Influence Wave Mode Computations of Multi-Passage Cascade Flows

2000 ◽  
Author(s):  
Ismail H. Tuncer ◽  
Stefan Weber
Keyword(s):  
Experimental Data ◽  
Traveling Wave ◽  
Solution Method ◽  
Wave Mode ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Overset Grids ◽  
Shock Position ◽  
Flow Domain

A Navier-Stokes solution method with overset grids is employed to compute the Influence Wave Modes of a compressor cascade in transonic flow conditions. The computed predictions are compared against the experimental data and the predictions based on Traveling Wave Mode computations performed using a different Navier-Stokes solver. In the present method, a five-passage flow domain is discretized with O-type subgrids around each blade and a rectangular background subgrid. A simple, robust numerical algorithm is used to localize moving intergrid boundary points, and to interpolate solution variables across the subgrids. The influence wave mode computation predicts a strong influence of the pitching mid-blade on the shock position of the neighboring blades. The predictions agree with the experimental data fairly well, and shows an improvement over the Traveling Wave Mode predictions.

Investigation of Periodic Boundary Conditions in Multipassage Cascade Flows Using Overset Grids

1999 ◽  
Vol 121 (2) ◽  
pp. 341-347 ◽  
Author(s):  
I. H. Tuncer ◽  
S. Weber ◽  
W. Sanz
Keyword(s):  
Solution Method ◽  
Grid Method ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Overset Grid ◽  
Overset Grids ◽  
Single Passage ◽  
Overset Grid Method ◽  
Background Grid

A Navier–Stokes solution method with overset grids is applied to unsteady multipassage cascade flows, and the unsteady blade loadings are compared against the single-passage solutions with the direct store interblade boundary condition. In the overset grid solutions, the multipassage domain is discretized with O-type grids around each blade and a rectangular background grid. Blade grids are allowed to move in time relative to the background grid, as prescribed by the oscillatory plunging motion. The overset grid method uses a simple, robust numerical algorithm to localize moving intergrid boundary points and to interpolate solution variables across grids. Computational results are presented for two and four-passage, subsonic and transonic flows through a turbine and a compressor cascade. The overset grid solutions over the multipassage periodic domains agree well with the single-passage solutions and the experimental data. It is concluded that the time linearization error introduced by the direct store approach is negligible in the range of flow conditions studied.

scholarly journals Investigation of Periodic Boundary Conditions in Multi-Passage Cascade Flows Using Overset Grids

1998 ◽  
Author(s):  
Ismail H. Tuncer ◽  
Stefan Weber ◽  
Wolfgang Sanz
Keyword(s):  
Solution Method ◽  
Grid Method ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Overset Grid ◽  
Overset Grids ◽  
Single Passage ◽  
Overset Grid Method ◽  
Background Grid

A Navier-Stokes solution method with overset grids is applied to unsteady multi-passage cascade flows, and the unsteady blade loadings are compared against the single passage solutions with the direct store interblade boundary condition. In the overset grid solutions, the multi-passage domain is discretized with O-type grids around each blade and a rectangular background grid. Blade grids are allowed to move in time relative to the background grid as prescribed by the oscillatory plunging motion. The overset grid method uses a simple, robust numerical algorithm to localize moving intergrid boundary points and to interpolate solution variables across grids. Computational results are presented for two and four passage, subsonic and transonic flows through a turbine and a compressor cascade. The overset grid solutions over the multi-passage periodic domains agree well with the single passage solutions and the experimental data. It is concluded that the time linearization error introduced by the direct store approach is negligible in the range of flow conditions studied.

Computation of Multi-Passage Cascade Flows With Overset and Deforming Grids

1997 ◽  
Author(s):  
Ismail H. Tuncer ◽  
Wolfgang Sanz
Keyword(s):  
Moving Boundary ◽  
Grid Method ◽  
Navier Stokes ◽  
Computational Results ◽  
Compressor Cascade ◽  
Overset Grid ◽  
Overset Grids ◽  
Overset Grid Method ◽  
Background Grid ◽  
Good Agreement

An overset grid method is applied to the solution of single and multi-passage cascade flows with a compressible Navier-Stokes solver. C-type grids around individual blades are overset onto a Cartesian background grid. Overset grids are allowed to move in time relative to each other as prescribed by the oscillatory plunging motion. The overset grid method uses a simple, robust numerical algorithm to localize moving boundary points and to interpolate solution variables across intergrid boundaries. Computational results and comparisons with single/staggered, deforming grid solutions are presented for in- and out-of-phase multi-passage flows through a compressor cascade. Very good agreement is obtained against the deforming grid solutions.

Prediction of Compressor Cascade Performance Using a Navier–Stokes Technique

1988 ◽  
Vol 110 (4) ◽  
pp. 520-531 ◽  
Author(s):  
R. L. Davis ◽  
D. E. Hobbs ◽  
H. D. Weingold
Keyword(s):  
Experimental Data ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Viscous Flows ◽  
Navier Stokes ◽  
Grid Refinement ◽  
Compressor Cascade ◽  
Pressure Distributions ◽  
Time Marching ◽  
Profile Loss

An explicit, time marching, multiple-grid Navier–Stokes technique is demonstrated for the prediction of quasi-three-dimensional turbomachinery compressor cascade performance over the entire incidence range. A numerical investigation has been performed in which the present Navier–Stokes procedure was used to analyze a series of compressor cascade viscous flows for which corresponding experimental data are available. Results from these calculations show that the current viscous flow procedure is capable of predicting cascade profile loss and airfoil pressure distributions with high accuracy. The results from this numerical investigation in the form of comparisons between the predicted profile loss, exit gas angle, and pressure distributions with experimental data are presented in this paper. Results from a grid refinement study are also shown to demonstrate that the Navier–Stokes solutions are grid independent.

A Simultaneous Variable Solution Procedure for Laminar and Turbulent Flows in Curved Channels and Bends

2000 ◽  
Vol 122 (3) ◽  
pp. 552-559 ◽  
Author(s):  
Jianrong Wang ◽  
Siamack A. Shirazi
Keyword(s):  
Experimental Data ◽  
Numerical Solution ◽  
Numerical Method ◽  
Solution Method ◽  
Stokes Equations ◽  
Turbulence Models ◽  
Solution Procedure ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Curved Channels

Direct Numerical Simulation of turbulent flow requires accurate numerical techniques for solving the Navier-Stokes equations. Therefore, the Navier-Stokes equations in general orthogonal and nonorthogonal coordinates were employed and a simultaneous variable solution method was extended to solve these general governing equations. The present numerical method can be used to accurately predict both laminar and turbulent flow in various curved channels and bends. To demonstrate the capability of this numerical method and to verify the method, the time-averaged Navier-Stokes equations were employed and several turbulence models were also implemented into the numerical solution procedure to predict flows with strong streamline curvature effects. The results from the present numerical solution procedure were compared with available experimental data for a 90 deg bend. All of the turbulence models implemented resulted in predicted velocity profiles which were in agreement with the trends of experimental data. This indicates that the solution method is a viable numerical method for calculating complex flows. [S0098-2202(00)01803-4]

Comparison of Theoretical and Experimental Data for an Oscillating Transonic Compressor Cascade

1999 ◽  
Author(s):  
Volker Carstens ◽  
Stefan Schmitt
Keyword(s):  
Experimental Data ◽  
Transonic Flow ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Test Case ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Blade Passage ◽  
Aerodynamic Damping ◽  
Transonic Compressor

Numerical and experimental results are compared for a compressor cascade performing harmonic oscillations in transonic flow. The flow field was calculated by a Q3D Navier Stokes code, the basic features of which are the use of an upwind flux difference scheme for the convective terms, the implementation of an effective one-equation turbulence model and the use of deforming multi-block grids. The experimental investigations were performed in an annular cascade windtunnel where unsteady blade pressures were measured for two different operating conditions of the cascade. The present data were all obtained for tuned torsional modes where the blades performed pitching oscillations with the same frequency and amplitude, but with a constant interblade phase angle. In the first test case the steady flow around the blades was purely subsonic. For the second test case the compressor cascade was run under transonic flow conditions where a normal shock in the front part of the blades’ suction side is followed by a blade passage shock. It becomes apparent that under subsonic flow conditions the predicted aerodynamic damping coefficients are in resonable agreement with the experimental data, although the numerical pressure amplitudes are much higher than the measured ones. In transonic flow significant discrepancies between computed and experimentally determined pressure amplitudes are observed, whereas the accuracy of the pressure phase prediction is comparable to the subsonic test case. Another important result of these investigations is that oscillations of the blade passage shock lead to strong variations of the local aerodynamic damping of the blades, but do not significantly change the global damping coefficient of the tested compressor cascade.

scholarly journals Analysis of Transonic Turbomachinery Flows Using a 2-D Explicit Low-Reynolds k-ε Navier-Stokes Solver

1994 ◽  
Author(s):  
F. Dejean ◽  
C. Vassilopoulos ◽  
G. Slmandirakis ◽  
K. C. Giannakoglou ◽  
K. D. Papailiou
Keyword(s):  
Stokes Equations ◽  
Guide Vane ◽  
Navier Stokes ◽  
Fractional Step ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Navier Stokes Equations ◽  
Time Marching ◽  
Low Reynolds ◽  
The Stability

An explicit, time-marching fractional-step solver for the calculation of the two-dimensional compressible Navier-Stokes equations is presented. The advantage of using a fractional-step analysis is its simplicity and the fact that greater time-steps are allowed, since the stability criterion is less strict compared to other explicit solvers. Turbulence is modeled through a low-Reynolds k-ε model, for which a novel artificial viscosity scheme is implemented, ensuring a smooth ε-distribution close to solid walls. The method is used in order to numerically investigate the flow field in three different cascades, namely a highly loaded transonic linear turbine guide vane cascade in six different flow conditions, a transonic steam turbine cascade in two different flow conditions and a low supersonic compressor cascade. Calculations are performed using both H- and C-type grids.

Multiscale Partially Averaged Navier Stokes Approach for the Prediction of Flow in Linear Compressor Cascade With Moving Casing

2011 ◽  
Author(s):  
Domenico Borello ◽  
Giovanni Delibra ◽  
Franco Rispoli
Keyword(s):  
Turbulence Models ◽  
Navier Stokes ◽  
Test Case ◽  
Compressor Cascade ◽  
Preliminary Assessment ◽  
Linear Compressor ◽  
Tip Leakage ◽  
Experimental Campaign ◽  
Elliptic Relaxation ◽  
Linear Compressor Cascade

In this paper we present an innovative Partially Averaged Navier Stokes (PANS) approach for the simulation of turbomachinery flows. The elliptic relaxation k-ε-ζ-f model was used as baseline Unsteady Reynolds Averaged Navier Stokes (URANS) model for the derivation of the PANS formulation. The well established T-FlowS unstructured finite volume in-house code was used for the computations. A preliminary assessment of the developed formulation was carried out on a 2D hill flow that represents a very demanding test case for turbulence models. The turbomachinery flow here investigated reproduces the experimental campaign carried out at Virginia Tech on a linear compressor cascade with tip leakage. Their measurements were used for comparisons with numerical results. The predictive capabilities of the model were assessed through the analysis of the flow field. Then an investigation of the blade passage, where experiments were not available, was carried out to detect the main loss sources.

Comparison of LES of Steady Transitional Flow in an Idealized Stenosed Axisymmetric Artery Model With a RANS Transitional Model

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
F. P. P. Tan ◽  
N. B. Wood ◽  
G. Tabor ◽  
X. Y. Xu
Keyword(s):  
Experimental Data ◽  
Turbulence Intensity ◽  
Eddy Viscosity ◽  
Flow Analysis ◽  
Wall Turbulence ◽  
Transitional Flow ◽  
Navier Stokes ◽  
Turbulence Structures ◽  
Eddy Simulation ◽  
Accurate Treatment

In this study, two different turbulence methodologies are investigated to predict transitional flow in a 75% stenosed axisymmetric experimental arterial model and in a slightly modified version of the model with an eccentric stenosis. Large eddy simulation (LES) and Reynolds-averaged Navier–Stokes (RANS) methods were applied; in the LES simulations eddy viscosity subgrid-scale models were employed (basic and dynamic Smagorinsky) while the RANS method involved the correlation-based transitional version of the hybrid k-ε/k-ω flow model. The RANS simulations used 410,000 and 820,000 element meshes for the axisymmetric and eccentric stenoses, respectively, with y+ less than 2 viscous wall units for the boundary elements, while the LES used 1,200,000 elements with y+ less than 1. Implicit filtering was used for LES, giving an overlap between the resolved and modeled eddies, ensuring accurate treatment of near wall turbulence structures. Flow analysis was carried out in terms of vorticity and eddy viscosity magnitudes, velocity, and turbulence intensity profiles and the results were compared both with established experimental data and with available direct numerical simulations (DNSs) from the literature. The simulation results demonstrated that the dynamic Smagorinsky LES and RANS transitional model predicted fairly comparable velocity and turbulence intensity profiles with the experimental data, although the dynamic Smagorinsky model gave the best overall agreement. The present study demonstrated the power of LES methods, although they were computationally more costly, and added further evidence of the promise of the RANS transition model used here, previously tested in pulsatile flow on a similar model. Both dynamic Smagorinsky LES and the RANS model captured the complex transition phenomena under physiological Reynolds numbers in steady flow, including separation and reattachment. In this respect, LES with dynamic Smagorinsky appeared more successful than DNS in replicating the axisymmetric experimental results, although inflow conditions, which are subject to caveats, may have differed. For the eccentric stenosis, LES with Smagorinsky coefficient of 0.13 gave the closest agreement with DNS despite the known shortcomings of fixed coefficients. The relaminarization as the flow escaped the influence of the stenosis was amply demonstrated in the simulations, graphically so in the case of LES.

Sign in / Sign up

Export Citation Format

Share Document