine position. Cervical alignment with a C2–C7 angle of ≥ 0° was defined as lordosis, and that with an angle of < 0° was defined as kyphosis. Results: Postoperative kyphosis occurred in 11 patients (11.2%). Preoperatively, the kyphosis group showed significantly lower values in the T1S (23.5° vs. 30.3°, p = 0.034) and TIA (76.1° vs. 81.8°, p = 0.042). We performed ROC curve analysis to clarify the impact of the preoperative TIA and T1S on kyphotic deformity after laminoplasty. The optimal cutoff angles for TIA and T1S were 68° and 19°, respectively, with similar diagnostic accuracy. Conclusion: This study demonstrated the clinical utility of the preoperative TIA for predicting the risk of postoperative kyphotic deformity after cervical laminoplasty. These findings suggest the importance of the preoperative assessment of thoracic inlet alignment in cervical spine surgery. [ABSTRACT FROM AUTHOR]

Direct numerical simulations were performed to examine the control mechanism of a plasma actuator using a dielectric barrier discharge in a rectangular jet with an inlet disturbance. The nozzle has a ratio of 75–10 mm, while the Reynolds number is 3300, and the peak frequency near the nozzle exit is 55 Hz. The jet is controlled by the actuators with conditions of 55 Hz burst frequency, 10% duty ratio, and π phase difference between the upper and lower actuators. The flow field spreads downstream more than that without control. Moreover, the controlling mechanism generates a vortex by inducing flow from the actuator, which grows in size by merging with other vortices generated upstream. Furthermore, the induced flows generate vortices on the upper and lower shear layers that grow in opposite phases of π, and these vortices cause upward and downward flow, respectively, thereby accelerating the spread of the jet. The vortex generated by the induced flow can grow due to its low-streamwise velocity. This occurs regardless of the inlet disturbance because the streakline from the induced flow moves downward near the nozzle surface, causing a rapid decrease in the streamwise velocity after the actuator is stopped. Thus, the actuator's control effect can be explained by the momentary change in the location of the streaklines around it. [ABSTRACT FROM AUTHOR]

Extracorporeal life support (ECLS) includes life-saving support in severe acute cardiac and/or pulmonary failure. In the past 20 years, centrifugal pumps have become the primary choice to deliver the required blood flow. Pumps of various designs, with different approved operating ranges, are today available to clinicians. The use of centrifugal pumps in the low flow condition has been shown to increase hemolytic and thrombogenic risks of the treatment. Further, low flow operation has been associated with retrograde flow at the pump inlet. In this study, experimental and numerical methods have been applied to investigate the operating conditions and fluid dynamical mechanisms leading to reverse flow (or backflow) at the inlet. Reverse flow was predominantly observed in pumps having a top shroud covering the impeller blades, showing a relation between pump geometry and backflow. The shroud divides the pump volume above the impeller into two regions, separating the swirling reverse flow migrating toward the upper pump volute from the main flow, reducing the dissipation of the vortical structures, and allowing the swirling reverse flow to reach further in the pump inlet. At the inlet, backflow was observed as stable recirculation areas at the side of the pump inlet. [ABSTRACT FROM AUTHOR]

This article explores the relationship between stall types and speed ratios in contra-rotating boost stages, discovering stationary circumferential stall cells and dual stall cell phenomena, and examines the relationship between stall characteristics and inlet distortions. These stall characteristics of counter-rotating boost stages are markedly different from the single stall patterns of traditional compressor rotor-stator structures, highlighting the complexity of the flow field in counter-rotating stages. The study uses the experimental methods to investigate different speed ratios under both uniform and distorted inlet conditions, conducting both accelerating and decelerating stall tests, with each stall condition analyzed using data from 25 s. The main focus is on the stall types, frequencies, and development patterns under different distortion conditions at various speed ratios, filling a research gap in counter-rotating boost stages. It explores the unstable flow characteristics of counter-rotating boost stages under distorted conditions, particularly the stall disturbance characteristics and pressure fluctuation patterns at the blade tip during stall entry and recovery under distortions. Comparing distortions with uniform inlet conditions provides an intuitive understanding of the influence of various types of distortions on wall pressure and stall in the flow field. Researchers can use this knowledge to design casings or blowing devices to suppress stall disturbances, thereby achieving stall prevention and enhancing stability. [ABSTRACT FROM AUTHOR]

The operational efficiency of the airlift reactors relies significantly on the aeration and mixing provided by the inlet system. The diffused aeration system is the most energy-intensive component affecting the operation of the bioreactor, accounting for 45–75 % of the energy costs. This study presents a coupled CFD-PBM to investigate the collective impacts of multiple bubble diameters, variations in inlet gas distribution types, and flow rates on the hydrodynamic characteristics of bubble columns. The simulation results were validated through comprehensive comparisons with experimental data. The experimental data and simulations of the single bubble size model (SBSM) and multi-bubble size model (MBSM) were compared, proposing an enhanced inlet gas distribution type. The results indicate a close resemblance between the MBSM data and the experimental results, with an error margin not exceeding 5 %. Moreover, different flow rates were found to cause varying sensitivities in the bubble size distribution (BSD) within the column. Furthermore, the simulation results validate the similarity between lift coefficients and critical diameters to experiments and shed light on favorable conditions for reactor design. The key findings of this study encompass: (1) the use of MBSM can accurately predict the tower system characteristics; (2) the column circulation is intensified with small inlet bubble size and high gas velocity, which is favorable for chemical reactions and microbial aggregation to proceed; and (3) the BSD is not sensitive to the inlet gas distribution type at high flow rates. [ABSTRACT FROM AUTHOR]

Fjords are deep nearshore zones that connect watersheds and oceans, typically behaving as an estuary. In some fjords, strong katabatic winds in winter (also known as Arctic outflow wind events) can lead to cooling and reoxygenation of subsurface waters, with effects lasting until the following autumn, as observed in 2019 in Bute Inlet, British Columbia, Canada. We used high-resolution, three-dimensional ocean model summer simulations to investigate the mechanisms allowing for the persistence of these cool, oxygen-rich subsurface conditions in Bute Inlet. The slow residual circulation underneath the brackish outflow (and consequent slow advection) in this long, deep fjord is a main reason why the cold subsurface water mass stays in place until conditions change in autumn (i.e., start of stronger wind mixing and reduced freshwater forcing). Another mechanism is a positive feedback provided by the presence of this subsurface water mass, since it further reduces the already weak residual circulation. These findings are applicable to any similar long, deep fjord that experiences katabatic winds in winter, and they could have implications not only for the preservation of water masses but other possible subsurface features (e.g., pollutant spills, planktonic larvae). Furthermore, the identification of mechanisms that permit persistent cold and oxygenated conditions is key to understanding potential areas of ecological refugia in a warming and deoxygenating ocean. [ABSTRACT FROM AUTHOR]

Microorganisms are a vital part of lake ecosystems, which drive nutrient cycling and energy conversion in aquatic ecosystems, and on the other hand are highly sensitive to changes of environmental factors, being oftentimes used as indicator organisms for the evolution of lake ecosystems. As for Chaohu Lake, it is of great significance to study the differences in microbial community structure at different lake inlets and their relationship with environmental factors. In this study, the high-throughput sequencing technology based on 16S rRNA gene was used to analyze the structure of microbial communities in different inlets of the Lake, and a covariate network of dominant microorganisms was constructed by adopting the principle of stochastic matrix to investigate the differences in inter-species relationships among microorganisms in different inlets, and then MRM and Mantel Test analyses were used to reveal the driving factors of the microbial communities and their response strategies to the environmental changes. The analysis by methods of MRM (multiple linear regression) and Mantel Test revealed the driving factors of different microbial communities in the lake inlets and their responsive strategies to cope with the environmental changes. Findings of the study showed that microbial communities in inlets of into-lake rivers of the Nanfei River and Paihe River were of a rather good similarity, and the microbial community structure of the into-lake river Hangbu River inlet was obviously different, and the common dominant microorganisms of these three inlets were related to nitrification and denitrification, and the microorganisms of the three inlets are all related to the function of nitrification and denitrification; the dominant microorganisms endemic in the Nanfei River inlet included Flavobacteriaceae, Steroidobacteraceae, Sphingomonadaceae and Sutterellaceae, the unique dominant microorganisms in the inlet of the Paihe River was Rhodanobacteraceae and Hydrogenophilaceae, and the unique dominant microorganisms in the Hangbu River inlet were Vicinamibacteraceae and Methylomonadaceae. The results of the microbial co-linear network suggested that the Nanfei River inlet had the highest symbiotic microbial network, and the key species in the microbial network of different inlets were related to the nitro - gen transformation function; the MRM analysis showed that there existed differences in the driving factors of microbial community structure in different lake inlets; the key driving factors in the inlet of the Nanfei River were water temperature and the content of NO3--N, the key driving factor in the inlet of the Paihe River was the content of NH4+-N, and the key driving factors in the inlet of the Hangbu River were temperature, TP, and COD content; and the Mantel Test analysis indicated that all of the microorganisms in different lakes were dominant microorganisms with large differences in relative abundance, which were affected by the driving factors. Mantel Test analysis showed that the microorganisms affected by the driving factors in different lake inlets were dominant microorganisms with greater differences in relative abundance. In conclusion, the environmental differences in the lake inlets resulted in certain differences in terms of the composition and structure of microbial communities; the microbial symbiosis was more distinct in the inlets with higher nutrient levels; and the environment naturally had a selective effect on the microorganisms to maintain the stability of the ecological environment. [ABSTRACT FROM AUTHOR]

Gas turbine combustors are often subjected to combustion instabilities because of variability of operating conditions, affecting components, and altering exhaust emissions. Herein, the analysis focuses on simulating numerically the non‐premixed combustion as unsteady flamelet combustion and detailed kinetic mechanism. The goal is analyzing exhaust gases under unsteady inlet airflow conditions to define operation guidelines. The numerical approach is validated using data from the literature for nonperturbed cases. Three periodical perturbations of different amplitude show differences with the nonperturbed case. Besides emission of exhaust gases, the temperature field is sensitive to airflow inlet conditions. According to the simulation results, a strong dependence of temperature and pressure in primary and dilution zones of combustor exists on the inlet air pressure condition. Emissions of flue gases like CO and NOx respond to combustor thermal behavior showing high sensitivity to inlet air pressure as well. Results indicate that moderate pressure oscillations may derive into flashback effects. [ABSTRACT FROM AUTHOR]

In vanadium redox flow batteries, the flow field geometry plays a dramatic role on the distribution of the electrolyte and its design results from the trade-off between high battery performance and low pressure drops. In the literature, it was demonstrated that electrolyte permeation through the porous electrode is mainly regulated by pressure difference between adjacent channels, leading to the presence of under-the-rib fluxes. With the support of a 3D computational fluid dynamic model, this work presents two novel flow field geometries that are designed to tune the direction of the pressure gradients between channels in order to promote the under-the-rib fluxes mechanism. The first geometry is named Two Outlets and exploits the splitting of the electrolyte flow into two adjacent interdigitated layouts with the aim to give to the pressure gradient a more transverse direction with respect to the channels, raising the intensity of under-the-rib fluxes and making their distribution more uniform throughout the electrode area. The second geometry is named Four Inlets and presents four inlets located at the corners of the distributor, with an interdigitated-like layout radially oriented from each inlet to one single central outlet, with the concept of reducing the heterogeneity of the flow velocity within the electrode. Subsequently, flow fields performance is verified experimentally adopting a segmented hardware in symmetric cell configuration with positive electrolyte, which permits the measurement of local current distribution and local electrochemical impedance spectroscopy. Compared to a conventional interdigitated geometry, both the developed configurations permit a significant decrease in the pressure drops without any reduction in battery performance. In the Four Inlets flow field the pressure drop reduction is more evident (up to 50%) due to the lower electrolyte velocities in the feeding channels, while the Two Outlets configuration guarantees a more homogeneous current density distribution. [ABSTRACT FROM AUTHOR]

In this study, a new ridge surface is proposed and its impact on the aerodynamic efficiency of a generic top-mounted submerged inlet is investigated at Mach 0.3 to 0.5. The concept is developed to investigate the possibility of vortex breakdown manipulation by the ridge surface to control the chaotic flow pattern after the breakdown, measuring the overall drag increment and total pressure recovery due to the ridge integration. For this purpose, a conceptual submerged inlet is designed with a semi-elliptic entrance for integration with a generic fuselage and ridge surfaces; then different study cases are modeled based on this configuration for numerical simulations by Ansys Fluent. Key factors such as the quality of the captured streamtube, vortex patterns on the fuselage, induced lift, and vortex breakdown patterns are investigated and compared by second order accuracy. Results indicate that the modified ridge surface improves the overall efficiency of the fuselage-inlet configuration both in the terms of lift over drag and pressure recovery. [ABSTRACT FROM AUTHOR]

A scramjet engine consisting of several components is a highly coupled system that urgently needs a universal performance metric. Exergy is considered as a potential universal currency to assess the performance of scramjet engines. In this paper, a control-volume-based exergy method for the Reynolds-averaged Navier–Stokes solution of truncated and corrected Busemann inlets was proposed. An exergy postprocessing code was developed to achieve this method. Qualitative and quantitative analyses of exergies in the Busemann inlets were performed. A complete understanding of the evolution process of anergy and the location where anergy occurs in the inlet at various operation conditions was also obtained. The results show that the exergy destroyed in the Busemann inlet can be decomposed into shock wave anergy, viscous anergy and thermal anergy. Shock wave anergy accounts for less than 4% of the total exergy destroyed while thermal anergy and viscous anergy, in a roughly equivalent magnitude, contribute to almost all the remaining. The vast majority of inflow exergy is converted into boundary pressure work and thermal exergy. Some of the thermal exergy excluded by the computation of the total pressure recovery coefficient belongs to the available energy, as this partial energy will be further converted into useful work in combustion chambers. [ABSTRACT FROM AUTHOR]

The performance of an industrial air amplifier is assessed through experimental and numerical characterization, with a focus on examining the influence of various operating conditions (isolated, "blowing," and "suction" modes) and direct geometric scaling of the device within the specified range of the injection gap (δ) and the inlet pressure characteristic values. The findings underscore the presence of a linear trend of the entrained mass flow and a nonlinear decay of the amplification factor, both with notable sensitivity to the gap width. Numerical RANS simulations validate the experimental data, characterize the asymmetric flow downstream from the device, and facilitate the exploration of more complex scenarios. In this regard, scaling the device's dimensions reveals an optimal aspect ratio between the minimum diameter ( D m ) and δ to maximize the entrained mass flow. This research provides valuable insights into the behavior of air amplifiers, offering guidance for their design and application across various industrial contexts. [ABSTRACT FROM AUTHOR]

The drying of suspensions in a spouted bed is usually performed by atomizing the solution onto the surface of the bed. However, drying of concentrated suspensions, such as those of kaolin, leads to particle agglomeration. Placing the atomizer at the air inlet pipe might be an alternative, since suspension droplets are fed into the spout, where high particle velocities are attained. Moreover, the presence of the fountain confiner above the bed surface allows increasing the air-solid contact. However, the atomizer may lead to bed instabilities due to changes in the air trajectory. Therefore, the spouted bed performance for drying kaolin suspensions with this new atomizer location has been addressed. Spouted bed hydrodynamics with and without atomizer were evaluated and drying experiments were conducted in this new setup. Although the atomizer increases the total pressure drop of the system, it hardly changes spouted bed hydrodynamics. Furthermore, the new setup allows operating at the maximum dryer's capacity. [ABSTRACT FROM AUTHOR]

Black garlic is a fermented product from garlic (Allium sativum L.) that is processed by heating fresh garlic at a certain temperature and humidity for several days. Black garlic has higher antioxidant activity and is rich in organosulfur compounds. Therefore, black garlic has an unpleasant taste and odor. Spray drying of black garlic extract is important for wider application, preservation and prolongation of its shelflife. Black garlic powders were produced using SD-18A mini spray dryer. The purpose of this research was to evaluate the effect of inlet temperatures on the physical properties and antioxidant activity of aqueous black garlic powder. The inlet temperatures ranged from 165 to 225 °C, whereas other conditions were kept constant such as maltodextrin concentration (8 %) and feed flow rate (4.5 mL/min). The black garlic powders were examined for powder yield, moisture content, hygroscopicity, bulk density, wettability, antioxidant activity and total phenolic and flavonoid content. The optimal conditions for the drying process were achieved with an inlet temperature of 225 °C. An increase in the inlet temperature of the spray dryer has increased the powder yield, hygroscopicity, antioxidant activity and total phenolic and flavonoid content of the black garlic powder, but reduced the water content, bulk density and wettability of the spraydried product. [ABSTRACT FROM AUTHOR]

Intake system structure design is categorized under gas turbine marine technology, and its performance affects the inlet flow field of the compressor, thereby impacting the overall operation stability of the gas turbine. Therefore, this study analyses the structural characteristics of various types of intake systems and establishes a computational domain model. Numerical simulation methods are used to systematically study the internal and external flow fields of the intake system. By varying the structure of the intake system, we compare and study the distribution form of the flow field inside and outside the intake system, velocity and total pressure distribution of the compressor inlet section, and flow loss inside the intake system. The speed and total pressure distortion of the compressor inlet section are analysed quantitatively. It was concluded that inlet distortion causes the leakage flow from some channels to spill into adjacent blade channels at the leading edge of the higher span, resulting in an early compressor stall. Specifically, the compressor stall and working flow margins are reduced by 2.51% and 2.76%, respectively. [ABSTRACT FROM AUTHOR]

Urban flooding is a problem faced by most countries because of climate change. Without storm drainage systems, negative impacts may occur, such as traffic problems and increasing groundwater levels, especially in lowlands. The implementation of storm drainage networks and their fittings in poor countries is affecting their economic development. Therefore, improving the efficiency of the storm drainage network is an important issue that should be considered. This paper aims to study the most appropriate position or arrangements of grate inlets to upgrade drainage efficiency at less cost. Different arrangements of grates were studied and their efficiency was determined. A comparison between the total grate's efficiency was conducted and the best arrangement was selected. Additionally, a dimensional analysis equation was developed to determine the total efficiency of the system. Finally, the FLOW-3D program was used to simulate the laboratory results using different discharges and numbers of inlets. The error of calculation ranged between 5% and 8%. Therefore, the results indicated that this program is a powerful tool for predicting the discharge efficiency and velocity direction for large discharges. A comparison was made between this study and previous studies. The results indicated that the same trend existed. A new equation was developed to correlate discharge efficiency (E) with relative total discharge Q and number of inlets. The equation can be used by planning engineers to conduct initial planning of storm drainage layout systems and achieve cost saving. [ABSTRACT FROM AUTHOR]

According to the use of marine gas turbines, inlet distortion is caused by the bending of the compressor inlet port. The total pressure distortion is the external stability reduction factor that has the greatest impact on the engine's aerodynamic stability. This research designs a pressure distortion simulation device, which achieves the goal of providing the target distortion flow field for marine compressors by inserting plugboards of different heights and shapes into the inlet duct. The variation pattern of the entire flow field after inserting different parameter plugboards is obtained through distortion experiments and numerical simulations. Summarizes a prediction formula for total pressure distortion under different working conditions, with a verified error of less than 1.5%. In addition, the straight plugboard is changed to arc plugboard or concave and convex plugboard, the total pressure distortion distribution pattern can be changed while the range of the circumferential low-pressure zone remains unchanged. The distortion index of the distortion simulator designed by this research institute can be adjusted within the range of 0.5%-5%, while providing various distortion pattern. The distortion simulator meets the requirements of the comprehensive distortion index needed for the relevant distortion test of the marine engine and provides assistance for ship engine design and optimization. [ABSTRACT FROM AUTHOR]

Mixed-flow pumps, which amalgamate centrifugal and axial-flow attributes, playa pivotal role in various sectors due to their high efficiency and versatility. This paper, utilizing numerical simulation and experimental validation, addresses the critical role of impeller blade count in mixed-flow pump performance. It investigates the effect of the number of impeller blades on the energy dissipation mechanism and inlet flow pattern of a mixed-flow pump. The results reveal that dynamic and static interference effects, along with the separation vortex due to flow separation, are the main sources of energy dissipation in the pump. Under part-load and part- overload conditions, the increase in the number of blades contributes to the improvement of the flow pattern and performance but may induce more intense rotating stall effects under part-load conditions. In overload conditions, the increase in the number of blades significantly amplifies the volume of the inlet vortex structure, consequently deteriorating the inlet conditions of the impeller. This study provides valuable insights for the design and optimization of mixed- flow pumps. [ABSTRACT FROM AUTHOR]

The flow distribution characteristics at core inlet directly determines the thermal and hydraulic characteristics in the core, and it is closely related to the safety of nuclear reactor. The primary coolant is subjected to additional inertial force in ocean motion, which influence the flow distribution characteristics at core inlet. In the present paper, numerical simulation method is adopted to analyze the coolant flow distribution characteristics at core inlet of the Reactor Pressure Vessel (RPV) of a Small Reactor under rolling condition. Then the results of the flow distribution characteristics were compared with those under steady state. The results show the variation range of flow distribution factors in each channel under rolling condition is within 5%. And the uneven distribution of coolant at the core inlet increases with the increase of rolling amplitude, and decrease with the rolling period in short period. Standard deviation of flow distribution factor at the core inlet changes little under rolling condition, which indicates the flow distribution at the core inlet keeps good uniformity. [ABSTRACT FROM AUTHOR]

Advanced inlet guide vane (IGV) and diffuser vane (DV) geometries were constructed in an effort to increase the energy performance of an axial-flow pump at the best efficiency point (BEP). DV setting angles were also investigated to increase energy performance at the off-design points. By integrating the advantages of an adjustable IGV, combinations of adjustable IGV and DV geometries were constructed and thoroughly analyzed by way of energy loss. The asymmetrical geometry of the IGV, upgraded through the use of a hydrofoil profile, resulted in higher hydraulic performance compared to that of the reference model. The efficiency and total head at the BEP increased significantly with the implementation of the new DV, by 1.456% and 5.756% over those of the reference model, respectively. Using the new DV reduced the unsteady turbulent flow behind the trailing edge of the DV under all flow rate conditions, resulting in a reduction in vibration and noise. The positive setting angles of the DV increased the energy performance in the high-flow-rate region, whereas the negative DV setting angles produced a good performance in the low-flow-rate region. Combining an adjustable IGV with an adjustable DV model resulted in a significant increase in the total head, with more optimal energy performance provided by the positive IGV setting angles. At the BEP and under high-flow-rate conditions, the low-velocity zone is closely related to high entropy generation. Furthermore, these high-entropy generation regions follow the trajectory of the low-velocity zones. However, the low-velocity zone is not strongly associated with the high-entropy generation region when operating under low-flow-rate conditions. [ABSTRACT FROM AUTHOR]