ON OPTIMUM WEDGES AND SEMICONES IN HYPERSONIC VISCOUS FLOW,
RICE UNIV HOUSTON TX AERO-ASTRONAUTICS GROUP
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The class of wedges and semicones whose upper surfaces are parallel to the undisturbed flow is considered and, with reference to the range where viscous interaction can be neglected, the effect of the thickness ratio on the lift-to-drag ratio is investigated under the hypotheses that 1 the pressure distribution is that of the hypersonic, small-disturbance theory and 2 the local shear stress is proportional to the square root of the static pressure at the outer edge of the boundary layer, assumed laminar. A solution is derived for the optimum thickness ration parameter and the maximum lift-to-drag ratio parameter as functions of the similarity parameter. This solution is then compared with the approximate solution obtained by assuming a modified Newtonian pressure coefficient and an average skin-friction coefficient which is independent of the shape during the optimization process. It is found that the latter solution is a good approximation to the former, since the predicted lift-to-drag ratios are within 2.5wedge and 1.4semiconeof the maximum values.
- Fluid Mechanics