Simulink modeling of an ejector based on CFD simulation

A modeling and simulation study is conducted on a supersonic ejector. CFD simulations are carried out to examine the performance of the ejector, considering water vapor in the secondary flow. First, the study investigates how the composition variation of the secondary flow affects its static pressure. It is shown that when the molecular weight of the secondary flow goes up, the static pressure of the secondary flow goes down. If the water vapor is ignored in the secondary flow, the static pressure of the secondary flow changes by -4.5%. The simulation results demonstrate that the static pressure of the secondary flow normally increases with the secondary flow rate and outlet pressure and decreases with the total pressure of the primary flow. However, when the outlet pressure is too low or the secondary flow rate is too high, the static pressure of the secondary flow increases with the total pressure of the primary flow. Based on the CFD simulation data, a Simulink model for predicting the static pressure of the secondary flow is developed. Compared with the original CFD date, the maximum relative error of the Simulink prediction is -1.08%, indicating good accuracy of the Simulink model.