Design and implementation of an internal stress wave force balance in a shock tunnel

Abstract

A stress wave internal force balance for the High Enthalpy Shock Tunnel Gottingen (HEG) of the German Aerospace Center (DLR) to measure lift, pitching moment and drag was designed, calibrated and tested. The balance is designed to measure forces in ground based test facilities with test times in the order of milliseconds on models additionally instrumented with surface pressure and wall heat flux gauges from angles of attack of −40° to 20°. Experiments in HEG were performed on a 303 mm long, 10° half angle blunt cone at angles of attack from −20° to 0°. The tests were conducted utilizing two different operating conditions at total specific enthalpies of 3.0 and 3.5 MJ/kg and dynamic pressures of 30 and 72 kPa. The performance of the balance was assessed by comparing the measured force and moment coefficients with computational fluid dynamics (CFD) predictions.