Reentry Vehicle Aerodynamics and Control at Very High Angle of Attack

In recent flight tests the X-38 reentry test vehicle spins during the deployment of the drogue parachute. An experimental aerodynamic study has been conducted at the University of Illinois using a scale model of the X-38 to explore the cause of this problem. A six-component sting balance was used to measure the forces and moments on the 4.7% wind tunnel model at angles of attack from -7° to 95°. In addition, surface pressure taps and flow visualization techniques were utilized to determine the forebody pressures and surface flowfield on the model. The effect of Reynolds number and boundary-layer state were also examined. The investigation suggests that the spinning under the drogue parachute was caused by asymmetric vortex formation. At angles of attack between 75° and 90° vortex asymmetry developed in all of the cases without separation geometrically fixed. This flow asymmetry produced large side forces and yawing moments. The Reynolds number effect and the effect of the boundary-layer state were noticeable, but did not greatly change the side force and yawing moment characteristics of the model. The micro-geometry of the model had a large effect on the side force generated by the vortex positioning. The effects of forced oscillations were also examined and it was determined that the side forces were still present during the oscillations. Control of the vortices and side forces was obtained by applying strakes to the side of the forebody of the model.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Merret, Jason Michael

Contributors dc:contributor

• Bragg, Michael B.

• Engineering, Aerospace

Language dc:language

eng

Identifier

(MiAaPQ)AAI3160924

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85091