TY - JOUR
T1 - Kinetic modeling of unsteady hypersonic flows over a tick geometry
AU - Tumuklu, Ozgur
AU - Levin, Deborah A.
AU - Theofilis, Vassilis
N1 - The research of O.T. and D.A.L. was supported by the Air Force Office of Scientific Research through AFOSR Grant No. FA9550-11-1-0129 with a subcontract Award No. 2010-06171-01 to UIUC. O.T. and D.A.L. are also grateful for the computational resource provided on ERDC Topaz and Onyx, and AFRL Thunder and Centennial. The work of V.T. was sponsored by the Air Force Office of Scientific Research, Air Force Material Command, USAF, under Grant No. FA9550-15-1-0387 Global transient growth mechanisms in high-speed flows with application to the elliptic cone and Grant No. FA9550-17-1-0115 Global Modal and Non-Modal Instability Analyses of Shock-Induced Separation Bubbles, with V.T. as the principal investigator and Dr. Ivett Leyva as the program officer. The authors are also grateful to Dr. Amna Khraibut, Dr. Sudhir L. Gai, and Dr. Sean O’Byrne for proving the experimental and CFD data and useful discussions.
PY - 2019/5/1
Y1 - 2019/5/1
N2 - Hypersonic separated flows over the so-called "tick" geometry have been studied using the time-accurate direct simulation Monte Carlo (DSMC) method and global linear theory. The free stream condition for two experimental cases studied in the free-piston shock tunnel (named T-ADFA) was modeled. These two cases span a Knudsen number from transitional to continuum, a Mach number of about 10, a free stream enthalpy from 10 to 3 MJ/kg, a Reynolds number varying by a factor of four, and a leading edge geometry varied from sharp to one with a bevel of 0.2 mm. For the first time, the time dependence of flow macroparameters on the leading edge nose radius and the Reynolds number are studied using global linear theory. High-fidelity DSMC simulations showed that the temporal behavior of the separation region, which has significant effects on the surface parameters, depends closely on the leading edge bluntness and wall temperature. The formation of a secondary vortex was seen in about 2 ms for the sharp leading edge, whereas in the rounded leading edge geometry, it formed at earlier 0.7 ms. At a steady state, the size and structure of the separation zone, vortex structures, and surface parameters predicted by DSMC were found to be in good agreement with computational fluid dynamics for the higher density case. Finally, linear stability theory showed that for some leading edge shapes and flow densities, the time to reach the steady state was longer than the facility measurement time.
AB - Hypersonic separated flows over the so-called "tick" geometry have been studied using the time-accurate direct simulation Monte Carlo (DSMC) method and global linear theory. The free stream condition for two experimental cases studied in the free-piston shock tunnel (named T-ADFA) was modeled. These two cases span a Knudsen number from transitional to continuum, a Mach number of about 10, a free stream enthalpy from 10 to 3 MJ/kg, a Reynolds number varying by a factor of four, and a leading edge geometry varied from sharp to one with a bevel of 0.2 mm. For the first time, the time dependence of flow macroparameters on the leading edge nose radius and the Reynolds number are studied using global linear theory. High-fidelity DSMC simulations showed that the temporal behavior of the separation region, which has significant effects on the surface parameters, depends closely on the leading edge bluntness and wall temperature. The formation of a secondary vortex was seen in about 2 ms for the sharp leading edge, whereas in the rounded leading edge geometry, it formed at earlier 0.7 ms. At a steady state, the size and structure of the separation zone, vortex structures, and surface parameters predicted by DSMC were found to be in good agreement with computational fluid dynamics for the higher density case. Finally, linear stability theory showed that for some leading edge shapes and flow densities, the time to reach the steady state was longer than the facility measurement time.
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U2 - 10.1063/1.5090341
DO - 10.1063/1.5090341
M3 - Article
AN - SCOPUS:85066789690
SN - 1070-6631
VL - 31
JO - Physics of fluids
JF - Physics of fluids
IS - 5
M1 - 056108
ER -