In order to study the effects of inlet total pressure ratio and back pressure on the front variable area bypass injector’s (FVABI) performance and mixing mechanisms

experiment method and three-dimensional numerical simulation approach were applied to analyze the injector’s performance with various inlet total pressure ratios and change regularity of main flow and secondary flow mixing flow fields under different inlet total pressure ratios and back pressures. Results revealed that the standard k -ε model had great accuracy in simulating injector mixing flow field. With the enlargement of inlet total pressure ratio

the total pressure loss of the injector increased. When the inlet total pressure ratio was constant

the total pressure loss increased firstly and then decreased as the back pressure ascended. The injector had an operating point with the minimum total pressure loss as the back pressure changed. When the back pressure reduced

there was a critical operating point for the injector

furthermore the injector’s back pressure was higher at its critical operating point if the inlet total pressure ratio got higher

meaning the adjustable bypass ratio range was narrowed down. The mixing process of the main flow and secondary flow was mainly concentrated in the position of x/l=03-06. The momentum and mass adequately exchanged

and the distribution of velocity was radically uniform along the flow direction.