Skin friction gauges for high enthalpy impulsive flows
Conference Paper
Overview
Overview
abstract
American Institute of Aeronautics and Astronautics, Inc., 1993. All rights reserved. A new gauge was developed to directly measure skill friction in 3-D, turbulent boundary layer produced iii high enthalpy impulse facilities with and without combustion. A miniature, plastic, cantilever sensor was developed. Plastic allowed high frequency response, high sensitivity, low specific gravity, low thermal conductivity. and low cost. The gauges were designed such that high temperature gradients would not contaminate the results until well after the usable shock tunnel test time. Even if the gauges are destroyed by the wall heating after the test, the low cost allows them to be disposable. However, testing has proven the current design to be durable in high enthalpy combustion flows (3kW/cm2 heat flux). In order to assess the accuracy of the gauges, controlled experiments were performed. These experiments included long (500 msec), medium (50 msec.). short (5 msec), and a very short (0.4 msec) duration tests, all with varying flow conditions. In the long duration test, the gauge produced results consistent with those measured via conventional floating element methods. The new gauge produced repeatable results that, for each of the test conditions, agreed with Van Driest I1 Theory and other accepted empirical correlations.
