MULTIPLE HOLE EJECTOR PERFORMANCE WITH SHORT WIDE-ANGLE DIFFUSERS

The performance of a thrust augmenting ejector with multiple nozzle outlets for the primary jets is discussed. The addition of short diffusers at the end of the ejector and the utilization of the primary jets for boundary-layer control have resulted in a new high level of performance with a force augmentation greater than two. Diffusers having ejector length-to-mixing chamber diameter ratios of approximately (1.5-3.7) with diffuser half angles from (4.6-11 deg), and mixing chamber inlet area-to-primary nozzle area ratios of 36:1 and 72:1, were designed and tested. Additionally, a theoretical analysis of ejector performance was formulated. Comparisons between predicted and experimental performances as a function of the primary nozzle pressure ratio are discussed. Incomplete mixing and diffuser losses are measured and accounted for in a compressibie control volume analysis. The data include selected experimental exit velocity profiles demonstrating the degradation of force augmentation at the higher pressure ratios.