Original Article

Shock Waves

, Volume 17, Issue 1, pp 65-70

First online:

Background oriented schlieren for flow visualisation in hypersonic impulse facilities

  • D. RamanahAffiliated withCentre for Hypersonics, School of Engineering, The University of Queensland
  • , S. RaghunathAffiliated withCentre for Hypersonics, School of Engineering, The University of Queensland
  • , D. J. MeeAffiliated withCentre for Hypersonics, School of Engineering, The University of Queensland Email author 
  • , T. RösgenAffiliated withInstitute of Fluid Dynamics, ETH Zurich
  • , P. A. JacobsAffiliated withCentre for Hypersonics, School of Engineering, The University of Queensland

Abstract

Experiments to demonstrate the use of the background-oriented schlieren (BOS) technique in hypersonic impulse facilities are reported. BOS uses a simple optical set-up consisting of a structured background pattern, an electronic camera with a high shutter speed and a high intensity light source. The visualization technique is demonstrated in a small reflected shock tunnel with a Mach 4 conical nozzle, nozzle supply pressure of 2.2 MPa and nozzle supply enthalpy of 1.8 MJ/kg. A 20° sharp circular cone and a model of the MUSES-C re-entry body were tested. Images captured were processed using PIV-style image analysis to visualize variations in the density field. The shock angle on the cone measured from the BOS images agreed with theoretical calculations to within 0.5°. Shock standoff distances could be measured from the BOS image for the re-entry body. Preliminary experiments are also reported in higher enthalpy facilities where flow luminosity can interfere with imaging of the background pattern.

Keywords

Background schlieren Shock tunnel Flow visualization

PACS

47.80.Jk 47.40.Ki