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.

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.

On the Theory of the Wells Turbine

1984 ◽  
Vol 106 (3) ◽  
pp. 628-633 ◽  
Author(s):  
L. M. C. Gato ◽  
A. F. de O. Falca˜o
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Aerodynamic Performance ◽  
Two Dimensional ◽  
Wells Turbine ◽  
Actuator Disk ◽  
Turbine Efficiency ◽  
Axial Velocity Profile ◽  
Profile Losses ◽  
Blade Shape

A theoretical investigation is presented concerning the aerodynamic performance of the Wells turbine, a self-rectifying, axial-flow turbine suitable for energy extraction from a reciprocating air flow. A two-dimensional analysis is developed, and expressions, based on potential flow, are derived for the blade shape maximizing the turbine efficiency. Three-dimensional effects and profile losses are then accounted for by means of an actuator disk theory, which shows that large radial distortions of axial velocity profile can occur, depending on blade shape, with important implications on the extent of the stall-free conditions.

A Genetic Algorithm Approach to the Problem of Minimum Ship Wave Resistance

2002 ◽  
Vol 39 (03) ◽  
pp. 187-195
Author(s):  
Roko Dejhalla ◽  
Zoran Mrša ◽  
Senka Vukovic´
Keyword(s):  
Genetic Algorithm ◽  
Potential Flow ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Wave Resistance ◽  
Ship Hull ◽  
Point Of View ◽  
Flow Solver ◽  
Genetic Algorithm Approach

A genetic algorithm-based optimization method is proposed for an optimization of a ship hull from a hydrodynamic point of view. In the optimization procedure, the wave resistance has been selected as an objective function. The genetic algorithm is coupled with a computer program for solving the three-dimensional potential flow around a ship hull. The potential flow solver is based upon the well-known Dawson method. The optimization procedure has been applied to the Series 60 CB = 0.60 hull taken as a basis hull. The computational examples show the optimization ability of the proposed method.

A Study of the Effects of Tip Clearance in a Supersonic Turbine

2000 ◽  
Vol 122 (4) ◽  
pp. 674-683 ◽  
Author(s):  
Daniel J. Dorney ◽  
Lisa W. Griffin ◽  
Frank W. Huber
Keyword(s):  
Three Dimensional ◽  
Flow Fields ◽  
Tip Clearance ◽  
Work Design ◽  
Navier Stokes ◽  
Turbine Performance ◽  
Shock System ◽  
Improved Performance ◽  
Performance Gains ◽  
High Work

Flow unsteadiness is a major factor in turbine performance and durability. This is especially true if the turbine is a high work design, compact, transonic, supersonic, counterrotating, or uses a dense drive gas. The vast majority of modern rocket turbine designs fall into these categories. In this study a parallelized unsteady three-dimensional Navier–Stokes analysis has been used to study the effects of tip clearance on the transient and time-averaged flow fields in a supersonic turbine. The predicted results indicate improved performance in the simulation including tip clearance. The main sources of the performance gains were: (1) a weakened shock system in the case with tip clearance, and (2) the fact that the reductions in the shock losses were greater than the losses introduced by tip clearance. [S0889-504X(00)02404-1]

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.

Non-Axisymmetric Endwall Contouring in a Compressor Cascade With Tip Gap

2014 ◽  
Author(s):  
Mahesh K. Varpe ◽  
A. M. Pradeep
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Axial Flow ◽  
Tip Clearance ◽  
Total Pressure Loss ◽  
Compressor Cascade ◽  
Flow Solver ◽  
Pressure Loss Coefficient ◽  
Flow Compressor

This paper describes the design of a non-axisymmetric hub contouring in a shroudless axial flow compressor cascade operating at near stall condition. Although, an optimum tip clearance reduces the total pressure loss, further minimization of the losses using hub contouring was achieved. The design methodology presented here combines an evolutionary principle with a three-dimensional CFD flow solver to generate different geometric profiles of the hub systematically. The total pressure loss coefficient was used as a single objective function to guide the search process for the optimum hub geometry. The resulting three dimensionally complex hub promises considerable benefits discussed in detail in this paper. A reduction of 15.2% and 16.23% in the total pressure loss and secondary kinetic energy, respectively, was achieved in the wake. The blade loading was observed to improve by about 4.53%. Other complementary benefits are also listed in the paper. The results confirm that non-axisymmetric contouring is an effective method for reducing the losses and thereby improving the performance of the cascade.

scholarly journals Comparison of Design Intent and Experimental Measurements in a Low Aspect Ratio Axial Flow Turbine With Three-Dimensional Blading

1998 ◽  
Author(s):  
A. M. Wallis ◽  
J. D. Denton
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Experimental Measurements ◽  
Stage Model ◽  
3D Design ◽  
Flow Measurements ◽  
Design Intent ◽  
Low Aspect Ratio ◽  
Turbine Efficiency ◽  
Pressure Steam

In recent years there has been considerable interest in improving turbine efficiency by the application of three-dimensional (3D) design techniques. However, there is no consensus on the optimum strategy to be adopted for this. The paper describes a strategy for the design of new 3D blading for a four stage model of a high pressure steam turbine. The new blading was tested and increased the turbine efficiency by 2% relative to the previous, very efficient 2D blading. Some details of the flow measurements in the turbine are presented and consideration is given to the effectiveness of current steady CFD codes to design this type of blading in the multistage environment.

Three-Dimensional Design Optimization of Multistage Axial Flow Turbines Using a RSM Based Approach

2012 ◽  
Author(s):  
Carlo Cravero ◽  
Paolo Macelloni ◽  
Giuseppe Briasco
Keyword(s):  
Neural Networks ◽  
Design Optimization ◽  
Three Dimensional ◽  
Axial Flow ◽  
Optimization Process ◽  
Navier Stokes ◽  
Specific Power ◽  
Flow Solver ◽  
Multistage Turbine ◽  
Coarse Meshes

The problem of the automatic design optimization for multistage axial flow turbines is considered and a design strategy based on a 3D Navier-Stokes solver and a RSM (Response Surface Method) approach is described. A multi-objective optimization code based on non-dominated sorting genetic algorithm (NSGA-2) is used to drive the optimization process in order to maximize the specific power while keeping the massflow rate constrained. In the present work the meridional channel is kept unchanged while for each blade the spanwise distribution of the profile restaggering is considered together with the inclusion of compound lean. The performance from the multistage turbine for the optimization loop are obtained from surrogate models built through a set of artificial neural networks. The neural networks are trained and tested using large DoEs and are not updated during the optimization process. This aspect is considered important to guarantee that the optimization converges to an optimum. The use of the 3D flow solver with coarse meshes in order to validate large DoEs in short times is discussed in some details. The above strategy has been applied to a four stage axial turbine from the open literature.

On the Influence of the Number of Stages on the Efficiency of Axial-Flow Turbines

1982 ◽  
Author(s):  
G. Lozza ◽  
E. Macchi ◽  
A. Perdichizzi
Keyword(s):  
Axial Flow ◽  
Optimization Procedure ◽  
Computer Code ◽  
Expansion Ratio ◽  
Physical Significance ◽  
Turbine Efficiency ◽  
Design Variables ◽  
Multistage Turbine ◽  
Optimizing Design ◽  
Selection Of

The selection of the number of stages of a turbine is a compromise between the two often conflicting requirements of increasing the efficiency and decreasing the machine complexity and cost. A sound prediction of the turbine efficiency variation with the number of stages is therefore useful. In the paper, a computer code capable of optimizing the more significant design variables of a multistage axial-flow turbine is described. The selection of the optimizing design variables, the assumptions made for the constraints within which the solution is searched and the optimization procedure are discussed. Losses are predicted by the Craig and Cox correlation. A computer program is used to design and predict the performance of a number of representative turbines. Similarity parameters are introduced to generalize the obtained results after a discussion of their physical significance for multistage turbine handling compressible flow. The influence on the overall turbine efficiency of the number of stages is derived as a function of expansion ratio, specific speed and turbine dimensions.

Two Dimensional Optimization of Centrifugal Compressor Impellers Using Online Quasi-3D Flow Solver and Genetic Algorithm

2010 ◽  
Author(s):  
Ying Ma ◽  
Abraham Engeda
Keyword(s):  
Genetic Algorithm ◽  
Centrifugal Compressor ◽  
Search Algorithm ◽  
Radial Basis Function Network ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Modeling Tools ◽  
Flow Solver ◽  
Performance Map ◽  
A Performance

Modeling tools are widely used to create a performance map and decrease design cycle time in computer-aided centrifugal compressor impeller optimization procedures. However, a high-dimensional performance map is difficult to create and application of the approximate performance map brings errors into optimization procedures. This paper presents an online flow solver optimization procedure, in which a Quasi-three dimensional flow solver is directly used to evaluate impeller performances in the genetic algorithm (GA). Also, this procedure is compared with offline flow solver optimization procedure. In offline flow optimization procedure, the flow solver is employed to calculate performances in training database for creating a performance map trained by one type of artificial neural network (ANN), radial basis function network (RBFN). This performance map is further used to calculate the performances of impeller geometries. Results of these two optimization procedures under same GA parameters setting are compared and show that online flow solver optimization procedure can find better optima than offline flow solver optimization procedure. Moreover, influences of GA operators, parameters and local search algorithm on online flow solver optimization procedure are also investigated.

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