Experiments in a Transonic Shock Tube at Subsonic Mach and High Reynolds Numbers

Abstract

SummaryModern civil transport aircraft cruise in the high transonic velocity region near the speed of sound. Mach numbers of up to 0.86 and Reynolds numbers based on the chord length of the wing of up to Rec = 50 × 106 and higher are operational for jet planes like the Airbus A340–600 and the Boeing 747–400. Even bigger aircraft are in the conceptual or design phase with higher passenger capacities e.g. the A380, resulting in larger wing chords to lift the increasing aircraft weights in order to accomodate more passengers or freight per aircraft. Another market trend tends to higher cruising Mach numbers to shorten flight time. So flight Reynolds and Mach numbers will increase in the future.At the Shock Wave Laboratory (SWL) of the RWTH Aachen University a new wind tunnel was put into operation to perform airfoil testing, duplicating true flight Mach and Reynolds numbers simultaneously. After the calibration phase of the tunnel, extensive airfoil testing has been started. A reproducible test flow for stationary airfoil testing is achieved. Pressure measurements of high temporal resolution and flow visualization are conducted. The tunnel flow in the test section reaches Reynolds numbers of up to Rec = 40 × 106 at Mach numbers between Ma∞ = 0.6 and 0.9.