Analysis of Profile and Unsteady Flow Performance of Variable Base Circle Radius Scroll Expander

To study the complex internal flow field variation and output characteristics of a variable base radius scroll expander, this paper uses dynamic mesh techniques and computational fluid dynamics (CFD) methods to perform transient numerical simulations of a variable base radius scroll expander. Analysis of the flow field in the working cavity of a variable base radius scroll expander at different spindle angles and the effect of different profiles, speeds and pressures on the output characteristics of the scroll expander. The results of the study show that due to the periodic blocking of the inlet by the orbiting scroll, the fluid hits the internal walls of the expander at different flow rates, with excessive mechanical losses, resulting in an uneven distribution of the internal flow field. At the same temperature, pressure and scroll plate diameter, the variable base radius scroll expander increases the output torque by 0.046 N·m, the output power by 9.634 W and the isentropic efficiency by 3.8% compared to the fixed base circle scroll expander. As the speed is inversely proportional to the output torque, the isentropic efficiency of the expander tends to increase and then decrease as the speed increases. The density of the fluid is directly proportional to the pressure over a range of pressures. As the pressure increases from 0.6 to 0.9 Mpa, the average mass flow rate and isentropic efficiency increase by 0.02357 kg/s, and 6.61%, respectively.