Method for Analysis of V/STOL Aircraft Ejectors

A digital computer program is described for aircraft ejector performance analyses. The effects on performance of temperature ratios, pressure ratios, specific-heat ratios, pressure losses, and aircraft forward speed are included. Momentum correction factors are computed within the program, and the method by which these are determined for rectangular ejectors with multiple nozzles is described. Theoretical and experimental results are compared for rectangular ejectors employing hypermixing nozzles and microjet nozzles. It is demonstrated that the predictions of thrust augmentation ratio are within 3% of the test data. The effects on performance of pressure ratio, temperature ratio, nozzle spacing, mixing section length, inlet and diffuser performances, and the degree of mixing achieved are presented. The analysis clearly demonstrates the importance of rapid mixing, and the role that the ARL hypermixing nozzle has played in advancing the state-of-the-art of aircraft ejectors.