Based on the design of the supercritical carbon dioxide (SCO2) centripetal compressor, this paper adopts the orthogonal design test method to optimize the pear-shaped volute, designs the front guide vane with the third-order Bezier curve, and designs the outlet by the equal section method. The numerical simulation calculation and analysis of the design conditions and variable conditions of the SCO2 centripetal compressor are carried out. The results at design conditions show that the isentropic efficiency is 92%, the pressure ratio is 1.21, and the mass flow rate is 195.9 kg/s, which is close to the thermal design and level simulation results; the results of variable conditions show that the efficiency of the SCO2 centripetal compressor-flow and pressure ratio-flow characteristic line is similar to that of multistage axial flow compressor. The supercritical carbon dioxide centripetal compressor designed in this paper meets the design requirements, and its feasibility is proved through numerical simulation.

This paper investigates spontaneous condensation of wet steam in a centrifugal turbine by means of three-dimensional computational fluid dynamics. The flow field and aerodynamic characteristics of the wet steam in the centrifugal turbine are compared and analyzed by using the equilibrium steam and nonequilibrium steam models, respectively, where the latter applies the classical droplet nucleation theory and neglects velocity slip between the liquid phase and the gaseous phase. The state parameters of wet steam are described here based on the IAPWS’97 formulation. It is concluded that under the design condition, the mass flow rate, wetness fraction, and flow angle of the wet steam centrifugal turbine in the nonequilibrium steam model all change compared with the equilibrium steam model, with values of 4.4%, 0.5%, and 10.57%, respectively. Then the performance variation of the wet steam centrifugal turbine is analyzed under different steam conditions and different outlet back-pressure conditions. The results show that the change law of the mass flow rate, shaft power, and wetness fraction in the centrifugal turbine are basically identical in both models, and the mass flow rate, shaft power, wheel efficiency, and entropy loss coefficient of the centrifugal turbine in the nonequilibrium steam model are all higher than those in the equilibrium steam model, whereas the outlet wetness fraction is lower than that in the equilibrium steam model.