Supersonic nozzle mixer ejector

Abstract

The intent of this article is to describe recent experimental findings relative to supersonic nozzle mixer ejector performance. Such ejectors are a candidate means to reduce jet noise of commercial supersonic aircraft during takeoff and landing. The mixer ejector concept involves the introduction of an array of large-scale, low-intensity streamwise vortices into the downstream mixing duct, which enhances mixing through an inviscid stirring process. This results in increased ejector pumping performance and more completely mixed flows exiting the ejector shroud. Past experimental and analytical investigations of mixer ejectors have been confined to low-speed subsonic flows, and low primary temperatures (less than 2000°F). In this flow regime, ejector static pumping benefits of over 100% were achieved relative to conventional ejector designs. The goal of the present study was to evaluate mixer ejector performance in the high-temperature, supersonic primary flow regime. A convergentdivergent primary lobed nozzle (i.e., mixer nozzle) was designed and tested at choked pressure ratios in an ejector. Ejector pumping and exit plane mixing were measured for the mixer ejector and a conventional slot nozzle ejector. The two configurations were operated at a nozzle exit Mach number of 1.5 (nozzle pressure ratio = 3.4), a primary fluid total temperature of 1000°F, and a simulated forward flight Mach number of 0.1. Results indicate that properly designed lobed nozzles can increase supersonic ejector pumping by over 15%, relative to conventional slot primary nozzles.