scholarly journals Unsteady heat-flux measurements of second-mode instability waves in a hypersonic flat-plate boundary layer

2016 ◽  
Vol 57 (8) ◽  
Author(s):  
Michael A. Kegerise ◽  
Shann J. Rufer
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Flat Plate ◽  
Plate Boundary ◽  
Mode Instability ◽  
Instability Waves ◽  
Second Mode ◽  
Flux Measurements ◽  
Flat Plate Boundary Layer

scholarly journals Development of second-mode instability in a Mach 6 flat plate boundary layer with two-dimensional roughness

2015 ◽  
Vol 27 (6) ◽  
pp. 064105 ◽  
Author(s):  
Qing Tang ◽  
Yiding Zhu ◽  
Xi Chen ◽  
Cunbiao Lee
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Plate Boundary ◽  
Two Dimensional ◽  
Mode Instability ◽  
Second Mode ◽  
Flat Plate Boundary Layer

Feedback control of instability waves in a transitional flat-plate boundary layer

2006 ◽  
Vol 9 (3) ◽  
pp. 283-289 ◽  
Author(s):  
Y. Fukunishi ◽  
T. Sakai ◽  
K. Sasaki ◽  
S. Izawa ◽  
A. K. Xiong
Keyword(s):  
Boundary Layer ◽  
Feedback Control ◽  
Flat Plate ◽  
Plate Boundary ◽  
Instability Waves ◽  
Flat Plate Boundary Layer

scholarly journals Instability wave–streak interactions in a supersonic boundary layer

2017 ◽  
Vol 831 ◽  
pp. 524-553 ◽  
Author(s):  
Pedro Paredes ◽  
Meelan M. Choudhari ◽  
Fei Li
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Boundary Layer Flow ◽  
Incompressible Flows ◽  
Plate Boundary ◽  
Supersonic Boundary Layer ◽  
Instability Wave ◽  
Instability Waves ◽  
Layer Flow ◽  
Flat Plate Boundary Layer

The interaction of stationary streaks undergoing non-modal growth with modally unstable instability waves in a supersonic flat-plate boundary-layer flow is studied using numerical computations. For incompressible flows, previous studies have shown that boundary-layer modulation due to streaks below a threshold amplitude level can stabilize the Tollmien–Schlichting instability waves, resulting in a delay in the onset of laminar–turbulent transition. In the supersonic regime, the most-amplified linear waves become three-dimensional, corresponding to oblique, first-mode waves. This change in the character of dominant instabilities leads to an important change in the transition process, which is now dominated by oblique breakdown via nonlinear interactions between pairs of first-mode waves that propagate at equal but opposite angles with respect to the free stream. Because the oblique breakdown process is characterized by a strong amplification of stationary streamwise streaks, artificial excitation of such streaks may be expected to promote transition in a supersonic boundary layer. Indeed, suppression of those streaks has been shown to delay the onset of transition in prior literature. This paper investigates the nonlinear evolution of initially linear optimal disturbances that evolve into finite-amplitude streaks in a two-dimensional, Mach 3 adiabatic flat-plate boundary-layer flow, followed by the modal instability characteristics of the perturbed, streaky boundary-layer flow. Both parts of the investigation are performed with the plane-marching parabolized stability equations. Consistent with previous findings, the present study shows that optimally growing stationary streaks can destabilize the first-mode waves, but only when the spanwise wavelength of the instability waves is equal to or smaller than twice the streak spacing. Transition in a benign disturbance environment typically involves first-mode waves with significantly longer spanwise wavelengths, and hence, these waves are stabilized by the optimal growth streaks. Thus, as long as the amplification factors for the destabilized, short wavelength instability waves remain below the threshold level for transition, a significant net stabilization is achieved, yielding a potential transition delay that may be comparable to the length of the laminar region in the uncontrolled case.

Interaction of intersecting shocks with a flat-plate boundary layer in the presence of an entropy layer

2013 ◽  
Vol 48 (5) ◽  
pp. 636-647 ◽  
Author(s):  
V. Ya. Borovoy ◽  
I. V. Egorov ◽  
V. E. Mosharov ◽  
V. N. Radchenko ◽  
A. S. Skuratov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Plate Boundary ◽  
Entropy Layer ◽  
Flat Plate Boundary Layer
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