Experimental and Computational Study of Oscillating Turbine Cascade and Influence of Part-Span Shrouds

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
X. Q. Huang ◽  
L. He ◽  
David L. Bell
Keyword(s):  
Experimental Data ◽  
Computational Study ◽  
Three Dimensional ◽  
Unsteady Flows ◽  
Correction Method ◽  
Influence Coefficient ◽  
Turbine Cascade ◽  
Test Configuration ◽  
Practical Applications ◽  
Influence Coefficient Method

This paper presents a combined experimental and computational study of unsteady flows in a linear turbine cascade oscillating in a three-dimensional bending/flapping mode. Detailed experimental data are obtained on a seven-bladed turbine cascade rig. The middle blade is driven to oscillate and oscillating cascade data are obtained using an influence coefficient method. The numerical simulations are performed by using a 3D nonlinear time-marching Navier–Stokes flow solver. Single-passage domain computations for arbitrary interblade phase angles are achieved by using the Fourier shape correction method. Both measurements and predictions demonstrate a fully 3D behavior of the unsteady flows. The influence of the aerodynamic blockage introduced by part-span shrouds on turbine flutter has been investigated by introducing flat plate shaped shrouds at 75% span. In contrast to practical applications, in the present test configuration, the mode of vibration of the blades remains unchanged by the introduction of the part-span shroud. This allows the influence of the aerodynamic blockage introduced by the part-span shroud to be assessed in isolation from the change in mode shape. A simple shroud model has been developed in the computational solver. The computed unsteady pressures around the shrouds are in good agreement with the experimental data, demonstrating the validity of the simple shroud model. Despite of notable variations in local unsteady pressures around the shrouds, the present results show that the blade aerodynamic damping is largely unaffected by the aerodynamic blockage introduced by part-span shrouds.

Unsteady Flow in Oscillating Turbine Cascades: Part 2—Computational Study

1998 ◽  
Vol 120 (2) ◽  
pp. 269-275 ◽  
Author(s):  
L. He
Keyword(s):  
Unsteady Flow ◽  
Flow Separation ◽  
Computational Study ◽  
Flow Behavior ◽  
Numerical Test ◽  
Computational Method ◽  
Influence Coefficient ◽  
Turbine Cascade ◽  
Influence Coefficient Method ◽  
Coefficient Method

Unsteady flow around a linear oscillating turbine cascade has been experimentally and computationally studied, aimed at understanding the bubble type of flow separation and examining the predictive ability of a computational method. It was also intended to check the validity of the linear assumption under an unsteady viscous flow condition. Part 2 of the paper presents a computational study of the experimental turbine cascade that was discussed in Part 1. Numerical calculations were carried out for this case using an unsteady Navier–Stokes solver. The Baldwin–Lomax mixing length model was adopted for turbulence closure. The boundary layers on blade surfaces were either assumed to be fully turbulent or transitional with the unsteady transition subject to a quasi-steady laminar separation bubble model. The comparison between the computations and the experiment was generally quite satisfactory, except in the regions with the flow separation. It was shown that the behavior of the short bubble on the suction surface could be reasonably accounted for by using the quasi-steady bubble transition model. The calculation also showed that there was a more apparent mesh dependence of the results in the regions of flow separation. Two different kinds of numerical test were carried out to check the linearity of the unsteady flow and therefore the validity of the influence coefficient method. First, calculations using the same configurations as in the experiment were performed with different oscillating amplitudes. Second, calculations were performed with a tuned cascade model and the results were compared with those using the influence coefficient method. The present work showed that the nonlinear effect was quite small, even though for the most severe case in which the separated flow region covered about 60 percent of blade pressure surface with a large movement of the reattachment point. It seemed to suggest that the linear assumption about the unsteady flow behavior should be adequately acceptable for situations with bubble-type flow separation similar to the present case.

Unsteady Flow in Oscillating Turbine Cascade: Part 2 — Computational Study

1996 ◽  
Author(s):  
L. He
Keyword(s):  
Unsteady Flow ◽  
Flow Separation ◽  
Computational Study ◽  
Separation Bubble ◽  
Computational Method ◽  
Influence Coefficient ◽  
Turbine Cascade ◽  
Suction Surface ◽  
Influence Coefficient Method ◽  
Coefficient Method

Unsteady flow around a linear oscillating turbine cascade has been experimentally and computationally studied, aimed at understanding the bubble type of flow separation and examining the predictive ability of a computational method. It was also intended to check the validity of the linear assumption under an unsteady viscous flow condition. Part 2 of the paper presents a computational study of the experimental turbine cascade as discussed in Part 1. Numerical calculations were carried out for this case using an unsteady Navier-Stokes solver. The Baldwin-Lomax mixing length model was adopted for turbulence closure. The boundary layers on blade surfaces were either assumed to be fully turbulent or transitional with the unsteady transition subject to a quasi-steady laminar separation bubble model. The comparison between the computations and the experiment were generally quite satisfactory, except in the regions with the flow separation. It was shown that the behaviour of the short-bubble on the suction surface could be reasonably accounted for by using the quasi-steady bubble transition model. The calculation also showed that there was a more apparent mesh dependence of the results in the regions of flow separation. Two different kinds of numerical tests were carried out to check the linearity of the unsteady flow and therefore the validity of the Influence Coefficient method. Firstly calculations using the same configurations as in the experiment were performed with different oscillating amplitudes. Secondly calculations were performed with a tuned cascade model and the results were compared with those using the Influence Coefficient method. The present work showed that nonlinear effect was quite small, even though for the most severe case in which the separated flow region covered about 60% of blade pressure surface with a large movement of the reattachment point. It seemed to suggest that the linear assumption about the unsteady flow behaviour should be adequately acceptable for situations with bubble type flow separation similar to the present case.

Computational Study of Edge Cooling for Open-Cathode Polymer Electrolyte Fuel Cell Stacks

2012 ◽  
Vol 9 (6) ◽  
Author(s):  
Agus P. Sasmito ◽  
Tariq Shamim ◽  
Erik Birgersson ◽  
Arun S. Mujumdar
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Thermal Management ◽  
Computational Study ◽  
Three Dimensional ◽  
Polymer Electrolyte Fuel Cell ◽  
Design Parameters ◽  
Two Phase ◽  
Practical Applications ◽  
The Impact

In open-cathode polymer electrolyte fuel cell (PEFC) stacks, a significant temperature rise can exist due to insufficient cooling, especially at higher current densities. To improve stack thermal management while reducing the cost of cooling, we propose a forced air-convection open-cathode fuel cell stack with edge cooling (fins). The impact of the edge cooling is studied via a mathematical model of the three-dimensional two-phase flow and the associated conservation equations of mass, momentum, species, energy, and charge. The model includes the stack, ambient, fan, and fins used for cooling. The model results predict better thermal management and stack performance for the proposed design as compared to the conventional open-cathode stack design, which shows potential for practical applications. Several key design parameters—fin material and fin geometry—are also investigated with regard to the stack performance and thermal management.

Three-dimensional influence coefficient method for cohesive crack simulations

2004 ◽  
Vol 71 (15) ◽  
pp. 2109-2124 ◽  
Author(s):  
James H. Hanson ◽  
Tulio N. Bittencourt ◽  
Anthony R. Ingraffea
Keyword(s):  
Three Dimensional ◽  
Cohesive Crack ◽  
Influence Coefficient ◽  
Influence Coefficient Method ◽  
Coefficient Method

Experiment on Linear Compressor Cascade With 3-D Blade Oscillation

2003 ◽  
Author(s):  
H. Yang ◽  
L. He
Keyword(s):  
Steady Flow ◽  
Three Dimensional ◽  
Diffusion Profile ◽  
Tip Clearance ◽  
Influence Coefficient ◽  
Pressure Amplitude ◽  
Compressor Cascade ◽  
Pressure Transducers ◽  
Influence Coefficient Method ◽  
Linear Compressor Cascade

An experiment has been carried out to enhance the understanding of 3D blade aeroelastic mechanisms and to produce test data of realistic configurations for validation of advanced 3D aeromechanical methods. A low speed rig with a compressor cascade consisting of seven prismatic blades of controlled diffusion profile has been commissioned. The middle blade is mechanically driven to oscillate in a 3D bending/flapping mode. At a nominal steady flow condition unsteady pressure measurements were performed at six spanwise sections for three different reduced frequencies and two different tip-clearance gaps. Off-board pressure transducers were utilized in conjunction with a transfer-function method to correct tubing distortion errors. The linearity of aerodynamic response is confirmed by the tests with different blade oscillation amplitudes, which enables the tuned cascade results to be constructed by using the Influence Coefficient Method. The measured results illustrate fully three-dimensional unsteady behaviour. Strong spanwise unsteady interaction leads to a non-proportional distribution of pressure amplitude at different spanwise locations. The tests with different tip-clearance gaps (1–2% span) show that the near tip region is destabilised as the tip gap is increased. This may be attributed to the local unloading of the corresponding steady flow. The destabilised region is seen to extend to approximately 20% of the blade span. The total aerodynamic damping at the least stable inter-blade phase angle has been reduced by 27%, when the tip gap is increased from nearly zero to 2% span.

A Computational Study of the Mixture Preparation in a Direct Injection Hydrogen Engine

2014 ◽  
Author(s):  
Jerome Le Moine ◽  
P. K. Senecal ◽  
Sebastian A. Kaiser ◽  
Victor M. Salazar ◽  
Jon W. Anders ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Computational Study ◽  
Early Stage ◽  
Direct Injection ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Fuel Mixture ◽  
Compression Stroke ◽  
Mixture Preparation

This paper reports the validation of a three-dimensional numerical simulation of the mixture preparation in a direct-injection hydrogen-fueled engine. Computational results from the commercial code CONVERGE are compared to the experimental data obtained from an optically accessible engine. The geometry used in the simulation is a passenger-car sized, four-stroke, spark-ignited engine. The simulation includes the geometry of the combustion chamber as well as the intake and exhaust ports. The hydrogen is supplied at 100 bar from a centrally located injector with a single-hole nozzle. The comparison between the simulation and experimental data is made on the central vertical plane. The fuel mole concentration and flow field are compared during the compression stroke at different crank angles. The comparison shows good agreement between the numerical and experimental results during the early stage of the compression stroke. The penetration of the jet and the interaction with the cylinder walls are correctly predicted. The fuel spreading is under predicted which results in differences in flow field and fuel mixture during the injection between experimental and numerical results. At the end of the injection, the fuel distribution shows some disagreement which gradually increases during the rest of the simulation.

Aerodynamic Damping Predictions for Oscillating Airfoils in Cascades Using Moving Meshes

2016 ◽  
Author(s):  
Ron Ho Ni ◽  
William Humber ◽  
Michael Ni ◽  
Vincent R. Capece ◽  
Michael Ooten ◽  
...  
Keyword(s):  
Experimental Data ◽  
Numerical Solutions ◽  
Harmonic Balance Method ◽  
Standard Test ◽  
Influence Coefficient ◽  
Flow Conditions ◽  
Suction Surface ◽  
Test Configuration ◽  
Aerodynamic Loading ◽  
Unsteady Aerodynamic

This paper presents a numerical analysis of oscillating airfoils in turbomachinery cascades using the unsteady nonlinear Reynold’s Averaged Navier-Stokes (URANS) equations. The periodic unsteady flow solutions are determined using a conventional time marching method (DTS) and the Nonlinear Harmonic Balance method (NHB). Mesh motions, using a weighted distortion procedure and a linear elastic method, are described. Comparison of computed results are made with the Eleventh Standard Test Configuration (STC11) experimental data for subsonic and transonic exit flow conditions. The solutions for the NHB and DTS methods exhibit excellent correlation with each other and good correlation with the experimental data on the pressure surface. The numerical solutions deviate from the experimental data on the suction surface especially in the vicinity of the shock wave for the transonic exit flow case. A numerical influence coefficient modeling method is shown for airfoil cascades that can be used to calculate unsteady aerodynamic loading over a range of interblade phase angles. Application to the STC11 illustrates that a cascade of five airfoils is sufficient to provide accurate unsteady aerodynamic loading predictions for the modeled flow conditions.

Analysis of Different Radiation Models in a Swirl Stabilized Combustor

2014 ◽  
Author(s):  
Aayush K. Sharma ◽  
Chandrachur Bhattacharya ◽  
Swarnendu Sen ◽  
Achintya Mukhopadhyay ◽  
Amitava Datta
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Computational Study ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Numerical Data ◽  
Ansys Fluent ◽  
Wall Functions ◽  
Radiation Modelling ◽  
Model Gas Turbine Combustor

A computational study on spray combustion, using kerosene (C12H23) as fuel, in a model gas turbine combustor has been carried out. The numerical modelling of radiation heat transfer is carried out in a three-dimensional swirl stabilized, liquid-fuelled combustor. The Favre-averaged governing equations are solved using Ansys Fluent 14.5 as the CFD package. The turbulence parameters are computed using realizable k-ε with standard wall functions model. Eulerian-Lagrangian approach is used to track stochastically the motion of the evaporation species in the continuous gas phase. The effect of different radiation models — Discrete Ordinate (DO), P1 and Discrete Transfer Radiation Model (DTRM) along with Soot are analysed in the present study. To validate the results of radiation modelling carried out in the present work, the computational results have been compared with previous experimental data for the same combustor geometry. The numerical data considering effect of soot along with radiation is shown to closely approximate the experimental data. An attempt has also been made to introduce a liner in the combustor and evaluate its effect and the heat transfer across the liner for the present numerical model.

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