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EXPERIMENTAL INVESTIGATION ON vortex breakdown IN SPIN-UP AND SPIN-DOWN PROCESSES VIA PIV

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Journal of Hydrodynamics 2003年第2期15卷 58-63页

作者： LiuYing-zheng KoyamaHideS. ChenHan-ping DepartmentofPowerMachineryEngineering ShanghaiJiaotongUniversityShanghai200030China DepartmentofMechanicalEngineering TokyoDenkiUniversityTokyo101-8457Japan

The whole field measurements of swirling flow in spin-up and spin-downprocesses via PIV are presented in the paper. Investigation of the flow patterns at H/R = 1. 50 wasexperimentally carried out for the first time in both processes. By means of symmetry analysis, itis found that the overall flow structure in the spin-up process still keep axi-symmetric to a greatextent, but deteriorated very fast in the spin-down process. The time to settle to the state of restin the spin-down process is found to be greatly shorter than the time to achieve the steady statein the spin-up process. Temporarily oscillatory vortex breakdown was discovered during the spin-upprocess, although no breakdown in the steady state at the same Reynolds number is found in preciousresearches.

关键词： vortex breakdown PIV swirling flow

JOINT INVESTIGATION OF ROTATING FLOW WITH vortex breakdown USING CFD, VISUALIZATION AND LDV

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Journal of Hydrodynamics 2005年第4期17卷 455-458页

作者： LIU Ying-zheng CHEN Han-ping KOYAMA Hide S. School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China Department of Mechanical Engineering Tokyo Denki University Tokyo Japan

vortex breakdown of the steady axisymmetic rotating flow in a confined cylindrical container with a rotating endwall was numerically and experimentally studied. High-quality precision-controlled turntable facilities were established at Shanghai Jiaotong University and Tokyo Denki University independently. Collaborative investigations of vortex breakdown were carried out using CFD, Laser Doppler Velocimetry （LDV） and streakline visualization, respectively. The characteristics of vortex breakdown were delineated in terms of comparative investigation using numerical and experimental results. SIMPLEC scheme and FMG multigrid was applied to numerical simulation. Numerical simulation was extensively compared with streakline visualization and LDV measurements, showing qualitative and quantitative agreements.

关键词： vortex breakdown CFD visualization Laser Doppler Velocimetry (LDV)

NUMERICAL SIMULATION OF vortex breakdown ON A DELTA WING AT LOW SPEED

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Chinese Journal of Aeronautics 1996年第4期9卷 235-238页

作者： Zhu Ziqiang Jia Jianbo(Institute of Fluid Mechanics, Beijing University Of Aeronauticsand Astronautics, Beijing, China, 100083 ) Institute of Fluid Mechanics Beijing Univ. Aero. and Astronaut. Beijing 100083 China

The incompressible N-S equations are solved by using a pseudo-compressibility method. Computation is made for both 60°and 70°sharp edged delta wings. Thepredictions for position and angle attack of vortex breakdown are investigated. The effectof the leading edge sweep angle on vortex breakdown is also discussed. Numerical resultsshow that the present method is an effective tool for investigation of vortex breakdown atlow speed.

关键词： vortex breakdown incompressible flow Navier-Stokes equation pseudocompressibility method

EXPERIMENTS AND ANALYSIS OF HYSTERESIS OF vortex breakdown OVER PITCHING-UP DELTA WINGS

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Chinese Journal of Aeronautics 1997年第1期10卷 9-13页

作者： Yang Xiaofeng L■ Zhiyong(Institute of Fluid Mechanics, Beijing University of Aeronauticsand Astronautics, Beijing, 100083, China) Institute of Fluid Mechanics Beijing Univ. Aero. and Astronaut. Beijing 100083 China

An investigation of the hysteresis of vortex breakdown over pitching-up deltawings is presented. Based on experiments, there are two main reasons which can be usedto explain the hysteresis of vortex breakdown. One is the time or phase lag due to the ini-tial suPerPOsition of linearized small disturbance, which enlarges the range of the incidenceof keeping attached flow and postpones the initial incidence of vortex breakdown. Theother is the reduction of adverse pressure gradient due to the periphery centrifugal instabil-ity after the concentrated vortex has come into being, which is the key reason of hystere-sis of vortex breakdown- The structure of vortex over a pitching up delta wing can be di-vided into three layers, which is not a significant a1teration compared with that of vortexover a static delta wing.

关键词： delta wings vortex breakdown centrifuging stability adverse pressure gradient pitching-up phase lag

Analysis of Shock and vortex breakdown Behavior in Unsteady Transonic Flow on A Slender Delta Wing

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Analysis of Shock and Vortex Breakdown Behavior in Unsteady ...

Aerodynamics of a Tandem-Bladed Axial Compressor Rotor under Circumferential Distortion at Different Rotational Speeds

2010亚太航空航天技术研讨会

作者： Li Xile~* Yang Yong Jiao Jin National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University Xi’an 710072 China

＜正＞A transonic flow around delta wing with sharp leading edge is simulated by detached eddy simulation（DES） *** behavior of the complex shock waves in unsteady flow on the top surface of delta wing is analyzed at moderate and high angles of *** well as the movement of the location of vortex breakdown induced by the *** results indicate that three normal shock waves exist on the top surface of delta wing at both incidence *** angle of incidence ofα=18.5°,the rear/terminating shock propagates upstream to the sting tip from trailing edge periodically,the strength of shock becomes weaker as it moves ***,the rear/ terminating shock amalgamates with the normal shock wave at the sting *** location of vortex breakdown is close to the trailing edge. At angle of incidence ofα=23°,a second shock appears upstream of the sting tip,which moves analogically with the terminating shock for the case ofα=18.5°,it indicates that this shock is the rear/terminating shock having undergone an upstream shift with the increase of *** while,the location of vortex breakdown induced by second shock moves periodically.

关键词： delta wing DES shock wave vortex breakdown periodic movement

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Journal of Thermal Science 2024年第4期33卷 1340-1356页

作者： Amit KUMAR Jerry T.JOHN A.M.PRADEEP R.A.DAKKERMANS Dragan KOZULOVIC Department of Aerospace Engineering Indian Institute of Technology BombayMumbai400076India Department of Automotive and Aeronautical Engineering Hamburg University of Applied Sciences20099HamburgGermany Institute of Jet Propulsion Bundeswehr University Munich85577NeubibergGermany

For most aircraft engines,inflow distortion is *** distortion is known to degrade the aerodynamic performance and stable operating limits of a *** rotor configuration is an arrangement that effectively controls the growth of the boundary layer over the suction surface of the ***,a higher total pressure rise can be achieved through this unconventional design approach involving the splitting of the blade into forward and aft *** is expected that the effect of inlet flow distortion would be more severe for a tandem-rotor design due to the greater flow turning inherent in such ***,this aspect needs to be thoroughly *** present study discusses the effect of circumferential distortion on the tandem-rotor at different rotational ***-annulus RANS simulations using ANSYS CFX are used in the present *** performance of the rotor at a particular flow coefficient and different rotational speeds is *** total pressure and efficiency are observed to drop at lower mass flow rates under the influence of circumferential *** loss region in each blade passage is mainly associated with the blade wake,tip leakage vortex,secondary flow,and boundary ***,their contribution varies from passage to passage,particularly in the distorted *** the lower span,the wake width is found to be higher than that at a higher *** to the redistribution of the mass flow,the circumferential extent reduces at a higher *** the undistorted sector,the strength of the tip leakage vortex is significantly higher at the design rotational speed than at lower *** distortion near the tip region promotes an early vortex breakdown even at the design operating *** adversely affects the total pressure,efficiency,and stall *** clean flow conditions,this phenomenon is only observed near the stall *** the design operating condition,the breakdown of the forward rotor tip l

关键词： tandem rotor circumferential distortion loss tip leakage vortex vortex breakdown diffusion factor aerodynamics of compressor blade

Investigation of flow unsteadiness in a highly-loaded compressor cascade using a dynamic mode decomposition method

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Chinese Journal of Aeronautics 2022年第5期35卷 275-290页

作者： Guangyao AN Yanhui WU Jinhua LANG Zhiyang CHEN Xiaobing ZHOU School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China Shaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine Xi’an 710129China

Unsteady flow in the hub endwall region has long been a hot topic in the turbomachinery *** important it is to the performance of the whole engine,the coherent unsteady flow phenomena are still not well *** this paper,the complex flow field in the hub endwall of a cantilevered compressor cascade has been investigated through numerical *** predicted results were validated by experimental *** highlight the dominant flow structures among irregular and chaotic motions of various vortices,a Dynamic Mode Decomposition(DMD)method was *** results show that there exist three dominant periodic flow structures:the oscillation of the leakage vortex,a circumferential migration of a breakdown Induced vortex(BIV)and the fluctuation of the passage *** three coherent structures all together form a self-sustained closed loop which accounts for the flow unsteadiness of the studied *** this process,the BIV plays a key role in inducing the flow *** if the BIV is strong enough to affect the passage vortex,the flow unsteadiness *** study expands current knowledge base of flow unsteadiness in a compressor environment,and shows the efficacy of the DMD method for revealing the origin of flow unsteadiness.

关键词： Cascade Compressor Dynamic Mode Decomposition(DMD) Endwall Unsteady flow vortex breakdown

Understanding of tip clearance flow structure in high speed mixed flow compressor

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Propulsion and Power Research 2023年第3期12卷 356-379页

作者： Hemant Kumar Chetan S.Mistry Department of Aerospace Engineering Indian Institute of TechnologyKharagpurWest Bengal 721302India

This paper addresses the necessity to make a physical interpretation of a highly complex three-dimensional tip clearance flow field study for high-speed mixed-flow compressor having stage exit static pressure to inlet total pressure ratio of 3.8 with 39,836 rpm rotor *** four different tip configurations namely the constant(l Z 0.016 and 0.019)and variable(l Z 0.011(inlet)-0.019(exit)and 0.019(inlet)-0.022(exit))tip clearances were numerically analysed using available experimental *** numerical investigation reveals that in contrast to the classic jet-wake pattern,two anomalous velocity profiles formed at the impeller exit which results in pressure losses in the vaneless *** the impeller inlet,the tip leakage flow rolls up to discrete tip leakage vortex structure for each tip clearance *** results in the formation of a region of momentum deficit,recirculation zone,which gets weakened as it moves *** tip clearance configuration is observed to profoundly influence the extent and vorticity of the tip leakage *** the splitter blade passage,the tip leakage flow and Coriolis flow interact with passage flow,resulting in the formation of two secondary passage vortices that move downstream along the pressure and suction surface of the splitter *** tip clearance configuration directly influences the impeller exit jetwake pattern by modulating the secondary passage vortices trajectory and ***,off-design analysis for tip clearances l Z 0.016 and l Z 0.019,depict distinctive tip leakage vortex *** operating near the stall conditions(80%of design mass flow rate),l Z 0.019 exhibits bubble shape tip leakage vortex breakdown occurring near the impeller *** result in a substantial change in the tip leakage vortex nature;expansion of the recirculation zone and early weakening of the vorticity in the tip leakage *** is observed that vortex breakdown plays a vital role in characte

关键词： Recirculation zone vortex breakdown Tip leakage flow Mixed-flow compressor Jet-wake flow Vaned-diffuser

Supersonic flow over a pitching delta wing using surface pressure measurements and numerical simulations

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Chinese Journal of Aeronautics 2018年第1期31卷 65-78页

作者： Mostafa HADIDOOLABI Hossein ANSARIAN Aerospace Engineering Department Malek Ashtar University of Technology

Experimental and numerical methods were applied to investigating high subsonic and supersonic flows over a 60°swept delta wing in fixed state and pitching oscillation. Static pressure coefficient distributions over the wing leeward surface and the hysteresis loops of pressure coefficient versus angle of attack at the sensor locations were obtained by wind tunnel tests. Similar results were obtained by numerical simulations which agreed well with the experiments. Flow structure around the wing was also demonstrated by the numerical simulation. Effects of Mach number and angle of attack on pressure distribution curves in static tests were investigated. Effects of various oscillation parameters including Mach number, mean angle of attack, pitching amplitude and frequency on hysteresis loops were investigated in dynamic tests and the associated physical mechanisms were discussed. vortex breakdown phenomenon over the wing was identified at high angles of attack using the pressure coefficient curves and hysteresis loops, and its effects on the flow features were discussed.

关键词： Delta wing Hysteresis loop Pitching oscillation Supersonic flow vortex breakdown