Wind-Tunnel Shock-Tube Simulation and Evaluation of Blast Effects on an Engine Inlet.

摘要

This report describes a program for simulating blast wave intercepts with a scaled aircraft engine in subsonic flight, using the shock tube technique for firing the blast-type waves. Three large 22.6 inch-diameter shock tubes were installed in the AEDC 16T (16 ft sq) transonic wind tunnel and were used to project blast waves at a 0.1-scale B-1 aircraft model. Forty-five firings were made, covering tunnel speeds of Mach 0, 0.55, 0.70, 0.85 and 0.90, blast overpressures (scaled to 1 atm. ambient pressure) from 2 to 6 psi, 0 deg and 5 deg yaw, and inlet flow rates representative of cruise and maximum power conditions. The model inlets were instrumented with 40 combination steady-state and dynamic total-pressure probes at each engine face section and other dynamic transducers to measure incident blast wave properties and inlet internal ramp and cowl pressures. Calculations of blast pressures in the inlets made with the KA BID code satisfactorily reproduced the principal features of the observed inlet duct and engine fact pressures. Four potentially adverse effects to engine operation from blast interaction were identified: blast-induced distortion, fan choking, afterburner blow-out and shock-boundary layer induced distortion.