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.

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

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.

711 Optimization of secondary flow loss reduction method for high loaded gas turbine cascade

2011 ◽  
Vol 2011.86 (0) ◽  
pp. _7-11_
Author(s):  
Toru TAMAGAWA ◽  
Masao OTO ◽  
Daichi FUZIMOTO ◽  
Yutaka KAWATA
Keyword(s):  
Secondary Flow ◽  
Gas Turbine ◽  
Reduction Method ◽  
Loss Reduction ◽  
Turbine Cascade ◽  
Flow Loss

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.

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.

scholarly journals Influence of Endwall Flow on Airfoil Suction Surface Mid-Height Boundary Layer Development in a Turbine Cascade

1982 ◽  
Author(s):  
O. P. Sharma ◽  
R. A. Graziani
Keyword(s):  
Boundary Layer ◽  
Reynolds Shear Stress ◽  
Cross Flow ◽  
Prediction Method ◽  
Conservation Equation ◽  
Turbine Cascade ◽  
Suction Surface ◽  
Extra Term ◽  
Boundary Layer Development ◽  
Layer Development

This paper presents the results of an analysis to assess the influence of cascade passage endwall flow on the airfoil suction surface mid-height boundary layer development in a turbine cascade. The effect of the endwall flow is interpreted as the generation of a cross flow and a cross flow velocity gradient in the airfoil boundary layer, which results in an extra term in the mass conservation equation. This extra term is shown to influence the boundary layer development along the mid-height of the airfoil suction surface through an increase in the boundary layer thickness and consequently an increase in the mid-height losses, and a decrease in the Reynolds shear stress, mixing length, skin friction, and Stanton number. An existing two-dimensional differential boundary layer prediction method, STAN-5, is modified to incorporate the above two effects.

Effects of Shock Wave Development on Secondary Flow Behavior in Linear Turbine Cascade at Transonic Condition

2020 ◽  
Author(s):  
Hoshio Tsujita ◽  
Masanao Kaneko
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Secondary Flow ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Flow Behavior ◽  
Turbine Cascade ◽  
Blade Loading ◽  
Passage Vortex ◽  
Exit Mach Number

Abstract Gas turbines widely applied to power generation and aerospace propulsion systems are continuously enhanced in efficiency for the reduction of environmental load. The energy recovery efficiency from working fluid in a turbine component constituting gas turbines can be enhanced by the increase of turbine blade loading. However, the increase of turbine blade loading inevitably intensifies the secondary flows, and consequently increases the associated loss generation. The development of the passage vortex is strongly influenced by the pitchwise pressure gradient on the endwall in the cascade passage. In addition, a practical high pressure turbine stage is generally driven under transonic flow conditions where the shock wave strongly influences the pressure distribution on the endwall. Therefore, it becomes very important to clarify the effects of the shock wave formation on the secondary flow behavior in order to increase the turbine blade loading without the deterioration of efficiency. In this study, the two-dimensional and the three-dimensional transonic flows in the HS1A linear turbine cascade at the design incidence angle were analyzed numerically by using the commercial CFD code with the assumption of steady compressible flow. The isentropic exit Mach number was varied from the subsonic to the supersonic conditions in order to examine the effects of development of shock wave caused by the increase of exit Mach number on the secondary flow behavior. The increase of exit Mach number induced the shock across the passage and increased its obliqueness. The increase of obliqueness reduced the cross flow on the endwall by moving the local minimum point of static pressure along the suction surface toward the trailing edge. As a consequence, the increase of exit Mach number attenuated the passage vortex.

The Effects of Inlet Boundary Layer Condition and Periodically Incoming Wakes on Secondary Flow in a Low Pressure Turbine Cascade

2020 ◽  
Author(s):  
Tobias Schubert ◽  
Silvio Chemnitz ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
High Speed ◽  
Low Pressure ◽  
Experimental Investigations ◽  
Turbine Cascade ◽  
Flow Conditions ◽  
Low Pressure Turbine ◽  
Speed Flow ◽  
Unsteady Inflow

Abstract A particular turbine cascade design is presented with the goal of providing a basis for high quality investigations of endwall flow at high-speed flow conditions and unsteady inflow. The key feature of the design is an integrated two-part flat plate serving as a cascade endwall at part-span, which enables a variation of the inlet endwall boundary layer conditions. The new design is applied to the T106A low pressure turbine cascade for endwall flow investigations in the High-Speed Cascade Wind Tunnel of the Institute of Jet Propulsion at the Bundeswehr University Munich. Measurements are conducted at realistic flow conditions (M2th = 0.59, Re2th = 2·105) in three cases of different endwall boundary layer conditions with and without periodically incoming wakes. The endwall boundary layer is characterized by 1D-CTA measurements upstream of the blade passage. Secondary flow is evaluated by Five-hole-probe measurements in the turbine exit flow. A strong similarity is found between the time-averaged effects of unsteady inflow conditions and the effects of changing inlet endwall boundary layer conditions regarding the attenuation of secondary flow. Furthermore, the experimental investigations show, that all design goals for the improved T106A cascade are met.

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