Bypass-regulated solid fuel ramjet combustor in variable flight conditions

A comprehensive experimental investigation aimed at the examination of a solid fuel ramjet (SFRJ) regulation concept using an air-division valve has been conducted. By controlling the ratio between the port and bypass flows, one can maintain a desirable working state over a wide range of flight conditions. A general regulation law based on maintaining a constant fuel-to-air ratio has been tested. The experimental strategy was to isolate key parameters influencing the fuel regression rate, testing them one at a time, keeping the other parameters constant. Experiments aimed at airflow rate, total air temperature and pressure, as well as port diameter effects, simulated a broad flight envelope, from Mach 1.5 to Mach 4.7 and from sea level to 13-km altitude. The test results showed a very good agreement with the theory, demonstrating the feasibility, effectiveness, and characteristics of the air-division valve regulation technique in SFRJ motors.