THE EFFECTS OF COMBUSTION IN A RAMJET ON THE PERFORMANCE OF A SUPERSONIC DIFFUSER.

Experimental data are presented for 6-inch ramjet tests employing a normal shock diffuser, with and without combustion. Tests were made with the diffuser intake in both M 1.59 and M 1.90 free jet streams. Additional data were obtained from flight tests in the Mach number range of 1.4 to 2.0 at both sea level and altitude. High-frequency, diffuser-exit, pressure-fluctuation data are included for tests of an 18-inch ramjet in a M 1.90 free jet stream. It is concluded that cold flow simulated combustion tests can provide a sufficient background for the design of supersonic diffusers for ramjet applications and that unidimensional theory, at least for the particular diffuser geometry described in the report, is adequate for the description of internal flow. It is suggested that failures to correlate diffuser performance in cold flow tests with that during combustion is due to malfunction of the combustor which can be avoided by proper design. Author