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Aerodynamic Optimization and Flow Mechanism for a Compressor Cascade at Low Reynolds Number

Journal of Thermal Science 2025年第1期 92-109页

作者： LI Lin ZHANG Jianshe CHEN Caiyan TAN Wei ZHANG Yanfeng Key Laboratory of Light-Duty gas-turbine Institute of Engineering ThermophysicsChinese Academy of Sciences University of chinese Academy of Sciences National Key Laboratory of Science and Technology on Advanced Light-duty gas-turbine

Low-Reynolds-number effect is an important factor affecting the performance of compressors and other main components of high-altitude long-endurance unmanned aerial *** improve the flow condition and reduce flow loss under the condition of high altitude and low Reynolds number(Re),this paper proposes an optimization process based on a surrogate model,which combines the class-shape transformation method(CST),the Latin hypercube sampling(LHS) method,the light gradient-boosting machine algorithm(LightGBM),and a genetic algorithm(GA) to optimize a high-subsonic compressor *** surrogate model is verified to be accurate and can be used in the optimization *** accuracy of the GA is higher than the other algorithms under common test *** optimization results are verified by numerical simulation,and the flow differences before and after optimization are compared,especially the flow within the boundary *** changing the blade shape,the optimization process adjusts the loading distribution to delay the transition of the optimized blade on the suction surface,which changes the turbulent reattachment in the laminar separation bubble(LSB) into laminar ***,the mixing loss induced by the turbulent reattachment of the LSB and the wake loss of turbulent separation at the trailing edge are significantly reduced,and the performance of the compressor profile is finally *** addition,turbulent separation of the optimized profile is delayed reducing the range of the wake region on the suction *** this optimization process,the reduction of total pressure loss coefficient at Re of 2.5×10～5,3.5×10～5,and 4.5×10～5 are 16.32%,20.76%,and 22.16%,respectively.

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Experiment and application of parameter-induced stochastic resonance in an over-damped random linear system

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chinese Physics B 2009年第7期18卷 2667-2673页

作者：蒋世奇侯敏杰贾春华何吉荣古天祥 China gas turbine establishment School of Automation Engineering University of Electronic Science and Technology of China

This paper investigates the parameter-induced stochastic resonance using experimental methods in an over-damped random linear system with asymmetric dichotomous noise. Non-monotonic dependence of signal-to-noise ratio on the system parameter is observed. Several potential applications of parameter-induced stochastic resonance are given in circuits.

关键词： parameter-induced stochastic resonance asymmetric dichotomous noise over-dampedlinear system signal-to-noise ratio

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Separation control using synthetic vortex generator jets in axial compressor cascade

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Acta Mechanica Sinica 2006年第6期22卷 521-527页

作者： Xinqian Zheng Sheng Zhou Anping Hou Zhengli Jiang Daijun Ling National Key Laboratory of Aircraft Engine Beihang University Beijing 100083 China chinese gas turbine establishment JiangyouSichuan 621700 China

An experimental investigation conducted in a high-speed plane cascade wind tunnel demonstrates that unsteady flow control by using synthetic （zero mass flux） vortex generator jets can effectively improve the aerodynamic performances and reduce （or eliminate） flow separation in axial compressor cascade. The Mach number of the incoming flow is up to 0.7 and most tested cases are at Ma = 0.3. The incidence is 10° at which the boundary layer is separated from 70% of the chord length. The roles of excitation frequency, amplitude, location and pitch angle are investigated. Preliminary results show that the excitation amplitude plays a very important role, the optimal excitation location is just upstream of the separation point, and the optimal pitch angle is 35°. The maximum relative reduction of loss coefficient is 22.8%.

关键词： Flow control Compressor Synthetic jet

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A fault tolerant model for multi-sensor measurement

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chinese Journal of Aeronautics 2015年第3期28卷 874-882页

作者： Li Liang Shi Wei Information and Ecommerce Institute University of Electronic Science & Technology of China China gas turbine establishment

Abstract Multisensor systems are very powerful in the complex environments. The cointegration theory and the vector error correction model, the statistic methods which widely applied in economic analysis, are utilized to create a fitting model for homogeneous sensors measurements. An algorithm is applied to implement the model for error correction, in which the signal of any sensor can be esti mated from those of others. The model divides a signal series into two parts, the training part and the estimated part. By comparing the estimated part with the actual one, the proposed method can iden tify a sensor with possible faults and repair its signal. With a small amount of training data, the right parameters for the model in real time could be found by the algorithm. When applied in data analysis for aero engine testing, the model works well. Therefore, it is not only an effective method to detect any sensor failure or abnormality, but also a useful approach to correct possible errors.

关键词： Cointegration Fault tolerant Measurement Multi-sensor turbine engine

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Experimental and Numerical Investigations on Ignition and LBO Performances for Staged Combustor under Sub-Atmospheric Conditions

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Journal of Thermal Science 2023年第3期32卷 1251-1262页

作者： ZHAO Qianpeng XU Gang MU Yong YANG Jinhu WANG Kaixing Laboratory of Light-Duty gas-turbine Institute of Engineering ThermophysicsChinese Academy of Sciences University of chinese Academy of Sciences Innovation Academy for Light-duty gas turbine

In order to effectively widen the high-altitude operating limits of the multi-swirl staged combustor,the ignition and lean blow-out(LBO)performances of the model combustor were experimentally acquired under the conditions of room temperature and sub-atmospheric pressure with the altitude ranging from 0 km to 12 ***,the isothermal flow fields inside a staged model combustor with different sub-atmospheric conditions were *** results show that the minimum ignition and LBO fuel-air ratio(FAR)increase rapidly with the increase of simulated *** addition,as the relative pressure drop of injector increases from1%to 3%,the ignition and LBO performances are gradually *** visualization of the flame by high-speed camera shows that the time-averaged flames under stable combustion have a similar distribution pattern under different pressure *** luminous intensity is stratified into dim-bright-dim layers along axial *** flame near LBO shrinks to the outlet of pilot stage with a great reduction in luminous *** numerical results reveal that with the decrease of air pressure,the air mass flow rate involved in atomization and combustion is significantly reduced,and the aerodynamic shear force of swirling air is weakened,which are adverse to atomization and fuel-air mixing for airblast atomizer and further lead to the deterioration of ignition and LBO performances.

关键词： ignition lean blow-out sub-atmospheric pressure staged combustor airblast atomizer

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Analysis of oil shedding and ligaments formation on bearing rotary elements

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chinese Journal of Aeronautics 2023年第2期36卷 377-387页

作者： Donglei ZHU Guoding CHEN Yanjun LI Chaoyang ZHANG Lin WANG School of Mechanical Engineering Northwestern Polytechnical UniversityXi'an 710072China China gas turbine establishment Chengdu 610500China

For designing efficient lubrication system of an aeroengine bearing chamber,sufficient knowledge on oil/air two-phase flow characteristics is *** analyzing bearing chamber two-phase flow,the essential prerequisite is quantifying the oil ligaments,which are detached from bearing rotary elements and shed into the bearing *** investigations are mainly targeted at liquid shedding on the rotating disk as opposed to the bearing rotary ***,the research based on bearing rotary elements is conducted by *** to the limited operating conditions,experimental studies cannot guide engineering *** overcome these limitations,a theoretical model is established in this paper,for revealing the mechanism of oil shedding from bearing rotary elements and quantifying the shedding *** theoretical model is validated against experimental results from classical *** addition,the correlation for shedding ligaments number based on aeroengine bearing structural and operational parameters is obtained via theoretical *** analytical results demonstrate that oil shedding and ligaments formation appear at the edge of bearing inner race *** number of shedding ligaments increases with the rise of shaft rotational speed while decreases with the growth of oil viscosity.

关键词： Aeroengine bearing chamber Ligaments Lubrication Mechanical analysis Shedding Wave

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A 3D CFD simulation of oil spray-collection and delivery process in an aeroengine inter-shaft bearing

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chinese Journal of Aeronautics 2022年第9期35卷 366-378页

Under-race lubrication applied to the inter-shaft bearing of aeroengine is characterized by spray oil collection and oil delivery to the bearing via flow-path structure. Droplet splashing induced by the collision between spray oil and the scoop as well as oil flowing characteristics in the flow-path influence bearing lubrication efficiency. In previous investigations, the spray oil collection and oil delivery analysis were separated, and the effect of droplet splashing on bearing lubrication efficiency was not considered. Moreover, time-varying characteristics of oil delivered to the bearing were not accounted for. This is caused by time variations of the circumferential position of rollers and under-race feed holes. To overcome these limitations, a numerical model which integrates the spray oil collection and oil delivery analysis is proposed in this paper. The model is embedded with the function of calculating the flow rate of splashing droplets and analyzing time-varying characteristics of the oil fed to the bearing. Furthermore, the numerical model is validated by experimental investigation. The proposed numerical model facilitates the accurate calculation of bearing lubrication efficiency as well as the design of an efficient lubrication structure.

关键词： Integrated Inter-shaft bearing Splash-spray Time-varying Under-race lubrication

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Investigation of the Effect of Pilot Burner on Lean Blow Out Performance of A Staged Injector

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Journal of Thermal Science 2014年第6期23卷 600-608页

作者： YANG Jinhu ZHANG Kaiyu LIU Cunxi RUAN Changlong LIU Fuqiang XU Gang Key Laboratory of Light-duty gas-turbine Institute of Engineering ThermophysicsChinese Academy of Sciences

The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, which requires most of the combustion air enters the combustor through injector to reduce smoke emission. However, lean staged injector is prone to combustion instability and extinction in low load operation, so techniques for broadening its stable operation ranges are crucial for its application in real *** this work, the LBO performance of a staged injector is assessed and analyzed on a single sector test *** experiment was done in atmospheric environment with optical access. Kerosene-PLIF technique was used to visualize the spray distribution and common camera was used to record the flame patterns. Emphasis is put on the influence of pilot burner on LBO performance. The fuel to air ratios at LBO of six injectors with different pilot swirler vane angle were evaluated and the obtained LBO data was converted into data at idle condition. Results show that the increase of pilot swirler vane angle could promote the air assisted atomization, which in turn improves the LBO performance slightly. Flame patterns typical in the process of LBO are analyzed and attempts are made to find out the main factors which govern the extinction process with the assistance of spray distribution and numerical flow field results. It can be learned that the flame patterns are mainly influenced by structure of the flow field just behind the pilot burner when the fuel mass flow rate is high; with the reduction of fuel, atomization quality become more and more important and is the main contributing factor of LBO. In the end of the paper,conclusions are drawn and suggestions are made for the optimization of the present staged injector.

关键词： Staged injector LBO Spray distribution Flame pattern

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Performance Improvements of a Subsonic Axial-Flow Compressor by Means of a Non-Axisymmetric Stator Hub End-Wall

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Journal of Thermal Science 2013年第6期22卷 539-546页

作者： ZHANG Xuefeng LU Xingen ZHU Junqiang Key Laboratory of Light-duty gas-turbine IETCAS Graduate School of chinese Academy of Sciences

This paper deals with the application of a non-axisyrmnetric hub end-wall on the stator of a single stage high subsonic axial-flow compressor. In order to obtain a state-of-the-art stator non-axisymmetric hub end-wall con- figuration fulfilling the requirements for higher efficiency and total pressure ratio, an automated multi-objective optimizer was used, in conjunction with 3D-RANS-flow simulations. For the purpose of quantifying the effect of the optimal stator non axis-symmetric hub contouring on the compressor performance and its effects on the sub- sonic axial-flow compressor stator end-wall flow field structure, the coupled flow of the compressor stage with the baseline, axisymmetric and the non-axisynunetric stator hub end-wall was simulated with a state-of-the- art multi-block flow 3D CFD solver. Based on the CFD simulations, the optimal compressor hub end-wall con- figuration is expected to increase the peak efficiency by approximately 2.04 points and a slight increase of the to- tal pressure ratio. Detailed analyses of the numerical flow visualization at the hub have uncovered the different hub flow topologies between the cases with axisymmetric and non-axisymmetric hub end-walls. It was found that that the primary performance enhancement afforded by the non-axisymmelric hub end-wall is a result of the end-wall flow structure modification. Compared to the smooth wall case, the non-axisymmetric hub end-wall can reduce the formation and development of in-passage secondary flow by aerodynamic loading redistribution.

关键词： Axial-flow compressor Non-axisymmetric end-wall Numerical simulation

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A New Methodology for Early Detection of Thermoacoustic Combustion Oscillations Based on Permutation Entropy

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Journal of Thermal Science 2023年第6期32卷 2310-2320页

作者： LI Yao HU Chunyan SHEN Youhao HAN Bo YANG Jinhu XU Gang Key Laboratory of Light Duty gas turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing100190China University of chinese Academy of Sciences Beijing100049China Innovation Academy for Light-Duty gas turbine Chinese Academy of SciencesBeijing100190China

We carry out a series of experimental investigations in a model combustor to detect a precursor of thermoacoustic combustion oscillations based on permutation entropy,which can amplify the subtle changes effected in the time sequence to identify the *** changing the flame’s location or the fuel flow to a value,an abrupt switch from aperiodic small-amplitude oscillations to periodic large-amplitude oscillations would occur in pressure *** characteristic frequency of combustion oscillation is obtained by spectral analysis,with which a modified algorithm of the permutation entropy is *** impact evaluation on key parameters such as moving step sizes and window sizes reveals that the moving data permutation entropy has strong robustness,and can accurately detect the onset of thermoacoustic *** nonlinear analysis exhibits peculiar dynamics of the combustion system,which result in specific patterns in the time series and provide a theoretical basis for anomaly *** results suggest that the permutation entropy has a certain potential in early warning and detection of combustion oscillations.

关键词： thermoacoustic combustion oscillation permutation entropy moving data anomaly detection precursors

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