Influence Of Air Intake Distortion On Performance Of Centrifugal Compressor

As an important small aircraft engine and exhaust turbocharger components,centrifugal compressor is widely used in automotive,military and other industries.In practical applications,the bent pipes are usually adopted in the intake inlets of the vehicle turbocharger centrifugal compressors due to the limitation of the arrangement of the engine.While the air flow through the elbow,under the action of centrifugal force and viscous force,in the inlet flow field there will be complex total pressure distortion and whirlpool distortion.As the using of the circumferential asymmetric geometric structure of the volute at the centrifugal compressor downstream,resulting the internal flow field with circumferential nonuniformity in volute and compressor,and the reduced performance of compressor.The intake air distortion caused by the intake form of the bend coupled with the circumferential heterogeneity of the flow field caused by the volute so the compressor flow field complex changes,The compressor performance and stability of the scope of work have a significant impact.Based on this,this article adopts the method of experiment and numerical simulation,take the centrifugal compressor used on the turbocharger as the object of study and studied the 180 ° elbow intake model for two mounting angles,At the same time,we also studied the four-screw-type centrifugal compressor model with 0 ° angle of installation,which was obtained from the 180 ° elbow.The results show that the inlet pressure model has a great influence on the static pressure in the circumferential direction at the top of impeller of the compressor inlet,and the circumferential position of the high pressure zone formed by the different elbows is different in the circumferential direction.The effect on the downstream gradually weakened while the static pressure circumferential distortion caused by the elbow propagates to the impeller exit position along the flow direction.The downstream flow field distortion of the compressor produced by the volute is transmitted to the impeller during the reverse propagation to the upstream,the flow is separated at the radial and axial transition positions of the impeller,forming two peak points and coupling with the static pressure circumferential distortion that propagating to the same position formed by the elbow model.In the case of small flow conditions,the 300 ° elbow model can effectively reduce the static pressure peak at the axial and radial transition positions and the position front of the splitter blade.When the high pressure zone circumferentially at impeller exit position propagates to the impeller inlet,there is a phase difference from the circumferential position of the impeller.For the torsional tube intake model,form the experimental results,we can find out that the 270 ° torsion model has the effect of stabilizing the flow at the small flow condition.Aiming at this phenomenon,the numerical simulation of four kinds of torsion model is carried out.It is found that the 270 ° torsional tube model forms a bias vortex at the inlet of the intake pipe and the direction of rotation of the main vortex coincides with the direction of rotation of the impeller.the impeller channel internal total pressure and flow distribution of this model is the most uniform with less flow loss,effectively improved the stability of the compressor,achieved the effect of stability at small flow condition,delay the occurrence of compressor stall.