Effects of the leading edge injection slot on the film cooling and heat transfer performance of the vane endwall

2016 ◽  
Vol 102 ◽  
pp. 1308-1320 ◽  
Author(s):  
Kun Du ◽  
Zhigang Li ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Heat Transfer Performance ◽  
Leading Edge ◽  
Transfer Performance

Platform Film Cooling Investigation on an HP Nozzle Vane Cascade With Discrete Shaped Holes and Slot Film Cooling

2020 ◽  
Author(s):  
G. Barigozzi ◽  
A. Perdichizzi ◽  
L. Abba ◽  
L. Pestelli
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Heat Transfer Performance ◽  
Leading Edge ◽  
Suction Side ◽  
Secondary Flows ◽  
Intensity Level ◽  
Transfer Performance ◽  
Film Cooling Effectiveness ◽  
Exit Mach Number

Abstract The present paper reports on an experimental investigation on the aerodynamic and heat transfer performance of different platform cooling schemes: two based on cylindrical and shaped holes and one featuring a slot located upstream of the leading edge plane simulating the combustor to stator interface gap. Tests were run on a 6-vane cascade operated at an isentropic cascade exit Mach number of 0.4 and a significant inlet turbulence intensity level of about 9%. The cooling schemes were first tested to quantify their impact on secondary flows and related losses for variable injection conditions. Heat transfer performance was then assessed through adiabatic film cooling effectiveness and heat transfer coefficient measurements. The Net Heat Flux Reduction parameter was then computed to critically assess the cooling schemes. When compared with the cylindrical hole scheme, shaped holes outperform for all tested injection rates, while the slot alone is able to thermally protect only the front of the passage. Discrete holes are required to cool the platform region along the whole pressure side and the suction side leading edge region.

Influence of Pin Shape on Heat Transfer Characteristics of Laminated Cooling Configuration

2019 ◽  
Author(s):  
Lei Li ◽  
Honglin Li ◽  
Wenjing Gao ◽  
Fujuan Tong ◽  
Zhonghao Tang
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Heat Transfer Performance ◽  
Internal Flow ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Cooling Effectiveness ◽  
Pin Fin ◽  
Blowing Ratio ◽  
Transfer Characteristics

Abstract The laminated cooling configuration can effectively enhance heat transfer and improve cooling effectiveness through combining the advantage of impingement cooling, film cooling and pin fin cooling. In this study, four laminated configurations with different pin shape including circular pin shape, curved rib pin shape, droplet pin shape and reverse droplet pin shape are numerically investigated. Extensive analysis are conducted within the blowing ratio range of 0.2–1.8 to reveal the influence of pin shape on heat transfer characteristics and cooling performance. Compared with circular pin shape, other three pin shapes can enable more complex internal flow field, which greatly affect the heat transfer performance. Among these shapes, the droplet pin shape presents the best capacity on improving heat transfer performance and distribution due to its stramlined shape and little upstream surface, especially at relatively high blowing ratio and the augmentation can be up to 7.91% under the blowing ratio of 1.7. Besides, results show that the cooling effectiveness can be enhanced by adopting curved rib pin shape and the enhancement monotonously increases as the blowing ratio increases. When blowing ratio is 1.7, the improvement can be 2.7%. The reason is that the large lateral blockage decreases the exhausted velocity and hence forms relative firm film coverage.

Optimization of Turbine Squealer Tip Cooling Design by Combining Shaping and Flow Injection

2020 ◽  
Author(s):  
P. H. Duan ◽  
L. He
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Heat Transfer Performance ◽  
Leakage Flow ◽  
Fluid Temperature ◽  
Transfer Performance ◽  
Tip Leakage Flow ◽  
Aerodynamic Efficiency ◽  
Tip Leakage ◽  
Conventional Film

Abstract In this study, a turbine squealer tip is optimized by a multi-objective genetic algorithm (MOGA) with varying the squealer heights and the tip cooling configurations. The three objectives selected are the aerodynamic efficiency, the film cooling effectiveness and the surface fluid temperature variance. The multi-scale methodology is implemented to reduce the computational cost and to skip the meshing of cooling holes. Two optimization approaches are compared: a) a conventional method that optimizes an uncooled shape first and then the cooling configuration sequentially, and b) a method that optimize shaping and cooling concurrently. The concurrent method is found to obtain a heat transfer performance that is not achieved by the conventional optimization. Moreover, by adding the cooling, the performance ranking of the uncooled blades in terms of the aerodynamic efficiency is changed. These observations are due to the strong interaction between the coolant and the tip leakage flow. They indicate that the coolant injected at the tip is not passive as expected in the conventional film cooling designs. By altering the tip leakage flow structure, the coolant can reduce the tip leakage loss, which contradicts the conventional wisdom that the added coolant should always lead to extra losses due to the extra mixing. More detailed observations of the flow field indicate that the influence of the squealer height towards the aerodynamic efficiency is caused by two competing effects: the blockage effect to reduce the tip leakage mass flow rate and the sudden expansion loss effect to generate additional losses. The heat transfer performance can be significantly influenced by increasing the squealer height because of the trapped coolant in the cavity.

scholarly journals Numerical study on heat transfer characteristics of swirling flow on dimpled surfaces with effusion holes at turbine blade leading edge

2021 ◽  
Vol 2088 (1) ◽  
pp. 012009
Author(s):  
Dehai Kong ◽  
Cunliang Liu ◽  
S A Isaev
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Heat Transfer Performance ◽  
Swirling Flow ◽  
Numerical Study ◽  
Leading Edge ◽  
Target Surface ◽  
Transfer Performance ◽  
Staggered Arrangement ◽  
Blade Leading Edge

Abstract In this paper, we conducted a numerical study to investigate the effect of the offset of the jet holes on heat transfer of swirling flow in a concave target chamber with various dimple structures and effusion holes at the turbine blade leading edge. The distance of the jet holes off the centerline e/d varies from 0 to 2.0. Four types of dimple structure, including spherical dimples (SDs) and oval-trench dimples (OTDs) in the inline and staggered arrangement, are considered. The heat transfer performance of the different leading-edge, impingement-effusion cooling structures is evaluated and compared at a Reynolds number of 30,000 based on the jet hole diameter. Results show that the offset of the jet holes provides 15% higher overall heat transfer performance and more uniform heat transfer of the target surface within the e/d range of 0-2.0. The introduction of the dimple structures on the target surface slightly decreases the overall averaged Nusselt number but enhance the heat transfer quantity due to the clear increase of heat transfer areas. Under the same e/d, the OTD structure, especially with the staggered arrangement, is superior to SD structure.

Effects of Impinging Hole Shapes on Double Swirl Cooling Performance at Gas Turbine Blade Leading Edge

2018 ◽  
Author(s):  
Junfei Zhou ◽  
Xinjun Wang ◽  
Jun Li ◽  
Daren Zheng
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Leading Edge ◽  
Transfer Performance ◽  
Cooling Performance ◽  
Impingement Cooling ◽  
Cooling Method ◽  
Blade Leading Edge

A double swirl cooling method has been raised recently to enhance the internal cooling performance at the blade leading edge. This paper mainly focuses on investigating the flow and heat transfer characteristics of the double swirl cooling method. Further more, four kinds of elliptical holes are applied to show effects of impinging hole shapes on the cooling performance. Results of all double swirl cooling cases are compared with that of an impingement cooling structure under four Reynolds numbers. Overall averaged Nusselt number, friction factor and thermal performance factor are compared in all cases, Vortexes induced by different impinging hole types and target chambers are studied and compared. The spanwise averaged Nusselt number, Nusselt number contours and Nusselt number distributions at several cross sections are studied and compared. Results show that the double swirl cooling method can significantly enhance the heat transfer performance compared with the traditional impingement cooling structure. Double swirl cooling with cylindrical impinging hole shows the best thermal performance and lowest flow losses. By applying the elliptical impinging hole with the sharp side faced the mainstream flow direction and a larger major to minor axis length ratio, the rotational vortex inside the double swirl chamber can be better developed and the heat transfer performance is also promoted.

Experimental Characterization of Reverse-Oriented Film Cooling

2017 ◽  
Author(s):  
Robin Prenter ◽  
Mohammad A. Hossain ◽  
Lucas Agricola ◽  
Ali Ameri ◽  
Jeffrey P. Bons
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Freestream Turbulence ◽  
Oriented Film ◽  
Cylindrical Holes ◽  
Film Cooling Holes

Reverse-oriented film cooling, which consists of film cooling holes oriented to inject coolant in the opposite direction of the freestream, is experimentally investigated. Tests are conducted at various blowing ratios (M = 0.25, 0.5, and 1.0) under both low and high freestream turbulence (Tu = 0.4% and 10.1%), with a density ratio near unity. The interesting flow field that results from the reverse-jet-in-crossflow interaction is characterized using flow visualization, particle image velocimetry, and thermal field measurements. Heat transfer performance is evaluated with adiabatic film effectiveness and heat transfer coefficient measurements obtained using infrared thermography. Adiabatic effectiveness results show that reverse film cooling produces very uniform and total coverage downstream of the holes, with some reduction due to increased freestream turbulence. The reverse film cooling holes are evaluated against cylindrical holes in the conventional configuration, and were found to perform better in terms of average effectiveness and comparably in terms of net heat flux reduction, despite augmented heat transfer coefficient. Compared to shaped hole data from previous studies, the reverse film cooling holes generally had worse heat transfer performance. The aerodynamic losses associated with the film cooling are characterized using total pressure measurements down-stream of the holes. Losses from the reverse configuration were found to be higher when compared to cylindrical holes in the conventional and compound angle configurations.

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