EFFECTS OF DIFFUSER LENGTH ON THE PERFORMANCE OF EJECTORS WITHOUT INDUCED FLOW

An investigation of ejectors without induced flow was made to determine the effects of varying diffuser lengths on ejector performance. Four 18-deg half angle conical nozzles having constant exit diameters and different throat diameters and two contoured nozzles having zero-deg half angles at the exit were used as the ejector driving nozzles. Unheated air was used for all tests. The diffuser length-to-diameter ratios were varied between 0.7 and 21.5, and three cylindrical ducts of different diameters were used both with and without a subsonic diffuser. An empirical method was developed to estimate the starting and operating pressure ratios of such ejector configurations using simple-determined one-dimensional normal shock relationships.