Experimental Investigation of Gas Injection into the Boundary Layer on a Slender Body in Supersonic Flow
A method for injection of gas into the boundary layer on a slender body in supersonic flow while minimizing perturbation to the mean flow is examined experimentally. Injection of gas is equivalent to a sudden increase in the displacement thickness of the boundary layer, which produces an oblique shock that propagates into the inviscid region of the flow. It is found that modification of the geometry of the body can compensate for the increased displacement thickness created by injection and minimize the production of oblique waves. However, the resulting near-wall injection layer is observed to be unstable and a turbulent boundary layer develops downstream of the injection region. The instability of the flow is examined using velocity profiles from a compressible Navier-Stokes computation. In-depth analysis of the mean flow and stability are performed by Fedorov in a companion paper.
© 2014 American Institute of Aeronautics and Astronautics. Published Online: 13 Jun 2014. The authors would like to thank Dr. Nicholaus Parziale and Mr. Bahram Valiferdowsi for guidance and assistance in the laboratory. The authors would additionally like to acknowledge Dr. Joseph Jewell, Dr. Ivett Leyva, and Dr. Ross Wagnild for previous work done on this topic. Finally, the authors thank Dr. Alexander Fedorov for the concept of using a negative slope on the cone surface to compensate for injection. Without this key idea this work would not have been performed. This work was sponsored in part by AFOSR and NASA through the National Center for Hypersonic Research in Laminar-Turbulent Transition and also by AFOSR award number FA9550-10-1-0491. The views expressed herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of AFOSR or the U.S. Government.