TY - JOUR
T1 - Leading-edge bluntness effects on hypersonic three-dimensional flows over a compression ramp
AU - Cao, Shibin
AU - Hao, Jiaao
AU - Klioutchnikov, Igor
AU - Olivier, Herbert
AU - Heufer, Karl Alexander
AU - Wen, Chih Yung
N1 - Funding Information:
This work was jointly supported by RWTH Aachen University and The Hong Kong Polytechnic University. The authors gratefully acknowledge the computing time granted by the JARA Vergabegremium and provided on the JARA Partition part of the supercomputer CLAIX at RWTH Aachen University under project JARA0218.
Publisher Copyright:
© 2021 SPIE. All rights reserved.
PY - 2021/7/30
Y1 - 2021/7/30
N2 - Hypersonic flows over a compression ramp with different leading-edge radii are numerically investigated. Flow separation occurs on the cold-wall compression ramp with a free-stream Mach number of 7.7 and a unit Reynolds number of m. By performing direct numerical simulations (DNS), it is shown that the separation bubble enlarges when the leading-edge radius is increased from zero up to a critical value. Beyond the critical radius, the separation bubble conversely shrinks as the radius is further increased. Global stability analysis (GSA) is employed to investigate the three-dimensional instability of the two-dimensional base flows. It is found that the inherent instability in the flow field also exhibits a reversal trend, that is, the flow system firstly becomes more unstable and then tends to be more stable with increasing leading-edge radius. The growth rate and spanwise wavelength of the unstable modes identified by GSA are verified by DNS. Accompanying the occurrence of three-dimensionality, streamwise heat-flux streaks are formed on the ramp surface downstream of reattachment. The present study demonstrates that a proper blunting of the leading edge can suppress flow separation, reduce aerodynamic heating and stabilise the flow system for a hypersonic compression-ramp flow.
AB - Hypersonic flows over a compression ramp with different leading-edge radii are numerically investigated. Flow separation occurs on the cold-wall compression ramp with a free-stream Mach number of 7.7 and a unit Reynolds number of m. By performing direct numerical simulations (DNS), it is shown that the separation bubble enlarges when the leading-edge radius is increased from zero up to a critical value. Beyond the critical radius, the separation bubble conversely shrinks as the radius is further increased. Global stability analysis (GSA) is employed to investigate the three-dimensional instability of the two-dimensional base flows. It is found that the inherent instability in the flow field also exhibits a reversal trend, that is, the flow system firstly becomes more unstable and then tends to be more stable with increasing leading-edge radius. The growth rate and spanwise wavelength of the unstable modes identified by GSA are verified by DNS. Accompanying the occurrence of three-dimensionality, streamwise heat-flux streaks are formed on the ramp surface downstream of reattachment. The present study demonstrates that a proper blunting of the leading edge can suppress flow separation, reduce aerodynamic heating and stabilise the flow system for a hypersonic compression-ramp flow.
KW - absolute/convective instability
KW - boundary-layer separation
KW - shock waves
UR - http://www.scopus.com/inward/record.url?scp=85111640643&partnerID=8YFLogxK
U2 - 10.1017/jfm.2021.552
DO - 10.1017/jfm.2021.552
M3 - Journal article
AN - SCOPUS:85111640643
SN - 0022-1120
VL - 923
JO - Journal of Fluid Mechanics
JF - Journal of Fluid Mechanics
M1 - A27
ER -