APPLICATION OF A PRESSURE CORRECTION METHOD FOR MODELING INCOMPRESSIBLE FLOW THROUGH TURBOMACHINES

2009 ◽  
Vol 06 (03) ◽  
pp. 399-411 ◽  
Author(s):  
M. T. RAHMATI
Keyword(s):  
Experimental Data ◽  
Incompressible Flow ◽  
Numerical Scheme ◽  
Numerical Solutions ◽  
Turbulence Modeling ◽  
Flow Analysis ◽  
Correction Method ◽  
Pressure Correction ◽  
Flow Simulations ◽  
Flow Through

This article presents the application of a RANS algorithm based on a pressure correction method for incompressible flow simulations of low-speed rotating machines. A numerical scheme is developed by extending a flow analysis in a stationary frame to a rotating frame for turbomachinery applications. The numerical scheme is explained with emphasis on the effect of rotation on the flow fields and turbulence modeling. The results of the numerical calculations for flow through an enclosed turbomachine and an extended turbomachine are compared with the experimental data to judge them on realistic flow patterns. The numerical solutions have shown reasonable agreement with the experimental data which demonstrates the merits and robustness of this numerical scheme.

scholarly journals Mixing in Axial-Flow Compressors: Conclusions Drawn From 3-D Navier-Stokes Analyses and Experiments

1990 ◽  
Author(s):  
J. H. Leylek ◽  
D. C. Wisler
Keyword(s):  
Experimental Data ◽  
Numerical Solutions ◽  
Turbulence Modeling ◽  
Axial Flow ◽  
Separated Flow ◽  
Navier Stokes ◽  
Tracer Gas ◽  
Flow Through ◽  
First Time ◽  
Axial Flow Compressors

Extensive numerical analyses and experiments have been conducted to understand mixing phenomena in multistage, axial-flow compressors. For the first time in the literature the following are documented: detailed 3-D Navier-Stokes solutions, with high-order turbulence modeling, are presented for flow through a compressor vane row at both design and off-design (increased) loading; comparison of these computations with detailed experimental data show excellent agreement at both loading levels; the results are then used to explain important aspects of mixing in compressors. The 3-D analyses show the development of spanwise and cross-passage flows in the stator and the change in location and extent of separated flow regions as loading increases. The numerical solutions support previous interpretations of experimental data obtained on the same blading using the ethylene tracer-gas technique and hot-wire anemometry. These results, plus new tracer-gas data, show that both secondary flow and turbulent diffusion are mechanisms responsible for both spanwise and cross-passage mixing in axial-flow compressors. The relative importance of the two mechanisms depends upon the configuration and loading levels. It appears that using the correct spanwise distributions of time-averaged inlet boundary conditions for 3-D Navier-Stokes computations enables one to explain much of the flow physics for this stator.

Mixing in Axial-Flow Compressors: Conclusions Drawn From Three-Dimensional Navier–Stokes Analyses and Experiments

1991 ◽  
Vol 113 (2) ◽  
pp. 139-156 ◽  
Author(s):  
J. H. Leylek ◽  
D. C. Wisler
Keyword(s):  
Experimental Data ◽  
Numerical Solutions ◽  
Turbulence Modeling ◽  
Three Dimensional ◽  
Axial Flow ◽  
Separated Flow ◽  
Navier Stokes ◽  
Tracer Gas ◽  
Flow Through ◽  
Axial Flow Compressors

Extensive numerical analyses and experiments have been conducted to understand mixing phenomena in multistage, axial-flow compressors. For the first time in the literature the following are documented: Detailed three-dimensional Navier–Stokes solutions, with high order turbulence modeling, are presented for flow through a compressor vane row at both design and off-design (increased) loading; comparison of these computations with detailed experimental data show excellent agreement at both loading levels; the results are then used to explain important aspects of mixing in compressors. The three-dimensional analyses show the development of spanwise (radial) and circumferential flows in the stator and the change in location and extent of separated flow regions as loading increases. The numerical solutions support previous interpretations of experimental data obtained on the same blading using the ethylene tracer-gas technique and hot-wire anemometry. These results, plus new tracer-gas data, show that both secondary flow and turbulent diffusion are mechanisms responsible for both spanwise and circumferential mixing in axial-flow compressors. The relative importance of the two mechanisms depends upon the configuration and loading levels. It appears that using the correct spanwise distributions of time-averaged inlet boundary conditions for three-dimensional Navier–Stokes computations enables one to explain much of the flow physics for this stator.

Secondary Flow in Repeating Stages of Axial Turbomachines

1995 ◽  
Vol 209 (2) ◽  
pp. 101-110 ◽  
Author(s):  
J H Horlock
Keyword(s):  
Experimental Data ◽  
Secondary Flow ◽  
Flow Analysis ◽  
Axial Flow ◽  
Streamwise Vorticity ◽  
Flow Phenomenon ◽  
Multi Stage ◽  
Axial Velocity Profile ◽  
Flow Through ◽  
Flow Compressor

In a well-designed multi-stage axial flow compressor, the flow settles down to a repeating condition, in which the axial velocity profile does not deteriorate further; it is more or less unchanged between the entry and the exit of a deeply embedded stage. However, experimental data also show that the flow angles repeat, and it is this flow phenomenon that is discussed in the paper. Secondary flow analysis, coupled with empirical data on clearance flows, is used to give a description of the flow in such a repeating stage. The secondary flow at exit from a row involves both the streamwise vorticity generated in that row and the vorticity that exists at entry—the so-called ‘skew’ vorticity due to a non-uniform velocity from a stator being received by a moving rotor (and a similar effect from the rotor to the stator). However, clearance vorticity—shed from the rotor tip (casing) section and the stator root (hub) section—is also present and can be taken into account. Calculations made using the analyses are compared with some limited experimental data drawn from the published literature. Predicted underturning at rotor tip (casing) sections is confirmed by experiments; similarly, predicted underturning at stator tip (casing) sections accords with observations in one compressor but not in another. However, no universal conclusion (on whether underturning or overturning usually occurs) can be drawn for the flow through the rotor and stator root (hub) sections, as either entry or generated secondary vorticity may dominate.

Two-equation Turbulence Modeling of Pulsatile Flow in a Stenosed Tube

2004 ◽  
Vol 126 (5) ◽  
pp. 625-635 ◽  
Author(s):  
J. Ryval ◽  
A. G. Straatman ◽  
D. A. Steinman
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Numerical Simulations ◽  
Pulsatile Flow ◽  
Turbulence Modeling ◽  
Area Reduction ◽  
The Standard Model ◽  
Pulsatile Flows ◽  
Flow Through ◽  
Inlet Conditions

The study of pulsatile flow in stenosed vessels is of particular importance because of its significance in relation to blood flow in human pathophysiology. To date, however, there have been few comprehensive publications detailing systematic numerical simulations of turbulent pulsatile flow through stenotic tubes evaluated against comparable experiments. In this paper, two-equation turbulence modeling has been explored for sinusoidally pulsatile flow in 75% and 90% area reduction stenosed vessels, which undergoes a transition from laminar to turbulent flow as well as relaminarization. Wilcox’s standard k-ω model and a transitional variant of the same model are employed for the numerical simulations. Steady flow through the stenosed tubes was considered first to establish the grid resolution and the correct inlet conditions on the basis of comprehensive comparisons of the detailed velocity and turbulence fields to experimental data. Inlet conditions based on Womersley flow were imposed at the inlet for all pulsatile cases and the results were compared to experimental data from the literature. In general, the transitional version of the k-ω model is shown to give a better overall representation of both steady and pulsatile flow. The standard model consistently over predicts turbulence at and downstream of the stenosis, which leads to premature recovery of the flow. While the transitional model often under-predicts the magnitude of the turbulence, the trends are well-described and the velocity field is superior to that predicted using the standard model. On the basis of this study, there appears to be some promise for simulating physiological pulsatile flows using a relatively simple two-equation turbulence model.

Modelling of a Turbocharger Turbine Under Pulsating Inlet Conditions

1996 ◽  
Vol 210 (5) ◽  
pp. 397-408 ◽  
Author(s):  
H Chen ◽  
I Hakeem ◽  
R F Martinez-Botas
Keyword(s):  
Experimental Data ◽  
Unsteady Flow ◽  
Flow Analysis ◽  
Predictive Capability ◽  
Mixed Flow ◽  
One Dimensional ◽  
Turbine Performance ◽  
Flow Through ◽  
Inlet Conditions ◽  
Unsteady Flow Analysis

This paper describes the results of the simulation of a mixed flow turbine under pulsating inlet conditions. The volute casing of the turbine is simulated as a tapered duct with one-dimensional unsteady flow analysis applied to this duct, while one-dimensional steady flow analysis is used in a quasi-steady manner to simulate the flow through the rotor of the turbine. The physical model of the turbine is an improved version of that described by Chen and Winterbone (1), and its predictive capability is evaluated against experimental data of the turbine performance obtained in the Imperial College's unsteady flow turbocharger rig.

On the Compressible Flow Losses Through Abrupt Enlargements and Contractions

1994 ◽  
Vol 116 (4) ◽  
pp. 756-762 ◽  
Author(s):  
Predrag Marjanovic´ ◽  
Vladan Djordjevic´
Keyword(s):  
Experimental Data ◽  
Compressible Flow ◽  
Incompressible Flow ◽  
System Of Equations ◽  
Basic System ◽  
Area Change ◽  
Flow Losses ◽  
Flow Parameters ◽  
Flow Through ◽  
D Model

The well-known structure of incompressible flow through abrupt enlargements and contractions is applied to the subsonic compressible flow through the same area change. Using the basic system of equations for 1-D model of flow, both cases are solved for adiabatic and isothermal conditions. The changes for all flow parameters (M, v, p, p0, T, T0, s) are obtained analytically and shown graphically. The results are compared with the available experimental data.

Numerical treatment of mass continuity in pressure-correction methods for patient specific flow simulations

2018 ◽  
Vol 28 (10) ◽  
pp. 2307-2323 ◽  
Author(s):  
Anastasios Skiadopoulos ◽  
Panagiotis Neofytou ◽  
Christos Housiadas
Keyword(s):  
Numerical Scheme ◽  
Patient Specific ◽  
Computational Domain ◽  
Imaging Data ◽  
Specific Flow ◽  
Content Type ◽  
Pressure Correction ◽  
Flow Simulations ◽  
Open Boundaries ◽  
Domain Boundaries

Purpose The purpose of this paper is the development of a robust numerical scheme for fluid flow simulations in complex domains with open boundaries. Design/methodology/approach A modified pressure correction algorithm is presented. The proposed modifications are derived through a step-by-step analysis of the importance of mass continuity enforcement in pressure correction methods, the boundary conditions of the pressure correction equation and the special nature of open boundaries. Findings The algorithm is validated by performing steady state laminar flow simulations in two backward facing step geometries with progressively truncated outlet channels. The efficiency of the methodology is demonstrated by simulating the pulsatile flow field in a patient specific iliac bifurcation reconstructed by medical imaging data. Originality/value The proposed numerical scheme provides accurate and mass conserving solutions in complex domains with open boundaries. The proposed methodology may be directly implemented in any computational domain without any prerequisites regarding the location or type of domain boundaries.

Large eddy simulation of shock train in a convergent–divergent nozzle

2014 ◽  
Vol 25 (04) ◽  
pp. 1450003 ◽  
Author(s):  
Seyed Mahmood Mousavi ◽  
Ehsan Roohi
Keyword(s):  
Experimental Data ◽  
Large Eddy Simulation ◽  
Numerical Solutions ◽  
Turbulence Modeling ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Shock Train ◽  
Eddy Simulation ◽  
Starting Point ◽  
Large Eddy

This paper discusses the suitability of the Large Eddy Simulation (LES) turbulence modeling for the accurate simulation of the shock train phenomena in a convergent-divergent nozzle. To this aim, we selected an experimentally tested geometry and performed LES simulation for the same geometry. The structure and pressure recovery inside the shock train in the nozzle captured by LES model are compared with the experimental data, analytical expressions and numerical solutions obtained using various alternative turbulence models, including k–ε RNG, k–ω SST, and Reynolds stress model (RSM). Comparing with the experimental data, we observed that the LES solution not only predicts the "locations of the first shock" precisely, but also its results are quite accurate before and after the shock train. After validating the LES solution, we investigate the effects of the inlet total pressure on the shock train starting point and length. The effects of changes in the back pressure, nozzle inlet angle (NIA) and wall temperature on the behavior of the shock train are investigated by details.

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