An Analysis of Nosetip Boundary Layer Transition Data
Interim rept. 1 Jul 1975-30 Jun 1976
PHYSICAL SCIENCES INC ANDOVER MA
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A critical analysis is presented of the available wind tunnel data simulating nosetip boundary layer transition on reentry vehicles. It is agreed that transition should depend on surface roughness, surface temperature, and surface curvature. The Reynolds number based on momentum thickness at the transition location Re sub theta is used to measure transition, and the surface roughness effect is described by the Reynolds number Rek,k based on roughness height and conditions at the tops of the roughness elements. The wall temperature dependence may be removed by use of the kinematic viscosity in the middle of the boundary layer to compute Re sub theta. The available data suggest a dependence on thetaRc Rc surface radius of curvature, which could be due to centrifugal acceleration or pressure gradient. Accounting for this curvature effect appears to eliminate the need for a separate transition onset criterion. A tentative correlation is presented, and the limitations of the existing data are discussed.
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