An Experimental Investigation of an Underexpanded Rectangular Jet Ejector.
STANFORD UNIV CA JOINT INST OF AERONAUTICS AND ACOUSTICS
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An experimental investigation was carried out on a rectangular ejector constant area mixing duct with an underexpanded rectangular jet as primary flow. This study investigated the mixing behavior of the ejector flow in general and attempted to identify the effects of the screech tones on the mixing and performance of the ejector. The quantities measured include frequency and amplitude of the screech tone, surface pressure on the ejector duct wall, and the mean flow velocity at the ejector exit in the two central planes of the primary jet. Schlieren flow visualization was made in the plane containing the short dimension of the primary nozzle. The screech tone frequency of the ejector depends not only on the primary jet pressure ratio but also on the ejector duct width. Variations of the screech tone frequency with both the pressure ratio and the duct width show staging behavior. For a given duct width, each screech tone stage matches with one of the transverse modes of the duct. The ejector performance, as determined from the static pressure distribution on the walls, shows irregular variation with pressure ratio, and is found to be related to the screech tone stages.
- Fluid Mechanics
- Jet and Gas Turbine Engines