Navier-Stokes Simulation of Boundary-Layer Transition

1990 ◽  
Author(s):  
Helen L. Reed
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Layer Transition

Numerical Investigation on the Second Stator Boundary Layer Under Clocking Effects: Comparison of v2f and LCL-Model

2008 ◽  
Author(s):  
Axel Heidecke ◽  
Bernd Stoffel
Keyword(s):  
Boundary Layer ◽  
Numerical Investigation ◽  
Separation Bubble ◽  
Measurement Data ◽  
Turbulence Models ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Layer Transition ◽  
Numerical Work ◽  
Boundary Layer Development

This paper presents the results of a numerical investigation of a 1.5-stage low pressure turbine. The main focus of the numerical work was the prediction of the stator-2 boundary layer development under the influence of the stator stator clocking. The turbine profile used for the examination is a so called high-lift-profile and was designed for a laminar-turbulent transition over a steady separation bubble. The boundary conditions were defined by the 1.5-stage test turbine located at our laboratory, where also the measurement data was derived from. The calculations were conducted with a two-dimensional Navier-Stokes solver using a finite volume discretisation scheme. The higher level turbulence models v′2-f and the LCL-turbulence model, which are capable to predict boundary layer transition were compared with measurement data at midspan.

Intermittency Based Unsteady Boundary Layer Transition Modeling: Implementation Into Navier-Stokes Equations

2005 ◽  
Author(s):  
M. T. Schobeiri
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Navier Stokes ◽  
Transition Model ◽  
Unsteady Boundary Layer ◽  
Layer Transition ◽  
Navier Stokes Equations ◽  
Unsteady Wake

This paper presents recent advances in boundary layer research that deal with an intermittency based unsteady boundary layer transition model and its implementation into the Reynolds averaged Navier-Stokes equations (RANS). RANS equations are conditioned to include the ensemble averaged unsteady intermittency function. The unsteady boundary layer transition model is based on a universal unsteady intermittency function developed earlier. It accounts for the effects of periodic unsteady wake flow on the boundary layer transition. The transition model is the result of an inductive approach analyzing the unsteady data obtained by experiments on a curved plate at zero-streamwise pressure gradient under periodic unsteady wake flow. To validate this model, systematic experimental investigations were conducted on the suction and pressure surfaces of turbine blades that were integrated into a turbine cascade test facility, which was designed for unsteady boundary layer investigations. This model is implemented into the above mentioned conditioned RANS-equations and calculation results are presented.

scholarly journals Compressible Direct Numerical Simulation of Low-Pressure Turbines—Part I: Methodology

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Richard D. Sandberg ◽  
Vittorio Michelassi ◽  
Richard Pichler ◽  
Liwei Chen ◽  
Roderick Johnstone
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Direct Numerical Simulation ◽  
Environmental Parameters ◽  
Boundary Layer Separation ◽  
Low Pressure ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Layer Transition ◽  
Background Turbulence

Modern low pressure turbines (LPT) feature high pressure ratios and moderate Mach and Reynolds numbers, increasing the possibility of laminar boundary-layer separation on the blades. Upstream disturbances including background turbulence and incoming wakes have a profound effect on the behavior of separation bubbles and the type/location of laminar-turbulent transition and therefore need to be considered in LPT design. Unsteady Reynolds-averaged Navier–Stokes (URANS) are often found inadequate to resolve the complex wake dynamics and impact of these environmental parameters on the boundary layers and may not drive the design to the best aerodynamic efficiency. LES can partly improve the accuracy, but has difficulties in predicting boundary layer transition and capturing the delay of laminar separation with varying inlet turbulence levels. Direct numerical simulation (DNS) is able to overcome these limitations but has to date been considered too computationally expensive. Here, a novel compressible DNS code is presented and validated, promising to make DNS practical for LPT studies. Also, the sensitivity of wake loss coefficient with respect to freestream turbulence levels below 1% is discussed.

The transient period for boundary layer disturbances

1999 ◽  
Vol 381 ◽  
pp. 89-119 ◽  
Author(s):  
D. G. LASSEIGNE ◽  
R. D. JOSLIN ◽  
T. L. JACKSON ◽  
W. O. CRIMINALE
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Temporal Evolution ◽  
Initial Conditions ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Spatial Evolution ◽  
Layer Transition ◽  
Transient Period ◽  
The Continuum

The onset of transition in a boundary layer is dependent on the initialization and interaction of disturbances in a laminar flow. Here, theory and full Navier–Stokes simulations focus on the transient period just after disturbances enter the boundary layer. The temporal evolution of disturbances within a boundary layer is investigated by examining a series of initial value problems. In each instance, the complete spectra (i.e. the discrete and the continuum) are included so that the solutions can be completely arbitrary. Both numerical and analytical solutions of the linearized Navier–Stokes equations subject to the arbitrary initial conditions are presented. The temporal evolution of disturbances during the transient period are compared with the spatial evolution of the same disturbances and a strong correlation between the two approaches is demonstrated indicating that the theory may be used for the transient period of disturbance evolution. The theory and simulations demonstrate that strong amplification of the disturbances can occur as a result of the inclusion of the continuum in the prediction of disturbance evolution. The results further show that any approach proposed for use in bypass boundary layer transition must include the transient growth that results from the continuum. Finally, although a connection between temporal and spatial evolution in the transient period has been demonstrated, a theoretical basis as an explanation for this connection remains the focus of additional study.

A FEniCS-based model for prediction of boundary layer transition in low-speed aerodynamic flows

2019 ◽  
Vol 233 (15) ◽  
pp. 5729-5745
Author(s):  
Amir Kolaei ◽  
Götz Bramesfeld
Keyword(s):  
Boundary Layer ◽  
High Performance ◽  
Stokes Equations ◽  
Element Model ◽  
Least Square ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Layer Transition ◽  
Low Speed ◽  
Aerodynamic Flows

In the paper, a finite element model is developed that predicts boundary layer transition in low-speed aerodynamic flows. The model is based on a Reynolds-averaged Navier-Stokes approach, where the incompressible form of the Navier-Stokes equations is solved together with a three-equation eddy-viscosity model utilizing the FEniCS framework. A least-square stabilized Galerkin method is employed in order to prevent numerical oscillations that can arise from dominant advection terms. The proposed FEniCS model is ideal for applications with complex geometries and is tested on high performance computing platforms for parallel processing. The FEniCS model is validated by comparing the skin friction coefficient as well as profiles of velocity and total fluctuation kinetic energy with the benchmark experimental data for transitional boundary layers on a flat plate. The validity of the solver is further examined using experimental measurements reported for a NLF(1)-0416 natural laminar flow airfoil at different angles of attack. The airfoil results are also compared with those obtained using XFOIL, a well-known tool for the design of two-dimensional airfoils. These comparisons suggest that the proposed FEniCS-based model can effectively simulate aerodynamic flow fields that involve laminar-to-turbulent transition.

Simulation of Passing Wakes Inducing Unsteady Boundary Layer Transition Around Low-Pressure Turbine Blade

2021 ◽  
Author(s):  
Antoine Dufau ◽  
Julien Marty ◽  
Daniel Man ◽  
Estelle Piot
Keyword(s):  
Boundary Layer ◽  
Numerical Study ◽  
Separation Bubble ◽  
Bubble Formation ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Layer Transition ◽  
Laminar Separation ◽  
Low Pressure Turbine ◽  
Bubble Length

Abstract The present study focuses on the very high-lift T106C cascade with passing wakes and aims to validate the γ - Re θ ¯ model of Menter-Langtry used to predict laminar-turbulent transition based on unsteady Reynolds-Averaged Navier-Stokes simulations. The comparison to experimental data provided by Von Karman Institute, shows that the transition model is able to capture the influence of passing wakes on transition phenomenon. Like the experiments, the simulations show a reduction of the time-averaged separation bubble length and of the overall losses in the presence of passing wakes. For this numerical study, four other wakes have been generated in order to study the influence of wake parameters on the transition onset, on the laminar separation bubble formation and on the turbine cascade performances. For a given averaged turbulence intensity and total pressure deficit, thinner wakes seem to have a more positive effect on boundary layer, reducing the separation and the overall losses.

Direct numerical simulation of passive control of three-dimensional phenomena in boundary-layer transition using wall heating

1994 ◽  
Vol 264 ◽  
pp. 213-254 ◽  
Author(s):  
L. D. Kral ◽  
H. F. Fasel
Keyword(s):  
Boundary Layer ◽  
Growth Rates ◽  
Passive Control ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Layer Transition ◽  
Wall Heating ◽  
Uniform Wall

A numerical model is presented for investigating control of the three-dimensional boundary-layer transition process. Control of a periodically forced, spatially evolving boundary layer in water is studied using surface heating techniques. The Navier–Stokes and energy equations are integrated using a fully implicit finite difference/spectral method. The Navier–Stokes equations are used in vorticity–velocity form and are coupled with the energy equation through the viscosity dependence on temperature. Passive control of small amplitude two-dimensional waves and three-dimensional oblique waves is numerically simulated with either uniform or non-uniform wall heating applied. Both amplitude levels and amplification rates are strongly reduced with heating applied. Comparison is made with parallel and non-parallel linear stability theory and experiments. Control of the early stages of the nonlinear breakdown process is also investigated using uniform wall heating. Both control of the fundamental and subharmonic routes to turbulence are investigated. For both breakdown processes, a strong reduction in amplitude levels and growth rates results. In particular, the high three-dimensional growth rates that are characteristic of the secondary instability process are significantly reduced below the uncontrolled levels.

scholarly journals Boundary Layer Transition Models for Naval Applications: Capabilities and Limitations

2019 ◽  
Vol 63 (4) ◽  
pp. 294-307 ◽  
Author(s):  
Dongyoung Kim ◽  
Yagin Kim ◽  
Jiajia Li ◽  
Robert V. Wilson ◽  
J. Ezequiel Martin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Turbulence Models ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Flat Plates ◽  
University Of Iowa ◽  
Layer Transition ◽  
Small Vessels ◽  
Transition Models

We describe the implementation of several recently developed boundary layer transition models into the overset computational fluid dynamics code, REX, developed at the University of Iowa, together with an evaluation of its capabilities and limitations for naval hydrodynamics applications. Models based on correlations and on amplification factor transport were implemented in one- and two-equation Reynolds-averaged Navier‐Stokes turbulence models, including modifications to operate in crossflow. Extensive validation of the transition models implemented in REX is performed for several 2- and 3-dimensional geometries of naval relevance. Standard tests with extensive available experimental data include flat plates in zero pressure gradient, an airfoil, and sickle wing. More complex test cases include the propeller, P4119, with some experimental data available, and the generic submersible, Joubert BB2, with no relevant experimental data available, to validate the transition models. Simulations for these last two cases show that extensive regions of laminar flow can be present on the bodies at laboratory scale and field scale for small vessels, and the potential effects on resistance and propulsion can be significant.

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