Gang D.   Yi S.   He L.   Fu J.  

Visualization of Supersonic laminar Flow over Protuberances Mounted on a Flat Plate

Reporter: Gang D.

Although supersonic vehicles are usually designed to be smooth and streamline shaped, the real ones often have some protuberances of various scales and shapes on its surface which would disturb the quiet flow [1]. On the other hand, the roughness mounted on the surface of the vehicle can be used as an effective flow controlling method [2,3]. The protuberances can cause local heating, which may bring damage to the vehicle.
In the present study, Mach 3.0 supersonic flow over circular protuberances has been in-vestigated by the schlieren and NPLS (Nano-tracer based planar laser scattering) technique. The high definition CCD camera captures the scattering light of the nano-tracers, thereby NPLS images of the flow field are obtained. The fine structures of the flow field have been clearly visualized, including the separation and reattachment. The protuberances are mounted on a flat plate departing from the floor of the wind tunnel, free of the disturbance of the turbulent boundary layer on the wall. The diameters of the protuberances are all 4 mm, while the heights are 1 mm, 2 mm and 4 mm. The undisturbed laminar boundary at the mounting position has a thickness of about 1.2 mm.

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