An Experimental Investigation of TIP Bluntness Effects on the Turbulent Compressible Boundary Layer on an Axisymmetric Body.
Final technical rept. 1 oct 77-31 May 81,
PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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An experimental study has been carried out in which the effect of tip bluntness on the turbulent boundary layer over an axisymmetric body was examined. It was performed at a Mach number of 2.94 with a unit Reynolds number of roughly 6.34 x 10 to the 7th power per meter and a nearly adiabatic wall condition. A tangent ogive-cylinder was used with a noise fineness ratio of approximately 3. Six model tips were constructed with hemispherical and flat blunting of various dimensions. In addition, to establish a reference baseline, tests were made using a model with a pointed tip. Bow shock shapes and surface pressures were obtained at 0 deg and 2.9 deg angle of attack for each model tip. Boundary layer surveys were made along the windward and leeward meridians of the model for each tip. Experimental results show that the boundary layer is influenced by the tip bluntness through the entropy wake, a region of hot gas next to the body. This high entropy region is caused by the strong shock section of the bow shock. The downstream development of boundary layer parameters--such as the displacement and momentum deficit thickness, form factor, and skin friction coefficient--was found to be strongly dependent on the geometry and size of the tip blunting.
- Fluid Mechanics