Numerical Simulation of Nosetip Transition: Model Refinement and Validation.
Final rept. 15 Jul 75-15 Jul 76,
DCW INDUSTRIES SHERMAN OAKS CALIF
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A set of constitutive equations suitable for predicting boundary-layer transition has been developed. The equations are an improved version of the turbulence-model equations devised by Saffman and Wilcox. Detailed study of the viscous sublayer of a turbulent boundary layer establishes suitable viscous modifications to the high-Reynolds-number form of the equations. Analysis of the sublayer also establishes boundary conditions suitable for surfaces with roughness and mass injection. Additional modifications based on linear stability theory obviate difficulties previously encountered in treating effects on transition of pressure gradient and surface heat transfer. The model accurately predicts many of the salient features of incompressible boundary-layer transition including effects of freestream turbulence intensity, width of the transition region, and transitional velocity profiles. Application to the nonequilibrium relaxation of a turbulent boundary layer passing from a rough to a smooth surface demonstrates the models ability to accurately predict surface roughness effects. Most pertinent to the overall project objectives, the model accurately simulates ground-test transition experiments on re-entry vehicle geometries, including effects of surface roughness, surface cooling, and surface mass addition. Author
- Fluid Mechanics