Transition Analysis for the Mars Science Laboratory Entry Vehicle

Abstract

Viscous Laminar-turbulent transition plays an important role in the design of the Mars Science Laboratory (MSL) entry vehicle. The lift-to-drag ratio required for the precision landing trajectory will be achieved via an angle of attack equal to 16 degrees. At this relatively high angle of attack, the boundary layer flow near the leeward meridian is expected to transition early in the trajectory, resulting in substantially increased heating loads. This paper presents stability calculations and transition correlations for a series of wind tunnel models of the MSL vehicle. Experimentally measured transition onset locations are used to correlate with the N-factor calculations for various wind tunnel conditions. Due to relatively low post-shock Mach numbers near the edge of the boundary layer, the dominant instability waves are found to be of the first mode type. The N-factor values correlating with measured transition onset at selected test points from the Mach 6 conventional facility experiments fall between 3.5 and 4.5 and apparently vary linearly with the wind tunnel unit Reynolds number, indicating strong receptivity effect. The small transition N value is consistent with previous correlations for second-mode dominant transition in the same wind tunnel facility. Stability calculations for stationary and traveling crossflow instability waves in selected configurations indicate that an N value of 4 and 6, respectively, correlates reasonably well with transition onset discerned from one experimentally measured thermographic image.

Numerical Investigation of Roughness Effects on Transition on Spherical Capsules

“…3,4 Blunt re-entry capsules with a sphere-cone shaped forebody like the Mars Science Laboratory (MSL) support modal growth of boundary-layer instabilities on the conical part of the heat shield strong enough to trigger laminarturbulent transition. [5][6][7] Configurations where the forebody consists of a spherical segment only, like the Apollo capsule or the Orion Crew Exploration Vehicle (CEV), require a much higher Reynolds number for the onset of modal disturbance growth. 8 Owing to the strong bow shock, the boundary-layer edge Mach number remains subsonic or slightly supersonic on the spherical heat shield, which excludes the possibility of second mode amplification.…”

Investigation on the wake flow instability behind isolated roughness elements on the forebody of a blunt generic reentry capsule

“…For the design of future returning space vehicles, those correlations should be replaced by the methods based on stability theory and transient growth considerations as demanded by Reshotko [2]. So far, stability analyses have only been performed for the MSL capsule, where transition was dominated by ¦rst-mode and cross- §ow instabilities [3,4] and recently by Theiss et al [5] for an Apollo-shaped capsule. Because of a strong favourable pressure gradient, the boundary layer in the latter investigation did not feature any ampli¦ed modal disturbances at similar freestream conditions to [4].…”

Developing Mechanism-Based Methods for Estimating Hypersonic Boundary-Layer Transition in Flight: The Role of Quiet Tunnels

“…For example, a possiblydominant first-mode instability was computed in 2009 for the Mars Science Laboratory vehicle [108]. However, modern computations of this kind have not yet been verified with instability-wave measurements, due in part to the fragile nature of the hotwire instrumentation that was once the only method available.…”