Non-Axisymmetric Turbine Endwall Aerodynamic Optimization Design: Part I — Turbine Cascade Design and Experimental Validations

2014 ◽  
Author(s):  
Hao Sun ◽  
Jun Li ◽  
Liming Song ◽  
Zhenping Feng
Keyword(s):  
Secondary Flow ◽  
Evaluation Method ◽  
Pressure Coefficient ◽  
Optimization Method ◽  
Experimental Measurements ◽  
Turbine Cascade ◽  
Aerodynamic Optimization ◽  
Flow Losses ◽  
Flow Intensity ◽  
Performance Evaluation Method

The non-axisymmetric endwall profiling has been proven to be an effective tool to reduce the secondary flow loss in turbomachinery. In this work, the aerodynamic optimization for the non-axisymmetric endwall profile of the turbine cascade and stage was presented and the design results were validated by annular cascade experimental measurements and numerical simulations. The parametric method of the non-axisymmetric endwall profile was proposed based on the relation between the pressure field variation and the secondary flow intensity. The optimization system combines with the non-axisymmetric endwall parameterization method, global optimization method of the adaptive range differential evolution algorithm and the aerodynamic performance evaluation method using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and k–ω SST turbulent with transition model solutions. In the part I, the optimization method is used to design the optimum non-axisymmetric endwall profile of the typical high loaded turbine stator. The design objective was selected for the maximum total pressure coefficient with constrains on the mass flow rate and outlet flow angle. Only five design variables are needed for one endwall to search the optimum non-axisymmetric endwall profile. The optimized non-axisymmetric endwall profile of turbine cascade demonstrated an improvement of total pressure coefficient of 0.21% absolutely, comparing with the referenced axisymmetric endwall design case. The reliability of the numerical calculation used in the aerodynamic performance evaluation method and the optimization result were validated by the annular vane experimental measurements. The static pressure distribution at midspan was measured while the cascade flow field was measured with the five-hole probe for both the referenced axisymmetric and optimized non-axisymmetric endwall profile cascades. Both the experimental measurements and numerical simulations demonstrated that both the secondary flow losses and the profile loss of the optimized non-axisymmetric endwall profile cascade were significantly reduced by comparison of the referenced axisymmetric case. The weakening of the secondary flow of the optimized non-axisymmetric endwall profile design was also proven by the secondary flow vector results in the experiment. The detailed flow mechanism of the secondary flow losses reduction in the non-axisymmetric endwall profile cascade was analyzed by investigating the relation between the change of the pressure gradient and the variation of the secondary flow intensity.

Secondary Flow Loss Reduction Method by Use of Endwall Contouring in Gas Turbine Cascade Using Optimization Method

2021 ◽  
Author(s):  
Kazuki Yamamoto ◽  
Ryota Uehara ◽  
Shohei Mizuguchi ◽  
Masahiro Miyabe
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Cross Flow ◽  
Internal Flow ◽  
Optimization Method ◽  
Loss Reduction ◽  
Turbine Cascade ◽  
Flow Loss ◽  
Endwall Contouring

Abstract High efficiency is strongly demanded for gas turbines to reduce CO2 emissions. In order to improve the efficiency of gas turbines, the turbine inlet temperature is being raised higher. In that case, the turbine blade loading is higher and secondary flow loss becomes a major source of aerodynamic losses due to the interaction between the horseshoe vortex and the strong endwall cross flow. One of the authors have optimized a boundary layer fence which is a partial vane to prevent cross-flow from pressure-side to suction-side between blade to blade. However, it was also found that installing the fence leads to increase another loss due to tip vortex, wake and viscosity. Therefore, in this paper, we focused on the endwall contouring and the positive effect findings from the boundary layer fence were used to study its optimal shape. Firstly, the relationship between the location of the endwall contouring and the internal flow within the turbine cascade was investigated. Two patterns of contouring were made, one is only convex and another is just concave, and the secondary flow behavior of the turbine cascade was investigated respectively. Secondly, the shape was designed and the loss reduction effect was investigated by using optimization method. The optimized shape was manufactured by 3D-printer and experiment was conducted using cascade wind tunnel. The total pressure distributions were measured and compared with CFD results. Furthermore, flow near the endwall and the internal flow of the turbine cascade was experimentally visualized. The internal flow in the case of a flat wall (without contouring), with a fence, and with optimized endwall contouring were compared by experiment and CFD to extract the each feature.

Secondary Flow Loss Reduction Method by Use of 3D-Fence in a Gas Turbine Cascade

2019 ◽  
Author(s):  
Ryota Uehara ◽  
Syohei Mizuguchi ◽  
Kakeru Kusano ◽  
Masahiro Miyabe ◽  
Yutaka Kawata
Keyword(s):  
Secondary Flow ◽  
Gas Turbine ◽  
Optimization Method ◽  
Horseshoe Vortex ◽  
Good Effect ◽  
Design Parameters ◽  
Loss Reduction ◽  
Turbine Cascade ◽  
Secondary Loss ◽  
Flow Loss

Abstract The aerodynamic loss accounted to the secondary flow, or secondary loss is one of the most prominent causes of the internal losses in turbine cascades. The secondary flow losses are mostly due to the interaction between horseshoe vortex and endwall crossflow. The authors have developed a so-called endwall fence experimentally to reduce the secondary loss in a gas turbine cascade. However, it is very difficult to handle many design parameters simultaneously in experiment. The objective of this research work is to optimize the shape of the 3D-fence with considering many design parameters and clarify the flow mechanism of loss reduction. In addition, one of the most important objectives of this paper is to show this optimization method is effective for the designer of the turbine. In this study, the optimization framework and CFD were applied to the endwall fence (3D-fence) and the effect of it on the crossflow was investigated. As a result, the optimized shape, installation position, and the setting angle of the 3D-fence to mitigate the interaction between the horseshoe vortex and endwall crossflow was specified. In order to validate the effectiveness of the optimization method, total pressure was measured and loss analysis was implemented and flow visualization using oil-film and smoke were implemented. Then, the good agreement can be seen qualitatively between the experimental results and CFD results. It is clarified the 3D-fence delays the confluence between suction side leg and pressure side leg of the horseshoe vortex. Based on both calculation and experiment, it is revealed that the 3D-fence has good effect to reduce the secondary flow loss.

Growth of Secondary Flow Losses Downstream of a Turbine Blade Cascade

1986 ◽  
Vol 108 (2) ◽  
pp. 270-276 ◽  
Author(s):  
L. D. Chen ◽  
S. L. Dixon
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
Secondary Flow ◽  
Total Pressure ◽  
Turbine Cascade ◽  
Pressure Losses ◽  
Flow Losses ◽  
Blade Cascade ◽  
Flow Loss ◽  
Loss Coefficients

Endwall total pressure losses downstream of a low-speed turbine cascade have been measured at several planes in order to determine the changes in secondary flow loss coefficients and the growth of the mixing loss with distance downstream. The results obtained are compared with various published secondary flow loss correlations in an attempt to explain some of the anomalies which presently exist. The paper includes some new correlations including one for the important gross secondary loss coefficient YSG with loading and aspect ratio parameters as well as the upstream boundary layer parameters.

Study on Secondary Flow Loss Reduction in Gas Turbine Cascade by Optimization method

2018 ◽  
Vol 2018.93 (0) ◽  
pp. 907
Author(s):  
Kakeru KUSANO ◽  
Shohei MIZUGUCHI ◽  
Rin OKUBO ◽  
Ryo NAGAOKA ◽  
Hiroharu OHYAMA ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Gas Turbine ◽  
Optimization Method ◽  
Loss Reduction ◽  
Turbine Cascade ◽  
Flow Loss

scholarly journals Applications of an Improved Aerodynamic Optimization Method on a Low Reynolds Number Cascade

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1150 ◽  
Author(s):  
Shuyi Zhang ◽  
Bo Yang ◽  
Hong Xie ◽  
Moru Song
Keyword(s):  
Reynolds Number ◽  
Simulated Annealing Algorithm ◽  
Design Method ◽  
Incidence Angle ◽  
Thickness Distribution ◽  
Low Reynolds Number ◽  
Pressure Coefficient ◽  
Optimization Method ◽  
Aerodynamic Optimization ◽  
Low Reynolds

The effect of cascade aerodynamic optimization on turbomachinery design is very significant. However, for most traditional cascade optimization methods, aerodynamic parameters are considered as boundary conditions and rarely directly used as the optimization variables to realize optimization. Given this problem, this paper proposes an improved cascade aerodynamic optimization method in which an incidence angle and nine geometric parameters are used to parameterize the cascade and one modified optimization algorithm is adopted to find the cascade with the optimal aerodynamic performance. The improved parameterization approach is based on the Non-Uniform Rational B-Splines (NURBS) method, the camber line superposing thickness distribution molding (CLSTDM) method, and the plane cascade design method. To rapidly and effectively find the cascade with the largest average lift-drag ratio within a certain range of incidence angles, modified particle swarm optimization combined with the modified very fast simulated annealing algorithm (PSO-MVFSA) is adopted. To verify the feasibility of the method, a cascade with NACA4412 and a practical cascade are optimized. It is found that the average lift-drag ratios of two optimal performance cascades are respectively increased by 13.38% and 15.21% in comparison to those of two original cascades. Meanwhile, through optimizing the practical cascade of the Blade D500, under different volume flow rates, the pressure coefficient of the optimized cascade is increased by an average of more than 6.12% compared to that of the prototype, and the average efficiency is increased by 11.15%. Therefore, this improved aerodynamic optimization method is reliable and feasible for the performance improvement of cascades with a low Reynolds number.

The nonaxismmetric endwall aerodynamic optimization design for a large turbine cascade with a midgap

2017 ◽  
Vol 233 (3) ◽  
pp. 1000-1010
Author(s):  
Lei He ◽  
Hao Liu ◽  
Xiaocheng Zhu ◽  
Ouyang Hua ◽  
Zhaohui Du
Keyword(s):  
Secondary Flow ◽  
Optimization Design ◽  
Transport Model ◽  
Design Procedure ◽  
Turbine Cascade ◽  
Evaluation Tool ◽  
Aerodynamic Optimization ◽  
Pressure Loss Coefficient ◽  
Shear Stress Transport Model ◽  
Assembly Features

The nonaxisymmetric endwall has been verified to be an effective method in reducing the endwall secondary flow loss. Some assembly features, such as the midgap in the hub of real aircraft engines, may have an influence on the endwall secondary flow. In the present work, a nonaxisymmetric endwall with midgap structure is designed for a large linear turbine cascade. A nonaxisymmetric endwall optimization design procedure is developed to minimize the total pressure loss coefficient at the passage exit. The profile of the endwall is designed using automatic numerical optimization with the Kriging surrogate method. The numerical simulation based on a transition shear stress transport model is used as the aerodynamic evaluation tool for the optimization system. When the midgap is considered in the design, mixing loss between midgap flows and main flow is significantly reduced. However, the loss relative to the passage vortex is increased to some extent.

Efficient Aerodynamic Optimization of an Impulse Turbine Rotor Cascade

2009 ◽  
Author(s):  
Ernesto Benini ◽  
Rita Ponza ◽  
Claudio Comis da Ronco ◽  
Irene Ventrucci
Keyword(s):  
Total Pressure ◽  
Fitness Function ◽  
Pressure Coefficient ◽  
Optimization Procedure ◽  
Suction Side ◽  
Optimization Method ◽  
Turbine Rotor ◽  
Aerodynamic Optimization ◽  
Impulse Turbine ◽  
Pressure Losses

This paper describes an efficient aerodynamic optimization method for an impulse turbine rotor cascade. The aim of the optimization is to minimize the total pressure losses through the cascade by controlling the shape of a portion of the turbine airfoil, i.e. the pressure side and the rear part of the suction side. This is done with the intention of reducing the complexity of the problem to be solved, as well as because of the particular nature of the losses being generated. For this purpose, the commercial Computational Fluid Dynamics (CFD) code Fluent© is used where a transition model is implemented, prior an accurate validation has been carried out. A proper optimization procedure is developed which is based on a sequential use of several modules: first, a Design of Experiment (DOE) analysis is performed, then a Response Surface Methodology (RSM) is employed to build a surrogate model of the fitness function, which is in turn minimized using a Sequential Quadratic Programming (SQP) algorithm. The benefits of this approach are demonstrated, in that the total pressure coefficient of the cascade can be lowered up to 13%.

Growth of Secondary Flow Losses Downstream of a Turbine Blade Cascade

1985 ◽  
Author(s):  
L. D. Chen ◽  
S. L. Dixon
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
Total Pressure ◽  
Turbine Cascade ◽  
Pressure Losses ◽  
Flow Losses ◽  
Blade Cascade ◽  
Flow Loss ◽  
Loss Coefficients ◽  
End Wall

End wall total pressure losses downstream of a low-speed turbine cascade have been measured at several planes in order to determine the changes in secondary flow loss coefficients and the growth of the mixing loss with distance downstream. The results obtained are compared with various published secondary flow loss correlations in an attempt to explain some of the anomalies which presently exist. The paper includes some new correlations including one for the important gross secondary loss coefficient YSG with loading and aspect ratio parameters as well as the upstream boundary layer parameters.

Sign in / Sign up

Export Citation Format

Share Document