Wind Tunnel and Flight Performance of the YF-12 Inlet System

Abstract

x/3-scale and full-scale wind tunnel models of the YF-12 inlet system is compared with results from flight tests. All systems were thoroughly instrumented for static and total pressure measurements. Results obtained included the inlet mass flows, surface pressure distributions, boun- dary-layer profiles, and detailed total pressure measurements at the engine face. Inlet performance is compared at Mach numbers 2.1 and 2.8 and at several Reynolds numbers over a wide range of inlet operating conditions. The data generally show good agreement between the three systems when inlet conditions are closely matched. tering the inlet, flight Reynolds numbers will not be achieved. Conversely, if large-scale isolated .inlets are tested, any nonuniform flowfield found in flight will not be duplicated. To answer these questions and to provide a sound data base for comparing results between flight and scaled models, a comprehensive program involving wind tunnel and flight tests of the YF-12 inlet system was undertaken. The principal ob- jective was to develop methods for the extrapolation of the inlet dynamic performance characteristics from wind tunnel to flight. Secondarily, the objectives were to determine the sensitivity of the systems to variables such as scale, Reynolds number, and flowfield entering the inlet. Development of methods for the extrapolation of dynamic results from wind tunnel to flight is considered to depend on good correlation of steady-state performance. This steady-state correlation is based on factors such as pressure recovery and distortion at the engine face and the main and auxiliary inlet mass flows. This paper is addressed to the correlation of these steady-state parameters between wind tunnel and flight. In addition, the effects of Reynolds number and local flowfield entering the inlet are discussed. One-third and full-scale YF-12 inlet models were tested in wind tunnels and the performance of the YF-12 inlet system was measured in flight. All systems were thoroughly in- strumented for both steady-state and dynamic total and static pressures. From these measurements the steady-state pressure recovery and distortion at the engine fact, the main and auxiliary mass flows, and boundary-layer profiles along both walls were determined. This paper gives representative steady- state performance comparisons at Mach numbers 2.1 and 2.8. References 1 — 6 give other steady-state and dynamic results from the wind tunnel and flight tests. Analysis of dynamic data is in progress and is expected to be reported in the near future.