The design and combustion performance of practical swirlers for integral rocket/ramjets

A method was devised for the design and fabrication of swirl inlet hardware with practical application to the integral rocket/ramjet dump combustor. A total of seven swirl inserts were tested to determine the effects of different swirl profiles on combustor performance. Combustor length-to-diameter ratio (LC/D) was varied between 1.5 and 3, and the ratio of the nozzle throat to combustor area (A*/A3) between 40 and 60%. Combustor wall static distributions were measured in all configurations in which LC/D = 3. Airflow immediately downstream of the swirler was probed in cold flow to determine actual swirl angles to compare with prediction. Combustion instability data was recorded for subsequent spectral analysis by fast Fourier transform.