Improving Efficiency of a High Work Turbine Using Non-Axisymmetric Endwalls: Part I—Endwall Design and Performance

2008 ◽  
Author(s):  
T. Germain ◽  
M. Nagel ◽  
I. Raab ◽  
P. Schuepbach ◽  
R. S. Abhari ◽  
...  
Keyword(s):  
Numerical Optimization ◽  
Axial Flow ◽  
Loss Reduction ◽  
Numerical Investigations ◽  
Turbine Efficiency ◽  
Transition Modeling ◽  
And Performance ◽  
High Work ◽  
Stage Efficiency ◽  
Probe Measurements

This paper is the first part of a two part paper reporting the improvement of efficiency of a one-and-half stage high work axial flow turbine by non-axisymmetric endwall contouring. In this first paper the design of the endwall contours is described and the CFD flow predictions are compared to five-hole-probe measurements. The endwalls have been designed using automatic numerical optimization by means of an Sequential Quadratic Programming (SQP) algorithm, the flow being computed with the 3D RANS solver TRACE. The aim of the design was to reduce the secondary kinetic energy and secondary losses. The experimental results confirm the improvement of turbine efficiency, showing a stage efficiency benefit of 1%±0.4%, revealing that the improvement is underestimated by CFD. The secondary flow and loss have been significantly reduced in the vane, but improvement of the midspan flow is also observed. Mainly this loss reduction in the first row and the more homogeneous flow is responsible for the overall improvement. Numerical investigations indicate that the transition modeling on the airfoil strongly influences the secondary loss predictions. The results confirm that non-axisymmetric endwall profiling is an effective method to improve turbine efficiency, but that further modeling work is needed to achieve a good predictability.

Improving Efficiency of a High Work Turbine Using Nonaxisymmetric Endwalls— Part I: Endwall Design and Performance

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
T. Germain ◽  
M. Nagel ◽  
I. Raab ◽  
P. Schüpbach ◽  
R. S. Abhari ◽  
...  
Keyword(s):  
Axial Flow ◽  
Programming Algorithm ◽  
Navier Stokes ◽  
Turbine Efficiency ◽  
Computational Fluid Dynamics Cfd ◽  
Transition Modeling ◽  
And Performance ◽  
High Work ◽  
Sequential Quadratic Programming Algorithm ◽  
Probe Measurements

This paper is the first part of a two part paper reporting the improvement of efficiency of a one-and-half stage high work axial flow turbine by nonaxisymmetric endwall contouring. In this first paper the design of the endwall contours is described, and the computational fluid dynamics (CFD) flow predictions are compared with five-hole-probe measurements. The endwalls have been designed using automatic numerical optimization by means of a sequential quadratic programming algorithm, the flow being computed with the 3D Reynolds averaged Navier-Stokes (RANS) solver TRACE. The aim of the design was to reduce the secondary kinetic energy and secondary losses. The experimental results confirm the improvement of turbine efficiency, showing a stage efficiency benefit of 1%±0.4%, revealing that the improvement is underestimated by CFD. The secondary flow and loss have been significantly reduced in the vane, but improvement of the midspan flow is also observed. Mainly this loss reduction in the first row and the more homogeneous flow is responsible for the overall improvement. Numerical investigations indicate that the transition modeling on the airfoil strongly influences the secondary loss predictions. The results confirm that nonaxisymmetric endwall profiling is an effective method to improve turbine efficiency but that further modeling work is needed to achieve a good predictability.

The Design and Performance of a High Work Research Turbine

1996 ◽  
Vol 118 (4) ◽  
pp. 792-799 ◽  
Author(s):  
E. P. Vlasic ◽  
S. Girgis ◽  
S. H. Moustapha
Keyword(s):  
Pressure Ratio ◽  
Limit Load ◽  
Gas Generator ◽  
Part Load ◽  
Cold Flow ◽  
Turbine Efficiency ◽  
Load Pattern ◽  
Design Speed ◽  
And Performance ◽  
High Work

This paper describes the design and performance of a high work single-stage research turbine with a pressure ratio of 5.0, a stage loading of 2.2, and cooled stator and rotor. Tests were carried out in a cold flow rig and as part of a gas generator facility. The performance of the turbine was assessed, through measurements of reaction, rotor exit conditions and efficiency, with and without airfoil cooling. The measured cooled efficiency in the cold rig was 79.9 percent, which, after correcting for temperature and measuring plane location, matched reasonably well the efficiency of 81.5 percent in the gas generator test. The effect of cooling, as measured in the cold rig, was to reduce the turbine efficiency by 2.1 percent. A part-load turbine map was obtained at 100, 110, and 118 percent design speed and at 3.9, 5.0, and 6.0 pressure ratio. The influence of speed and the limit load pattern for transonic turbines are discussed. The effect of the downstream measuring distance on the calculated efficiency was determined using three different locations. An efficiency drop of 3.2 percent was measured between the rotor trailing edge plane and a distance four chords downstream.

Design Optimization of Profiled Endwall in a High Work Turbine

2014 ◽  
Author(s):  
Huimin Tang ◽  
Shuaiqiang Liu ◽  
Hualing Luo
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Optimization Procedure ◽  
Flow Solver ◽  
Turbine Efficiency ◽  
Spline Surface ◽  
Improved Performance ◽  
Steady Simulation ◽  
High Work ◽  
Profile Loss

In this paper, a method based on non-uniform rational B-spline surface (NURBS) technique coupled with mesh deforming technique is implemented to design the profiled endwall of turbines. This method has the advantages of flexible geometry representation and automatic rapid remeshing. An optimization procedure has been implemented by integrating the in-house geometry manipulator, a commercial three-dimensional CFD flow solver and the optimization driver, IsightTM. This procedure is applied to design the profiled endwalls of the first stage of a one-and-half stage high work axial flow turbine. Genetic Algorithm is used in the optimization process, and the aim is to minimize the total pressure loss. The influences of the profiled endwalls on the secondary flow in the stator and rotor have been analyzed by steady simulation. The results indicate a 0.4% improvement in stage efficiency. The secondary loss as well as the profile loss has been significantly reduced, and the increase of the reaction which influences the turbine efficiency is also observed. The unsteady simulations are also presented in this paper to confirm the improved performance of the optimum profiled endwalls.

The Design and Performance of a High Work Research Turbine

1995 ◽  
Author(s):  
E. P. Vlasic ◽  
S. Girgis ◽  
S. H. Moustapha
Keyword(s):  
Pressure Ratio ◽  
Limit Load ◽  
Gas Generator ◽  
Part Load ◽  
Cold Flow ◽  
Turbine Efficiency ◽  
Load Pattern ◽  
Design Speed ◽  
And Performance ◽  
High Work

This paper describes the design and performance of a high work single stage research turbine with a pressure ratio of 5.0, a stage loading of 2.2 and cooled stator and rotor. Tests were carried out in a cold flow rig and as part of a gas generator facility. The performance of the turbine was assessed, through measurements of reaction, rotor exit conditions and efficiency, with and without airfoil cooling. The measured cooled efficiency in the cold rig was 79.9%, which, after correcting for temperature and measuring plane location, matched reasonably well the efficiency of 81.5% in the gas generator test. The effect of cooling, as measured in the cold rig, was to reduce the turbine efficiency by 2.1%. A part load turbine map was obtained at 100, 110 and 118% design speed and at 3.9, 5.0 and 6.0 pressure ratio. The influence of speed and the limit load pattern for transonic turbines are discussed. The effect of the downstream measuring distance on the calculated efficiency was determined using three different locations. An efficiency drop of 3.2% was measured between the rotor trailing edge plane and a distance four chords downstream.

NUMERICAL INVESTIGATIONS AND PERFORMANCE EVALUATION OF A FOLDED TUBE HEAT TRANSPORT SYSTEM UNDER BOILING CONDITIONS

2018 ◽  
Vol 30 (4) ◽  
pp. 267-291
Author(s):  
Mukesh Kumar ◽  
Avinash Moharana ◽  
Raj K. Singh ◽  
Arun K. Nayak ◽  
Jyeshtharaj B. Joshi
Keyword(s):  
Performance Evaluation ◽  
Heat Transport ◽  
Transport System ◽  
Numerical Investigations ◽  
And Performance

Paper 10: Pressure Losses in the Inlet and Outlet Casings of Axial Flow Turbines for Turbo-Chargers

1967 ◽  
Vol 182 (4) ◽  
pp. 71-79 ◽  
Author(s):  
C. W. Simpson ◽  
D. E. Y. Scarlett
Keyword(s):  
Axial Flow ◽  
Annular Nozzle ◽  
Design Studies ◽  
Pressure Losses ◽  
Pressure Loss Coefficient ◽  
Turbine Efficiency ◽  
Annular Section ◽  
Turbine Casing ◽  
Transition Piece ◽  
Experimental Pressure

During initial design studies for a new range of turbo-chargers it was apparent that a considerable gain of efficiency could be achieved by a reduction of turbine casing losses. In this paper the theoretical and experimental pressure losses obtained from rig tests on the inlet and outlet casings for old and new designs will be presented. The inlet casing tests were completed on an axial entry casing with transition from circular to semi-annular section. The effect of this transition piece on gas incidences is also shown for the semi-annular nozzle entry. Studies on the outlet casing as a transition from annular through radial to axial flow have been completed and will be presented as a pressure loss coefficient for various designs. The tests have been undertaken with both convex and flat plate radial diffusers, with or without swirl. Different outlet ducts were used to determine the effects on pressure losses in the casings, and the results are discussed. Finally, the gains in overall turbine efficiency obtained by adopting the beneficial results from these tests are considered.

Aspirating Probe Measurements of the Unsteady Total Temperature Field Downstream of an Embedded Stator in a Multistage Axial Flow Compressor

1996 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana ◽  
J. Prato
Keyword(s):  
Axial Flow ◽  
Pressure Data ◽  
Peak Efficiency ◽  
Axial Flow Compressor ◽  
Composite Flow ◽  
Total Temperature ◽  
Temperature And Pressure ◽  
Flow Compressor ◽  
Isentropic Efficiency ◽  
Probe Measurements

The results from the area traverse measurements of the unsteady total temperature using a high response aspirating probe downstream of the second stator of a three stage axial flow compressor are presented. The measurements were conducted at the peak efficiency operating point. The unsteady total temperature data is resolved into deterministic and unresolved components. Hub and casing regions have high levels of unsteadiness and consequently high levels of mixing. These regions have significant levels of shaft resolved and unresolved unsteadiness. Comparisons are made between the total temperature and the total pressure data to examine the rotor 2 wake characteristics and the temporal variation of the stator exit flow. Isentropic efficiency calculations at the midpitch location show that there is about a 4% change in the algebraically averaged efficiency across the blades of the second rotor and if all the rotor 2 blades were behaving as a “best” blade, the improvement in efficiency would be about 1.3%. An attempt is made to create a composite flow field picture by correlating the unsteady velocity data with temperature and pressure data.

Performance prediction of axial flow compressors using stage characteristics and simultaneous calculation of interstage parameters

2001 ◽  
Vol 215 (1) ◽  
pp. 89-98 ◽  
Author(s):  
T. W. Song ◽  
T. S. Kim ◽  
J. H. Kim ◽  
S. T. Ro
Keyword(s):  
Gas Turbine ◽  
System Analysis ◽  
Axial Flow ◽  
Performance Estimation ◽  
Predicting Performance ◽  
Functional Formulation ◽  
Compressor Inlet ◽  
Multistage Compressors ◽  
And Performance ◽  
Axial Flow Compressors

A new method for predicting performance of multistage axial flow compressors is proposed that utilizes stage performance curves. The method differs from the conventional sequential stage-stacking method in that it employs simultaneous calculation of all interstage variables (temperature, pressure and flow velocity). A consistent functional formulation of governing equations enables this simultaneous calculation. The method is found to be effective, i.e. fast and stable, in obtaining solutions for compressor inlet and outlet boundary conditions encountered in gas turbine analyses. Another advantage of the method is that the effect of changing the angles of movable stator vanes on the compressor's operating behaviour can be simulated easily. Accordingly, the proposed method is very suitable for complicated gas turbine system analysis. This paper presents the methodology and performance estimation results for various multistage compressors employing both fixed and variable vane setting angles. The effect of interstage air bleeding on compressor performance is also demonstrated.

Blade Loadings for Hovercraft and other Radial Flow Fans

1967 ◽  
Vol 9 (4) ◽  
pp. 265-277 ◽  
Author(s):  
A. D. S. Carter
Keyword(s):  
Radial Flow ◽  
Axial Flow ◽  
Maximum Temperature ◽  
Centrifugal Fan ◽  
Blade Loading ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Flow Compressor ◽  
High Work ◽  
Outside Diameter

The layout of a hovercraft leads naturally to the choice of a radial outward flow fan, but the aerodynamic requirements are more stringent than those normally associated with industrial fans. In this paper a blade loading criterion used extensively in axial flow compressor practice has been adapted to the more general case of radial flow fans. Using this criterion maximum fluid deflections and maximum temperature rise coefficients have been calculated. It is shown that fluid deflections in radial fans should be substantially lower than those in axial flow machines. For high work output the ratio of rotor outside diameter to rotor inside diameter should be as close to unity as is mechanically possible. Inlet guide vanes would be of no benefit to the conventional industrial type centrifugal fan, but for such applications as hovercraft inlet guide vanes could be most beneficial. The paper outlines those areas in which further research is necessary fully to confirm the approach, and hence the quantitative values, given in this paper.

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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