scholarly journals To the analysis of the natural pulsation development during laminar-turbulent transition in supersonic boundary layer

2017 ◽  
Author(s):  
A. D. Kosinov ◽  
Yu. G. Yermolaev ◽  
N. V. Semionov ◽  
G. L. Kolosov ◽  
A. V. Panina
Keyword(s):  
Boundary Layer ◽  
Supersonic Boundary Layer ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

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.

scholarly journals Laminar–turbulent transition induced by a discrete roughness element in a supersonic boundary layer

2013 ◽  
Vol 735 ◽  
pp. 613-646 ◽  
Author(s):  
N. De Tullio ◽  
P. Paredes ◽  
N. D. Sandham ◽  
V. Theofilis
Keyword(s):  
Boundary Layer ◽  
Shear Layer ◽  
Roughness Element ◽  
Three Dimensional ◽  
Supersonic Boundary Layer ◽  
Low Velocity ◽  
Adiabatic Wall ◽  
Turbulent Transition ◽  
Displacement Thickness ◽  
Laminar Turbulent Transition

AbstractThe linear instability and breakdown to turbulence induced by an isolated roughness element in a boundary layer at Mach $2. 5$, over an isothermal flat plate with laminar adiabatic wall temperature, have been analysed by means of direct numerical simulations, aided by spatial BiGlobal and three-dimensional parabolized (PSE-3D) stability analyses. It is important to understand transition in this flow regime since the process can be slower than in incompressible flow and is crucial to prediction of local heat loads on next-generation flight vehicles. The results show that the roughness element, with a height of the order of the boundary layer displacement thickness, generates a highly unstable wake, which is composed of a low-velocity streak surrounded by a three-dimensional high-shear layer and is able to sustain the rapid growth of a number of instability modes. The most unstable of these modes are associated with varicose or sinuous deformations of the low-velocity streak; they are a consequence of the instability developing in the three-dimensional shear layer as a whole (the varicose mode) or in the lateral shear layers (the sinuous mode). The most unstable wake mode is of the varicose type and grows on average ${\sim }17\hspace{0.167em} \% $ faster than the most unstable sinuous mode and ${\sim }30$ times faster than the most unstable boundary layer mode occurring in the absence of a roughness element. Due to the high growth-rates registered in the presence of the roughness element, an amplification factor of $N= 9$ is reached within ${\sim }50$ roughness heights from the roughness trailing edge. The independently performed Navier–Stokes, spatial BiGlobal and PSE-3D stability results are in excellent agreement with each other, validating the use of simplified theories for roughness-induced transition involving wake instabilities. Following the linear stages of the laminar–turbulent transition process, the roll-up of the three-dimensional shear layer leads to the formation of a wedge of turbulence, which spreads laterally at a rate similar to that observed in the case of compressible turbulent spots for the same Mach number.

scholarly journals Experimental Study of the Influence of Unit Reynolds Number on the Laminar-Turbulent Transition on the Model Swept Wing with a Subsonic Leading Edge at M = 2

2021 ◽  
Vol 16 (1) ◽  
pp. 44-52
Author(s):  
Vasilii L. Kocharin ◽  
Nikolai V. Semionov ◽  
Alexander D. Kosinov ◽  
Aleksey A. Yatskikh ◽  
Sofia A. Shipul ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Experimental Studies ◽  
Leading Edge ◽  
Supersonic Boundary Layer ◽  
Swept Wing ◽  
Unit Reynolds Number ◽  
Flow Parameters ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

Experimental studies of the influence of unit Reynolds number on the laminar-turbulent transition in a supersonic boundary layer of a swept wing with a subsonic leading edge at Mach number 2 are performed. The experiments were performed on a model of a swept wing with a swept angle of the leading edge of 72 degrees and with a 3% profile with a variable chord length in span. The hot-wire measurements showed that a laminar-turbulent transition in a supersonic boundary layer of a swept wing with a subsonic leading edge occurs earlier (~25-30%) than on a model with a supersonic leading edge with the same oncoming flow parameters. It is shown that a change unit Reynolds number insignificant influence the laminar-turbulent transition in the boundary layer of a swept wing with a subsonic leading edge.

Influence Of Heavy Gas Blowing Into The Wall Layer Of Supersonic Boundary-Layer On Its Transition

2017 ◽  
Vol 12 (1) ◽  
pp. 50-56
Author(s):  
Vladimir Lysenko ◽  
Boris Smorodsky ◽  
Yuri Yermolaev ◽  
Sergey Gaponov ◽  
Aleksandr Kosinov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sulfur Hexafluoride ◽  
Plate Boundary ◽  
Leading Edge ◽  
Wall Layer ◽  
Supersonic Boundary Layer ◽  
Turbulent Transition ◽  
Heavy Gas ◽  
Gas Blowing ◽  
Laminar Turbulent Transition

The experimental investigation of the influence of the distributed blowing of heavy gas (sulfur hexafluoride of SF6) into the wall layer of supersonic flat-plate boundary layer (at free-stream Mach number M = 2) on the laminar-turbulent transition have been performed. For the first time experimentally it is shown that in case of such blowing there is a boundary-layer stabilization, and the laminar-turbulent transition is removed from the model leading edge.

scholarly journals Laminar—Turbulent Transition in a Supersonic Boundary Layer

1999 ◽  
Vol 11 (9) ◽  
pp. S10-S10
Author(s):  
Ch. Mielke ◽  
L. Kleiser ◽  
J. M. Favre
Keyword(s):  
Boundary Layer ◽  
Supersonic Boundary Layer ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition
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