|
Christopher D. Marley
Missouri University of Science and Technology
Dr. David W. Riggins
Abstract
Forward facing injection of mass can be used for the drag reduction on blunt bodies in hypersonic flows. However experimental and some computational investigations have shown that such injection is usually highly unstable, i.e. generally demonstrates collapse of the jet along the surface with little forward penetration and little beneficial effect on blunt body drag. Most numerical studies of injection impose an axi-symmetric boundary condition along the stagnation streamline (for the body at zero angle of attack). Such a boundary condition results in increased (non-physical) stability of the jet hence yielding overly optimistic drag reduction predictions. In the present study, a numerical simulation of a full three-dimensional hemispherical body is conducted and innovative forward injection methods, including annular (ring) and swirled injection as well as forward energy deposition, are investigated. Target outcomes of interest are 1) drag reduction achieved on the blunt body (including the detrimental drag effect caused by the forward-facing injection itself) and 2) stability characteristics of the jet. Studies are conducted at free stream Mach numbers of 10 and 6.4 at standard atmospheric conditions corresponding to 30 km altitude. While centered forward injection without upstream energy deposition is confirmed to be highly unstable either with or without swirl, ring injection exhibits a stabilizing influence on the jet. Energy deposition upstream of the body is shown to significantly enhance stability and penetration of the forward facing jet for all techniques.
Chris Marley is originally from North Chicago Illinois where his father was an instructor at Great Lakes Naval Station. After his father retired from the navy, Chris and his family moved to Springfield Missouri. After graduating from Parkview High School in Springfield, Chris went on to major in aerospace engineering at the Missouri University of Science and Technology. Chris is currently a graduate student at Missouri S&T and hopes to become a researcher the field of aeronautical science.
|
