Investigation of the Flow Field Downstream of a Turbine Trailing Edge Cooled Nozzle Guide Vane

1996 ◽  
Vol 118 (2) ◽  
pp. 291-300 ◽  
Author(s):  
C. H. Sieverding ◽  
T. Arts ◽  
R. De´nos ◽  
F. Martelli
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Guide Vane ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Coolant Flow ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Additional Information ◽  
Flow Visualizations

A trailing edge cooled low aspect ratio transonic turbine guide vane is investigated in the VKI Compression Tube Cascade Facility at an outlet Mach number M2, is = 1.05 and a coolant flow rate m˙c/m˙g = 3 percent. The outlet flow field is surveyed by combined total-directional pressure probes and temperature probes. Special emphasis is put on the development of low blockage probes. Additional information is provided by oil flow visualizations and numerical flow visualizations with a three-dimensional Navier–Stokes code. The test results describe the strong differences in the axial evolution of the hub and tip endwall and secondary flows and demonstrate the self-similarity of the midspan wake profiles. According to the total pressure and temperature profiles, the wake mixing appears to be very fast in the near-wake but very slow in the far-wake region. The total pressure wake profile appears to be little affected by the coolant flow ejection.

Investigation of the Flow Field Downstream of a Turbine Trailing Edge Cooled Nozzle Guide Vane

1994 ◽  
Author(s):  
C. H. Sieverding ◽  
T. Arts ◽  
R. Dénos ◽  
F. Martelli
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Guide Vane ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Coolant Flow ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Additional Information ◽  
Flow Visualizations

A trailing edge cooled low aspect ratio transonic turbine guide vane is investigated in the VKI Compression Tube Cascade Facility at an outlet Mach number M2,i s=1.05 and a coolant flow rate ṁc/ṁg=3%. The outlet flow field is surveyed by combined total-directional pressure probes and temperature probes. Special emphasis is put on the development of low blockage probes. Additional information is provided by oil flow visualizations and numerical flow visualizations with a three-dimensional Navier-Stokes code. The test results describe the strong differences in the axial evolution of the hub and tip endwall and secondary flows and demonstrate the self-similarity of the mid-span wake profiles. According to the total pressure and temperature profiles the wake mixing appears to be very fast in the near-wake but very slow in the far-wake region. The total pressure wake profile appears to be little affected by the coolant flow ejection.

Aerothermal Investigation of a Rib-Roughened Trailing Edge Channel With Crossing-Jets—Part I: Flow Field Analysis

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Alessandro Armellini ◽  
Filippo Coletti ◽  
Tony Arts ◽  
Christophe Scholtes
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Side Wall ◽  
Field Analysis ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Present Contribution ◽  
Cross Sectional ◽  
Numerical Predictions ◽  
Rib Roughened

The present contribution addresses the aerothermal, experimental, and computational studies of a trapezoidal cross-sectional model simulating a trailing edge cooling cavity with one rib-roughened wall. The flow is fed through tilted slots on one side wall and exits through straight slots on the opposite side wall. The flow field aerodynamics is investigated in Part I of the paper. The reference Reynolds number is defined at the entrance of the test section and set at 67,500 for all the experiments. A qualitative flow model is deduced from surface-streamline flow visualizations. Two-dimensional particle image velocimetry measurements are performed in several planes around midspan of the channel and recombined to visualize and quantify three-dimensional flow features. The crossing-jets issued from the tilted slots are characterized and the jet-rib interaction is analyzed. Attention is drawn to the motion of the flow deflected by the rib-roughened wall and impinging on the opposite smooth wall. The experimental results are compared with the numerical predictions obtained from the finite volume Reynolds-averaged Navier–Stokes solver, CEDRE.

Investigation of the Flow Field on a Transonic Turbine Nozzle Guide Vane With Rim Seal Cavity Flow Ejection

2009 ◽  
Author(s):  
M. Pau ◽  
G. Paniagua
Keyword(s):  
Flow Field ◽  
Static Pressure ◽  
Numerical Study ◽  
Guide Vane ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Cavity Flow ◽  
Trailing Edge ◽  
Dynamic Simulations ◽  
Purge Flow

Ensuring an adequate life of high pressure turbines requires efficient cooling methods, such as rim seal flow ejection from the stator-rotor wheel space cavity interface, which prevents hot gas ingress into the rotor disk. The present work addresses the potential to improve the efficiency in transonic turbines at certain rim seal ejection rates. To understand this process a numerical study was carried out combining computational fluid dynamic simulations (CFD) and experiments on a single stage axial test turbine. The three dimensional steady CFD analysis was performed modeling the purge cavity flow ejected downstream of the stator blade row, at three flow regimes, subsonic M2 = 0.73, transonic M2 = 1.12 and supersonic M2 = 1.33. Experimental static pressure measurements were used to calibrate the computational model. The main flow field-purge flow interaction is found to be governed by the vane shock structures at the stator hub. The interaction between the vane shocks at the hub and the purge flow has been studied and quantitatively characterized as function of the purge ejection rate. The ejection of 1% of the core flow from the rim seal cavity leads to an increase of the hub static pressure of approximately 7% at the vane trailing edge. This local reduction of the stator exit Mach number decreases the trailing edge losses in the transonic regime. Finally, a numerically predicted loss breakdown is presented, focusing on the relative importance of the trailing edge losses, boundary layer losses, shock losses and mixing losses, as a function of the purge rate ejected. Contrary to the experience in subsonic turbines, results in a transonic model demonstrate that ejecting purge flow improves the vane efficiency due to the shock structures modification downstream of the stator.

Flow Field Analysis of Inlet Distortion in a Transonic Fan With Straight and Bowed Stator Blade

2007 ◽  
Author(s):  
Peng Sun ◽  
Jingjun Zhong ◽  
Guotai Feng
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Three Dimensional ◽  
Field Analysis ◽  
Navier Stokes ◽  
Fan Performance ◽  
Inlet Distortion ◽  
Flow Loss ◽  
Stator Blade ◽  
Transonic Fan

The performance and stability of a fan in clean and distorted inlet flow can be improved through the use of bowed stator blades. Measurements between the blade rows in transonic and supersonic flow are too complex to provide any useful insights, so 3D flow simulations are required. In this paper, a time-accurate three-dimensional Navier-Stokes solver of the unsteady flow field in a transonic fan is carried out using “Fluent-parallel” in a parallel supercomputer. Two sets of simulations are performed. The first simulation focuses on a better understanding of inlet total pressure distortion effects on a transonic fan. The second set of numerical simulation aims at studying the improvements of fan performance made by bowed stator blades. Three aspects are contained in this paper. The first is about the distortion effects on characteristics of the fan stage with straight stator. The effects of bowed stator on fan performance with inlet distortion are demonstrated secondly. One hand bowed stator increases the loss in rotor. On the other hand, it reduces the flow loss in stator. Finally, the patterns of flow loss caused by total pressure distortion with straight/bowed stator are compared. The scale of vortex in stator induced by inlet total pressure distortion is weakened by bowed blades, which decreases the stator loss.

Influences of Axial Gap Between Blade Rows on Secondary Flows and Aerodynamic Performance in a Turbine Stage

2009 ◽  
Author(s):  
K. Yamada ◽  
K. Funazaki ◽  
M. Kikuchi ◽  
H. Sato
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Axial Direction ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Turbine Stage ◽  
Stator Vane ◽  
Is Design ◽  
Probe Measurements

A study on the effects of the axial gap between stator and rotor upon the stage performance and flow field of a single axial flow turbine stage is presented in this paper. Three axial gaps were tested, which were achieved by moving the stator vane in the axial direction while keeping the disk cavity constant. The effect of the axial gap was investigated at two different conditions, that is design and off-design conditions. The unsteady three-dimensional flow field was analyzed by time-accurate RANS (Reynolds-Averaged Navier-Stokes) simulations. The simulation results were compared with the experiments, in which total pressure and the time-averaged flow field upstream and downstream of the rotor were obtained by five-hole probe measurements. The effect of the axial gap was confirmed in the endwall regions, and obtained relatively at off-design condition. The turbine stage efficiency was improved almost linearly by reducing the axial gap at the off-design condition.

Nonaxisymmetric Turbine End Wall Design: Part I— Three-Dimensional Linear Design System

1999 ◽  
Vol 122 (2) ◽  
pp. 278-285 ◽  
Author(s):  
Neil W. Harvey ◽  
Martin G. Rose ◽  
Mark D. Taylor ◽  
Shahrokh Shahpar ◽  
Jonathan Hartland ◽  
...  
Keyword(s):  
Flow Field ◽  
Design Method ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Design System ◽  
Linear Superposition ◽  
Turbine Rotor Blade ◽  
End Wall

A linear design system, already in use for the forward and inverse design of three-dimensional turbine aerofoils, has been extended for the design of their end walls. This paper shows how this method has been applied to the design of a nonaxisymmetric end wall for a turbine rotor blade in linear cascade. The calculations show that nonaxisymmetric end wall profiling is a powerful tool for reducing secondary flows, in particular the secondary kinetic energy and exit angle deviations. Simple end wall profiling is shown to be at least as beneficial aerodynamically as the now standard techniques of differentially skewing aerofoil sections up the span, and (compound) leaning of the aerofoil. A design is presented that combines a number of end wall features aimed at reducing secondary loss and flow deviation. The experimental study of this geometry, aimed at validating the design method, is the subject of the second part of this paper. The effects of end wall perturbations on the flow field are calculated using a three-dimensional pressure correction based Reynolds-averaged Navier–Stokes CFD code. These calculations are normally performed overnight on a cluster of work stations. The design system then calculates the relationships between perturbations in the end wall and resulting changes in the flow field. With these available, linear superposition theory is used to enable the designer to investigate quickly the effect on the flow field of many combinations of end wall shapes (a matter of minutes for each shape). [S0889-504X(00)00902-8]

Deterministic Blade Row Interactions in a Centrifugal Compressor Stage

1992 ◽  
Vol 114 (2) ◽  
pp. 304-311 ◽  
Author(s):  
K. R. Kirtley ◽  
T. A. Beach
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Pressure Side ◽  
Compressor Stage ◽  
Trailing Edge ◽  
Tip Leakage ◽  
Centrifugal Compressor Stage ◽  
Blade Row

The three-dimensional viscous flow in a low-speed centrifugal compressor stage is simulated using an average passage Navier–Stokes analysis. The impeller discharge flow is of the jet/wake type with low-momentum fluid in the shroud-pressure side corner coincident with the tip leakage vortex. This nonuniformity introduces periodic unsteadiness in the vane frame of reference. The effect of such deterministic unsteadiness on the time mean is included in the analysis through the average passage stress, which allows the analysis of blade row interactions. The magnitude of the divergence of the deterministic unsteady stress is of the order of the divergence of the Reynolds stress over most of the span from the impeller trailing edge to the vane throat. Although the potential effects on the blade trailing edge from the diffuser vane are small, strong secondary flows generated by the impeller degrade the performance of the diffuser vanes.

Effects of Gap Leakage on Fluid Flow in a Contoured Turbine Nozzle Guide Vane

2000 ◽  
Author(s):  
Y.-L. Lin ◽  
T. I-P. Shih ◽  
M. K. Chyu ◽  
R. S. Bunker
Keyword(s):  
Computational Study ◽  
Guide Vane ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Hot Gas ◽  
Nozzle Guide Vane ◽  
A Cell ◽  
Nozzle Guide ◽  
Volume Method

Computations were performed to study the three-dimensional flow in a nozzle guide vane with leakage issuing from a narrow gap with a backward-facing step located upstream of the airfoil on each endwall. The nozzle guide vane investigated has one flat and one contoured endwall. For the contoured endwall, two configurations of the same contouring profile were investigated with and without gap leakage. In one configuration, all contouring is upstream of the airfoil passage. In the other, the contouring starts upstream of the airfoil passage and continues through it. Results obtained show that when there is gap leakage, secondary flows are reduced at all endwalls for both nozzle configurations investigated. Without gap leakage, secondary flows are reduced only on the contoured endwall in which the contouring started upstream of the airfoil passage and continued through it. When all of the contouring is located upstream of the airfoil passage, there is considerable hot gas ingestion into the gap at both endwalls. When the contouring starts upstream of the airfoil passage and continues throught it, hot gas ingestion was minimal at the contoured endwall and greatly reduced at the flat endwall. This computational study is based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy. Effects of turbulence were modeled by the low Reynolds number shear-stress transport k-ω model. Solutions were generated by a cell-centered finite-volume method that uses third-order accurate flux-difference splitting of Roe with limiters and multigrid acceleration of a diagonalized ADI scheme with local time stepping on patched structured grids.

Control of Secondary Flows in a Turbine Nozzle Guide Vane by Endwall Contouring

2000 ◽  
Author(s):  
T. I-P. Shih ◽  
Y.-L. Lin ◽  
T. W. Simon
Keyword(s):  
Film Cooling ◽  
Computational Study ◽  
Guide Vane ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Film Cooling Effectiveness ◽  
Nozzle Guide Vane ◽  
A Cell ◽  
Nozzle Guide

Computations were performed to study the three-dimensional flow and temperature distribution in a nozzle guide vane that has one flat and one contoured endwall with and without film cooling injected from two slots, one on each endwall located just upstream of the airfoil. For the contoured endwall, two locations of the same contouring were investigated, one with all contouring upstream of the airfoil and another with the contouring starting upstream of the airfoil and continuing through the airfoil passage. Results obtained show that when the contouring is all upstream of the airfoil, secondary flows on both the flat and the contoured endwalls are similar in magnitude. When the contouring starts upstream of the airfoil and continues through the airfoil passage, secondary flows on the contoured endwall are markedly weaker than those on the flat endwall. With weaker secondary flows on the contoured endwall, film-cooling effectiveness there is greatly improved. This computational study is based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy. Effects of turbulence were modeled by the low Reynolds number shear-stress transport k-ω model. Solutions were generated by a cell-centered, finite-volume method that uses third-order accurate flux-difference splitting of Roe with limiters and multigrid acceleration of a diagonalized ADI scheme with local time stepping on patched/embedded structured grids.

scholarly journals Deterministic Blade Row Interactions in a Centrifugal Compressor Stage

1991 ◽  
Author(s):  
K. R. Kirtley ◽  
T. A. Beach
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Pressure Side ◽  
Compressor Stage ◽  
Trailing Edge ◽  
Tip Leakage ◽  
Centrifugal Compressor Stage ◽  
Blade Row

The three-dimensional viscous flow in a low speed centrifugal compressor stage is simulated using an average passage Navier-Stokes analysis. The impeller discharge flow is of the jet/wake type with low momentum fluid in the shroud-pressure side corner coincident with the tip leakage vortex. This nonuniformity introduces periodic unsteadiness in the vane frame of reference. The effect of such deterministic unsteadiness on the time-mean is included in the analysis through the average passage stress, which allows the analysis of blade row interactions. The magnitude of the divergence of the deterministic unsteady stress is of the order of the divergence of the Reynolds stress over most of the span, from the impeller trailing edge to the vane throat. Although the potential effects on the blade trailing edge from the diffuser vane are small, strong secondary flows generated by the impeller degrade the performance of the diffuser vanes.

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