Validation of the PTM Transition Model on a 3D Flow Through a Turbine Cascade

2016 ◽  
Author(s):  
Sergiy Yershov ◽  
Viktor Yakovlev
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Numerical Results ◽  
Transitional Flow ◽  
Turbine Cascade ◽  
Production Term ◽  
Flow Acceleration ◽  
Turbulent Transition ◽  
Displacement Thickness ◽  
Laminar Turbulent Transition

This study presents a numerical simulation of a 3D viscous subsonic flow in the VKI-Genoa turbine cascade taking into account the laminar-turbulent transition. The numerical simulation is performed using the Reynolds-averaged Navier-Stokes (RANS) equations and the low-Reynolds k-ω SST turbulence model. The Langtry’s algebraic Production Term Modification (PTM) model is applied for modeling the laminar-turbulent transition. The governing equations are integrated using the second-order accurate Godunov’s type implicit ENO scheme. Computations of both fully turbulent and transitional flows are carried out. Much attention is given to the comparison between the present numerical results and the existing experimental data. The comparison was based on the surface distributions of the isentropic velocity, the friction velocity, the flow acceleration parameter, the displacement thickness, the shape-factor, and the momentum thickness Reynolds number. Velocity profiles upstream and downstream of the transition onset were compared also. The numerical results obtained show an influence of the transition on the secondary flow pattern. In the case of the transitional flow, when compared with the fully turbulence flow case, the endwall boundary layer cross-flow starts upstream, and it is more intensive, but less massive due to a thinner boundary layer in the laminar flow region.

Direct Numerical Simulation on Transition of an Incompressible Boundary Layer on a Flat Plate

2012 ◽  
Vol 268-270 ◽  
pp. 1143-1147
Author(s):  
Ning Li ◽  
Qi Hong Zeng
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Direct Numerical Simulation ◽  
Flat Plate ◽  
Flow Profile ◽  
Mean Flow ◽  
Turbulent Transition ◽  
Incompressible Boundary Layer ◽  
Incompressible Boundary ◽  
Laminar Turbulent Transition

Direct Numerical Simulation(DNS) was carried out for laminar-turbulent transition of an incompressible boundary layer on a flat plate based on disturbance Navier-Stokes(N-S) equation in spatial mode with Massage Passing Interface(MPI) technology. Study on breakdown mechanism of laminar-turbulent transition was carried on. The effect of mean flow distortion on the process of breakdown in laminar-turbulent transition was investigated. Results indicate that change of instability characteristic of mean flow profile plays a key role during process of breakdown.

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.

Numerical Simulation of the boundary layer laminar-turbulent transition caused by a small gap

2021 ◽  
Author(s):  
Felipe Oliveira Aguirre ◽  
Marlon Sproesser Mathias ◽  
Marcello Augusto Faraco de Medeiros
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

INFLUENCE OF THE PLATE LEADING-EDGE SHAPE AND THICKNESS ON THE BOUNDARY LAYER LAMINAR-TURBULENT TRANSITION IN HYPERSONIC FLOW

2019 ◽  
Vol 50 (5) ◽  
pp. 461-481
Author(s):  
Sergei Vasilyevich Aleksandrov ◽  
Evgeniya Andreevna Aleksandrova ◽  
Volf Ya. Borovoy ◽  
Andrey Vyacheslavovich Gubernatenko ◽  
Vladimir Evguenyevich Mosharov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Hypersonic Flow ◽  
Leading Edge ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition
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