Experimental study on flow visualization of hypersonic flat plate boundary layer

The classical problem of flat plate boundary layer which involves turbulence and transition is still hot, and a mass of work should be done to reach a high accuracy measurement of this flow, especially under the condition of high velocity. In the present paper, the application of the nano-based planar laser scattering (NPLS) method in a hypersonic short-duration facility is explored, and then the high accuracy measurement of a flat plate boundary layer is studied. The Mach number of the main flow is 7.3, the total pressure is 4.8 MPa, and the total temperature is 680 K. Through analysis and tests, the synchronization control of the NPLS system with the test facility is realized, and with the quantitative control, the tracer particle is uniformly seeded. Based on this, the transient boundary layer flow in the short-duration tunnel is visualized with high resolution, and the transition from laminar to turbulent flows is captured. The development characteristic of the flow is studied finally.