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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]

The over-under turbine based combined cycle (TBCC) propulsion system dynamic model is established, including the engine model and inlet model. A dual-channel inlet is designed to match the engine and the inlet performance parameters are obtained by computational fluid dynamics (CFD) calculation, which provides original data for the integrated Inlet/Engine matching model. Control plan is designed to ensure that the engine is not over-temperature, over-rotation or surging based on correlation analysis. The simulation results show that the designed control plan can keep the TBCC propulsion system continuous in thrust during the mode transition, and the thrust fluctuation is about 10%. [ABSTRACT FROM AUTHOR]

In this study, the adaptive mode switching process of rotating detonation waves (RDWs) in response to the change of inlet conditions is numerically explored and analytically explained. Once a quasi-steady rotating detonation flow field is obtained, the inlet total pressure of the reservoir is decreased and maintained at different levels for a certain period of time in order to observe the feedback on the RDWs. It shows that instead of being quenched immediately, the RDWs can adapt to the change of inlet conditions by a mode switching adjustment; it decreases the number of detonation waves and begins to run in a new operating mode, a process that is found to occur swiftly and is corroborated by experimental observations; moreover, an analytical analysis indicates that for a stable RDW flow field, the characteristic parameters such as the number and height of detonation waves are related to the combustor geometry and inlet conditions, which determine whether the RDWs are required to switch into a new operating mode as a means to ensure stability. Additionally, the results indicate that the rotating detonation engine (RDE) can work in different operating modes at the same mass flow rate, or conversely, the RDE can remain in the same operating mode even if the mass flow rate varies. • Numerical simulations are conducted to investigate the operating modes of rotating detonation engines (RDEs). • The RDE can adapt to the changes of inlet conditions and switch its operating mode when necessary. • A quasi-steady analysis of the rotating detention waves is provided to explain the adaptive mode switching process. [ABSTRACT FROM AUTHOR]

Submerged inlets have the advantages of low drag, clean outer profile, and excellent stealth performance. Previous studies indicate that the zones of large total-pressure loss, located at the bottom and top regions of the exit plane, are the main cause of the poor aerodynamic performance in a submerged inlet. To improve the performance, a flow-control method is proposed in this paper, which includes both ramp side boundary layer bleeding and entrance side-edge vortex diverting. With numerical simulations, the efficacy of the proposed flow control is examined by comparing the aerodynamic performance and flow-field pattern of a baseline inlet and a controlled inlet over the typical flight envelope. The results prove that the proposed flow-control method can effectively discharge the low-energy flow of the forebody boundary layer on the ramp and isolate the major low-energy flow of the side-edge vortex. The proposed flow-control method results in a large improvement in the aerodynamic performance over the whole flight envelope. Specifically, the total pressure recovery (σ) of the inlet with the proposed flow-control features raises 3.06%, and the distortion (DC60) and the swirl distortion (SC60) lessen by 72.57% and 17.73%, respectively, in contrast to the baseline inlet under the engine matching point of cruise state (⁠Ma0=0.72, α=2 deg, β=0 deg, Ma2=0.39 ⁠). [ABSTRACT FROM AUTHOR]

Emissions requirements, performance expectations, and expanding range of fuels for off-road engines are broadening engine air system requirements. As part of reducing engine development cost and risk, virtual engine simulation is used to select architecture and components capable of covering a broad range of requirements through low risk changes to the turbocharger turbine. A method is presented for predicting turbine performance changes due to turbine housing area change, the most effective of these low risk changes, from available turbine map data. The method, developed from a mean line model, learns four simplified geometry parameters, three loss coefficients, and two maximum efficiency rotor inlet incidence coefficients from a training turbine map data set, then predicts a scaled turbine map for changes to a simplified geometry parameter associated with housing area. Reduced mass flow RMS errors less than 4.3% and efficiency RMS errors less than 5.2% are expected when generating scaled turbine maps with this method, which is additional 2% error for flow and 3% error for efficiency over that expected when modeling actual turbine map data. • Turbocharger turbine mapping data is modeled using a mean-line model. • Simplified geometry parameters are determined from turbine mapping data. • When changing housing A/R, efficiency is shifted in pressure ratio and scaled. • Estimated turbine map is generated for changes to simplified geometry parameters. • Virtual engine can predict engine performance changes from estimated turbine map. [ABSTRACT FROM AUTHOR]

A computationally efficient mathematical model was developed to analyze high-speed engine flows. The inlet and nozzle flows were modelled using the space-marching method to automatically solve the shock reflection and nozzle plume flow. The combustor flow was treated using a quasi-one-dimensional model that considered the rise in pressure of the isolator owing to the shock train. The resulting model was compared with the experimental results. Three test cases were used to validate the model's accuracy: 1) a hydrogen-fuelled combustor experiment, 2) an integrated inlet/combustor configuration experiment, and 3) a single-expansion-ramp nozzle flow experiment. The results showed that the space-marching method predicted the pressure profiles of the inlet flow and nozzle plume flow with reasonable accuracy. The computational time for the inlet and nozzle flows merely takes several minutes on a CPU with 3.6 GHz. The quasi-one-dimensional model calculated the fuel ignition and pressure rise in the combustor with a high computational efficiency of several seconds. The integration of the space-marching method and quasi-one-dimensional method can be developed as a powerful tool for fast evaluations of high-speed engine performance. [ABSTRACT FROM AUTHOR]

Based on the equal-intensity shock theory, this article designed a supersonic inlet working in Mach number 3.0∼5.5 with the background of an air-breathing engine. The inlet applied the four-shock train mixed compression configuration and inserted a sidewall compression at the beginning of the isolator. Through developing effective 3D RANS computations validated by current experiments, the performance of the designed inlet was identified. The designed inlet self-starts at freestream Mach number Ma∞ = 3.0 under which the total pressure recovery coefficient has dramatic increment, and the aerodynamic choking at the inlet throat no longer presents; the inlet keeps working at all studied flight states with zero angle of attack (AoA) and achieves shock-on-lip at the design point Ma∞ = 5.0. Both positive and negative AoAs can disrupt the equal-intensity shock allocations, which degrade the inlet performance. The inlet obtains maximum total pressure recovery coefficient at zero AoA. The maximum back pressure at Ma∞ = 3.0∼5.5 obtained by the inlet surpasses the requirements and keeps a certain margin. The inlet performance basically meets all the goals proposed by the engine. [ABSTRACT FROM AUTHOR]

As an advanced method for initiating detonation, shock-wave focusing (SWF) can do so directly without a separate igniter, and the distance of focusing initiation is much smaller than that of the deflagration-to-detonation transition, thereby greatly improving the performance of detonation engines. In this paper, the process of SWF detonation initiation with decane as the fuel is simulated, and it is found that the energy in the focusing region is high enough to initiate detonation directly. The total temperature and pressure of the incident flow are changed to study how the inlet parameters influence SWF. It is found that the total pressure of the incoming flow affects the SWF considerably whereas the influence of the total temperature can be ignored. The experimental results show that a kerosene–air detonation can be initiated successfully by SWF, thereby verifying the feasibility of SWF detonation with no pre-combustion chamber or igniter. The simulation and experimental results show that SWF detonation initiation has considerable advantages and potential. [ABSTRACT FROM AUTHOR]

Effective and accurate diagnosis of engine health is key to ensuring the safe operation of engines. Inlet distortion is due to the flow or the pressure variations. In the paper, an acoustic emission (AE) online monitoring technique, which has a faster response time compared with the ordinary vibration monitoring technique, is used to study the inlet distortion of an engine. The results show that with the deterioration of the inlet distortion, the characteristic parameters of AE signals clearly evolve in three stages. Stage I: when the inlet distortion J ≤ 30%, the characteristic parameters of the AE signal increase as J increases and the amplitude saturates at J = 23%, faster than the other three parameters (the strength, the root mean square (RMS), and the average signal level (ASL)). Stage II: when the inlet distortion 30% < J ≤ 43.64%, all the parameters saturate with only slight fluctuations as J increases and the engine works in an unstable statue. Stage III: when the inlet distortion J > 43.64%, the engine is prone to surge. Furthermore, an intelligent recognition method of the engine inlet distortion based on a unit parameter entropy and the back propagation (BP) neural network is constructed. The recognition accuracy is as high as 97.5%, and this method provides a new approach for engine health management. [ABSTRACT FROM AUTHOR]

In current researches on the lubrication of engine piston ring, some were based on a hypothesis that the piston ring is on a flooded lubrication status. Although some others belong to the starved lubrication analysis, the one‐dimensional model, a certain form of starved lubrication status or simplified manner were used. In this paper, on the basis of the equations about the lubricating oil flow‐rate and control volume, a flow model of lubricating oil in the piston ring‐cylinder liner conjunction is established, and the influence of the situation of supplied lubricating oil film at the piston ring inlet on the two‐dimensional starved lubrication characteristics of piston ring for a four‐stroke engine is studied. The results indicate that the lubrication condition at the piston ring inlet has significant impact on the lubrication characteristics of piston ring. When the supplied lubricating oil at the piston ring inlet increases, the minimum film thickness of piston ring will increase, meanwhile the maximum film pressure, asperity contact force, friction force and power loss will decrease. If the film thickness at the piston ring inlet is smaller, the increase of the supplied film thickness can improve obviously the lubrication characteristics of piston ring. [ABSTRACT FROM AUTHOR]

To investigate the coupling effects of unit additional lift duration angle and unit additional lift peak value with the original valve type line peak interval angle on the gas path state parameters, the DK4A diesel engine was taken as the research object, and the different valve type lines were introduced to simulate under the engine speed of 2 800 km·h-1 and 50% load condition.The effects of unit additional lift duration angle, additional lift peak value and original valve profile peak interval angle on the weight of gas path state parameters were analyzed and discussed. The results show that the interval angle between the unit additional lift peak value and the original valve profile peak value is from 100° to 140°, and the additional lift duration angle is from 92° to 132°.The increases of the additional lift peak value and the original valve profile peak interval angle are beneficial to the increase of the influence weight on the air path state parameters, and the influence weights of the unit additional lift peak value and the original valve profile peak interval angle on the change rate of air inlet state parameters are greater than that of the unit additional lift duration angle. [ABSTRACT FROM AUTHOR]

This paper presents a mixed-fidelity model to investigate the effect of complex inlet distortion on aero gas turbine engines. The approach is developed by integrating a three-dimensional body force model of multistage compressors and a classical two-dimensional parallel engine model. The internal flow field of a high bypass ratio turbofan engine under different forms of total pressure distortion is simulated by the model. The simulations are discussed in depth to reveal the features of the distorted flow field in the compression components under the whole engine environment. The relationship between the overall performance of the engine and the intensity of inlet total pressure distortion is investigated quantitatively. It is evident that the mixed-fidelity model has the capability to quantitatively evaluate the effect of complex inlet distortion on the performance and the internal flow field of engines with low computational costs. [ABSTRACT FROM AUTHOR]

Inlet start/unstart detection is one of the most important issues of hypersonic inlets and is also the foundation of protection controls of scramjets. In ground and flight tests, it is inevitably to introduce the sensor noises to the measurement system. How to overcome or weaken the influence of the sensor noises and the outer disturbances is an important issue to the control system of the engine. To solve this problem, the 2D inner steady flow of hypersonic inlets was numerically simulated in different freestream conditions and backpressures, and two different inlet unstart phenomena were analysed. The membership function for hypersonic inlet start/unstart can be obtained by using probabilistic output support vector machine, and the algorithm of multiple classifiers fusion is introduced. The variations of the classification accuracy with the intensity of the sensor noises and the number of the classifier were discussed respectively. In conclusion, it is useful to introduce the algorithm of support vector machine and multiple classifiers fusion to overcome or weaken the influence of the sensor noises on the classification accuracy of hypersonic inlet start/unstart. The number of the practical fusion classifiers needs a tradeoff between the fusion classification accuracy and the complexity of the classification system. [ABSTRACT FROM AUTHOR]

The power output of a gas turbine (GT) is highly affected by ambient temperature. A higher ambient temperature will result in a lower power output, due to reduced inlet air density and mass flow rate. Therefore, GT power loss can be recovered by cooling the inlet air. Due to compression with intercooling, overspray inlet fogging (wet compression) can increase power more than using only evaporative inlet cooling. It can also be used to recover aircraft thrust loss due to high ambient temperature operation, or to boost takeoff thrust. This paper is focused on the effects of adding an overspray inlet fogging system to an existing GT power plant. Simulation runs were made for adding an overspray inlet fogging system to a GE 7111EA GT engine to compare with the baseline case (28.2°C, 75.7% relative humidity). Power augmentation using evaporative and overspray inlet fogging can range from 1.85 to 16.8 MW, which amounts to a 2.5–22.4% power increase. Moreover, the net efficiency is also increased by 1.62%. Therefore, overspray inlet fogging is capable of both boosting the GT power and improving the efficiency. Results from this study can be used as a guideline for GT power augmentation by overspray inlet fogging. [ABSTRACT FROM AUTHOR]

In the article titled "Study on Inlet and Engine Integrated Model with Normal Shock Position Feedback" [[1]], there was an error in the Acknowledgments section. The corrected section appears below: Acknowledgments This study is supported in part by the National Science and Technology Major Project under Grant 2017-V-0004-0054, Research on the Basic Problem of Intelligent Aero-engine under Grant 2017-JCJQ-ZD-047-21, National Natural Science Foundation of China under Grant 51906102, China Postdoctoral Science Foundation Funded Project under Grant 2019M661835, and Aeronautics Power Foundation under Grant 6141B09050385. REFERENCES 1 Chen H., Zhang H., Xi Z., Zheng Q. Study on inlet and engine integrated model with normal shock position feedback. [Extracted from the article]