On The Influence Of Porous Coating Thickness On Supersonic Boundary Layer Stability

2015 ◽  
Vol 10 (3) ◽  
pp. 41-47
Author(s):  
Vladimir Lysenko ◽  
Sergey Gaponov ◽  
Boris Smorodsky ◽  
Yuri Yermolaev ◽  
Aleksandr Kosinov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Coating Thickness ◽  
Free Stream ◽  
Plate Boundary ◽  
Quantitative Agreement ◽  
Supersonic Boundary Layer ◽  
Linear Stability Theory ◽  
Porous Coating ◽  
Free Stream Mach Number ◽  
The Stability

Theoretical and experimental investigation of the influence of porous-coating thickness on the stability of the supersonic flat-plate boundary layer at free-stream Mach number M = 2 have been performed. Good quantitative agreement of experimental data obtained with artificially generated disturbances performed on models with various porous inserts and calculations based on the linear stability theory has been achieved. It is shown that the increase of the porous-coating thickness leads to the boundary layer destabilization.

scholarly journals Experiments on Supersonic Boundary Layer Laminarization by Means of Foreign-Gas Injection

2019 ◽  
Vol 14 (3) ◽  
pp. 26-38
Author(s):  
V. I. Lysenko ◽  
B. V. Smorodsky ◽  
Yu. G. Yermolaev ◽  
A. A. Yatskih ◽  
A. D. Kosinov
Keyword(s):  
Boundary Layer ◽  
Sulfur Hexafluoride ◽  
Free Stream ◽  
Plate Boundary ◽  
Quantitative Agreement ◽  
Supersonic Boundary Layer ◽  
Linear Stability Theory ◽  
Free Stream Mach Number ◽  
Heavy Gas ◽  
First Time

Experimental investigation of the influence of the distributed heavy gas (sulfur hexafluoride, SF6) injection into the near-wall sub-layer of a boundary layer) on the hydrodynamic stability in relation to controlled disturbances of the supersonic flat-plate boundary-layer at free-stream Mach number M = 2 have been performed. It was for the first time in controlled experiments obtained that injection of this foreign gas leads to the boundary-layer stabilization that is manifested in reduction of disturbance amplification rates. Good quantitative agreement of collected experimental data with computations based on the linear stability theory is obtained.

Combined influence of coating permeability and roughness on supersonic boundary layer stability and transition

2016 ◽  
Vol 798 ◽  
pp. 751-773 ◽  
Author(s):  
V. I. Lysenko ◽  
S. A. Gaponov ◽  
B. V. Smorodsky ◽  
Yu. G. Yermolaev ◽  
A. D. Kosinov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Plate Boundary ◽  
Leading Edge ◽  
Quantitative Agreement ◽  
Supersonic Boundary Layer ◽  
Linear Stability Theory ◽  
Porous Coating ◽  
Boundary Layer Stability ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

A joint theoretical and experimental investigation of the influence of the surface permeability and roughness on the stability and laminar–turbulent transition of a supersonic flat-plate boundary layer at a free-stream Mach number of $M_{\infty }=2$ has been performed. Good quantitative agreement of the experimental data obtained with artificially generated disturbances performed on models with various porous inserts and calculations based on linear stability theory has been achieved. An increase of the pore size and porous-coating thickness leads to a boundary layer destabilization that accelerates the laminar–turbulent transition. It is shown that as a certain (critical) roughness value is reached, with an increase in the thickness of the rough and porous coating, the boundary layer stability diminishes and the laminar–turbulent transition is displaced towards the leading edge of the model.

Theoretical and Experimental Investigation of the First Instability Mode Development in Supersonic Boundary Layers on Porous Coatings

2014 ◽  
Vol 9 (2) ◽  
pp. 65-74
Author(s):  
Sergey Gaponov ◽  
Yuri Yermolaev ◽  
Aleksandr Kosinov ◽  
Vladimir Lysenko ◽  
Nikolay Semionov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Free Stream ◽  
Plate Boundary ◽  
Quantitative Agreement ◽  
Instability Mode ◽  
Instability Modes ◽  
Free Stream Mach Number ◽  
Surface Permeability ◽  
Flat Plate Boundary Layer

In the present study we have performed combined theoretical and experimental investigation of the surface permeability influence on the linear stability of the supersonic flat-plate boundary layer at free-stream Mach number M = 2. Good quantitative agreement was obtained between the data calculated by the linear theory of stability and the data obtained in experiments with artificially generated disturbances performed on models with various porous inserts. It is shown that increase of the permeable surface pore size leads to the destabilization of the first instability modes propagating under arbitrary angles in the boundary layer

Joint Influence Of Surface Roughness And Permeability On Stability And Transition Of Mach = 2 Boundary Layer

2016 ◽  
Vol 11 (2) ◽  
pp. 37-45
Author(s):  
Vladimir Lysenko ◽  
Boris Smorodsky ◽  
Yuri Yermolaev ◽  
Aleksandr Kosinov ◽  
Nikolay Semionov
Keyword(s):  
Boundary Layer ◽  
Plate Boundary ◽  
Leading Edge ◽  
Quantitative Agreement ◽  
Linear Stability Theory ◽  
Porous Coating ◽  
Boundary Layer Stability ◽  
Turbulent Transition ◽  
Surface Permeability ◽  
Laminar Turbulent Transition

Joint theoretical and experimental investigation of the influence of surface permeability and roughness on stability and laminar-turbulent transition of the supersonic flat-plate boundary layer at free-stream Mach number M = 2 have been performed. Good quantitative agreement of experimental data obtained with artificially generated disturbances performed on models with various porous inserts and calculations based on the linear stability theory has been achieved. At research of the joint effect of the model surface permeability and roughness on the boundary layer stability and transition, it is shown that, as a certain (critical) roughness value is reached, with the rough and porous coating thickness increase, the boundary layer stability diminishes and the laminar-turbulent transition is displaced toward the model leading edge.

Influence of porous-coating thickness on the stability and transition of flat-plate supersonic boundary layer

2012 ◽  
Vol 19 (4) ◽  
pp. 555-560 ◽  
Author(s):  
S. A. Gaponov ◽  
Yu. G. Ermolaev ◽  
A. D. Kosinov ◽  
V. I. Lysenko ◽  
N. V. Semenov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Coating Thickness ◽  
Supersonic Boundary Layer ◽  
Porous Coating ◽  
The Stability

scholarly journals Effect of free-stream turbulence and other vortical disturbances on a laminar boundary layer

1999 ◽  
Vol 380 ◽  
pp. 169-203 ◽  
Author(s):  
S. J. LEIB ◽  
DAVID W. WUNDROW ◽  
M. E. GOLDSTEIN
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Free Stream ◽  
Stokes Equations ◽  
Plate Boundary ◽  
Streamwise Velocity ◽  
Boundary Region ◽  
Quantitative Agreement ◽  
Free Stream Turbulence ◽  
Turbulent Reynolds Number

This paper is concerned with the effect of free-stream turbulence on the pretransitional flat-plate boundary layer. It is assumed that either the turbulent Reynolds number or the downstream distance (or both) is small enough that the flow can be linearized. The dominant disturbances in the boundary layer, which are of the Klebanoff type, are governed by the linearized unsteady boundary-region equations, i.e. the linearized Navier–Stokes equations with the streamwise derivatives neglected in the viscous and pressure-gradient terms. The turbulence is represented as a superposition of vortical free-stream Fourier modes and the corresponding Fourier component solutions to the boundary-region equations are obtained numerically. The results are then superposed to compute the root mean square of the fluctuating streamwise velocity in the boundary layer produced by the actual free-stream turbulence. It is found that the disturbances computed with isotropic free-stream turbulence do not reach the levels measured in experiments. However, good quantitative agreement is obtained with the relatively low turbulent Reynolds number data of Kendall when the measured strong anisotropy of the low-frequency portion of his spectrum is accounted for. Data at higher turbulent Reynolds numbers are affected by nonlinearity, which manifests itself through the generation of small spanwise length scales. We attempt to model this within the context of the linear theory by choosing a free-stream spectrum whose energy is concentrated at larger transverse wavenumbers and achieve very good agreement with the data. The results suggest that even small deviations from pure isotropy can be an important factor in explaining the large amplitudes of the Klebanoff modes in the pre-transitional boundary layer, and also point to the importance of nonlinear effects. We discuss some additional effects that may need to be accounted for in order to obtain a complete description of the Klebanoff modes.

Numerical investigation of the nonlinear transition regime in a Mach 2 boundary layer

2010 ◽  
Vol 668 ◽  
pp. 113-149 ◽  
Author(s):  
CHRISTIAN S. J. MAYER ◽  
STEFAN WERNZ ◽  
HERMANN F. FASEL
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Plate Boundary ◽  
Transition Process ◽  
Supersonic Boundary Layer ◽  
Subharmonic Resonance ◽  
Linear Stability Theory ◽  
Experimental Investigations ◽  
Weakly Nonlinear ◽  
Breakdown Mechanism

The transition process in a supersonic flat-plate boundary layer at Mach 2 is investigated numerically using linear stability theory (LST) and direct numerical simulations (DNS). The experimental investigations by Kosinov and his co-workers serve as a reference and provide the physical conditions for the numerical set-up. In these experiments, the weakly nonlinear regime of transition was studied. This led to the discovery of asymmetric subharmonic resonance triads, which appear to be relevant for transition in a Mach 2 boundary layer. These triads were composed of one primary oblique wave of frequency 20kHz and two oblique subharmonic waves of frequency 10kHz. While the experimentalists have focused on this new breakdown mechanism, we have found that the experimental data also indicate the presence of another mechanism related to oblique breakdown. This might be the first experimental evidence of the oblique breakdown mechanism in a supersonic boundary layer. With the simulations presented here, the possible presence of oblique breakdown mechanisms in the experiments is explored by deliberately suppressing subharmonic resonances in the DNS and by comparing the numerical results with the experimental data. The DNS results show excellent agreement with the experimental measurements for both linear and nonlinear transition stages. Most importantly, the results clearly show the characteristic features of oblique breakdown. In addition, we also investigated the subharmonic transition route using LST and DNS. When forcing both the subharmonic and the fundamental frequencies in the DNS, a subharmonic resonance mechanism similar to that in the experiments can be observed.

scholarly journals Stability of Supersonic Boundary Layer on the Sublimation Surface

2020 ◽  
Vol 15 (1) ◽  
pp. 42-61
Author(s):  
Vladimir I. Lysenko ◽  
Sergey A. Gaponov ◽  
Boris V. Smorodsky ◽  
Alexander D. Kosinov ◽  
Mikhail I. Yaroslavtsev
Keyword(s):  
Boundary Layer ◽  
Surface Coating ◽  
Plate Boundary ◽  
Supersonic Boundary Layer ◽  
Linear Stability Theory ◽  
Stagnation Temperature ◽  
Local Growth ◽  
Increasing Temperature ◽  
Effect Of Surface ◽  
Triple Point Temperature

Theoretical investigation of the supersonic flat-plate boundary-layer properties under conditions of the surface material sublimation has been performed for Mach number M = 2. Naphthalene (C10H8) was chosen as the substance for the sublimation coating. Performed computations show that with increasing surface temperature due to stagnation temperature increase, the mass flow rate of naphthalene evaporation increases. Calculations performed on the basis of linear stability theory show that such an increase of evaporation leads to a noticeable decrease of the local growth rates of unstable perturbations in the boundary layer. It is found that stabilization of the boundary layer by the surface coating sublimation occurs with increasing temperature of the sublimation coating, reaching a maximum near the triple point temperature of the sublimation material. The carried out experiments confirmed the stabilizing effect of surface sublimation.

Transition of streamwise streaks in zero-pressure-gradient boundary layers

2002 ◽  
Vol 472 ◽  
pp. 229-261 ◽  
Author(s):  
LUCA BRANDT ◽  
DAN S. HENNINGSON
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
High Speed ◽  
Plate Boundary ◽  
Transition Process ◽  
Free Stream Turbulence ◽  
Tollmien Schlichting ◽  
Streamwise Streaks ◽  
The Stability ◽  
Optimal Disturbances

A transition scenario initiated by streamwise low- and high-speed streaks in a flat-plate boundary layer is studied. In many shear flows, the perturbations that show the highest potential for transient energy amplification consist of streamwise-aligned vortices. Due to the lift-up mechanism these optimal disturbances lead to elongated streamwise streaks downstream, with significant spanwise modulation. In a previous investigation (Andersson et al. 2001), the stability of these streaks in a zero-pressure-gradient boundary layer was studied by means of Floquet theory and numerical simulations. The sinuous instability mode was found to be the most dangerous disturbance. We present here the first simulation of the breakdown to turbulence originating from the sinuous instability of streamwise streaks. The main structures observed during the transition process consist of elongated quasi-streamwise vortices located on the flanks of the low-speed streak. Vortices of alternating sign are overlapping in the streamwise direction in a staggered pattern. The present scenario is compared with transition initiated by Tollmien–Schlichting waves and their secondary instability and by-pass transition initiated by a pair of oblique waves. The relevance of this scenario to transition induced by free-stream turbulence is also discussed.

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