A study of viscous interaction effects on hypersonic waveriders.

摘要

In a continuing effort to generate new and improved classes of viscous optimized hypersonic waveriders, the present work takes a step forward and examines the effects of viscous interaction in the waverider design and analysis process. Parametric runs are made to produce L/D, {dollar}Csb{lcub}L{rcub}{dollar}, and {dollar}Csb{lcub}D{rcub}{dollar} contour plots for Mach number 6.0 to 30.0 at an altitude 30.0 to 80.0 Km, for waverider designer's reference. This is the first work to examine the effects of viscous interactions on hypersonic waveriders, and to generate a new family of waveriders wherein viscous interaction effects are included within the optimization process.; Corda's computer program is used to generate viscous optimized hypersonic waveriders from conical flowfields without viscous interaction. Each waverider is optimized for maximum L/D, and comparison studies are made between the cases with and without viscous interaction. Other results of the investigation agreed with viscous interaction theory in showing an increase in the surface pressure near the leading edge of a waverider, and also the tendency for it to approach the freestream value further downstream. This change in the surface pressure distribution as well as increases in the skin friction, resulted a decrease in the maximum Lift/Drag for the waverider. The influence of viscous interactions on the surface pressure distribution and hence the maximum L/D were found to result in noticeably different viscous optimized waveriders generated without considering viscous interactions.; Finally, the results show that aerodynamic performance of the viscous interaction waveriders are greatly reduced due mainly to a large increase in skin-friction drag associated with the viscous interaction phenomena that is increased with increasing the Mach number and altitude, but some of this loss can be recouped by including viscous interactions within the optimization procedure. When the waverider is optimized for viscous interaction, the shape can change dramatically.; The central conclusion of the present work delineates on a velocity-altitude map that region where viscous interaction effects are significant for modern hypersonic waveriders. In particular, viscous interaction effects become important at Mach numbers greater than sixteen and altitudes upwards of 140,000 feet.