Investigation Of Performance Test And Flow Field Characteristics Under Bend Pipe Inlet Conditions In Centrifugal Compressor

Centrifugal compressor is widely utilized in automotive turbochargers at present.In order to ensure uniform inlet conditions,the design and research of centrifugal compressor are based on straight pipe inet conditions.In fact,the form of elbow inlet is inevitable,and the distortion caused by the elbow inlet affects the performance and internal flow field of the compressor. In addition, the stall has been a difficult focus in the field of compressor, not only affects the stable operating range of the centrifugal compressor, but also directly affects the system’s security,so study the mechanism of stall and its development process is basis to avoid the stall and broaden the stable working range of the compressor.According to the existing research status,the theis mainly research two aspects based on a compressor used in automotive turbochargers: one is the influence of bend pipe on performance and internal flow field of compressor,another is the stall of compressor under straight pipe inlet condition.Firstly,the influence of bend pipe inlet on the compressor’s performance and internal flow field is studied by experimental methods. Compared with the straight pipe inlet, the 90° elbow inlet affect the performance of compressor least, 270° elbow inlet has the greatest influence on the performance, the influence of 0° and 180° elbow inlet are between the above two, and the influence is especially significant under big massflow. The static pressure distribution of rim shows that 90° elbow inlet is mostly same with straight pipe inlet, but the 270° elbow inlet is obviously descreased.Secondly, the numerical simulation is applied to study the vortex distortion caused by the elbow inlet and the influence on the downstream flow field. Find that 0° and 180° elbow inlet produce twin vortex, 90° and 270° elbow inlet produce offset vortex.The prewhirl flow caused by the vortex affects the impeller import relative flow angle, impellor channel and the flow field of volute inlet.Finally, use the experimental methods to study the stall occurrence and development process, get the ratio characteristic and the dynamic pressure in the different stage of stall process.Results show that stall inception is modal stall.Through the spectral analyses of dynamic pressure,find the stall process and stall frequency,also find the different surge energy due to the different locations.