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Chinese Journal of aeronautics 2024年第8期37卷 106-123页

作者： Yifan WANG Zhengping ZOU Pengcheng DU Lichao YAO Huoxing LIU Yusen XU Research institute of aero-engine Beihang UniversityBeijing 102206China National Key Laboratory of Science and Technology on aero-engine and aero-Thermodynamics Beihang UniversityBeijing 102206China

An advanced precooled airbreathing engine with a closed Brayton cycle is a promising solution for high-speed propulsion,of which the Synergetic Air Breathing Rocket engine(SABRE)is a representative *** performance of the latest SABRE-4 cycle was analyzed in this ***,a relatively complete engine performance model that considers the characteristics of turbomachinery and heat exchangers was ***,Sobol’global sensitivity analysis of key performance parameters was carried out to identify the most influential design *** specific impulses under different target specific thrusts were obtained by particle swarm optimization,of which the thermodynamic parameters corresponding to a specific thrust of 1.12 kN·s·kg^(-1)and a specific impulse of 3163 s were chosen as the design *** different control laws were analyzed in contrast,and the charge control method had the strongest ability of thrust regulation as well as maintaining a favorable specific impulse ***,working characteristics under the charge control and over a typical flight envelope were calculated,in which the average value of the maximum specific impulse was as high as 5315 *** study would help to deepen the understanding of SABRE-4 thermodynamic characteristics and other precooled airbreathing engine cycles with similar layouts.

关键词： Hypersonic Precooled airbreathing engine Thermodynamic cycle Control law Working characteristics

Development of a deviation package method for low-cost robust optimization in compressor blade design

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Chinese Journal of aeronautics 2024年第4期37卷 166-180页

作者： Mingzhi LI Xianjun YU Dejun MENG Guangfeng AN Baojie LIU Research institute of aero-engine Beihang UniversityBeijing 100191China National Key Laboratory of Science&Technology on aero-engine aero-Thermodynamics Beihang UniversityBeijing 100191China AECC Shenyang engine Research institute Shenyang 110015China

Manufacture variations can greatly increase the performance variability of compressor blades. Current robust design optimization methods have a critical role in reducing the adverse impact of the variations, but can be affected by errors if the assumptions of the deviation models and distribution parameters are inaccurate. A new approach for robust design optimization without the employment of the deviation models is proposed. The deviation package method and the interval estimation method are exploited in this new approach. Simultaneously, a stratified strategy is used to reduce the computational cost and assure the optimization accuracy. The test case employed for this study is a typical transonic compressor blade profile, which resembles most of the manufacture features of modern compressor blades. A set of 96 newly manufactured blades was measured using a coordinate measurement machine to obtain the manufacture variations and produce a deviation package. The optimization results show that the scatter of the aerodynamic performance for the optimal robust design is 20% less than the baseline value. By comparing the optimization results obtained from the deviation package method with those obtained from widely-used methods employing the deviation model, the efficiency and accuracy of the deviation package method are demonstrated. Finally, the physical mechanisms that control the robustness of different designs were further investigated, and some statistical laws of robust design were extracted.

关键词： Manufacture variations Robust design optimization Compressor leading edge aerodynamics Physical mechanism

Experimental Study of Fuel-Air Mixing and Dilution Jets on Outlet Temperature Distribution in a Small Gas Turbine Combustor

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Journal of Thermal Science 2024年第5期33卷 1883-1896页

作者： CAI Wenzhe WU Jing HU Yingqi YANG Zhiqiang XUE Xin LIN Yuzhen National Key Laboratory of Science and Technology on aero-engine aero-thermodynamics Research Institute of Aero-EngineBeihang UniversityBeijing 100191China Beijing institute of Power Machinery Beijing 100074China School of Energy and Power engineering Beihang UniversityBeijing 100191China

Experimental analysis was conducted to study the impact of fuel-air mixing and dilution jet on the temperature distribution in a small gas turbine combustor using various optical diagnostic *** strength and velocity of the swirler at the venturi exit were adjusted to modify the fuel-air mixture,which is presumed to dominate the heat release of the main combustion ***,the dilution hole configuration,including the number and size of the holes,was varied to investigate the dilution effect on outlet temperature *** optical diagnostic techniques,such as particle image velocimetry,planar Mie scattering,and OH~*chemiluminescence,were used to measure the flow field,fuel spray distribution,and flame structure,respectively.A reduction in swirling strength led to a decrease in the average flow rate in the throat,which improved the structure and symmetry of the axial vortex system in the sleeve,enhanced the mixing of fuel and gas in the dome swirling air,and ultimately,improved the temperature uniformity of the heat release *** to larger and sparse dilution jets,smaller and dense dilution jets tended to generate hot spots shifted towards the radial middle area.

关键词： small gas turbine combustor fuel-air mixing outlet temperature distribution dilution jet laser diagnostics

Flow characteristics of radial inflow in impeller rear cavity with baffle plate

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Chinese Journal of aeronautics 2024年第2期37卷 270-282页

作者： Yang BAI Xiang LUO Dongdong LIU Zeyu WU Xiaoqiang ZHANG Sipeng WANG Research institute of aero-engine Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on aero-engine aero-Thermodynamics Beihang UniversityBeijing 100191China School of Energy and Power engineering Beihang UniversityBeijing 100191China

The research purpose of this paper is to explore the influence of the baffle plate on the airflow in the rear cavity of the centrifugal impeller and optimize the performance of the secondary air system’s air bleed *** this paper,a comprehensive experimental study was carried out on the flow characteristics in the impeller rear cavity with baffle *** windage torque,flow structure and pressure drop between inlet and outlet were measured *** experiment was carried out with the condition that the range of rotational Reynolds number was from 8.33×10^(5)to 22.2×10^(5)and the range of mass flow rate coefficient was from 0.92×10^(4)to 2.92×10^(4).The results show that the static cavity and the narrow stator-rotor cavity formed by the baffle plate effectively suppress the overall swirl coefficient in the ***,the static pressure and total pressure drop in the rotor-stator cavity were *** influence of the baffle plate on the windage torque of the rotary disk is related to the turbulence *** large turbulence parameters,the windage torque would be reduced with baffle plate,while under small turbulence parameters,the baffle plate would increase with baffle *** general,the baffle plate can improve the flow capacity and optimize the bleed air performance with proper structure and operation conditions.

关键词： Impeller rear cavity Baffle plate Flow structure Windage torque Pressure drop

A multi-scale framework for life reduction assessment of turbine blade caused by microstructural degradation

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Chinese Journal of aeronautics 2024年第1期37卷 186-200页

作者： Xiaoguang YANG Menglei WANG Duoqi SHI Zhenlei LI Yongsheng FAN School of Energy and Power engineering Beihang UniversityBeijing 102206China Research institute of aero-engine Beihang UniversityBeijing 102206China National Key Laboratory of Science and Technology on aero-engine aero-Thermodynamics Beihang UniversityBeijing 102206China

The prolonged thermal exposure with centrifugal load results in microstructural degradation,which ultimately leads to a reduction in the fatigue and creep resistance of the turbine *** present work proposes a multi-scale framework to estimate the life reduction of turbine blades,which combines a microstructural degradation model,a two-phase constitutive model,and a microstructure-dependent fatigue and creep life reduction *** framework with multi-scale models is validated by a Single Crystal(SC)Ni-based superalloy at the microstructural length-scale and is then applied to calculate the microstructural degradation and the fatigue and creep life reduction of turbine blades under two specific service *** simulation results and quantitative analysis show that the microstructural degradation and fatigue and creep life reduction of the turbine blade are heavily influenced by the variations in the proportion of the intermediate state,namely,the maximum rotor speed status,in the two specific service *** intermediate state accelerates the microstructural degradation and leads to a reduction of the life,especially the effective fatigue life reserve due to the higher temperature and rotational speed than that of the 93%maximum rotor speed status marked as the reference *** proposed multi-scale framework provides a capable approach to analyze the reduction of the fatigue and creep life for turbine blade induced by microstructural degradation,which can assist to determine a reasonable Time Between Overhaul(TBO)of the engine.

关键词： Creep Fatigue Life reduction Microstructural degradation Multi-scale modeling Turbine blades

Nonlinear uncertainty impact of geometric variations on aerodynamic performance of low-pressure turbine blades with ultra-high loading under extreme operational conditions

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Chinese Journal of aeronautics 2024年第5期37卷 281-300页

作者： Xiaojing WANG Zhengping ZOU Chao FU Pengcheng DU School of Energy and Power engineering Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on aero-engine aero-Thermodynamics Beihang UniversityBeijing 100191China Research institute of aero-engine Beihang UniversityBeijing 100191China

Uncertainty impact of random geometric variations on the aerodynamic performance of low-pressure turbine blades is considerable,which is further amplified by the current ultra-high-lift design trend for weight ***,this uncertainty impact on ultra-highly loaded blades under extreme operational conditions near the margins with potential large-scale open separation is focused on in this *** is demonstrated that this impact is significant,unfavourable,and nonlinear,which is clearly severer under extreme *** addition to the overall attenuation and notable scattering of specific performance,the operational margins with open separation are also notably scattered with great risk of significant *** scattering and nonlinearity are dominated by the variations in leading-edge *** thinning of leading edge triggers local transition,enhancing downstream friction and reducing resistance to open separation,which is further exacerbated by operational ***,the opposite thickening yields less benefit,implying *** unfavourable impact highlights the need for robust aerodynamic design,where both a safer operational condition and a more robust blade are indispensable,i.e.,a compromise among performance,weight,and *** the necessary limitation of loading levels,a mid-loaded design is recommended to reduce adverse pressure gradients in both the leading edge and rear region of the suction side,which helps to decrease the susceptibility of the transition and open separation to random *** improvements can also be achieved by appropriately thickening the leading edge.

关键词： Ultra-highly loaded turbine blade Geometric variations Uncertainty analysis Operational margins Robust aerodynamic design Nonlinearity

Controlled flight of a self-powered micro blimp driven by insect-sized flapping-wing thrusters

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Chinese Journal of aeronautics 2024年第6期37卷 127-136页

作者： Xian YU Zhiwei LIU Jiaming LENG Mingjing QI Xiaojun YAN School of Energy and Power engineering Beihang UniversityBeijing 100191China Collaborative Innovation Center of Advanced aero-engine Beijing 100191China National Key Laboratory of Science and Technology on aero-engine aero-thermodynamics Beihang UniversityBeijng 100191China Beijing Key Laboratory of aero-engine Structure and Strength Beihang UniversityBeijing 100191China

Micro aerial platforms face significant challenges in achieving long controlled endurance as most of the energy is consumed to overcome the weight of the *** this study,we present a controllable micro blimp that addresses this issue through the use of a helium-filled *** micro blimp has a long axis of 23 cm and is propelled by four insect-sized flapping-wing thrusters,each weighing 80 mg and with a wingspan of 3.5 *** distributed thrusters enable controlled motions and provide the micro blimp with an advantage in flight endurance compared to multirotors or flapping-wing micro aerial vehicles at the same size *** enhance the performance of the controlled flight,we propose a wireless control module that enables manipulation from a distance of up to 100 ***,a smartphone application is developed to send instructions to the circuit board,allowing the blimp to turn left and right,ascend and descend,and achieve a combination of these movements *** findings demonstrate that this micro blimp is one of the smallest controlled self-powered micro blimps to date.

关键词： Microairvehicle Aircraft control Self-powered micro blimp Flapping-wing thruster Wireless flight

Experimental and computational investigation on flow characteristics of rotating cavities with high inlet pre-swirl axial throughflow

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Chinese Journal of aeronautics 2024年第4期37卷 276-293页

作者： Sipeng WANG Xiang LUO Linji GUO Zeyu WU Yang BAI Zongchao LI Lichun MA School of Energy and Power engineering Beihang UniversityBeijing 100191China Research Institude of aero-Enigine Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on aero-engine aero-Thermodynamics Beihang UniversityBeijing 100191China Shenyang aeroengine Research institute Aero Engine Corporation of ChinaShenyang 110015China

As an integral part of the internal air system of aero-engines,the axial throughflow of the cooling air can interact with the cavity flow between the rotating compressor disks,forming a threedimensional,unsteady,and unstable flow *** flow characteristics in an engine-like rotating multi-stage cavity with throughflow were investigated using particle image velocimetry,flow visualization technology and three-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS)*** focus of current research was to understand the distribution of the mean swirl ratio and its variation with a wide range of non-dimensional parameters in the co-rotating cavity with high inlet pre-swirl axial *** maximum axial Reynolds number and rotational Reynolds numbers could reach 4.41×10^(4)and 1.24×10^(6),*** velocity measurement results indicate that the mean swirl ratio is greater than 1 and decreases with an increase in the radial *** flow structure is dominated by the Rossby number,and two different flow patterns (flow penetration and flow stratification) are identified and confirmed by flow visualization *** the absence of buoyancy,the flow penetration caused by the precession of the throughflow makes it easier for the throughflow to reach a high radius *** consistency of results between measurements and numerical calculations is *** study provides a theoretical basis and data support for toroidal vortex breakdown,which is of practical significance for the design of high-pressure compressor cavities.

关键词： Compressor Axial throughflow Rotating cavity flow Particle image velocimetry Unsteady RANS Flow pattern

Effect of fore/aft-loaded rotor on compressor stability under inlet circumferential distortion

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Chinese Journal of aeronautics 2024年第5期37卷 199-213页

作者： Dakun SUN Benhao GU Fangfei NING Dengke XU Xiaofeng SUN School of Energy and Power engineering Beihang UniversityBeijing 102206China Research institute of aero-engine Beihang UniversityBeijing 102206China

A modified small perturbation stability prediction model for axial compressors with circumferential inlet distortions is established and applied to investigate the effect of fore/aft-loaded rotor on compressor stability under circumferentially distorted inlet *** inlet total pressure distribution downstream of the distortion screen is measured in experiments and employed for simulations which are implemented via time-space spectral *** stall inception prediction results via the stability model indicate that the compressor with aft-loaded rotor not only performs better in terms of stability under uniform inlet,but also maintains a larger stability margin under circumferentially distorted *** experiments for compressors with fore-loaded and aft-loaded rotor are respectively carried *** results validate the reliability of numerical simulations and the predicted conclusion that the aft-loaded rotor is beneficial for compressor ***,the ability of the developed theoretical model for compressor stability prediction under circumferential distortions is *** addition,dynamic pressure signals at rotor tip measured in experiments illustrate that the circumferential distortion has little effect on the compressor stall pattern.

关键词： Axial compressor stability Inlet distortion Blade loading Small perturbation Time-space spectral method

Ammonia storage and slip under steady and transient state in close-coupled SCR

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Journal of Environmental Sciences 2024年第4期138卷 470-481页

作者： Shiyu Liu Zhaohuan Zhang Zexian Guo Boyuan Wang Buyu Wang Xiao Ma Shijin Shuai State Key Laboratory of Automotive Safety and Energy Tsinghua UniversityBeijing 100084China institute for aero engine Tsinghua UniversityBeijing 100084China

The close-coupled selective catalytic reduction(cc-SCR)catalyst is an effective technology to reduce tailpipe NOx emission during cold *** paper investigated the optimal ammonia storage under steady and transient state in the *** study showed that a trade-off between NOx conversion efficiency and ammonia slip is observed on the pareto solutions under steady state,and the optimal ammonia storage is calculated with ammonia slip less than 10μL/L based on the ChinaⅥemission *** rapid temperature increase will lead to severe ammonia slip in the transient test cycle.A simplified 0-D calculation method on ammonia slip under transient state is proposed based on kinetic model of ammonia adsorption and *** addition,the effect of ammonia storage,catalyst temperature and temperature increasing rate on ammonia slip are *** optimal ammonia storage is calculated with maximum ammonia slip less than 100μL/L according to the oxidation efficiency of ammonia slip catalyst(ASC)downstream *** was found that the optimal ammonia storage under transient state is much lower than that under steady state in cc-SCR at lower temperature,and a phase diagram is established to analyze the influence of temperature and temperature increasing rate on optimal ammonia storage.

关键词： Close-coupled SCR Ammonia storage and slip Steady and transient state Generic algorithm