研究目的
To measure hypersonic boundary-layer transition on a three-dimensional body using infrared thermography in a Mach-6 quiet tunnel and compare with previous temperature-sensitive paint results.
研究成果
Infrared thermography provided less noisy data and good agreement with temperature-sensitive paint results for centerline transition locations and crossflow vortex wavelengths, reinforcing confidence in both techniques. The forward-facing step in TSP did not significantly affect transition, and the new IR-based method is viable for hypersonic boundary-layer studies.
研究不足
The study is limited to ground-test conditions in a specific wind tunnel, which may not fully replicate flight conditions. Uncertainties in heat-flux calculation arise from assumptions like one-dimensional conduction and adiabatic backface boundary conditions. Differences in model surface roughness and alignment could affect off-centerline results.
1：Experimental Design and Method Selection:
The study involved testing a
2：1% scale model of the HIFiRE-5 vehicle in the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT) at Purdue University. Infrared thermography was used for global heat-flux measurements, with data reduction involving image calibration, registration, and heat-flux calculation using a one-dimensional finite difference method. Sample Selection and Data Sources:
A new HIFiRE-5 model was fabricated with a polyether ether ketone (PEEK) shell for IR thermography, maintaining the same outer mold line as previous models. Tests were conducted at zero angle of attack and Reynolds numbers of 8–12 × 10^6/m under quiet flow conditions.
3：List of Experimental Equipment and Materials:
Equipment included the BAM6QT wind tunnel, a Xenics Onca IR camera, Kulite pressure sensors, and the HIFiRE-5 model made of stainless steel and PEEK. Materials included PEEK with specific thermal properties.
4：Experimental Procedures and Operational Workflow:
The tunnel was operated for approximately 7 seconds per test. IR images were acquired at 80 Hz, and pressure data were recorded simultaneously. Image processing involved calibration, registration, and heat-flux calculation. Transition locations were determined from heat-flux profiles.
5：Data Analysis Methods:
Heat flux was calculated using a MATLAB subroutine based on QCALC, accounting for model curvature. Transition onset was identified by the intersection of linear fits to laminar and transitional heat-flux regions. Discrete Fourier transformation was used to analyze crossflow vortex wavelengths.
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