Tip-Shaping for HP Turbine Blade Aero-Thermal Performance Management

2012 ◽  
Author(s):  
Q. Zhang ◽  
L. He
Keyword(s):  
Heat Transfer ◽  
Performance Management ◽  
Turbine Blade ◽  
Heat Load ◽  
High Speed ◽  
Effective Means ◽  
Tip Leakage Flow ◽  
Local Flow ◽  
Flow Acceleration ◽  
Tip Leakage

A large portion of the over-tip leakage flow is often transonic for a typical high pressure (HP) turbine blade. It has been observed that the tip heat transfer is noticeably lower in a high speed flow tip region than in a low speed region. The present study therefore investigates the feasibility of controlling blade heat transfer by tip shaping to locally accelerate the flow to a transonic regime. The results show that a significant heat load reduction can be achieved by the local flow acceleration. Such over-tip-shaping provides a great potential as an effective means to control heat load distribution (and hence thermal stress) over the blade tip surface. The feasibility of the concept and flow physics have been demonstrated in detail by CFD analyses, with and without the effect of moving casing. The experimental results obtained from a high speed linear cascade facility have also been presented. In addition, the proposed tip-shaping concept may also provide a potential for promoting choking inside the tip gap as a way to control the over-tip leakage mass flow.

Tip-Shaping for HP Turbine Blade Aerothermal Performance Management

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Q. Zhang ◽  
L. He
Keyword(s):  
Heat Transfer ◽  
Performance Management ◽  
Turbine Blade ◽  
Heat Load ◽  
High Speed ◽  
Effective Means ◽  
Tip Leakage Flow ◽  
Local Flow ◽  
Flow Acceleration ◽  
Tip Leakage

A large portion of the over-tip leakage flow is often transonic for a typical high pressure (HP) turbine blade. It has been observed that the tip heat transfer is noticeably lower in a high speed flow tip region than in a low speed region. The present study therefore investigates the feasibility of controlling blade heat transfer by tip shaping to locally accelerate the flow to a transonic regime. The results show that a significant heat load reduction can be achieved by the local flow acceleration. Such over-tip-shaping provides a great potential as an effective means to control heat load distribution (and hence thermal stress) over the blade tip surface. The feasibility of the concept and flow physics have been demonstrated in detail by CFD analyses, with and without the effect of moving casing. The experimental results obtained from a high speed linear cascade facility have also been presented. The novel tip-shaping concept proposed in this paper could provide a potential for promoting choking inside the tip gap as a new way to control the over-tip leakage mass flow.

Effect of Turbine Blade Tip Cooling Configuration on Tip Leakage Flow and Heat Transfer

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Sergen Sakaoglu ◽  
Harika S. Kahveci
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Thermal Response ◽  
Thermal Conditions ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip

Abstract The pressure difference between suction and pressure sides of a turbine blade leads to tip leakage flow, which adversely affects the first-stage high-pressure (HP) turbine blade tip aerodynamics. In modern gas turbines, HP turbine blade tips are exposed to extreme thermal conditions requiring cooling. If the coolant jet directed into the blade tip gap cannot counter the leakage flow, it will simply add up to the pressure losses due to leakage. Therefore, the compromise between the aerodynamic loss and the gain in tip-cooling effectiveness must be optimized. In this paper, the effect of tip-cooling configuration on the turbine blade tip is investigated numerically from both aerodynamics and thermal aspects to determine the optimum configuration. Computations are performed using the tip cross section of GE-E3 HP turbine first-stage blade for squealer and flat tips, where the number, location, and diameter of holes are varied. The study presents a discussion on the overall loss coefficient, total pressure loss across the tip clearance, and variation in heat transfer on the blade tip. Increasing the coolant mass flow rate using more holes or by increasing the hole diameter results in a decrease in the area-averaged Nusselt number on the tip floor. Both aerodynamic and thermal response of squealer tips to the implementation of cooling holes is superior to their flat counterparts. Among the studied configurations, the squealer tip with a larger number of cooling holes located toward the pressure side is highlighted to have the best cooling performance.

Effect of Turbine Blade Tip Cooling Configuration on Tip Leakage Flow and Heat Transfer

2019 ◽  
Author(s):  
Sergen Sakaoglu ◽  
Harika S. Kahveci
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Thermal Response ◽  
Thermal Conditions ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip

Abstract The pressure difference between suction and pressure sides of a turbine blade leads to the so-called phenomenon, the tip leakage flow, which most adversely affects the first-stage high-pressure (HP) turbine blade tip aerodynamics. In modern gas turbines, HP turbine blade tips are also exposed to extreme thermal conditions requiring the use of tip cooling. If the coolant jet directed into the blade tip gap cannot counter the leakage flow, it will simply add up to the pressure losses due to this leakage flow. Therefore, it is necessary to handle the design of tip cooling in such a way that the compromise between the aerodynamic loss and the gain in the tip cooling effectiveness is optimized. In this paper, the effect of tip cooling configuration on the turbine blade tip is investigated numerically both from the aerodynamics and thermal aspects in order to determine the optimum tip cooling configuration. The studies are carried out using the tip cross-section of General Electric E3 (Energy Efficient Engine) HP turbine first-stage blade for two different tip geometries, squealer tip and flat tip, where the number, location, and diameter of the cooling holes are varied. The study presents a discussion on the overall loss coefficient, the total pressure loss across the tip clearance, and the variation of heat transfer on the blade tip. The aerodynamic and heat transfer results are compared with the experimental data from literature. It is observed that increasing the coolant mass flow rate by using more holes or by increasing the hole diameter results in a decrease in the area-averaged Nusselt number on the tip floor, as expected. The findings show that both aerodynamic and thermal response of the squealer tips to the implementation of cooling holes is superior to their flat counterparts. Among the studied configurations, the squealer tip with larger number of cooling holes located towards the pressure side is highlighted as the configuration having the best cooling performance.

scholarly journals Turbine blade tip aero-thermal management: Some recent advances and research outlook

2017 ◽  
Vol 1 ◽  
pp. K7ADQC ◽  
Author(s):  
Qiang Zhang ◽  
Li He
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Turbine Blade ◽  
High Speed ◽  
Design Space ◽  
Tip Leakage ◽  
The Past ◽  
Blade Tip ◽  
Flow Turbulence ◽  
And Control

AbstractThis article provides an overview of some recent progress in understanding HP turbine blade shroudless tip heat transfer and aerodynamics, especially in a transonic regime. The review is mostly based on the experimental and numerical efforts the authors have been involved in during the past ten years. Some fundamental flow physics especially in high speed Over-Tip-Leakage (OTL) flows are highlighted, including tip choking, shock waves, and the roles played by flow turbulence, etc. These mechanisms bring qualitative differences in tip heat transfer and loss generation, and prospects in tip aerothermal management and control. Of great interest is the strong OTL flow–coolant interaction, which can dramatically affect the tip aerodynamics, and thus would challenge any “optimized” tip geometry based on an uncooled configuration. It is suggested that optimal tip aero-thermal configurations should be an iterative process between blade tip shaping and cooling injection scheme. Combining tip geometry shaping and cooling injection patterns concurrently may provide more extensive exploitation of tip aerothermal design space.

scholarly journals Heat Transfer and Flow on the Blade Tip of a Gas Turbine Equipped With a Mean-Camberline Strip

2001 ◽  
Vol 123 (4) ◽  
pp. 704-708 ◽  
Author(s):  
A. A. Ameri
Keyword(s):  
Heat Transfer ◽  
Sharp Edge ◽  
Tip Leakage Flow ◽  
Transfer Coefficients ◽  
Large Power ◽  
Tip Leakage ◽  
Numerical Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Blade Tip ◽  
Convective Heat Transfer Coefficients

Experimental and computational studies have been performed to investigate the detailed distribution of convective heat transfer coefficients on the first-stage blade tip surface for a geometry typical of large power generation turbines (>100 MW). In a previous work the numerical heat transfer results for a sharp edge blade tip and a radiused blade tip were presented. More recently several other tip treatments have been considered for which the tip heat transfer has been measured and documented. This paper is concerned with the numerical prediction of the tip surface heat transfer for radiused blade tip equipped with mean-camberline strip (or “squealer” as it is often called). The heat transfer results are compared with the experimental results and discussed. The effectiveness of the mean-camberline strip in reducing the tip leakage and the tip heat transfer as compared to a radiused edge tip and sharp edge tip was studied. The calculations show that the sharp edge tip works best (among the cases considered) in reducing the tip leakage flow and the tip heat transfer.

Investigation of Leakage Flow and Heat Transfer in a Gas Turbine Blade Tip With Emphasis on the Effect of Rotation

2008 ◽  
Author(s):  
Dianliang Yang ◽  
Xiaobing Yu ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Relative Motion ◽  
Turbulence Models ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Blade Height ◽  
Tip Leakage ◽  
Flow And Heat Transfer ◽  
Blade Rotation ◽  
Blade Tip

In this paper, numerical methods have been applied to the investigation of the effect of rotation on the blade tip leakage flow and heat transfer. Using the first stage rotor blade of GE-E3 engine high pressure turbine, both flat tip and squealer tip have been studied. The tip gap height is 1% of the blade height, and the groove depth of the squealer tip is 2% of the blade height. Heat transfer coefficient on tip surface obtained by using different turbulence models was compared with experimental results. And the grid independence study was carried out by using the Richardson extrapolation method. The effect of the blade rotation was studied in the following cases: 1) blade domain is rotating and shroud is stationary; 2) blade domain is stationary and shroud is rotating; and 3) both blade domain and shroud are stationary. In this approach, the effects of the relative motion of the endwall, the centrifugal force and the Coriolis force can be investigated respectively. By comparing the results of the three cases discussed, the effects of the blade rotation on tip leakage flow and heat transfer are revealed. It indicated that the main effect of the rotation on the tip leakage flow and heat transfer is resulted from the relative motion of the shroud, especially for the squealer tip blade.

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