U-RANS Model for the Prediction of the Acoustic Sound Power Generated in a Whistling Corrugated Pipe

2013 ◽  
Author(s):  
Joachim Golliard ◽  
Néstor González-Díez ◽  
Stefan Belfroid ◽  
Güneş Nakiboğlu ◽  
Avraham Hirschberg
Keyword(s):  
Velocity Profile ◽  
Shear Layer ◽  
Turbulence Modeling ◽  
Acoustic Power ◽  
Gas Production ◽  
Transport Systems ◽  
Navier Stokes ◽  
Acoustic Oscillations ◽  
High Reynolds ◽  
Single Cavity

Corrugated pipes, as used in flexible risers for gas production or in domestic appliances, can whistle when a flow is imposed through the pipe. Nakiboğlu et al [1, 2] have developed a method to compute the acoustic source term for axi-symmetric cavities. The method is based on the resolution of incompressible Navier-Stoke equations without turbulence modeling. This is a quasi-laminar flow model. A single cavity in a short pipe is considered with, as inlet boundary condition, a pipe flow with an imposed harmonic velocity perturbation. At low Reynolds numbers most of the effect of the turbulence is accounted by the steady velocity profile imposed at the inlet. However, this model fails when applied to high Reynolds number flows as encountered in gas-transport systems (Re = 106 or higher). In this paper, a modified model, using a 2-D unsteady Reynolds Averaged Navier Stokes turbulent solver, is presented. Turbulence determines the development of the approaching boundary layer and of the shear layer above the cavity. The shear-layer velocity profile controls the acoustic power generated by the cavity in response to the imposed acoustic oscillations. Comparison with experimental results obtained for a single cavity shows that the modification of the method considerably increases its accuracy for a deep cavity.

scholarly journals Heat Transfer Predictions for Two Turbine Nozzle Geometries at High Reynolds and Mach Numbers

1997 ◽  
Vol 119 (2) ◽  
pp. 270-283 ◽  
Author(s):  
R. J. Boyle ◽  
R. Jackson
Keyword(s):  
Heat Transfer ◽  
Turbulence Modeling ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Gas Temperature ◽  
Algebraic Models ◽  
Pressure Distributions ◽  
Nozzle Geometries ◽  
High Reynolds ◽  
Computational Analyses

Predictions of turbine vane and endwall heat transfer and pressure distributions are compared with experimental measurements for two vane geometries. The differences in geometries were due to differences in the hub profile, and both geometries were derived from the design of a high rim speed turbine (HRST). The experiments were conducted in the Isentropic Light Piston Facility (ILPF) at Pyestock at a Reynolds number of 5.3 x 106, a Mach number of 1.2, and a wall-to-gas temperature ratio of 0.66. Predictions are given for two different steady-state three-dimensional Navier–Stokes computational analyses. C-type meshes were used, and algebraic models were employed to calculate the turbulent eddy viscosity. The effects of different turbulence modeling assumptions on the predicted results are examined. Comparisons are also given between predicted and measured total pressure distributions behind the vane. The combination of realistic engine geometries and flow conditions proved to be quite demanding in terms of the convergence of the CFD solutions. An appropriate method of grid generation, which resulted in consistently converged CFD solutions, was identified.

scholarly journals Heat Transfer Predictions for Two Turbine Nozzle Geometries at High Reynolds and Mach Numbers

1995 ◽  
Author(s):  
R. J. Boyle ◽  
R. Jackson
Keyword(s):  
Heat Transfer ◽  
Turbulence Modeling ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Gas Temperature ◽  
Algebraic Models ◽  
Pressure Distributions ◽  
Nozzle Geometries ◽  
High Reynolds ◽  
Computational Analyses

Predictions of turbine vane and endwall heat transfer and pressure distributions are compared with experimental measurements for two vane geometries. The differences in geometries were due to differences in the hub profile, and both geometries were derived from the design of a high rim speed turbine (HRST). The experiments were conducted in the Isentropic Light Piston Facility (ILPF) at Pyestock at a Reynolds No. of 5.3 × 106, a Mach No. of 1.2, and a wall-to-gas temperature ratio of 0.66. Predictions are given for two different steady state three-dimensional Navier-Stokes computational analyses. C-type meshes were used, and algebraic models were employed to calculate the turbulent eddy viscosity. The effects of different turbulence modeling assumptions on the predicted results are examined. Comparisons are also given between predicted and measured total pressure distributions behind the vane. The combination of realistic engine geometries and flow conditions proved to be quite demanding in terms of the convergence of the CFD solutions. An appropriate method of grid generation, which resulted in consistently converged CFD solutions, was identified.

scholarly journals Numerical study of airfoil with wavy leading edge at high Reynolds number regime

2020 ◽  
Author(s):  
William Denner Pires Fonseca ◽  
Rafael Rosario Da Silva ◽  
Reinaldo Marcondes Orselli ◽  
Adson Agrico De Paula ◽  
Ricardo Galdino da Silva
Keyword(s):  
Reynolds Number ◽  
Turbulence Modeling ◽  
Stokes Equations ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Numerical Data ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
High Reynolds

In this work, a numerical study of flow around an airfoil with wavy leading edge is presented at a Reynolds number of 3X106. The flow is resolved by considering the RANS (Reynolds Average Navier-Stokes)equations. The baseline geometry is based on the NACA 0021 profile. The wavy leading edge has an amplitude of 3% and wavelength of 11%, both with respect to the airfoil chord. Cases without and with wavy leadingedges are simulated and compared. Initially, studies of the numerical sensitivity with respect to the obtained results, considering aspects such as turbulence modeling and mesh refinement, are carried out as well as bycomparison with corresponding results in the literature. Numerical data such as pressure distribution, shear stress lines on the wing surface, and aerodynamics coefficients are used to describe and investigate the flowfeatures around the wavy leading airfoil. Comparisons between the straight leading edge and the wavy leading edge cases shows an increase of the maximum lift coefficient as well as stall angle for the wavy leading edge configuration. In addition, at an angle of attack near the stall, the present numerical results shows an increase of the drag coefficient with the wavy leading edge airfoil when compared with the corresponding straight leading edge case.

Simulating flow separation from continuous surfaces: routes to overcoming the Reynolds number barrier

2009 ◽  
Vol 367 (1899) ◽  
pp. 2885-2903 ◽  
Author(s):  
Michael Leschziner ◽  
Ning Li ◽  
Fabrizio Tessicini
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
Major Elements ◽  
Wall Layer ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Rans Models ◽  
High Reynolds ◽  
Near Wall

This paper provides a discussion of several aspects of the construction of approaches that combine statistical (Reynolds-averaged Navier–Stokes, RANS) models with large eddy simulation (LES), with the objective of making LES an economically viable method for predicting complex, high Reynolds number turbulent flows. The first part provides a review of alternative approaches, highlighting their rationale and major elements. Next, two particular methods are introduced in greater detail: one based on coupling near-wall RANS models to the outer LES domain on a single contiguous mesh, and the other involving the application of the RANS and LES procedures on separate zones, the former confined to a thin near-wall layer. Examples for their performance are included for channel flow and, in the case of the zonal strategy, for three separated flows. Finally, a discussion of prospects is given, as viewed from the writer's perspective.

Modeling of Compressor Drum Cavities With Radial Inflow

2016 ◽  
Author(s):  
D. Amirante ◽  
Z. Sun ◽  
J. W. Chew ◽  
N. J. Hills ◽  
N. R. Atkins
Keyword(s):  
Thermal Stratification ◽  
Turbulence Modeling ◽  
Navier Stokes ◽  
Inflow Rate ◽  
Cfd Models ◽  
Flow And Heat Transfer ◽  
Rotating Discs ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Conditions ◽  
Cooling Air

Reynolds-Averaged Navier-Stokes (RANS) computations have been conducted to investigate the flow and heat transfer between two co-rotating discs with an axial throughflow of cooling air and a radial bleed introduced from the shroud. The computational fluid dynamics (CFD) models have been coupled with a thermal model of the test rig, and the predicted metal temperature compared with the thermocouple data. CFD solutions are shown to vary from a buoyancy driven regime to a forced convection regime, depending on the radial inflow rate prescribed at the shroud. At a high radial inflow rate, the computations show an excellent agreement with the measured temperatures through a transient rig condition. At a low radial inflow rate, the cavity flow is destabilized by the thermal stratification. Good qualitative agreement with the measurements is shown, although a significant over-prediction of disc temperatures is observed. This is associated with under prediction of the penetration of the axial throughflow into the cavity. The mismatch could be the result of strong sensitivity to the prescribed inlet conditions, in addition to possible shortcomings in the turbulence modeling.

Simulation of the Transitional Flow in a Low Pressure Gas Turbine Cascade With a High-Order Discontinuous Galerkin Method

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
A. Ghidoni ◽  
A. Colombo ◽  
S. Rebay ◽  
F. Bassi
Keyword(s):  
Discontinuous Galerkin ◽  
Turbulence Model ◽  
Stokes Equations ◽  
Time Integration ◽  
High Order ◽  
Transitional Flow ◽  
Navier Stokes ◽  
Implicit Time ◽  
Turbine Cascade ◽  
High Reynolds

In the last decade, discontinuous Galerkin (DG) methods have been the subject of extensive research efforts because of their excellent performance in the high-order accurate discretization of advection-diffusion problems on general unstructured grids, and are nowadays finding use in several different applications. In this paper, the potential offered by a high-order accurate DG space discretization method with implicit time integration for the solution of the Reynolds-averaged Navier–Stokes equations coupled with the k-ω turbulence model is investigated in the numerical simulation of the turbulent flow through the well-known T106A turbine cascade. The numerical results demonstrate that, by exploiting high order accurate DG schemes, it is possible to compute accurate simulations of this flow on very coarse grids, with both the high-Reynolds and low-Reynolds number versions of the k-ω turbulence model.

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