Analysis of Flow Characteristics at the Inlet of a Circular Involute Variable Wall Thickness Scroll Expander

Abstract

This paper mainly studies the effects of the inlet shape on the internal flow field and the output characteristics of a scroll expander. Based on circular involute variable wall thickness scroll profiles, three inlet working cavities are numerically simulated using the CFD method and dynamic mesh technique, thus obtaining the internal flow field, the inlet flow rate, the transient gas force, and the change rule of inlet power loss in the working cavity. The results show that the pressure distribution in the working cavity of the scroll expanders with elliptical and double circular groove inlets is more uniform than that in expanders with circular inlets. The high-pressure gas impacting the wall of the scroll teeth at different speeds results in a serious loss of mechanical energy of the gas and a large amount of swirling phenomena in the working cavity. Compared to the circular inlet, the output torque and inlet flow rate of scroll expanders with double circular grooves and elliptical inlets are increased, and the inlet power loss is decreased by more than 40%. Therefore, the double arc groove and elliptical air inlet provide superior performance compared to conventional circular air inlet scroll expanders.