Direct numerical simulation of transition in a sharp cone boundary layer at Mach 6: fundamental breakdown

2015 ◽  
Vol 768 ◽  
pp. 175-218 ◽  
Author(s):  
Jayahar Sivasubramanian ◽  
Hermann F. Fasel
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Nonlinear Interactions ◽  
Fundamental Resonance ◽  
Hypersonic Boundary Layers ◽  
Turbulent Transition ◽  
Breakdown Region ◽  
Complete Breakdown ◽  
Sharp Cone

Direct numerical simulations (DNS) were performed to investigate the laminar–turbulent transition in a boundary layer on a sharp cone with an isothermal wall at Mach 6 and at zero angle of attack. The motivation for this research is to make a contribution towards understanding the nonlinear stages of transition and the final breakdown to turbulence in hypersonic boundary layers. In particular, the role of second-mode fundamental resonance, or (K-type) breakdown, is investigated using high-resolution ‘controlled’ transition simulations. The simulations were carried out for the laboratory conditions of the hypersonic transition experiments conducted at Purdue University. First, several low-resolution simulations were carried out to explore the parameter space for fundamental resonance in order to identify the cases that result in strong nonlinear interactions. Subsequently, based on the results from this study, a set of highly resolved simulations that proceed deep into the turbulent breakdown region have been performed. The nonlinear interactions observed during the breakdown process are discussed in detail in this paper. A detailed description of the flow structures that arise due to these nonlinear interactions is provided and an analysis of the skin friction and heat transfer development during the breakdown is presented. The controlled transition simulations clearly demonstrate that fundamental breakdown may indeed be a viable path to complete breakdown to turbulence in hypersonic cone boundary layers at Mach 6.

scholarly journals Boundary Layers on Rough Compressor Blades

1972 ◽  
Author(s):  
K. Bammert ◽  
R. Milsch
Keyword(s):  
Boundary Layer ◽  
Friction Coefficient ◽  
Boundary Layers ◽  
Axial Flow ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Compressor Blades ◽  
Turbulent Transition ◽  
Good Reproduction ◽  
Compressor Efficiency

Blades of axial flow compressors are often roughened by corrosion or erosion. There is only scant information about the influence of this roughening on the boundary layers of the blades and thereby on the compressor efficiency. To obtain detailed information for calculating the efficiency drop due to the roughness, experimental investigations with an enlarged cascade have been executed. The results enabled to develop new formulas for a modified friction coefficient in the laminar region and for the laminar-turbulent transition and the separation points of the boundary layer. Thus, together with the Truckenbrodt theory, it was possible, to get a good reproduction of the experimental results.

Review: Laminar-to-Turbulent Transition of Three-Dimensional Boundary Layers on Rotating Bodies

1994 ◽  
Vol 116 (2) ◽  
pp. 200-211 ◽  
Author(s):  
Ryoji Kobayashi
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Three Dimensional ◽  
Speed Ratio ◽  
Stream Velocity ◽  
Turbulent Transition ◽  
Centrifugal Instability ◽  
Crossflow Instability ◽  
Dimensional Boundary ◽  
Axisymmetric Bodies

The laminar-turbulent transition of three-dimensional boundary layers is critically reviewed for some typical axisymmetric bodies rotating in still fluid or in axial flow. The flow structures of the transition regions are visualized. The transition phenomena are driven by the compound of the Tollmien-Schlichting instability, the crossflow instability, and the centrifugal instability. Experimental evidence is provided relating the critical and transition Reynolds numbers, defined in terms of the local velocity and the boundary layer momentum thickness, to the local rotational speed ratio, defined as the ratio of the circumferential speed to the free-stream velocity at the outer edge of the boundary layer, for the rotating disk, the rotating cone, the rotating sphere and other rotating axisymmetric bodies. It is shown that the cross-sectional structure of spiral vortices appearing in the transition regions and the flow pattern of the following secondary instability in the case of the crossflow instability are clearly different than those in the case of the centrifugal instability.

Statistical Analysis of Nonlinear Processes on a Porous Surface in a Hypersonic Boundary Layer

2009 ◽  
Vol 4 (3) ◽  
pp. 43-49
Author(s):  
Dmitriy Buntin ◽  
Anatoliy Maslov ◽  
Timur Chimytov ◽  
Aleksandr Shiplyuk
Keyword(s):  
Boundary Layer ◽  
Statistical Analysis ◽  
Porous Surface ◽  
Transition To Turbulence ◽  
Hypersonic Boundary Layer ◽  
Hot Wire ◽  
Turbulent Transition ◽  
Hypersonic Wind Tunnel ◽  
Sharp Cone ◽  
Skewness And Kurtosis

Experimental investigation of nonlinear stage of the transition to turbulence in a hypersonic boundary layer is presented. The experiments were carried out in a hypersonic wind tunnel T-326 at the Institute of theoretical and applied mechanics SB RAS. The model was a sharp cone with porous surface. Using the statistical analysis of the signals obtained by means of hot-wire it was shown that skewness and kurtosis distribution in a boundary layer on both solid and porous surface are in a qualitative agreement. At the same time the growing of skewness and kurtosis on a porous surface was shown. Analysis of mean voltage and rms voltage pulsation profiles of the hot-wire sensors showed that there is a delay of the laminar-turbulent transition on a porous surface.

scholarly journals NUMERICAL MODELING OF A TURBULENT BOTTOM BOUNDARY LAYER UNDER SOLITARY WAVES ON A SMOOTH SURFACE

2018 ◽  
pp. 26
Author(s):  
Ahmad Sana ◽  
Hitoshi Tanaka
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Solitary Waves ◽  
Bottom Boundary Layer ◽  
Stream Velocity ◽  
Bottom Boundary ◽  
Sediment Movement ◽  
Bottom Boundary Layers ◽  
Turbulent Models

A number of studies on bottom boundary layers under sinusoidal and cnoidal waves were carried out in the past owing to the role of bottom shear stress on coastal sediment movement. In recent years, the bottom boundary layers under long waves have attracted considerable attention due to the occurrence of huge tsunamis and corresponding sediment movement. In the present study two-equation turbulent models proposed by Menter(1994) have been applied to a bottom boundary layer under solitary waves. A comparison has been made for cross-stream velocity profile and other turbulence properties in x-direction.

Investigation of the Laminar-Turbulent Transition of Boundary Layers Disturbed by Wakes

1982 ◽  
Author(s):  
H. Pfeil ◽  
R. Herbst ◽  
T. Schröder
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Boundary Layers ◽  
Transition Process ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Turbulent Spots ◽  
Turbulent Transition ◽  
Time Space ◽  
Favorable Pressure Gradient

The boundary layer transition under instationary afflux conditions as present in the stages of turbomachines is investigated. A model for the transition process is introduced by means of time-space distributions of the turbulent spots during transition and schematic drawings of the instantaneous boundary layer thicknesses. To confirm this model, measurements of the transition with zero and favorable pressure gradient are performed.

The development of horizontal boundary layers in stratified flow. Part 2. Diffusive flow

1970 ◽  
Vol 42 (3) ◽  
pp. 513-525 ◽  
Author(s):  
L. G. Redekopp
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Horizontal Plane ◽  
Stratified Flow ◽  
First Approximation ◽  
Diffusive Flow ◽  
Buoyancy Forces ◽  
Flow Part ◽  
And Diffusion

The boundary layer on the upper surface of a horizontal plane in a diffusive, stratified flow is examined. The analysis shows that density diffusion increases the role of the buoyancy forces and causes a significant change in the properties of the boundary layer when compared to the non-diffusive case. A uniformly valid first approximation for moderate Russell numbers is derived, and the effects of buoyancy and diffusion are evaluated by solving the resulting equations numerically.

Experiments in a boundary layer subjected to free stream turbulence. Part 2. The role of TS-waves in the transition process

1994 ◽  
Vol 281 ◽  
pp. 219-245 ◽  
Author(s):  
A. V. Boiko ◽  
K. J. A. Westin ◽  
B. G. B. Klingmann ◽  
V. V. Kozlov ◽  
P. H. Alfredsson
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Small Amplitude ◽  
Free Stream ◽  
Transition Process ◽  
Natural Occurrence ◽  
Free Stream Turbulence ◽  
Onset Of Turbulence ◽  
Tollmien Schlichting

The natural occurrence of Tollmien-Schlichting (TS) waves has so far only been observed in boundary layers subjected to moderate levels of free stream turbulence (Tu < 1%), owing to the difficulty in detecting small-amplitude waves in highly perturbed boundary layers. By introducing controlled oscillations with a vibrating ribbon, it is possible to study small-amplitude waves using phase-selective filtering techniques. In the present work, the effect of TS-waves on the transition is studied at Tu = 1.5%. It is demonstrated that TS-waves can exist and develop in a similar way as in an undisturbed boundary layer. It is also found that TS-waves with quite small amplitudes are involved in nonlinear interactions which lead to a regeneration of TS-waves in the whole unstable frequency band. This results in a significant increase in the number of turbulent spots, which promote the onset of turbulence.

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