An Overview of the Advanced Nonintrusive Measurement Techniques in Hypersonic Flow Field

摘要

Hypersonic flow-field measurement techniques have been studied for about 50 years.Despite truly remarkable progress with a probe or other device to measure the temperature,pressure or velocity,there are still serious problems for these "intrusive" techniques.The intrusive measurement techniques introduce unexpected shock waves or flow-field structures,even make the boundary layer transition earlier and show a converse result.In recent years,nonintrusive diagnostics have been in urgent demand to give a more accurate and comprehensive flow-field for hypersonic testing.In this paper,an overview of some advanced nonintrusive measurement techniques such as embedded thermocouples for heat flux measurement,Pressure Sensitive Paint (PSP),Particle Image Velocimetry (PIV),infrared thermographs,and focusing Schlieren system are introduced.All of these techniques are nonintrusive and provide measurement of various parameters such as temperature,static pressure,dynamic pressure,flow velocity and visualization of flow structure,which gives us an exact and direct understanding of the hypersonic flow.