A novel clocking effect between inlet bend and volute in an automotive turbocharging system

Abstract

Numerical methods were carried out on a turbocharger compressor with inlet bent pipe to research a novel clocking effect between the inlet bend and the volute. It was found that the clocking effect with 3.4 percent of variations (1.9 percentage points) in compressor efficiency positively exists at the research point near chock. The reason for the changed efficiency loss is that the inlet bend induces a serious distortion of approaching flow to impeller inlet on one hand, and the downstream volute causes a circumferentially non-uniform distribution of pressure in vaneless diffuser. By adjusting the clocking positions between inlet bend and volute, not only is the unsteadiness of the flow rate through single impeller channel changed, but the uniformity of the incoming flow at the vaneless diffuser inlet is modulated as well. It is the dominant reason for the novel clocking effect that the bad uniformity causes more flow loss in both diffuser and volute.