2002 Fiscal Year Final Research Report Summary
Application of an optical pressure measurement technique with pressure-sensitive paint to blow-down supersonic wind tunnel testing
| Project/Area Number |
12650176
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Toyama Prefectural University |
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Principal Investigator |
SUZUKI Tateyuki Toyama Prefectural University, Department of Mechanical systems Engineering, Professor, 工学部, 教授 (20118665)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMURA Yoshitaka Toyama Prefectural University Department of Mechanical Systems Engineering, Associate Professor, 工学部, 助教授 (00264680)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Pressure-sensitive paint / Blow-down supersonic wind tunnel / Surface pressure measurement / Light-emitting diode / CCD camera / Porous material binder / Shock wave / Image processing |
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| Research Abstract |
Pressure-sensitive paint (PSP) attracts attention as a novel optical pressure measurement technique to obtain the full-field pressure distribution with very high spatial resolutions. However, conventional polymer-based PSPs cannot be used in short-duration supersonic wind tunnels of blow-down type due to the slow response to a rapid change in pressure. The aim of the present study is to establish PSP measurement technique applicable to aerodynamic tests in blow-down supersonic wind tunnels by improving the time response of PSP itself and the stability of excitation lights. The main results of the present work are as follows:
1. The fluctuation of the output of a blue light-emitting diode (LED) array light source is extremely small (less than 0.2%), hence it is suitable for the illumination light for the PSP measurements in short-duration wind tunnels of blow-down type.
2. The time constants of PSPs based on porous thin-layer chromatography plates are on the order of 10 microseconds. The fast-responding porous PSP has been applied to a surface pressure measurement in a Laval nozzle of the blow-down wind tunnel of Toyama Prefectural University, and pressure jumps due to a system of oblique shock waves generated in the nozzle wall and temporal fluctuations of the shock locations have been successfully visualized.
3. The wall temperature change during a run seriously affects the pressure measurements. The use of a thermally-conductive adhesive tape to fix the porous PSP on a brass wall (as a heat sink) was effective to reduce the surface temperature change during the experiment.
4. The signal-to-noise ratio (SNR) of a single image obtained is not enough due to the inevitable shot noise. It suggests that the image processing procedure for the noise reduction is important for PSP measurements in short-duration wind tunnels.
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