Numerical investigation of the effect of sudden expansion of the solid fuel ramjet combustion chamber on the regression rate

In this research, modeling and numerical simulation of the effect of sudden expansion ratio (ratio of port diameter to inlet diameter) of high-density polyethylene-based solid fuel ramjet combustion chamber in the reactive turbulent flow on the regression rate are presented. The effect of sudden expansion of solid fuel ramjet combustion chamber in three different samples with different port diameters and fixed inlet diameter with ratios of 1.75, 1.875 and 2.125 is investigated on the parameters of temperature and regression rate. The simulation results show that increasing the ratio of port diameter to inlet diameter decreases the temperature. The highest temperature was obtained in the original sample with the ratio of port diameter to inlet diameter equal to 1.75.  Also, the results show that the sudden increase in expansion causes a decrease in the fuel regression rate, which causes a decrease in ramjet performance.