Development of local nonintrusive measurements of inlet and exhaust flows for the ground testing of air-breathing engines

Abstract

Ground testing of advanced full-scale engines gives rise to requirements for local nonintrusive measurements of gas flows. These requirements e%st in the inlet flow field in subsonic and transient free-jet testing of turbine engines and in the inlet and exhaust flow fields of full-scale hypersonic, hydrogen engines being tested a t Mach numbers s 4. This paper gives the test parameter requirements, the implications of these requirements in the development of candidate measurement techniques, the development path that these INTRODUCTION Air-Breathing Propulsion Ground Testing Requiring Nonintrusive Diagnostics There are many requirements for nonintrusive diagnostics and measurements of gas flows in the ground testing of propulsion systems. First, there are requirements for verification of ground test facility performance at high Mach numbers. Such a requirement may involve a time-averaged measurement a t one key location in a facility flow during initial facility runs. techniques must follow, the techniques whose development has either been begun or continued by AEDC, and their status. NOMENCLATURE There are requirements for obtaining shock wave and density structure in the flows in engine inlets a t medium and high Mach number. These are usually met using schlieren or holographic interferometry. All gas properties are local (point) properties: There are requirements springing from hydrogen id v k indicator of gas-flow constituent i or j Boltzmann's constant total ~ m b e r density of molecules of the gas flow number density of molecules of gas-flow constituent i scramjet combustor development. These involve the instantaneous location and properties of flames, particularly as indicated by the OH radical, and usually deal with a smaller spatial scale than a fullsized engine. Much is heard about the development activity in this area. n