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Numerical Investigation of Rotating Stall in Centrifugal Compressor with Vaned and vaneless diffuser

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Journal of Thermal Science 2015年第4期24卷 323-333页

作者： Taher Halawa Mohamed Alqaradawi Mohamed S.Gadala Ibrahim Shahin Osama Badr Mechanical Engineering Department UBC-University of British ColumbiaVancouverB.C.Canada Mechanical Engineering Department Cairo University Mechanical & Industrial Engineering Department Qatar University Mechanical Engineering Department Abu Dhabi University Mechanical and Industrial Engineering Department Qatar UniversityDohaQatar Mechanical Engineering Department Benha University Mechanical Engineering Department British University

This study presents a numerical simulation of the stall and surge in a centrifugal compressor and presents a description of the stall development in two different *** first case is for a compressor with vaneless diffuser and the second is for a compressor with vaned diffuser of the vane island *** main aim of this study is to compare the flow characteristics and behavior for the two compressors near the surge operating condition and provide further understanding of the diffuser role when back flow occurs at *** showed that for a location near the diffuser entrance,the amplitude of the static pressure fluctuations for the vaneless diffuser case is higher than that for the vaned diffuser case near surge *** pressure fluctuations in the case of the vaneless diffuser appear with a gradual decrease of the mean pressure value as a part of the surge *** for the case of the vaned diffuser,the pressure drop during surge occurs faster than the case of the vaneless ***,results indicated that during surge in the case of vaneless diffuser,there is a region with low velocity and back flow that appears as a layer connecting all impeller passages near shroud surface and this layer develops in size with *** the other hand,for the case of vaned diffuser during surge,the low velocity regions appear in random locations in some passages and these regions expand with time towards the shroud *** showed that during stall,the impeller passages are exposed to identical impact from stall cells in the case of vaneless diffuser while the stall effect varies from passage to another in the case of the vaned diffuser.

关键词： centrifugal compressors rotating stall surge vaneless diffuser vaned diffuser

Computational and Experimental Study of Pinch on the Performance of a vaneless diffuser in a Centrifugal Compressor

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Journal of Thermal Science 2006年第4期15卷 306-313页

作者： T.Turunen-Saaresti A.Reunanen J.Larjola Lappeenranta University of Technology Department of Energy and Environmental TechnologyLappeenrantaFinland teemu

This study focuses on the vaneless diffuser of a centrifugal compressor. The examined stage consists of an unshrouded impeller, a parallel wall vaneless diffuser and a volute. The walls of the diffuser were movable allowing different pinch configurations to be investigated. The baseline geometry had no pinch i.e. the height of the diffuser was equal to the height of the impeller flow channel plus the axial running clearance. The work consists of both numerical and experimental parts. Quasi-steady, turbulent, fully 3D numerical simulations were conducted. The inlet cone, rotor and diffuser were modelled. Six different configurations were studied. The height of the pinch was altered and the pinch made to different walls was tested. Two of the numerically studied cases were also experimentally investigated. The overall performance of the compressor, the circumferential static and total pressure and the spanwise total pressure distribution before and after the diffuser were measured. The numerical and experimental studies showed that the pinch improved the efficiency of the compressor.

关键词： Centrifugal compressor vaneless diffuser pinch

Receptivity and structural sensitivity study of the wide vaneless diffuser flow with adjoint method

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Chinese Journal of Aeronautics 2018年第8期31卷 1679-1690页

作者： Xiaocheng ZHU Chenxing HU Zezhao LIU Hao LIU Zhaohui DU School of Mechanical Engineering/2011 Aero-Engine Collaborative Innovation Center Shanghai Jiao Tong University College of Politics and Law Hebei University

The stability of the flow in the vaneless diffuser of a centrifugal compressor is studied with the linear theory. The characteristics of direct and adjoint perturbation modes are investigated,and the receptivity of the instability mode to momentum forcing or mass injection is identified based on the adjoint modes. Analysis shows that the perturbation with the largest amplitude is located at the outlet of the vaneless diffuser, while the highest-receptivity region is located in the middle of the vaneless diffuser along the radial direction. The large difference between the direct and adjoint modes indicates that the instability mechanism cannot be identified from a study of either eigenmode separately. Therefore, the structural sensitivity analysis is adopted to study the feedback of the instability mode. The structural sensitivity of the eigenvalue which is proportional to the perturbation pressure and velocity is used to explain the mechanism of flow control for the vaneless diffuser.

关键词： Adjoint method Receptivity Rotating stall Structural sensitivity vaneless diffuser

Rotating instability in the vaneless diffuser of a radial flow pump

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Journal of Thermal Science 2008年第4期17卷 368-374页

作者： A.Dazin O.Coutier-Delgosha P.Dupont S.Coudert G.Caignaert G.Bois Laboratoire de Mécanique de Lille(UMR CNRS 8107) Arts et Métiers ParisTech Laboratoire de Mécanique de Lille Ecole Centrale de Lille Laboratoire de Mécanique de Lille CNRS

The paper refers to the behavior of a vaneless diffuser of a radial flow pump in partial flow operating conditions. Some experimental data have been obtained using 2D/2C PIV and unsteady pressure measurements within the diffuser, in various operating conditions. The experimental results at the lower flow rate are compared with two-dimensional numerical calculations.

关键词： vaneless diffuser Radial flow pump Instability Particle Image Velocimetry Pressure measurements 2D calculations.

Effect of diffuser Vane Shape on the Performance of a Centrifugal Compressor Stage

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Journal of Thermal Science 2014年第2期23卷 127-132页

作者： T Ch Siva Reddy GV Ramana Murty MVSSSM Prasad Sreenidhi Institute of Science and Technology GhatkesarHyderabadA.P.India Vasavi College of Engineering Hhyderabad

The present paper reports the results of experimental investigations on the effect of diffuser vane shape on the performance of a centrifugal compressor stage. These studies were conducted on the chosen stage having a back- ward curved impeller of 500 turn tip diameter and 24.5 mm width and its design flow coefficient is Фd=0.0535. Three different low solidity diffuser vane shapes namely uncarnbered aerofoil, constant thickness flat plate and circular arc cambered constant thickness plate were chosen as the variants for diffuser vane shape and all the three shapes have the same thickness to chord ratio （t/c=0.1）. Flow coefficient, polytropic efficiency, total head coeffi- cient, power coefficient and static pressure recovery coefficient were chosen as the parameters for evaluating the effect of diffuser vane shape on the stage performance. The results show that there is reasonable improvement in stage efficiency and total head coefficient with the use of the chosen diffuser vane shapes as compared to conven- tional vaneless diffuser. It is also noticed that the aero foil shaped LSD has shown better performance when com- pared to flat plate and circular arc profiles. The aerofoil vane shape of the diffuser blade is seen to be tolerant over a considerable range of incidence.

关键词： Centrifugal compressor vaneless diffuser Low solidity diffuser

EXPERIMENTAL INVESTIGATION OF ROTATING STALL FOR A LOW-SPEED CENTRIFUGAL COMPRESSOR

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Chinese Journal of Mechanical Engineering 2008年第3期21卷 76-83页

作者： ZHU Xiaocheng GUO Qiang DU Zhaohui CHEN Hua ZHAO Yan School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China Honeywell Corporation Shanghai 200030 China

Unsteady flows and rotating stall of a low-speed centrifugal compressor are investigated by measuring vaneless diffuser wall static pressure fluctuation and internal flow fields at different small flow fluxes. During the experiment, firstly the real time static pressure fluctuations on the vaneless diffuser shroud at different circumferential and radial position were acquired by high-frequency dynamic pressure transducers. Discrete Fourier transformation analysis and cross-correlation analysis were applied to the experimental results to ascertain the rotating stall beginning operation conditions and stall cells numbers and rotating speed. Secondly, the vaneless diffuser inlet flow angle distribution along diffuser width direction was acquired by single hotwire, which was compared with SENOO＇s analysis results. At last, the internal flow fields of the centrifugal compressor were investigated with a particle image velocimetry （PIV） system at different small flow fluxes. The flow field development of vaneless diffuser and blade flow passage are given at rotating stall conditions. The experiments enrich the understanding of rotating stall flow phenomenon of the low-speed centrifugal compressor and provide full experiment data for designing high performance centrifugal compressor.

关键词： Rotating stall Centrifugal compressor vaneless diffuser Particle image velocimetry (PIV)