Discrete-Roughness Transition for Hypersonic Flight Vehicles

Abstract

The importance of discrete roughness and the correlations developed to predict the onset of boundary layer transition on hypersonic flight vehicles are discussed. The paper is organized by hypersonic vehicle applications characterized in a general sense by the boundary layer: slender with hypersonic conditions at the edge of the boundary layer, moderately blunt with supersonic, and blunt with subsonic. This paper is intended to be a review of recent discrete roughness transition work completed at NASA Langley Research Center in support of agency flight test programs. First, a review is provided of discrete roughness wind tunnel data and the resulting correlations that were developed. Then, results obtained from flight vehicles, in particular the recently flown Hyper-X and Shuttle missions, are discussed and compared to the ground-based correlations.

A high-order cut-cell method for numerical simulation of hypersonic boundary-layer instability with surface roughness

“…Transition can have a first-order impact on the lift and drag, stability and control, and heat transfer properties of the vehicles [2]. For example, roughness induced transition is an important consideration in the design of thermal protection systems (TPS) of hypersonic vehicles [3,4]. Fig.…”

Compression Pad Cavity Heating Augmentation on Orion Heat Shield

“…For such correlations (e.g. [20]), boundary-layer transition is treated as a function of Re =M e (rather than just Re ) and the ratio of trip height (or in this case cavity depth) to boundary-layer thickness, H=.…”

Numerical Simulations of Transition due to Isolated Roughness Elements at Mach 6

“…For example, transition on the space shuttle orbiter during reentry occurred usually up to a Mach number of eight [2], but protruding gap fillers were found to act as discrete surface roughness and promote transition at higher Mach numbers [3], which might bring the aerothermal surface heating of the vehicle outside its allowable envelope. Even though roughness-induced transition in high-speed flows is of such importance, the mechanisms responsible for it are only partially understood and prediction of transition still relies mainly on engineering correlations from flight-test data and wind-tunnel experiments.…”