Simulation of Three-Dimensional Viscous Flow Within a Multistage Turbine

1990 ◽  
Vol 112 (3) ◽  
pp. 370-376 ◽  
Author(s):  
J. J. Adamczyk ◽  
M. L. Celestina ◽  
T. A. Beach ◽  
M. Barnett
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Three Dimensional ◽  
Equation System ◽  
Aerodynamic Performance ◽  
Experimental Measurements ◽  
Low Aspect Ratio ◽  
Blade Row ◽  
Multistage Turbine ◽  
Secondary Flow Field

This work outlines a procedure for simulating the flow field within multistage turbomachinery, which includes the effects of unsteadiness, compressibility, and viscosity. The associated modeling equations are the average passage equation system, which governs the time-averaged flow field within a typical passage of a blade row embedded within a multistage configuration. The results from a simulation of a low aspect ratio stage and one-half turbine will be presented and compared with experimental measurements. It will be shown that the secondary flow field generated by the rotor causes the aerodynamic performance of the downstream vane to be significantly different from that of an isolated blade row.

scholarly journals Simulation of Three-Dimensional Viscous Flow Within a Multistage Turbine

1989 ◽  
Author(s):  
John J. Adamczyk ◽  
Mark L. Celestina ◽  
Tim A. Beach ◽  
Mark Barnett
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Three Dimensional ◽  
Equation System ◽  
Aerodynamic Performance ◽  
Experimental Measurements ◽  
Low Aspect Ratio ◽  
Blade Row ◽  
Multistage Turbine ◽  
Secondary Flow Field

This work outlines a procedure for simulating the flow field within multistage turbomachinery which includes the effects of unsteadiness, compressibility, and viscosity. The associated modeling equations are the average passage equation system which governs the time-averaged flow field within a typical passage of a blade row embedded within a multistage configuration. The results from a simulation of a low aspect ratio stage and one-half turbine will be presented and compared with experimental measurements. It will be shown that the secondary flow field generated by the rotor causes the aerodynamic performance of the downstream vane to be significantly different from that of an isolated blade row.

scholarly journals Endwall and Unsteady Flow Phenomena in an Axial Turbine Stage

1994 ◽  
Author(s):  
H. E. Gallus ◽  
J. Zeschky ◽  
C. Hah
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Secondary Flow ◽  
Radial Distribution ◽  
Three Dimensional ◽  
Hot Wire ◽  
Turbine Stage ◽  
Flow Properties ◽  
Blade Row ◽  
Secondary Flow Field

Detailed experimental and numerical studies have been performed in a subsonic, axial-flow turbine stage to investigate the secondary flow field, the aerodynamic loss generation, and the spanwise mixing under a stage environment. The experimental study includes measurements of the static pressure distribution on the rotor blade surface and the rotor exit flow field using three-dimensional hot-wire and pneumatic probes. The rotor exit flow field was measured with an unsteady hot-wire probe which has high temporal and spatial resolution. Both steady and unsteady numerical analyses were performed with a three-dimensional Navier-Stokes code for the multiple blade rows. Special attention was focused on how well the steady multiple-blade-row calculation predicts the rotor exit flow field and how much the blade interaction affects the radial distribution of flow properties at the stage exit. Detailed comparisons between the measurement and the steady calculation indicate that the steady multiple-blade-row calculation predicts the overall time-averaged flow field very well. However, the steady calculation does not predict the secondary flow at the stage exit accurately. The current study indicates that the passage vortex near the hub of the rotor is transported toward the mid-span due to the blade interaction effects. And, the structure of the secondary flow field at the exit of the rotor is significantly modified by the unsteady effects. The time-averaged secondary flow field and the radial distribution of the flow properties, which are uses for the design of the following stage, can be predicted more accurately with the unsteady flow calculation.

Endwall and Unsteady Flow Phenomena in an Axial Turbine Stage

1995 ◽  
Vol 117 (4) ◽  
pp. 562-570 ◽  
Author(s):  
H. E. Gallus ◽  
J. Zeschky ◽  
C. Hah
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Secondary Flow ◽  
Radial Distribution ◽  
Three Dimensional ◽  
Hot Wire ◽  
Turbine Stage ◽  
Flow Properties ◽  
Blade Row ◽  
Secondary Flow Field

Detailed experimental and numerical studies have been performed in a subsonic, axial-flow turbine stage to investigate the secondary flow field, the aerodynamic loss generation, and the spanwise mixing under a stage environment. The experimental study includes measurements of the static pressure distribution on the rotor blade surface and the rotor exit flow field using three-dimensional hot-wire and pneumatic probes. The rotor exit flow field was measured with an unsteady hot-wire probe, which has high temporal and spatial resolution. Both steady and unsteady numerical analyses were performed with a three-dimensional Navier–Stokes code for the multiple blade rows. Special attention was focused on how well the steady multiple-blade-row calculation predicts the rotor exit flow field and how much the blade interaction affects the radial distribution of flow properties at the stage exit. Detailed comparisons between the measurement and the steady calculation indicate that the steady multiple-blade-row calculation predicts the overall time-averaged flow field very well. However, the steady calculation does not predict the secondary flow at the stage exit accurately. The current study indicates that the passage vortex near the hub of the rotor is transported toward the midspan due to the blade interaction effects. Also, the structure of the secondary flow field at the exit of the rotor is significantly modified by the unsteady effects. The time-averaged secondary flow field and the radial distribution of the flow properties, which are used for the design of the following stage, can be predicted more accurately with the unsteady flow calculation.

Flow Structure in the Wake of a Wall-Mounted Bluff Body

2010 ◽  
Author(s):  
James H. J. Buchholz ◽  
Seyed Mohammad Hajimirzaie ◽  
Craig J. Wojcik
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Bluff Body ◽  
Three Dimensional ◽  
Vortex Pair ◽  
Major Axis ◽  
Tip Vortex ◽  
Streamwise Vorticity ◽  
Low Aspect Ratio ◽  
Obstacle Height

This paper discusses an experimental study of the flow field around three different wall-mounted obstacles in a boundary layer within a relatively shallow flow (d/H ≈ 4, where d is the flow depth and H is the obstacle height). The first two obstacles consist of a semi-ellipsoidal body with the major axis of the base ellipse oriented in the streamwise and the transverse direction. The third obstacle is a low-aspect-ratio cylinder, bearing greater similarity to geometries investigated in other studies. Reynolds numbers of 5500 and 17800, based on obstacle height, were investigated. Digital particle image velocimetry was used to characterize the flow field in each case. At ReH = 17800, isocontours of streamwise vorticity reveal the presence of a tip vortex pair and a base vortex pair for each geometry; however, the ratio of the relative strengths of the tip and base vortices varies considerably, with the streamwise-oriented ellipsoid having the largest ratio of tip/base vortex circulation and the transverse ellipsoid having the smallest ratio. The presence of a base vortex for such low-aspect-ratio obstacles is unexpected, and therefore we hypothesize that its existence is related to the small d/H. It is anticipated that variation of geometry and d/H will help to elucidate the role of the base vortex in the three-dimensional vortex structure of the wake.

scholarly journals Incidence Angle and Pitch-Chord Effects on Secondary Flows Downstream of a Turbine Cascade

1992 ◽  
Author(s):  
A. Perdichizzi ◽  
V. Dossena
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Incidence Angle ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Pressure Probe ◽  
Turbine Cascade ◽  
Oil Flow ◽  
Secondary Velocity ◽  
Secondary Flow Field

This paper describes the results of an experimental investigation of the three-dimensional flow downstream of a linear turbine cascade at off-design conditions. The tests have been carried out for five incidence angles from −60 to +35 degrees, and for three pitch-chord ratios: s/c = 0.58,0.73,0.87. Data include blade pressure distributions, oil flow visualizations, and pressure probe measurements. The secondary flow field has been obtained by traversing a miniature five hole probe in a plane located at 50% of an axial chord downstream of the trailing edge. The distributions of local energy loss coefficients, together with vorticity and secondary velocity plots show in detail how much the secondary flow field is modified both by incidence and cascade solidity variations. The level of secondary vorticity and the intensity of the crossflow at the endwall have been found to be strictly related to the blade loading occurring in the blade entrance region. Heavy changes occur in the spanwise distributions of the pitch averaged loss and of the deviation angle, when incidence or pitch-chord ratio is varied.

Calculation of the Rise and Pitch of a Three-Dimensional Low-Aspect-Ratio Flat Ship

1991 ◽  
Vol 35 (04) ◽  
pp. 314-324
Author(s):  
Todd McComb
Keyword(s):  
Aspect Ratio ◽  
Three Dimensional ◽  
Static Case ◽  
Equilibrium Flow ◽  
Low Aspect Ratio ◽  
Fast Speed ◽  
Flow Past

Using low-aspect-ratio flat ship theory, this paper defines a procedure to determine the position of a hull which is in equilibrium at some "fast" speed in terms of a given hull shape for the same hull at rest. This procedure is then used to find the equilibrium flow past a moving ship, when given the shape of the hull at rest. The method is then extended to find the hull configuration at various speeds based on either the configuration in the static case or at some other equilibrium speed, leading to a calculation of drag versus speed. Some general formulas and some simple examples are given.

Blade-Row Interactions in an LP Turbine at Design and Strong Off-Design Operation

2014 ◽  
Author(s):  
Martin Lipfert ◽  
Jan Habermann ◽  
Martin G. Rose ◽  
Stephan Staudacher ◽  
Yavuz Guendogdu
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Three Dimensional ◽  
Suction Side ◽  
Test Facility ◽  
Time Resolved ◽  
Joint Project ◽  
Multi Stage ◽  
Blade Row ◽  
Wake Interactions

In a joint project between the Institute of Aircraft Propulsion Systems (ILA) and MTU Aero Engines a two-stage low pressure turbine is tested at design and strong off-design conditions. The experimental data taken in the altitude test-facility aims to study the effect of positive and negative incidence of the second stator vane. A detailed insight and understanding of the blade row interactions at these regimes is sought. Steady and time-resolved pressure measurements on the airfoil as well as inlet and outlet hot-film traverses at identical Reynolds number are performed for the midspan streamline. The results are compared with unsteady multi-stage CFD predictions. Simulations agree well with the experimental data and allow detailed insights in the time-resolved flow-field. Airfoil pressure field responses are found to increase with positve incidence whereas at negative incidence the magnitude remains unchanged. Different pressure to suction side phasing is observed for the studied regimes. The assessment of unsteady blade forces reveals that changes in unsteady lift are minor compared to changes in axial force components. These increase with increasing positive incidence. The wake-interactions are predominating the blade responses in all regimes. For the positive incidence conditions vane 1 passage vortex fluid is involved in the midspan passage interaction leading to a more distorted three-dimensional flow field.

The Effect of a Downstream Rotor on the Measured Performance of a Transonic Turbine Nozzle

1986 ◽  
Vol 108 (2) ◽  
pp. 269-274
Author(s):  
R. G. Williamson ◽  
S. H. Moustapha ◽  
J. P. Huot
Keyword(s):  
Performance Evaluation ◽  
Aspect Ratio ◽  
Flow Field ◽  
Large Scale ◽  
Outer Wall ◽  
Nozzle Flow ◽  
Turning Angle ◽  
Low Aspect Ratio ◽  
Transonic Turbine ◽  
Mach Numbers

Two nozzle designs, involving the same low aspect ratio, high turning angle vanes, and differing in outer wall contour, were tested over a range of exit Mach numbers up to supersonic values. The experiments were conducted on a large-scale, full annular configuration with and without a representative rotor downstream. Nozzle performance was found to be significantly affected by rotor operation, the influence depending on the detailed characteristics of the nozzle flow field, as well as on the design and operation of the rotor itself. It is suggested that performance evaluation of low aspect ratio nozzles of high turning angle may require appropriate testing with a rotor.

Improving the Performance of a Turbine With Low Aspect Ratio Stators by Aft-Loading

2004 ◽  
Vol 128 (3) ◽  
pp. 492-499 ◽  
Author(s):  
Graham Pullan ◽  
John Denton ◽  
Eric Curtis
Keyword(s):  
Aspect Ratio ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Loss Reduction ◽  
Low Aspect Ratio ◽  
Surface Pressure Distribution ◽  
Loaded Surface ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Stage Efficiency

Experimental data and numerical simulations are presented from a research turbine with low aspect ratio nozzle guide vanes (NGVs). The combined effects of mechanical and aerodynamic constraints on the NGV create very strong secondary flows. This paper describes three designs of NGV that have been tested in the turbine, using the same rotor row in each case. NGV 2 used three-dimensional design techniques in an attempt to improve the performance of the datum NGV 1 blade, but succeeded only in creating an intense vortex shed from the trailing edge (as previously reported) and lowering the measured stage efficiency by 1.1% points. NGV 3 was produced to avoid the “shed vortex” while adopting a highly aft-loaded surface pressure distribution to reduce the influence of the secondary flows. The stage with NGV 3 had an efficiency 0.5% points greater than that with NGV 1. Detailed comparisons between experiment and computations, including predicted entropy generation rates, are used to highlight the areas where the loss reduction has occurred and hence to quantify the effects of employing highly aft-loaded NGVs.

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