Impact of inlet distortion on turbocharger compressor stage performance

In a turbocharger system, curved pipes are usually used to connect compressors with other parts due to limited packaging space. It is well known that an elbow can generate flow distortion to and interact with the compressor inducer and therefore deteriorate compressor stage performance. The compressor efficiency change may vary with relative positions of inlet elbow and volute. The compressor's stable flow range is also possible to vary due to the shift of surge and/or chock points. In this paper, eight relative circumferential positions between the inlet elbow and the volute were studied by 3D numerical simulations with experimental validations. The numerical results confirm that adjusting the inlet bend from one circumferential orientation to others does cause an obvious deviation in the compressor aerodynamic efficiency. The result also indicates that the total pressure deficit and the vortices at the compressor inlet are the main contributors to the compressor operating range. With the numerical findings in this paper which was validated by experimental measurements, it is suggested that unfavorable orientations of an elbow relative to volute should be avoided in an intake system.