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In the present study, flow visualizations and quantitative measurements around a NACA0012 airfoil are performed under air and CO2 operation modes. A diaphragmless shock tube system is used for a high-subsonic airfoil testing. This system has the possibility of efficient aerodynamic experiments as an intermittent wind tunnel. A point diffraction interferometry (PDI) is used for a flow measurement technique. Moreover, the comparison with numerical results by the OpenFOAM is performed. The driver tube of this shock tube is the circular cross section with a diameter of 150 mm. The driven tube is the rectangular cross section with a width of 60 mm and a height of 150 mm. The hot gas Mach number (uniform high-subsonic flow condition) is M2 = 0.65. The angle of attack is α = 0 • and 2 • , and the range of the Reynolds number is Re = 1.7-7.4 × 10 5. The results of the present study are as follows. In the present Reynolds numbers, if the shock wave does not generate, the shock tube airfoil flows of CO2 mode showed almost the same trend as the case of air mode quantitatively. The difference of operation gas was confirmed when the shock wave generated on the airfoil surface. In the high-subsonic flow, the pressure coefficients Cp by the PDI are in relatively agreement with the CFD results. The numerical results by the OpenFOAM give useful results for the comparison with aerodynamic data. Therefore, this shock tube system with a PDI measurement technique is considered as one of useful facilities for different operational modes.

This paper describes a method for measuring flow fields around an airfoil in high subsonic flows by using a point diffraction interferometer (PDI). The PDI is a useful technique for obtaining quantitative information of flow fields since the PDI system can be easily and inexpensive constructed by modifying an existing schlieren system. The diaphragmless shock tube was used for