Theoretical Performance Limits for Non-Static Ejector Thrust Augmentors
Abstract
An analytical study was performed to determine the theoretical limits on the performance of non-static ejector thrust augmentors. Idealizing assumptions were made, such as inviscid compressible working fluids, isentropic flows in inlets, diffusers, nozzles and ducts, constant pressure mixing, and thermally and calorically perfect fluids. By ignoring details of the primary flow 'pump', the performance of ejector augmentors was found in terms of three parameters (the secondary/primary mass flow ratio, a pressure parameter and a temperature parameter) in a form which was not an explicit function of the flight Mach number. It was also shown that multi-stage ejectors offered no performance improvement over ideal single-stage ejectors. Two primary 'pump' devices, a turbine engine gas generator and an isentropic compressor, were considered. With them, the Mach number dependent behavior of ideal ejectors was determined. As a result of this study, the following conclusions were drawn: (1) The performance of ideal ejector is severely degraded by increasing the primary fluid temperature, (2) the performance of ideal ejectors is degraded faster than that of ideal turbofans as the flight Mach number is increased, (3) Neither the turbine engine nor the isentropic compressor is a suitable 'pump' for ideal ejectors, except at very low Mach numbers, and (4) Ejector augmentors should be most useful for low flight speed applications; e.g., V/STOL. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1980
- Accession Number
- ADA083246
Entities
People
- James S. Petty
Organizations
- Air Force Research Laboratory