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The motivation to design a more efficient and compact aircraft engine leads to a continuous increase in overall pressure ratio and decrease in the stage number in compressors. Compared to the traditional multi-stage compressor, a single-stage ultra-high-pressure-ratio centrifugal compressor with a pressure ratio higher than 10.0 can significantly improve the engine's power-to-weight ratio and fuel economy with a reduced structure complexity. Thus, it has great potential to be adopted in the compression system of advanced aero engines, such as turboshaft engines, in the future. However, the highly narrow Stable Flow Range (SFR) of ultra-high-pressure-ratio centrifugal compressors is a severe restriction for engineering applications. This research focuses on the aerodynamic performance of a ultra-high-pressure-ratio centrifugal compressor, and three-dimensional simulation is employed to investigate the effect of Self-Recirculating Casing Treatment (SRCT) on the performance and stability of the centrifugal compressor. Firstly, the parametric model of SRCT is established to investigate the effect of geometry parameters (rear slot distance and rear slot width) on the aerodynamic performance of the centrifugal compressor. It is concluded that SRCT improves the compressor's SFR but deteriorates its efficiency. Also, a non-linear and non-monotone relationship exists between the SFR and rear slot distance or width. Then, the flow mechanism behind the effect of SRCT is explored in detail. By introducing the SRCT, an additional flow path is provided across the blade along the circumferential direction, and the behavior of the shock wave and tip leakage flow is significantly changed, resulting in the obviously different loading distribution along the streamwise direction. As a result, the mixing and flow separation loss are enhanced in the impeller flow passage to deteriorate the efficiency. On the other hand, the blockage effect caused by the mixing of slot recirculation and mainstream flow near the impeller inlet increases the axial velocity and reduces the incidence angle below the 90% spanwise section, which is considered to effectively stabilize the impeller flow field and enhance the stability. [ABSTRACT FROM AUTHOR]

This review article presents a summary of currently used and proposed methods of manufacturing fir tree slots of discs in turbine engines. The production of aircraft, including aircraft engines during times of overlapping global economic crises related to the COVID-19 pandemic or the war in Eastern Europe requires a quick response to the changing numbers of passengers and cargo. Similarly, the aviation industry must adapt to these conditions, and thus utilize flexible production methods allowing for a quick change in the design or type of a given part. Due to the constant adoption of new materials for the most critical aero engine parts and the necessity of complying with environmental regulations, it is necessary to search for new methods of manufacturing these parts, including fir tree slots. As an alternative to currently used expensive and energy-intensive broaching, many manufacturers try to implement creep feed grinding CFG or contour milling. However, other manufacturing methods, thus far rarely used for crucial machine parts such as WEDM, ECDM or AWJ, are gaining more and more popularity in the aviation industry. This article presents the advantages and shortcomings of these methods in the context of manufacturing fir tree slots. [ABSTRACT FROM AUTHOR]

The aviation industry generates a wide range of climate pollutants, which often leads to an underestimation of its impact on global warming. Constructing aircraft components using environmentally friendly materials could significantly reduce the environmental burden associated with aviation growth. The objective of this study is to evaluate the Global Warming Potential (GWP) of commonly used alloys in gas turbine engines of aircraft. Material information on aircraft engine components was extracted, and GWP data for each metal was obtained using SimaPro software, and the GWP of components was determined. The study revealed that RENE 15 and GTD111 turbine alloys had the highest GWP impact, ranging from 13.53 to 14.05 kg CO 2 e /kg, while AISI 403 and GTD-450 used in the compressor, M152 used in the turbine, and Cr-Mo-V alloys used in both the turbine and shafts had the lowest GWP effect, ranging from 1.61 to 1.90 kg CO 2e /kg. Moreover, the study evaluated the environmental impact associated with the manufacturing of aircraft engine components. The findings indicated that Ti-based materials had the highest GWP rate, with a value of 3.29 kg CO 2 e /kg, which was almost the sum of all other metals. In particular, Ti-based materials used in fan components were identified as the largest source of environmental impact during aircraft engine production, with a value of 2.02 kg CO 2 e /kg. These results underscore the crucial role of material selection in mitigating environmental impacts during aviation engine component production. The study highlights the need for more effective and efficient approaches to material selection from an environmental standpoint in the aviation industry, especially in the context of reducing global warming potential. The results of this research could inform decision-making related to material selection for aircraft engine components, and help the aviation industry to reduce its overall environmental impact and mitigate the effects of global warming. [ABSTRACT FROM AUTHOR]

We experimentally conduct an early detection of thermoacoustic instability in a staged single-sector combustor using a novel methodology that combines symbolic dynamics and machine learning. We propose two invariants in this study: the determinisms of the joint symbolic recurrence plots D J and the ordinal transition pattern-based recurrence plots D T. These invariants enable us to capture the phase synchronization between acoustic pressure and heat release rate fluctuations associated with a precursor of thermoacoustic instability. The latent space consisting of D J and D T , which is obtained by a support vector machine in combination with the k -means clustering method, can appropriately determine a transitional regime between stable combustion and thermoacoustic instability. [ABSTRACT FROM AUTHOR]

Ni–Co alloy has high temperature resistance, corrosion resistance, excellent magnetic and catalytic capabilities, and is widely used in energy development, chemical industry, electronics, aviation and aerospace, such as combustion chamber hot end parts, aircraft engine working blades and hydrogen evolution catalysts. It is well known that the properties of materials depend on the structure and morphology, which depend on the preparation method. At present, the main methods for preparing nano-Ni–Co alloy are electrodeposition, sol–gel method and solution reduction method. The parameters in these preparation methods affect the morphology and properties of nano-Ni–Co alloy, so it is particularly important to study the influence of various parameters on the properties of Ni–Co alloy. In this work, the preparation methods and research progress of nano-Ni–Co alloy in recent decades are summarized, hoping to provide valuable information for the development of Ni–Co alloy. [ABSTRACT FROM AUTHOR]

Scientific research studies on jet noise generation have been ongoing since the early 1950s, when turbojets were first used in commercial aircraft. Several numerical methods have been developed with the aim of reducing the environmental issues related to the impact of jet noise on community annoyance. Among them, the development of fast and comprehensive tools for jet noise prediction captured the attention of researchers and engineers, being very useful in the preliminary design phase of aircraft engines. This work deals with an extensive survey of James R. Stone's models, initially formulated for the National Aeronautics and Space Administration (NASA) by Modern Technologies Corporation (MTC), and their implementation in a contemporary numerical framework. The models and their implementation are validated by simulating different engine settings and nozzle configurations taken from the literature with the main scope of highlighting the strengths and weaknesses of the different semi-empirical formulations and setting guidelines for their effective use during the design phases of the next generation of supersonic aircraft. [ABSTRACT FROM AUTHOR]

DZ22B alloy is commonly used as a blade material for aircraft engines and gas turbines, and its preparation process is an important factor affecting its performance. In the present work, a reliable numerical model is established through ProCAST numerical simulation and auxiliary experimental verification methods, based on which the effect of casting speed on the grain and dendrite growth of DZ22B superalloy blades is studied. The results indicate that increasing the pulling speed can reduce the spacing between secondary dendrites, which is beneficial for the growth of dendrites. Based on numerical simulation and experimental verification, it is suggested that the pulling rate of the directional solidification DZ22B superalloy blade should be 6-2 mm/min variable speed pulling to improve the production success rate. [ABSTRACT FROM AUTHOR]

High-performance gas turbines and aircraft engines necessitate MCrAlY (M = Ni, Co, or Ni/Co) coatings with exceptional oxidation resistance. Pre-heat-treatment can enhance the performance of MCrAlY bond coatings in the following ways: First, it reduces the porosity of the bond coating and promotes the diffusion of elements within it. Second, pre-heat-treatment allows for the formation of a continuous, dense, and moderately thick layer of pure Al2O3 scale, which helps to delay the formation of mixed oxides. Lastly, proper pre-heat-treatment can increase the grain size of the Al2O3 scale, leading to a lower growth rate of the oxide scale. Additionally, this article proposes new directions for developing more reasonable and effective pre-heat-treatment methods, laying the foundation for the creation of thermal barrier coatings (TBCs) with greater durability and higher performance. [ABSTRACT FROM AUTHOR]

This article deals with the exhaust emissions from aircraft turbine engines, which is related to the rapidly growing market for this type of aircraft and its contribution to toxic emissions. The test carried out was done on a business jet turbine engine exhaust pollutants. The test object was the DGEN 380 engine. In order to determine the toxic composition of the exhaust gas as a function of the engine's operating range, an experiment related to the actual engine was conducted in the first stage. The test performed on the static thrust stand of the DGEN 380 turbine engine provided the necessary data on the parameters of the working medium for further research. The actual rotational characteristics of the engine were obtained. It was also determined numerically using GasTurb software. A high correspondence between experimental and calculated parameters was obtained, which gave the possibility of using them in further analyses of the exhaust gas pollutants of the studied engine. The correspondence of the results showed the correctness of the computational model built, thus predestining it for use in further analysis. This paper presents a model of the reverse-flow combustor made for numerical thermal-fluid studies. The thermalfluid analysis of the model was performed in the ANSYS Fluent environment. The calculations were performed for three shaft speed. The numerical analysis provided information on changes in pollutant components of the exhaust gas of the DGEN 380 aircraft turbine engine as a function of changes in the shaft speed range. The results showed that the levels of nitrogen oxides depend greatly on shaft speed. The model built and the numerical analyses conducted also provided information about the zones inside of liner casing that affect significantly the amount of pollutant compounds obtained, which can then be used in the work on improving the design in terms of reducing the engine exhaust pollutants. [ABSTRACT FROM AUTHOR]

This paper proposes the use of vibroacoustic signal parameters to estimate the fuel consumption of a miniature GTM-400 engine. The method for testing engine vibrations is presented, followed by an analysis of the results obtained. Two vibration point measures were selected to build a fuel consumption model. The models obtained were verified, after which those that best describe the real fuel consumption of the engine were selected. The paper proves that the vibration signal, in addition to its applications in jet engine diagnostics, can be used to determine engine performance, which can contribute to reducing the complexity of construction and increasing the economics of engine operation. [ABSTRACT FROM AUTHOR]

Cascade flutter driven by aerodynamic instability leads to severe structural destruction of turbine blades in aircraft engines. The development of a sophisticated methodology for detecting a precursor of cascade flutter is one of the most important topics in current aircraft engineering and related branches of nonlinear physics. A novel detection methodology combining symbolic dynamics, dynamical systems, and machine learning is proposed in this experimental study to detect a precursor of cascade flutter in a low-pressure turbine. Two important measures, the weighted permutation entropy in terms of symbolic dynamics and the determinism in recurrence plots in terms of dynamical systems theory, are estimated for the strain fluctuations on turbine blades to capture the significant changes in the dynamical state during a transition to cascade flutter. A feature space consisting of the two measures obtained by a support vector machine, can appropriately be classified into three dynamical states: a stable state, a transition state, and a cascade flutter state. The proposed methodology is valid for detecting a precursor of cascade flutter. [ABSTRACT FROM AUTHOR]

Indirect noise is a significant contributor to aircraft engine noise, which needs to be minimized in the design of aircraft engines. Indirect noise is caused by the acceleration of flow inhomogeneities through a nozzle. High-fidelity simulations showed that some flow inhomogeneities can be chemically reacting when they leave the combustor and enter the nozzle (Giusti et al., Trans. ASME J. Engng Gas Turbines Power, vol. 141, issue 1, 2019). The state-of-the-art models, however, are limited to chemically non-reacting (frozen) flows. In this work, first, we propose a low-order model to predict indirect noise in nozzle flows with reacting inhomogeneities. Second, we identify the physical sources of sound, which generate indirect noise via two physical mechanisms: (i) chemical reaction generates compositional perturbations, thereby adding to compositional noise; and (ii) exothermic reaction generates entropy perturbations. Third, we numerically compute the nozzle transfer functions for different frequency ranges (Helmholtz numbers) and reaction rates (Damköhler numbers) in subsonic flows with hydrogen and methane inhomogeneities. Fourth, we extend the model to supersonic flows. We find that hydrogen inhomogeneities have a larger impact on indirect noise than methane inhomogeneities. Both the Damköhler number and the Helmholtz number markedly influence the phase and magnitude of the transmitted and reflected waves, which affect sound generation and thermoacoustic stability. This work provides a physics-based low-order model which can open new opportunities for predicting noise emissions and instabilities in aeronautical gas turbines with multi-physics flows. [ABSTRACT FROM AUTHOR]

We present pore-resolved compressible direct numerical simulations of turbulent flows grazing over perforated plates, that closely resemble the acoustic liners found on aircraft engines. Our direct numerical simulations explore a large parameter space including the effects of porosity, thickness and viscous-scaled diameter of the perforated plates, at friction Reynolds numbers Reτ = 500-2000, which allows us to develop a robust theory for estimating the added drag induced by acoustic liners. We find that acoustic liners can be regarded as porous surfaces with a wall-normal permeability and that the relevant length scale characterizing their added drag is the inverse of the wall-normal Forchheimer coefficient. Unlike other types of porous surfaces featuring Darcian velocities inside the pores, the flow inside the orifices of acoustic liners is fully turbulent, with a magnitude of the wall-normal velocity fluctuations comparable to the peak in the near-wall cycle. We provide clear evidence of a fully rough regime for acoustic liners, also confirmed by the increasing relevance of pressure drag. Once the fully rough asymptote is reached, canonical acoustic liners provide an added drag comparable to that of sand-grain roughness with viscous-scaled height matching the inverse of the viscous-scaled Forchheimer permeability of the plate. [ABSTRACT FROM AUTHOR]

The accurate prediction of the remaining useful life (RUL) of aircraft engines is crucial for improving engine safety and reducing maintenance costs. To tackle the complex issues of nonlinearity, high dimensionality, and difficult-to-model degradation processes in aircraft engine monitoring parameters, a new method for predicting the RUL of aircraft engines based on the random forest algorithm and a Bayes-optimized multilayer perceptron (MLP) was proposed here. First, the random forest algorithm was used to evaluate the importance of historical monitoring parameters of the engine, selecting the key features that significantly impact the engine's lifetime operation cycle. Then, the single exponent smoothing (SES) algorithm was introduced for smoothing the extracted features to reduce the interference of original noise. Next, an MLP-based RUL prediction model was established using a neural network. The Bayes' online parameter updating formula was used to solve the objective function and return the optimal parameters of the MLP training model and the minimum value of the evaluation index RMSE. Finally, the probability density function of the predicted RUL value of the aircraft engine was calculated to obtain the RUL prediction results.The effectiveness of the proposed method was verified and analyzed using the C-MAPSS dataset for turbofan engines. Experimental results show that, compared with several other methods, the RMSE of the proposed method in the FD001 test set decreases by 6.1%, demonstrating that the method can effectively improve the accuracy of RUL prediction for aircraft engines. [ABSTRACT FROM AUTHOR]

In this paper, reliability models of competing failure processes for the product subject to degradation and random shocks are established, which are accompanied by degradation path slope change caused by specific shock patterns. The two related failure modes are hard failure arising from different random shocks, and soft failure due to consecutive structure damage or combined with a sudden increment of degradation because of an identical random shock. In sophisticated equipment like aircraft engine systems, the degradation path of performance parameters is characterized by multi‐stages when the product is more prone to fatigue or accelerated aging, as a consequence of experienced shocks. This article analyzes five random shock patterns that can change the slope of the degradation path and studies an example to explain the application of proposed reliability models as well as the sensitivity analysis of parameters. [ABSTRACT FROM AUTHOR]

In order to avoid radar detection of the aircraft engine in a combat aircraft, serpentine duct is used in the air intake system. Due to change in geometry, the core flow path undergoes change in direction resulting in secondary flows and possible separation. The main requirements of a combat aircraft air intake is to deliver design airflow to the engine with minimal distortion and pressure loss. While flow distortion can increase the chances of engine stalling, large pressure loss will adversely affect engine overall performance. To address these requirements, both active and passive flow control techniques have been used in practice. Mechanical vortex generator is one of the passive flow control technique and it is attractive due to lesser complexity and the cost involvement. The formation of vortex and its interaction with the core flow is to be carefully analysed to have better design. Co-flow and counter flow vortex generators are reported in the literature. In the present work, effect of co-flow vortex generator on the flow field in an elliptic to circular cross section serpentine duct has been considered. The curvature of the bends is high, and the flow in the lower surface of the first bend interacts with upper surface of the second band in the mid-plane. The vortex generators are placed at the lower surface of the first bend and also at the upper surface of the second bend.The flow field created by the vortex generators placed at the lower surface of the first bend interacts slightly more with the upper surface of the second bend than the baseline case due to slight reduction in separation length. It alters the internal pressure field and improves flow uniformity. In the case of placement of vortex generator at the upper surface of the second bend alone did not show any significant variation on flow uniformity. Vortex generator placed at the lower surface of the first bend and the upper surface of the second bend helps to achieve better flow uniformity except at the upper portion of the aerodynamic inlet plane of the engine. The flow uniformity is improved with reduction in DC-60 by 11% and the pressure recovery is reduced by 6% as compared to the base design without the vortex generators. The trade-off between flow uniformity and pressure recovery clearly indicates placing of vortex generator at the lower surface of first bend is better for this serpentine duct having 2.6% reduction in pressure recovery and improvement in flow uniformity having 9% reduction in DC-60 as compared with baseline duct. [ABSTRACT FROM AUTHOR]

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Smart data selection can quickly sieve valuable information from initial data. Doing so improves the efficiency of analyzing situations to aid in better decision-making. Past methods have mostly been based on expert experience, which may be subjective and inefficient when dealing with large, complex datasets. Recently, the system analysis method has been exploited to find the key data. However, few studies address the indirect effects and heterogeneity of time series data. In this study, a data selection method, the modified Decision-Making Trial and Evaluation Laboratory (DEMATEL) method based on the objective data grey relational analysis (GRA), is used to enhance the ability to analyze time-series data. GRA was first applied to assess the direct impact in the raw data indicators. Then, a modified DEMATEL was adopted to find the overall impact by including the indirect impact and data heterogeneity. We applied the method to analyze the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) dataset and perform the remaining useful life (RUL) prediction of aircraft engines. The results suggest that our method predicts well. Our work offers a nuanced approach of identifying key information in time series data and has potential applications. [ABSTRACT FROM AUTHOR]

In aerospace engine delivery systems, "one-in-two-out" bifurcation structures are commonly used for flow distribution to downstream pipelines. There are two common "one-in-two-out" bifurcation structures in aircraft engines: the planar orthogonal bifurcation and the spatial orthogonal bifurcation. By adjusting the flow supply upstream and the cross-sectional diameter downstream, the flow distribution in the two branches can be adjusted, i.e., the "splitting ratio" changes. In this paper, a dismantling and flexible experimental system is constructed to measure the pressure signals in each channel and use non-linear dynamic analysis methods to extract pressure characteristics. The particle image velocimetry (PIV) technique combined with the fine rope tracing technique is creatively used to observe the vortex structure in the cross section of the downstream branch. The study found that for spatial orthogonal bifurcation, the pressure signal characteristics in each channel are basically the same at larger splitting ratios, regardless of the chirality. As the splitting ratio decreases, the difference in pressure signal characteristics between the two branches gradually becomes evident and becomes related to the chirality. Moreover, unlike the planar orthogonal bifurcation structure, a complete large vortex structure has not been found in the downstream branch of the spatial orthogonal bifurcation structure, regardless of changes in the splitting ratio, and it is unrelated to the chirality. [ABSTRACT FROM AUTHOR]

Aiming at engine health management, a novel hybrid prediction method is proposed for exhaust gas temperature (EGT) prediction of gas turbine engines. This hybrid model combines a nonlinear autoregressive with exogenous input (NARX) model and a moving average (MA) model. A feature attention mechanism-enhanced long short-term memory network (FAE-LSTM) is first developed to construct the NARX model, which is used for identifying the aircraft engine using condition parameters and gas path measurement parameters that correlate to the EGT. A vanilla LSTM is then used for constructing the MA model, which is used for improving the difference between the actual EGT and the predicted EGT given by the NARX model. The proposed method is evaluated using real flight process data and compared to several dynamic prediction techniques. The results show that our hybrid model reduces the predicted RMSE and MAE by at least 13.23% and 18.47%, respectively. The developed FAE-LSTM network can effectively deal with dynamic data. Overall, the present work demonstrates a promising performance and provides a positive guide for predicting engine parameters. [ABSTRACT FROM AUTHOR]

Accurate prediction of aircraft engine thrust is crucial for engine health management (EHM), which seeks to improve the safety and reliability of aircraft propulsion. Thrust prediction is implemented using an on-board adaptive model for EHM. However, the conventional methods for building such a model are often tedious or overly data-dependent. To improve the accuracy of thrust prediction, domain knowledge can be leveraged. Hence, this study presents a strategy for building an on-board adaptive model that can predict aircraft engine thrust in real-time. The strategy combines engine knowledge and neural network architecture to construct a prediction model. The whole-model architecture is divided into separate modules that are mapped in a one-to-one form using a domain decomposition approach. The engine domain knowledge is used to guide feature selection and the neural network architecture design in the method. Furthermore, this study explains the relationships between aircraft engine features and how the model can predict engine thrust in flight condition. To demonstrate the effectiveness and robustness of the architecture, four different testing datasets were used for validation. The results show that the thrust prediction model created by the given architecture has maximum relative deviations below 4.0% and average relative deviations below 2.0% on all testing datasets. In comparison to the performance of the models created by conventional neural network architecture on the four testing datasets, the model created by the presented architecture proves more suitable for aircraft propulsion. [ABSTRACT FROM AUTHOR]

Superalloys are critical materials for the hottest sections of stationary gas turbines and aircraft engines. Homogeneously fine-grained microstructures are essential to unlock their superior high-temperature strength but are challenging to achieve in γ′-containing Ni-based superalloys. Such microstructures are achieved by recrystallization through hot working and grain boundary pinning viaμm-scale second phase particles. Discontinuous dynamic recrystallization is the predominant restoration mechanism, where grain growth is restricted by Zener pinning. Nanometer-scale γ′ precipitates may exercise similar pinning during the nucleation stage and thus delay recrystallization. While the effects of coarse, μm-scale, precipitates during recrystallization and grain growth are well-known, descriptions for fine coherent precipitates are currently lacking. To address this scarcity of knowledge, both γ′-rich and -lean microstructures of the γ′-containing Ni-base superalloy René 41 underwent identical uniaxial hot compression tests. Flow stress and microstructural analyses reveal the inhibition of recrystallization by nm-scale γ′ precipitates during both nucleation and growth stages. This effect is successfully described using thermo-kinetic modeling through application of a driving-force based model. These unique insights provide a novel pathway to unlock homogeneously fine-grained microstructures in γ′-containing Ni-based superalloys via advanced thermo-mechanical processing routes, required for applications in future generations of gas turbines and aircraft engines. [ABSTRACT FROM AUTHOR]

Joining dissimilar titanium alloys via plastic deformation bonding is quite important for manufacturing complex 'hybrid' components in aircraft engines, in which the plastic flow in the bonding interface significantly affects the interfacial void evolution and thus influences the mechanical properties of the joints. The plastic flow in titanium alloys is largely affected by the initial microstructure. Thus, investigation into the interfacial void evolution of dissimilar titanium bonds with different initial microstructures is necessary. In this study, Ti64 (the most widely used α + β two-phase titanium alloy in aerospace industry) with equiaxed microstructure and Ti17 (a near β titanium alloy to fabricate the jet engine and compressor components) with equiaxed microstructure (Ti17-E) and lamellar microstructure (Ti17-L) were joined by plastic deformation bonding. The macroscopic plastic deformation, interfacial void and bonding ratio during bonding of Ti64 and Ti17 were quantitative characterized, and the shear strength of Ti64/Ti17 bonds was obtained. The Ti64/Ti17-E bond showed smaller average interfacial void size and larger bonding ratio than those of Ti64/Ti17-L bond at a certain bonding condition. The large-sized interfacial voids at lower bonding pressure and bonding temperature significantly decreased the shear strength of Ti64/Ti17 bonds due to the formation of un-joined region, and the Ti64/Ti17-E bond at 840 °C, 10 MPa and 30 min almost matched that of the Ti64 due to the promoted interfacial void closure process. The enhanced plastic flow occurred in the Ti64/Ti17-E bonding interface in comparison with that in the Ti64/Ti17-L bonding interface due to the better deformation compatibility of Ti17-E than that of Ti17-L since the preferred slip occurred in the Ti17-L but not in the Ti17-E. The promoted plastic flow and higher temperature rise in the Ti64/Ti17-E bonding interface promoted the void shrinkage process of Ti64/Ti17-E bond. [ABSTRACT FROM AUTHOR]

In this work, a test bed and stand structure were designed for the thrust test of an aircraft. The engine test rig consists of a thrust stand, test bed, transport system, and hoisting device. In this study, structural design and analysis of the stand and bed for engine thrust test equipment were performed. The stand structure supported the engine, and the test bed moved the thrust test equipment and the engine. Structural design loads were defined by analyzing the operating conditions. Structural analysis was performed based on the structural design results. As a result of analyzing the structural safety against thrust, which is the main design load, it was considered to be sufficiently safe. Finally, the target structure was manufactured to verify the design result. [ABSTRACT FROM AUTHOR]

Aircraft technologies and materials have been developing and improving drastically over the last hundred years. Over the last three decades, an interest in the use of composites for external structures has become prominent. For this to be possible, thorough research on the performance of composite materials, specifically the impact performance, have been carried out. For example, research of impact testing for pristine carbon-reinforced epoxy composites mentions matrix cracks, fibre fracture, and delamination as the failure modes that require monitoring. In addition, thorough testing has been carried out on composites repaired with an adhesive bond to observe the effects of conditioning on the adhesively bonded repair. The results suggest there are no major changes in the adhesive under the testing condition. By reviewing the impact testing on the pristine and repaired composite materials for aerostructures, this paper aims to illustrate the main findings and also explore the potential future work in this research scope. [ABSTRACT FROM AUTHOR]

The aircraft is subjected to high-temperature and high-pressure conditions during flight, which renders it susceptible to the occurrence of creep phenomenon. Several academics have conducted extensive research on this issue. This research paper provides a comprehensive overview of the existing literature on creep phenomena in aircraft engines. First, several classical creep calculation models are enumerated and categorized as creep life calculation, creep-fatigue life calculation, and creep deformation calculation. Studies on creep phenomena are conducted in various components of aircraft engines, such as the engine's turbine blades, turbine disks, and combustion chambers. The creep behavior of turbine blades in aircraft engines has been extensively researched. Furthermore, the protective measures aimed at mitigating creep are presented. Materials with high creep resistance can be used, and alternative fuels could be implemented. This paper provides an in-depth analysis of the advantages of creep in aircraft, presented in a favorable perspective. Finally, the prospective future research direction is discussed. [ABSTRACT FROM AUTHOR]

The object of research is hydrostatic processes in sliding bearings with several layers of lubricant. The task addressed was the influence of the structural and operational parameters of dual hydrostatic plain bearings on their static and dynamic characteristics. As a static characteristic, the bearing capacities of dual and conventional sleeve hydrostatic bearings were considered. When analyzing the dynamic characteristics, the amplitude-frequency characteristics were determined. They were obtained by calculation and as a result of experimental studies. When calculating the amplitude-frequency characteristics, the trajectory method was used. As external forces in the equations of motion of the rotor, hydrodynamic forces, the weight of the rotor, and its unbalance were considered. Experimental determination of the trajectories of the rotor was carried out on a special bench. It has been established that the bearing capacity of a double type bearing is approximately 1.75-1.85 times higher than the bearing capacity of a conventional sleeve bearing. The range of stable operation of the rotor on double-type bearings is approximately 1.4 times greater in comparison with the range of stable operation of the rotor on sleeve hydrostatic bearings. The vibration amplitudes in the resonance region for double bearings were approximately 1.5 times less than the rotor vibration amplitudes for sleeve bearings. The results make it possible to recommend dual-type hydrostatic bearings for rotor bearings of nuclear power plants, in powerful aircraft engines with a gearbox, various types of pumps, and other power plant units. The derived theoretical dependences make it possible to carry out practical calculation of hydrostatic bearings of a double type. [ABSTRACT FROM AUTHOR]

Atmospheric mineral dust aerosol constitutes a threat to aircraft engines from deterioration of internal components. Here we fulfil an outstanding need to quantify engine dust ingestion at worldwide airports. The vertical distribution of dust is of key importance since ascent/descent rates and engine power both vary with altitude and affect dust ingestion. We use representative jet engine power profile information combined with vertically and seasonally varying dust concentrations to calculate the 'dust dose' ingested by an engine over a single ascent or descent. Using the Copernicus Atmosphere Monitoring Service (CAMS) model reanalysis, we calculate climatological and seasonal dust dose at 10 airports for 2003–2019. Dust doses are mostly largest in summer for descent, with the largest at Delhi (6.6 g). Beijing's largest dose occurs in spring (2.9 g). Holding patterns at altitudes coincident with peak dust concentrations can lead to substantial quantities of dust ingestion, resulting in a larger dose than the take-off, climb and taxi phases. We compare dust dose calculated from CAMS to spaceborne lidar observations from two dust datasets derived from the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP). In general, seasonal and spatial patterns are similar between CAMS and CALIOP though large variations in dose magnitude are found, with CAMS producing lower doses by a mean factor of 2.4±0.5, particularly when peak dust concentration is very close to the surface. We show that mitigating action to reduce engine dust damage could be achieved, firstly by moving arrivals and departures to after sunset and secondly by altering the altitude of the holding pattern away from that of the local dust peak altitude, reducing dust dose by up to 44 % or 41 % respectively. [ABSTRACT FROM AUTHOR]

Maintenance cost of aircraft engine is an important component of aircraft operation cost. The prediction of aircraft engine maintenance cost can provide decision support for airline to make reasonable maintenance plan and maintenance fund management. Considering that the prediction accuracy of engine maintenance cost is not high in the case of small samples, this paper proposes a bootstrapped support vector regression (SVR) prediction method based on improved recursive feature elimination, which realizes the point and interval prediction of engine maintenance cost in aircraft operation phase. First, the recursive feature elimination (RFE) is improved and then combined with SVR to select feature subsets. Second, particle swarm optimization (PSO) algorithm is applied to optimize the improved RFE-SVR model (IRFE-SVR) parameters. Finally, the point and interval estimates are obtained by bootstrapped IRFE-SVR. To demonstrate the performance of the bootstrapped IRFE-SVR, experiments on UCI and a real case study of engine maintenance cost prediction are conducted. The results on UCI and real datasets show that the bootstrapped IRFE-SVR method has high accuracy and reliability. [ABSTRACT FROM AUTHOR]

In this study, utilization of a bio-based fuel in a turbojet engine is comprehensively monitored with adapting various useful indicators for the scope of the study based on thermodynamic principles. In this regard, extensive energy and exergy, thermoecologic, environmental, enviroeconomic and sustainability analyses are performed for both the turbojet engines fueled by jet kerosene and fueled by a bio-based fuel. As per the main findings, the mass stream of combustion emissions is measured to be 4.547 kg s−1, when the engine is powered by biofuel. The specific fuel consumption and specific thrust are determined as 0.13 kg kN−1 s−1 and 147.81 kNs kg−1 for jet kerosene-powered case, while they are calculated as 0.15 kg kN−1 s−1 and 148.23 kNs kg−1 for biofuel-powered case. If biofuel is selected over jet-kerosene fuel, it is observed that the engine has better energy efficiency performance by 18.18%. The engine's environmental effect factor value is found as 4.88 for jet-kerosene usage condition, while it is found to be 4.93 for biofuel utilization case. The overall emitted CO2 emissions is measured as 336,672 kg-CO2 year−1 for jet-kerosene usage condition, while it is estimated as 222,012 kg-CO2 year−1 for the biofuel utilization case. Also, as far as biofuel is chosen as alternative to jet-kerosene, the environmental damage cost stream, namely the enviroeconomic parameter of the engine, falls from 59,254.27 US$ year−1 to 39,074.11 US$ year−1. It is observed that sustainable efficiency factor and exergetic sustainability index outputs of the components of air compressor are the same for jet-kerosene and biofuel utilization cases, which are 8.31 and 7.31, respectively. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to develop and test a new deep learning model to predict aircraft fuel consumption. For this purpose, real data obtained from different landings and take-offs were used. As a result, a new hybrid convolutional neural network (CNN)-bi-directional long short term memory (BiLSTM) model was developed as intended. Design/methodology/approach: The data used are divided into training and testing according to the k-fold 5 value. In this study, 13 different parameters were used together as input parameters. Fuel consumption was used as the output parameter. Thus, the effect of many input parameters on fuel flow was modeled simultaneously using the deep learning method in this study. In addition, the developed hybrid model was compared with the existing deep learning models long short term memory (LSTM) and BiLSTM. Findings: In this study, when tested with LSTM, one of the existing deep learning models, values of 0.9162, 6.476, and 5.76 were obtained for R2, root mean square error (RMSE), and mean absolute percentage error (MAPE), respectively. For the BiLSTM model when tested, values of 0.9471, 5.847 and 4.62 were obtained for R2, RMSE and MAPE, respectively. In the proposed hybrid model when tested, values of 0.9743, 2.539 and 1.62 were obtained for R2, RMSE and MAPE, respectively. The results obtained according to the LSTM and BiLSTM models are much closer to the actual fuel consumption values. The error of the models used was verified against the actual fuel flow reports, and an average absolute percent error value of less than 2% was obtained. Originality/value: In this study, a new hybrid CNN-BiLSTM model is proposed. The proposed model is trained and tested with real flight data for fuel consumption estimation. As a result of the test, it is seen that it gives much better results than the LSTM and BiLSTM methods found in the literature. For this reason, it can be used in many different engine types and applications in different fields, especially the turboprop engine used in the study. Because it can be applied to different engines than the engine type used in the study, it can be easily integrated into many simulation models. [ABSTRACT FROM AUTHOR]

Bird strikes have long been a source of concern for all airlines across the world. It is the most significant design criterion for aircraft engine fan blades. As it is not practical to manufacture and test aviation engines repeatedly for minor design modifications, simulation analysis can be used to investigate strategies to reduce the influence of a bird strike on a jet engine by employing proper design and manufacturing processes for blades. This study proposes using two fibers (hybrid) instead of the single-fiber composite blade presently in use to address delamination problems. As an idea validation test, the coupon-level analysis results are validated using a four-point bend test of similar-size coupons. Following this validation, dynamic analysis is used to investigate the impact behavior of a rectangular plate subjected to a bird strike. The current research focuses on analyzing bird strikes on a hybrid composite fan blade using blade-level models. This study concentrates on the position of the bird's impact and the joint region length of two materials. The results show that the joint region with a 40% length of glass composite shows the optimum level of normalized interlaminar shear strain in all three impact locations. [ABSTRACT FROM AUTHOR]

The article presents experimental research of kinematic and deformation parameters of die rolling of compressor-blades' workpieces made of titanium alloy BT-8, using a section mill 330 of 'Motor Sich' JSC. The experimental results confirm that the strain unevenness is associated with intense shear, which is determinant in the formation of individual elements of the profile. Metal moves from areas of high reduction to areas of lower reduction in both the transverse direction and the longitudinal one. The use of uneven plastic deformation to control the process of forming the rolled products of different configurations and purposes is of interest. [ABSTRACT FROM AUTHOR]

There are a large number of bearings in aircraft engines that are subjected to extreme operating conditions, such as high temperature, high speed, and heavy load, and their fatigue, wear, and other failure problems seriously affect the reliability of the engine. The complex and variable bearing operating conditions can lead to differences in the distribution of data between the source and target operating conditions, as well as insufficient labels. To solve the above challenges, a multi-scale attention mechanism-based domain adversarial neural network strategy for bearing fault diagnosis (MADANN) is proposed and verified using Case Western Reserve University bearing data and PT500mini mechanical bearing data in this paper. First, a multi-scale feature extractor with an attention mechanism is proposed to extract more discriminative multi-scale features of the input signal. Subsequently, the maximum mean discrepancy (MMD) is introduced to measure the difference between the distribution of the target domain and the source domain. Finally, the fault diagnosis process of the rolling is realized by minimizing the loss of the feature classifier, the loss of the MMD distance, and maximizing the loss of the domain discriminator. The verification results indicate that the proposed strategy has stronger learning ability and better diagnosis performance than shallow network, deep network, and commonly used domain adaptive models. [ABSTRACT FROM AUTHOR]

SiC fiber-reinforced silicon matrix (SiCf/SiC) composites are of significant interest for the aircraft engine. The thermal conductive behaviors of [0-90-0]s SiCf/SiC composites along in-plane and out-of-plane (thickness) directions were reported in this paper. The thermal conductivity of the SiCf/SiC composite was tested by using the steady-state measuring apparatus. Then, the thermal conductivity of the SiC matrix was predicted by finite element analysis (FEA). The representative volume element (RVE) models of SiCf/SiC composites were built, and FEA was used to investigate thermal conductive behaviors. It was found that the thermal conductivity along the fiber radial direction was greater than it was in the axial direction in the SiCf/SiC composite and that the thermal conductivity of the out-of-plane direction is lower than that of the in-plane one. The thermal conductivity of the SiCf/SiC composite in the in-plane direction at room temperature was 31.1 Wm−1K−1 and 28.5 Wm−1K−1, and the thermal conductivity in the thickness direction was 24.9 Wm−1K−1. The experimental thermal conductivity showed a good agreement with the thermal conductivity of FEA. [ABSTRACT FROM AUTHOR]

Cast and wrought Ni‐based superalloys are materials of choice for harsh high‐temperature environments of aircraft engines and gas turbines. Their compositional complexity requires sophisticated thermo‐mechanical processing. A typical microstructure consists of a polycrystalline γ‐matrix, strengthening Ni3(Al,Ti) γ′ precipitates, carbides (MC, M6C, and M23C6), borides (M2B, M3B2, and M5B3), and other inclusions. Microalloying additions of B, C, and Zr commonly improve high‐temperature strength and creep resistance, although excessive additions are detrimental. Grain boundary (GB) segregation may improve cohesion and displace embrittling impurities. Finely dispersed carbides and borides are desired to control grain size via GB pinning. However, excessive decoration of GBs may lead to failure during processing and in‐service. Hence, a systematic review on the roles of B, C, and Zr in cast and wrought Ni‐based superalloys is required. The current state of knowledge on GB segregation and precipitation is reviewed. Experimental and modeling results are compared across various processing steps. The impact of GB precipitation on mechanical properties is most well researched. Co‐precipitation in proximity to GBs interacting with local microstructure evolution and mechanical properties remains less explored. Addressing these gaps in knowledge allows a more complete understanding of processing–microstructure–properties relationships in advanced cast and wrought Ni‐based superalloys. [ABSTRACT FROM AUTHOR]

The importance of jet noise for prospective supersonic transport (SST) in takeoff and climb modes dictates the need to develop methods for reducing jet noise and their subsequent validation in large- and full-scale tests. This paper presents the results of Russia's first ground acoustic tests of a rectangular nozzle with a noise suppression system, installed on a subsonic aircraft engine to demonstrate the technology. The authors studied a rectangular beveled nozzle with an ejector and screens—elements of the SST airframe. The test results were compared for three nozzle geometries: a round nozzle corresponding to measurements for the original engine without modifications, a rectangular nozzle without screens, and a rectangular nozzle with screens. It was found that when the rectangular nozzle without screens is used, there two opposite effects occur: noise amplification compared to the round nozzle for angles of observation close to the jet axis, and noise attenuation at angles of observation close to the fan rotation plane. Installing screens increases noise up to 5 dB in the low-frequency region below 150 Hz and reduces noise by 2 dB for frequencies higher than 250 Hz. Estimation of community noise in the EPNL metric showed that this rectangular nozzle with the noise suppression system has the effect of reducing community noise in comparison with the baseline round nozzle. [ABSTRACT FROM AUTHOR]

The influence of the impedance variability of the acoustic liner of an air intake on aircraft engine fan noise in the far field has been studied. The calculations were carried out in an axisymmetric statement for single modes based on the finite element solution to the Blokhintsev equation for the acoustic potential. The acoustic liner impedance was determined from a well-developed semiempirical model that takes into account the influence of a high sound pressure level (SPL) and grazing flow. A procedure has been developed for calculating the propagation of single sound modes through the air intake of an aircraft engine with a variable liner impedance depending on the flow velocity and SPL at a local point. The calculation procedure has been validated. Calculations were made for single mode propagation into the forward hemisphere for an air intake on the wall of which the following conditions were set: rigid wall, constant impedance (the impedance does not change along the liner) and variable impedance (the impedance changes along the liner depending on the changes in the velocity of the grazing flow and SPL). According to the calculation results, it was found that constant and variable impedances yield different SPL values in the far field; as well, taking into account the impedance variability changes not only the SPL values in the far field, but also the direction of the maximum mode radiation. [ABSTRACT FROM AUTHOR]

Combustor casing experiences the highest pressure and temperature of gas turbine thermodynamic cycle and its failure or rupture can lead to catastrophic failure of the engine and aircraft. This paper presents the structural analysis of combustor casing to establish its margin of safety. The combustor is tested at twice the maximum operating pressure and also subjected to cyclic pressure for 20,000 min–max-min cycles. Demonstration of adequate safety margin, capability of withstanding overload and cyclic pressure ensures structural safety and adequate life of the casing for a reliable operation in aero engine. Non-linear buckling analysis also has established adequate margin for safe operation in the intended engine. [ABSTRACT FROM AUTHOR]

The limited energy source indicates the necessity of efficient energy consumption in every field of life. Especially, the prompt growth in aviation sector makes this issue more important. In this study, effects of power settings on several thermodynamic indicators regarding low by-pass turbofan engine (LBP-TFE) are investigated. For this aim, the energy and exergy analyses are implemented to the system of turbofan engine for eighteen operating points. According to performance analysis, thrust value of the LBP-TFE changes from 10.77 kN to 71.8 kN throughout RPM values. According to exergetic findings, relative exergy losses from Fan outlet decreases from 52.34 % to 30.58 % whereas exergy efficiency of the LBP-TFE increases from 10.9 % to 30.1 %. Considering improved exergy efficiency, it changes 25.03 % and 41.03 % at the same RPM intervals. As for environmental assessments, environmental effect factor (EEF) of LBP-TFE diminishes from 5.8 to 1.32 while ecological effect factor decreases from 9.16 to 3.31. Finally, specific irreversibility production of LBP-TFE decreases from 0.4811 MW/kN and 0.2716 MW/kN. Considering these outcomes, behaviour of the investigated metrics regarding main components is different from each other. Therefore, the results of these parameters calculated for the whole engine could help understanding optimum running point in terms of exergetic and environmental sustainability. [ABSTRACT FROM AUTHOR]