Role of three-dimensional instabilities in compliant wall boundary-layer transition

A new model for predicting heat transfer in the transitional boundary layer of rough turbine airfoils is presented. The new model makes use of extensive experimental work recently published by the current authors. For the computation of the turbulent boundary layer, a discrete element roughness model is combined with a two-layer model of turbulence. The transition region is modeled using an intermittency equation that blends between the laminar and turbulent boundary layer. Several intermittency functions are evaluated in respect of their applicability to rough-wall transition. To predict the onset of transition, a new correlation is presented, accounting for the influence of freestream turbulence and surface roughness. Finally, the new model is tested against transitional rough-wall boundary layer flows on high-pressure and low-pressure turbine airfoils.

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Three-Dimensional Spatio-Temporal Disturbance Flow Field Analysis of Particulate-Induced High-Speed Boundary-Layer Transition

AIAA Scitech 2021 Forum ◽

10.2514/6.2021-1657 ◽

2021 ◽

Author(s):

Sayed Mohammad Abdullah Al Hasnine ◽

Vincenzo Russo ◽

Anatoli Tumin ◽

Christoph Brehm

Keyword(s):

Boundary Layer ◽

Flow Field ◽

High Speed ◽

Three Dimensional ◽

Boundary Layer Transition ◽

Field Analysis ◽

Layer Transition ◽

Flow Field Analysis ◽

Spatio Temporal

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DNS study on the formation of Lambda rotational core and the role of TS wave in boundary layer transition

Journal of Turbulence ◽

10.1080/14685248.2016.1150596 ◽

2016 ◽

Vol 17 (6) ◽

pp. 572-601 ◽

Cited By ~ 3

Author(s):

Yonghua Yan ◽

Jie Tang ◽

Chaoqun Liu ◽

Fan Yang

Keyword(s):

Boundary Layer ◽

Boundary Layer Transition ◽

Layer Transition

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Numerical simulation of boundary-layer transition and transition control

Journal of Fluid Mechanics ◽

10.1017/s002211208900042x ◽

1989 ◽

Vol 199 ◽

pp. 403-440 ◽

Cited By ~ 74

Author(s):

E. Laurien ◽

L. Kleiser

Keyword(s):

Boundary Layer ◽

Stokes Equations ◽

Three Dimensional ◽

Transition Process ◽

Numerical Results ◽

Boundary Layer Transition ◽

Two Dimensional ◽

Layer Transition ◽

Longitudinal Vortices ◽

Tollmien Schlichting

The laminar-turbulent transition process in a parallel boundary-layer with Blasius profile is simulated by numerical integration of the three-dimensional incompressible Navier-Stokes equations using a spectral method. The model of spatially periodic disturbances developing in time is used. Both the classical Klebanoff-type and the subharmonic type of transition are simulated. Maps of the three-dimensional velocity and vorticity fields and visualizations by integrated fluid markers are obtained. The numerical results are compared with experimental measurements and flow visualizations by other authors. Good qualitative and quantitative agreement is found at corresponding stages of development up to the one-spike stage. After the appearance of two-dimensional Tollmien-Schlichting waves of sufficiently large amplitude an increasing three-dimensionality is observed. In particular, a peak-valley structure of the velocity fluctuations, mean longitudinal vortices and sharp spike-like instantaneous velocity signals are formed. The flow field is dominated by a three-dimensional horseshoe vortex system connected with free high-shear layers. Visualizations by time-lines show the formation of A-structures. Our numerical results connect various observations obtained with different experimental techniques. The initial three-dimensional steps of the transition process are consistent with the linear theory of secondary instability. In the later stages nonlinear interactions of the disturbance modes and the production of higher harmonics are essential.We also study the control of transition by local two-dimensional suction and blowing at the wall. It is shown that transition can be delayed or accelerated by superposing disturbances which are out of phase or in phase with oncoming Tollmien-Schlichting instability waves, respectively. Control is only effective if applied at an early, two-dimensional stage of transition. Mean longitudinal vortices remain even after successful control of the fluctuations.

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An Axial Compressor End-Wall Boundary Layer Calculation Method

Journal of Engineering for Power ◽

10.1115/1.3446474 ◽

1979 ◽

Vol 101 (2) ◽

pp. 233-245 ◽

Cited By ~ 5

Author(s):

J. De Ruyck ◽

C. Hirsch ◽

P. Kool

Keyword(s):

Experimental Data ◽

Boundary Layer ◽

Velocity Profile ◽

Three Dimensional ◽

Axial Compressor ◽

Tip Clearance ◽

Wall Region ◽

Wall Boundary Layer ◽

Wall Boundary ◽

End Wall

An axial compressor end-wall boundary layer theory which requires the introduction of three-dimensional velocity profile models is described. The method is based on pitch-averaged boundary layer equations and contains blade force-defect terms for which a new expression in function of transverse momentum thickness is introduced. In presence of tip clearance a component of the defect force proportional to the clearance over blade height ratio is also introduced. In this way two constants enter the model. It is also shown that all three-dimensional velocity profile models present inherent limitations with regard to the range of boundary layer momentum thicknesses they are able to represent. Therefore a new heuristic velocity profile model is introduced, giving higher flexibility. The end-wall boundary layer calculation allows a correction of the efficiency due to end-wall losses as well as calculation of blockage. The two constants entering the model are calibrated and compared with experimental data allowing a good prediction of overall efficiency including clearance effects and aspect ratio. Besides, the method allows a prediction of radial distribution of velocities and flow angles including the end-wall region and examples are shown compared to experimental data.

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