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| 1 | Investigation on Multiple Cylindrical Holes Casing Treatment for Transonic Axial Compressor Stability Enhancement显示文摘Casing treatment is one possible way of regaining axial compressor operating range. However, most of casing treatments extend the operating range with the cost of efficiency penalty. A new form of multiple cylindrical holes casing treatment(MHCT) with pre-swirl blowing for the NASA Rotor-37 has been designed based on profound understanding of the stall inception. Unsteady numerical simulations have been performed for Rotor-37 with and without MHCT. Parametric studies of the total extraction holes area and their axial locations show that the compressor performance deteriorates as the area ratio increases but the stall margin is extended and there is an optimum extraction holes axial location for stall margin extending. The better configuration of MHCT could extend the stall margin by 6.2% with only 0.23% peak efficiency reduction. Detailed analysis of the physical mechanism behind the stall margin improvement shows that the casing treatment could eliminate the passage blockage by suppressing breakup of tip leakage vortex and decrease the blade load in tip region, which both contribute to improve stall margin of transonic axial compressors. | YANG Chengwu ZHAO Shengfeng LU Xingen HAN Ge ZHU Junqiang | 2014 | Journal of Thermal Science2014，23，4： | 6 |
| 2 | Flow mechanism between purge flow and mainstream in different turbine rim seal configurations显示文摘The rim seal is used to prevent mainstream ingestion to the gap between the vane of a turbine and its blade. In this article, the dolphin lip with a hook configuration and a large seal cavity with hook structures are designed based on the high-pressure turbine datum single shark lip rim seal configuration. The sealing effect and parameters of the flow field are measured by an experiment method and a numerical simulation is used to explain the mechanism. For three configurations,the effect of the leakage slot vortex on the efficiency of the seal and the influence of leakage vortex,generated by the interaction between purge flow and mainstream flow, are discussed in depth. The result shows that the reverse vortex formed by the dolphin lip rim seal with hook structure will increase the sealing efficiency. The seal configuration with a large cavity improves sealing efficiency to a greater extent than the datum structure. At different purge flow rates and with unequal seal structures, the purge flow produces three types of leakage vortices in the passage. Besides, the seal configuration with dolphin lip produces a Kelvin-Helmholtz instability at the interface of the purge and the mainstream flows at a low purge flow rate to induce new leakage vortex branches in the passage of the blade. | Ziqing ZHANG Yingjie ZHANG Xu DONG Xiao QU Xingen LU Yanfeng ZHANG | 2020 | Chinese Journal of Aeronautics2020，33，8： | 5 |
| 3 | Numerical Investigation of the Unsteady Tip Leakage Flow and Rotating Stall Inception in a Transonic Compressor显示文摘It is well known that tip leakage flow has a strong effect on the compressor performance and stability. This paper reports on a numerical investigation of detailed flow structures in an isolated transonic compressor rotor-NASA Rotor 37 at near stall and stalled conditions aimed at improving understanding of changes in 3D tip leakage flow structures with rotating stall inception.Steady and unsteady 3D Navier-Stokes analyses were conducted to investigate flow structures in the same rotor.For steady analysis,the predicted results agree well with the experimental data for the estimation of compressor rotor global performance.For unsteady flow analysis, the unsteady flow nature caused by the breakdown of the tip leakage vortex in blade tip region in the transonic compressor rotor at near stall condition has been captured with a single blade passage.On the other hand, the time-accurate unsteady computations of multi-blade passage at near stall condition indicate that the unsteady breakdown of the tip leakage vortex triggered the short length-scale-spike type rotating stall inception at blade tip region.It was the forward spillage of the tip leakage flow at blade leading edge resulting in the spike stall inception. As the mass flow ratio is decreased,the rotating stall cell was further developed in the blade passage. | Yanfeng Zhang Xingen Lu Wuli Chu Junqiang Zhu | 2010 | Journal of Thermal Science2010，19，4： | 5 |
| 4 | Numerical Investigation of a High-subsonic Axial-flow Compressor Rotor with Non-axisymmetric Hub Endwall显示文摘The major source of loss in modern compressors is the secondary loss.Non-axisymmetric endwall profile contouring is now a well established design methodology in axial flow turbines.However,flow development in axial compressors is differ from turbines,the effects of non-axisymmetric endwall to axial compressors requires flow analysis in detail.This paper presents both experimental and numerical data to deal with the application of a non-axisymmetric hub endwall in a high-subsonic axial-flow compressor.The aims of the experiment here were to make sure the numerically obtained flow fields is the physical mechanism responsible for the improvement in efficiency,due to the non-axisymmetric hub endwall.The computational results were first compared with available measured data of axisymmetric hub endwall.The results agreed well with the experimental data for estimation of the global performance.The coupled flow of the compressor rotor with non-axisymmetric hub endwall was simulated by a state-of-the-art multi-block flow solver.The non-axisymmetric hub endwall was designed for a subsonic compressor rotor with the help of sine and cosine functions.This type of non-axisymmetric hub endwall was found to have a significant improvement in efficiency of 0.45% approximately and a slightly increase for the total pressure ratio.The fundamental mechanisms of non-axisymmetric hub endwall and their effects on the subsonic axial-flow compressor endwall flow field were analyzed in detail.It is concluded that the non-axisymmetric endwall profiling,though not optimum,can mitigate the secondary flow in the vicinity of the hub endwall,resulting in the improvement of aerodynamic performance of the compressor rotor. | Shuzhen Hu Xingen Lu Hongwu Zhang Junqiang Zhu Qiang Xu | 2010 | Journal of Thermal Science2010，19，1： | 4 |
| 5 | The Influence of Wedge Diffuser Blade Number and Divergence Angle on the Performance of a High Pressure Ratio Centrifugal Compressor显示文摘Wedge diffuser is widely used in centrifugal compressors due to its high performance and compact size. This paper is aimed to research the influence of wedge diffuser blade number and divergence angle on centrifugal compressor performance. The impact of wedge diffuser blade number on compressor stage performance is investigated, and then the wedge diffusers with different divergence angle are studied by varying diffuser wedge angle and blade number simultaneously. It is found that wedge diffuser with 27 blades could have about 0.8% higher adiabatic efficiency and 0.14 higher total pressure ratio than the wedge diffuser with 19 blades and the best compressor performance is achieved when diffuser divergence angle is 8.3°.These results could give some advices on centrifugal compressor design. | WANG Yi HAN Ge LU Xingen ZHU Junqiang | 2018 | Journal of Thermal Science2018，27，1： | 4 |
| 6 | Unsteady wakes-secondary flow interactions in a high-lift low-pressure turbine cascade显示文摘Detailed experimental measurements were conducted to study the interactions between incoming wakes and endwall secondary flow in a high-lift Low-Pressure Turbine(LPT)cascade.All of the measurements were conducted in both the presence and absence of incoming wakes,and numerical analysis was performed to elucidate the flow mechanism.With increasing Reynolds number,the influence of the incoming wakes on suppressing the secondary flow gradually increased owing to the greater influence of incoming wakes on reducing the negative incidence angle at higher Reynolds numbers,leading to a lower blade loading near the leading edge and suppression of the Pressure Side(PS)leg of the horseshoe vortex.However,the effect of unsteady wakes on suppressing the profile losses gradually became weaker owing to the reduced size of the Suction Side(SS)separation bubble and increased mixing loss in the free-flow region at high Reynolds numbers.Incoming wakes clearly improved the aerodynamic performance of the low-pressure turbine cascade at low Reynolds numbers of 25,000 and 50,000.In contrast,at the high Reynolds number of 100,000,the profile loss at the midspan and mass-averaged total losses downstream of the cascade were higher in the presence of wakes than in the absence of wakes,and the unsteady wakes exerted a negative influence on the aerodynamic performance of the LPT cascade. | Xiao QU Yanfeng ZHANG Xingen LU Junqiang ZHU | 2020 | Chinese Journal of Aeronautics2020，33，3： | 3 |
| 7 | Unsteady experimental and numerical investigation of aerodynamic performance in ultra-high-lift LPT显示文摘Detailed experimental and numerical investigations were performed for an ultra-high-lift front-loaded low-pressure turbine cascade (Zw=1.58) with periodic wakes.The interaction mechanisms between the incoming wakes and endwall secondary flow were carefully examined.Wakes were produced by moving upstream rods,and flow field downstream of the cascade was measured using a seven-hole probe.Experimental results revealed that incoming wakes influenced not only the boundary layer development of the blade suction surface but also the complex endwall secondary vortex structures.On the suction surface:Incoming wakes clearly suppressed the suction side separation bubble at a low Reynolds number of 25000.Nevertheless,the effects of different wake passing frequencies were not significantly different at Re=100000,and the profile losses under wake passing were even greater than in the absence of wakes.At the end walls:Incoming wakes more strongly suppressed secondary flow at Re=100000 than at Re=25000,because the lowmomentum fluid inside the incoming wakes clearly increased the endwall cross-passage pressure gradient at Re=25000.The experimental results indicated that periodic wakes decreased the passage vortex and counter vortex core strength by 25% and 30%,respectively,at Re=100000.Instantaneous results also demonstrated that endwall secondary vortices decreased significantly near the position of wakes passing. | Xiao QU Yanfeng ZHANG Xingen LU Junqiang ZHU | 2020 | Chinese Journal of Aeronautics2020，33，5： | 2 |
| 8 | Numerical Investigation of the Bowed Stator Effects in a Transonic Fan at LowReynolds Number显示文摘The performance of fan stage in a small turbofan engines is significantly affected at high-altitude low Reynolds number. In order to examine the effect of low Reynolds number on the fan stage, 3D numerical simulation method was employed to analyse the performance variations and the underlying flow structure in the fan stage. For the sake of decreasing the influence of low Reynolds number, the different bowed stator airfoils were redesigned and the effect of the modified design was evaluated. | HUANG Enliang ZHAO Shengfeng GONG Jianbo LU Xingen ZHU Junqiang | 2017 | Journal of Thermal Science2017，26，1： | 2 |
| 9 | Experimental and numerical investigation of a subsonic compressor with skewed slots casing treatment显示文摘 | LU Xingen CHU Wuli ZHU Junqiang | 2006 | Proceedings of the Institution of Mechanical Engineers Part C:Journal of Mechanical Engineering Science2006，220，12： | 1 |
| 10 | Numerical Investigation of Centerline Curvature Effects on a Compact S-shaped Intake显示文摘Taking into account stealth, structure and maintenance, ultra-compact S-shaped intake has been widely used in modern vehicles. In this paper a series of steady numerical simulation were carried out to investigate the complex flow mechanism in s-shaped intake, particular attention was given to examining the effect of centerline curvature on the performance and flowfield of an ultra-compact S-shaped intake. In order to validate the multi-block model, the computational results for Royal Aircraft Establishment intake 2129-M2129 which had modest centerline curvature distribution were corrected with available experimental test data. The numerical simulation results agreed fairly well with the experimental data, and the computational method was then used to investigate the effects of different centerline curvature distributions on performance and flow field in compact S-shaped intake. Detailed analyses of the flow visualization had exposed the different flow topologies between the cases with different centerline curvature. It was found that different centerline curvature distributions changed the initial location and the size of separation bubble, as well as the strength of two counter-rotating vortices at the entrance of engine. | Enliang Huang Shengfeng Zhao Zhijun Lei Jianxiong Kang Xingen Lu Junqiang Zhu | 2012 | Journal of Thermal Science2012，21，5： | 1 |
| 11 | Numerical investigations of the coupled flow through a subsonic corn-pressor rotor and axial skewed shot 显示文摘 | Lu Xingen Chu Wuli Zhu Junqiang | 2009 | Journal of Turbo- machinery2009，131，1： | 1 |
| 12 | Performance Improvements of a Subsonic Axial-Flow Compressor by Means of a Non-Axisymmetric Stator Hub End-Wall显示文摘This paper deals with the application of a non-axisymmetric 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 configuration 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 subsonic axial-flow compressor stator end-wall flow field structure, the coupled flow of the compressor stage with the baseline, axisymmetric and the non-axisymmetric stator hub end-wall was simulated with a state-of-theart multi-block flow 3D CFD solver. Based on the CFD simulations, the optimal compressor hub end-wall configuration is expected to increase the peak efficiency by approximately 2.04 points and a slight increase of the total 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-axisymmetric 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. | ZHANG Xuefeng LU Xingen ZHU Junqiang | 2013 | Journal of Thermal Science2013，22，6： | 1 |
| 13 | An Experimental Study of Separation Control on Ultra-Highly-Loaded Low Pressure Turbine Blade by Surface Roughness显示文摘An experimental study is conducted to improve an aft-loaded ultra-high-lift low pressure turbine(LPT) blade at low Reynolds number(Re) in steady state. The objective is to investigate the effect of blade roughness on the performance of LPT blade. The roughness is used as a passive flow control method which is to reduce total pressure loss and expand LPT operating margin. The experiment is performed on a low-speed cascade facility. 3 roughness heights and 3 deposit positions are investigated in the experiment which forms a large test matrix. A three-hole probe is used to detect flow aerodynamic performance and a hotwire probe is used to detect the characteristic of suction boundary layer. Regional roughness can suppress separation loss and bring fairly low turbulent dissipation loss. Detailed surveys near the blade surface shows that the loss reduction is due to the disappearance of separation bubble from the early transition onset. | SUN Shuang LEI Zhijun LU Xingen ZHAO Shengfeng ZHU Junqiang | 2015 | Journal of Thermal Science2015，24，3： | 1 |
| 14 | Exploring the intention of Using Aspirated Cascade to Replace Tandem Cascades显示文摘In the present paper,computational fluid dynamics(CFD) simulations were executed to exploring the intent of using aspirated cascade to replace tandem cascades.Firstly,the ONERA tandem cascades were investigated,and the performance of the cascades at the design point were listed,such as diffusion factor,total pressure loss coefficient,deviation angle etc.For replacing the ONERA tandem cascades,a new cascade was designed with the codes BLADEGEN developed by the authors.The quasi 3-D calculations were carried out using the collection of programs for cascade analysis and design,MISES.The cascade was analyzed and designed by using this code.And the cascade was simulated and analyzed by commercial CFD software.It is found there is an obvious separation on the suction side.Based on the 3D CFD simulation results of the cascade without aspiration,an aspirated cascade was designed by introducing a slot on the suction side.The performance of the aspirated cascade was investigated and compared with the tandem cascades,indicated that under the same inlet condition,the total pressure loss of the single row aspirated cascade was less than that of the tandem cascades,and the outlet static pressure is higher than that of the tandem cascades.Meanwhile,the different suction slot location,suction width and suction mass flow are studied for the aspirated cascade. | Shengfeng Zhao Jianfeng Luo Xingen Lu Junqiang Zhu | 2010 | Journal of Thermal Science2010，19，5： | 0 |
| 15 | Leakage and wear characteristics of carbon seals for aero-engines显示文摘Experimental investigation has been performed to study the leakage and wear characteristics of carbon seal working at high circumferential speed. To expand the scope of application, two newly designed carbon seals were compared: #1 Carbon Seal(CS1) with the inner diameter of136 mm and including 4 segments, #2 Carbon Seal(CS2) with the inner diameter of 212 mm and including 6 segments. Air leakage tests were firstly conducted in the Medium-speed Seal Test Rig. The pressure ratio changed from 1.04 to 2.02 with the rotating speed varying from 0 to18300 r/min. Of paramount concern was the durability test, including 300 h running time accumulated by three different working conditions, which was separately implemented on each carbon seal.The morphology variation of the friction surface, wear and leakage were recorded. Results indicated that the leakage monotonously increases with the pressure ratio and decreases with the rotating speed. Comparing with CS1, more typical features exist on the friction surface of CS2, which are generated by more severe wear. Continually, leakage characteristics deteriorate. Furthermore, fitted formula has been educed for the life prediction of carbon seal, which could provide some supports for aero-engine design. | Guoqing LI Shen ZHANG Zhong KANG Yanfeng ZHANG Xingen LU Junqiang ZHU | 2022 | Chinese Journal of Aeronautics2022，35，11： | 0 |
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