Pressure-sensitive paint measurements for microscale supersonic flow with wedge models

Abstract

The pressure distribution around wedge models inside a submillimeter supersonic wind tunnel was experimentally investigated using pressure-sensitive paint (PSP) at a flow speed of Mach 1.6. The throat of the submillimeter supersonic wind tunnel was 500 μm. The two wedge models were isosceles triangles with a width of 50 μm and vertex angles of 20° and 30°, respectively. The pressure profiles and pressure distributions along the centerline inside the submillimeter supersonic wind tunnel with the wedge models agreed with the results of numerical simulation performed using ANSYS Fluent. The pressure distributions around the wedge models were examined, and a strong pressure rise at the front end of the wedge models was observed. A low-pressure region in the wake region downstream of the wedge models was identified. However, these results differed from the simulation data for the middle layer of the wind tunnel, which revealed bow shock and a shock wave interaction. This difference occurred because the PSP coating was located at the bottom of the wind tunnel, which was embedded inside a viscous layer. The pressure data measured with PSP were smeared, and it was consistent with the simulation data for the bottom layer. The PSP results reveal the overall pressure variation around the wedge models, and they will be useful for future designs of micro propulsion systems with supersonic nozzles.