Investigations of Free-Jet Test Requirements and Techniques with Emphasis on the Adaptable Jet Stretcher
Abstract
Preliminary investigations of approaches that will permit relatively large air-breathing engine/inlet/forebody systems to be tested in free-jet test facilities were accomplished. Conclusions were based upon near field flow properties (Mach number and flow angle) obtained from inviscid flow computations for slender, axisymmetric bodies at zero incidence using current AEDC flow quality design goals as an acceptance criterion. Results obtained with subsonic and supersonic free-flight boundary conditions indicate that shortened forebodies can be used to reduce the overall length of test installations required for vehicles equipped with aft-mounted inlets. Bodies immersed in a supersonic free jet experience unacceptable flow distortions as a result of (1) bow shock reflections from the constant pressure free-jet boundary and (2) waves emanating from the nozzle lip because of exit plume static pressure mismatch. The adaptable jet stretcher can potentially eliminate these disturbances over a range of test conditions. A rigorous mathematical proof of a jet stretcher convergence to the desired interference-free geometry was developed for supersonic flow. Convergence was also demonstrated by a computer experiment for a slender axisymmetric body in an off-design supersonic jet stretcher. Near field flow disturbances were reduced to an acceptable level after two readjustments of the jet stretcher geometry.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1981
- Accession Number
- ADA098710
Entities
People
- E. M. Kraft
- R. J. Matz
Organizations
- Arnold Engineering Development Complex