Hypersonic Laminar-Turbulent Transition on Slender Cones at Zero Angle of Attack: Measurements in Support of Mechanism-Based Models for Scaling Ground- Test Data to Flight.

摘要

Maintaining low laminar heating may be critical to hypersonic gliding reentry vehicles such as the several which have been proposed for the Prompt Global Strike (PGS) mission. However, no single ground test can duplicate the Mach number, Reynolds number, enthalpy, surface temperature, scale, roughness, ablation and freestream noise of flight; thus, ground-test measurements oflaminar-turbulent transition must be compared and extrapolated to flight using analysis. Fortunately, the first mechanism-based prediction methods are now becoming available for some of the instabilities that lead to transition. Wind-tunnel measurements of these instabilities are being carried out in order to develop and calibrate these new semi-empirical methods. Recently-successful fast-response surface pressure transducers were further developed and applied on a circular cone at zero angle of attack in several hypersonic wind tunnels in order to measure second-mode waves, transition, and the effect of tunnel noise. Results to date are summarized, and plans for future research are outlined.