Abstract
Experiments in the Hypersonic Wind tunnel of NUAA(NHW) present synchronous measurements of bow shockwave and surface pressure of a standard blunt rotary model (AGARD HB-2), which was carried out in order to measure the Mach-5-flow above a blunt body by PIV (Particle Image Velocimetry) as well as unsteady pressure around the rotary body. Titanium dioxide (Al2O3) Nano particles were seeded into the flow by a tailor-made container. With meticulous care designed optical path, the laser was guided into the vacuum experimental section. The transient pressure was obtained around model by using fast-responding pressure-sensitive paint (PSP)sprayed on the model. All the experimental facilities were controlled by Series Pulse Generator to ensure that the data was time related. The PIV measurements of velocities in front of the detached bow shock agreed very well with the calculated value, with less than 3% difference compared to Pitot-pressure recordings. The velocity gradient contour described in accord with the detached bow shock that showed on schlieren. The PSP results presented good agreement with the reference data from previous studies. Our work involving studies of synchronous shock-wave and pressure measurements proved to be encouraging.
Highlights
The development of optical measurement technology shows the potential advantages in the research of flow field measurement
The current study focused on overcoming the challenges in simultaneous shock-wave and pressure measurements in transient hypersonic flows by using optical technology
Simultaneous PIV and pressure-sensitive paint (PSP) measurements in hypersonic flows are quite challenging mostly due to complex flow conditions
Summary
The development of optical measurement technology shows the potential advantages in the research of flow field measurement. Since the advent of Laser Doppler Velocimetry (LDV), Optical measurement techniques have been applied and developed for a long time in the aerodynamic experiments. The Particle Image Velocimetry (Particle Image Velocimetry, PIV) highly desirable for capturing the flow structures due to their low intrusiveness and high spatial resolution, gradually becoming predominant technology in flow field measurements [1,2,3,4]. With the advent of high-energy lasers and high resolution digital image recorders, the PIV technology made supersonic flow field measurement possible. For hypersonic flow, the high speed, high gradient and compressibility bring a lot of difficulties to the application of PIV in hypersonic flow field measurement
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