Cooling Performance of an Integrated Impingement and Pin Fin Cooling Configuration

2003 ◽  
Author(s):  
Shigemichi Yamawaki ◽  
Chiyuki Nakamata ◽  
Ryouji Imai ◽  
Shinsuke Matsuno ◽  
Toyoaki Yoshida ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Unit Area ◽  
Rapid Prototype ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Casting Technique ◽  
Fin Efficiency ◽  
Pin Fin ◽  
Pin Geometry ◽  
Efficiency Theory

The cooling configuration adopted in this study integrates impingement cooling and pin fin cooling devices into one body, the aim being enhancement of the effective heat transfer area. The purpose of the study is to confirm improvement of cooling effectiveness for two different pin density configurations by experimental verification. Experiments were conducted in similar conditions to actual engines using large-scaled flat-plate specimens manufactured by a new rapid prototype casting technique. The results were compared with predictions by one-dimensional analysis adopting the fin efficiency theory. Although the coarse pin density, one pin in a unit area, shows good agreement with the prediction, the fine pin density, four pins in the unit area, was overpredicted. It was found by numerical analysis that heat transfer of the new pin geometry did not increase, so that its surface area increased. CFD-aided prediction was proposed and validated with two specimen’s data.

Investigation on Cooling Performance of Impingement Cooling Devices Combined With Pins

2005 ◽  
Author(s):  
Dongliang Quan ◽  
Songling Liu ◽  
Jianghai Li ◽  
Gaowen Liu
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Film Cooling ◽  
Internal Heat ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
One Dimensional ◽  
Pin Fin ◽  
Cooling Devices ◽  
Internal Heat Transfer

Integrated impingement and pin fin cooling devices have comprehensive advantages of hot-side film cooling, internal impingement cooling, large internal heat transfer area and enhanced heat exchange caused by the pin fin arrays, so it is considered a promising cooling concept to meet the requirements of modern advanced aircraft engines. In this paper, experimental study, one dimensional model analysis and numerical simulation were conducted to investigate cooling performance of this kind of cooling device. A typical configuration specimen was made and tested in a large scale low speed closed-looped wind tunnel. The cooling effectiveness was measured by an infrared thermography technique. The target surface was coated carefully with a high quality black paint to keep a uniform high emissivity condition. The measurements were calibrated with thermocouples welded on the surface. Detailed two-dimensional contour maps of the temperature and cooling effectiveness were obtained for different pressure ratios and therefore different coolant flow-rates through the tested specimen. The experimental results showed that very high cooling effectiveness can be achieved by this cooling device with relatively small amount of coolant flow. Based on the theory of transpiration cooling in porous material, a one dimensional heat transfer model was established to analyze the effect of various parameters on the cooling effectiveness. The required resistance and internal heat transfer characteristics were obtained from experiments. It was found from this model that the variation of heat transfer on the gas side, including heat transfer coefficient and film cooling effectiveness, of the specimen created much more effect on its cooling effectiveness than that of the coolant side. The heat transfer intensities inside the specimen played an important role in the performance of cooling. In the last part of this paper, a conjugate numerical simulation was carried out using commercial software FLUENT 6.1. The domain of the numerical simulation included the specimen and the coolant. Detailed temperature contours of the specimen were obtained for various heat transfer boundary conditions. The calculated flow resistance and cooling effectiveness agree well with the experimental data and the predictions with the one-dimensional analysis model. The numerical simulations reveal that the impingement of the coolant jets in the specimen is the main contribution to the high cooling effectiveness.

Impingement/Effusion Cooling With Low Coolant Mass Flow

2017 ◽  
Author(s):  
H. I. Oguntade ◽  
G. E. Andrews ◽  
A. D. Burns ◽  
D. B. Ingham ◽  
M. Pourkashanian
Keyword(s):  
Heat Transfer ◽  
Mass Flow ◽  
Wall Heat Transfer ◽  
Internal Wall ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Impingement Heat Transfer ◽  
Design Changes ◽  
Wall Impingement ◽  
The Individual

A low coolant mass flow impingement/effusion design for a low NOx combustor wall cooling application was predicted, using conjugate heat transfer (CHT) computational fluid dynamics (CFD). The effusion geometry had 4306/m2 effusion holes in a square array with a hole diameter of D and pitch of X and X/D of 1.9. It had previously been shown experimentally and using CHT/CFD to have the highest adiabatic and overall cooling effectiveness for this number of effusion holes. The effect of adding an X/D of 4.7 impingement jet wall with a 6.6 mm impingement gap, Z, and Z/D of 2.0, on the overall cooling effectiveness was predicted for several coolant mass flow rates, G kg/sm2bar. At low G the internal wall heat transfer dominated the overall cooling effectiveness. The addition of impingement cooling to effusion cooling gave only a small increase in the overall cooling effectiveness at all G at 127mm downstream of the start of effusion cooling. An overall cooling effectiveness >0.7 was predicted for a low G of 0.30 kg/sm2bar. This represents about 15% of the combustion air for a typical industrial gas turbine combustor and design changes to reduce this further were suggested based on the predictions of this geometry. The main benefit of the impingement cooling was at the start of the effusion cooling, where the overall cooling effectiveness was dominated by the internal wall impingement and effusion cooling. The separate effusion and impingement cooling were also predicted for comparison with their combination. This showed that the combination of impingement and effusion was not the sum of the individual effusion and impingement heat transfer. The predictions showed that the aerodynamic interactions decreased the effusion and impingement internal wall heat transfer.

Conjugate Heat Transfer Characteristics of Double Wall Cooling on a Film Plate With Gradient Thickness

2020 ◽  
Author(s):  
Juan He ◽  
Qinghua Deng ◽  
Weilun Zhou ◽  
Wei He ◽  
Tieyu Gao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Flow Direction ◽  
Plate Thickness ◽  
Heat Transfer Characteristics ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Impingement Cooling ◽  
Blowing Ratio ◽  
Double Wall

Abstract Double wall cooling, consisting of internal impingement cooling and external film cooling, is an advanced cooling method of gas turbines. In this paper, the flow and conjugate heat transfer characteristics of double wall cooling which has a film plate with gradient thickness are analyzed numerically. The detailed overall cooling effectiveness distributions are obtained by solving steady three dimensional Reynolds-averaged Navier-Stokes equations. In the double wall cooling scheme, seven vertical film holes and six impingement holes are staggered with same diameter (D), and the hole pitch of them are both set to 6D in flow direction and lateral direction. The gradient thickness along the flow direction is realized by setting the angle (α) between the lower surface of the film plate and the horizontal plane at −1.5 deg and 1.5 deg respectively. By comparing the results of four broadly used turbulence models with experimental data, SST k-ω is selected as the optimal turbulence model for double wall cooling analysis in this paper. In addition, the number of grids are finally determined to be 5.2 million by grid sensitivity calculation. The influence of the thickness gradient on the overall cooling effectiveness is revealed by comparing with the constant thickness film plate (Baseline 1 and 2), and all the cases are performed under four various coolant mass flow rates, which correspond to blowing ratios ranging from 0.25 to 1.5. The calculated results show that the thickening of the film plate downstream is beneficial to improve overall cooling effectiveness at low blowing ratio, which is benefit from two aspects. One is the thicken film plate weakens the flow separation in film hole and velocity of film hole outlet, another is the thicken film plate makes the impingement channels convergence, and impingement cooling is strengthened to some extent. However, with the increase of blowing ratio, the increasing trend gradually weakens due to the jet-off and limited impinge ability. For thickening film plate, the variations of the double wall cooling configurations are considered at initial film plate thickness tf of 2D and 3D, it is found that the ability to improve the overall cooling effectiveness by thickening the film plate downstream decrease as the initial film plate thickness increases, which is due to the increase of heat transfer resistance, and another finding is the cooling effectiveness of downstream thickening film plate with initial thickness of 2D is higher than that of 3D, which will provide a theoretical foundation both for improving cooling performance and reducing turbine blade weight at the same time. The influence of initial impingement gap H is also observed, and the study come to the fact that the best cooling performance occurred in H = 2D.

Conjugate Heat Transfer Optimization of the Nonuniform Impingement Cooling Structure of a HPT 2nd Stage Vane

2015 ◽  
Author(s):  
Zhongran Chi ◽  
Haiqing Liu ◽  
Shusheng Zang ◽  
Guangyun Jiao
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
3D Model ◽  
Constant Pressure ◽  
Cooling System ◽  
Impingement Cooling ◽  
Turbine Cooling ◽  
Pin Fin ◽  
Heat Transfer Optimization ◽  
Pin Fin Array

This paper discusses the methodology of impingement cooling optimization of a gas turbine 2nd stage vane with 3D conjugate heat transfer (CHT) CFD analysis applied. The vane is installed with a novel impingement cooling structure in the leading cavity and a pin-fin array in the trailing edge. This study involves the optimization of the impingement cooling structure, including the location of the jet holes and the diameter of each hole. The generation of 3D model and CHT mesh was realized using an in-house code developed specifically for turbine cooling optimization. A constant pressure drop was assumed within the cooling system during optimization. To make the optimization computationally faster, a metamodel which can predict the detailed distribution of metal temperature on the vane surface was used in the second-level search together with a genetic algorithm. An optimal nonuniform impingement cooling structure in the leading cavity was automatically designed by the optimization process costing only dozens of CFD runs, which provided a more uniform temperature distribution on the vane surface and required no more coolant amount compared with the initial impingement cooling structure.

Parametrical Study of the Flat-Tube and Pin Fin Heat Exchangers

2007 ◽  
Author(s):  
Maria Pascu ◽  
Naser Sahiti ◽  
Franz Durst
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Automobile Industry ◽  
Heat Exchangers ◽  
Unit Area ◽  
Pin Fin ◽  
Flow Length ◽  
Louvered Fin ◽  
Pin Fins ◽  
Constant Versus

The main objective of the present work was the derivation of heat transfer and pressure drop characteristics for pin fins which could be applied in heat exchangers used in the automobile industry. For this, 34 models of pin fin heat exchangers, characterized by a pin diameter of 0.35 mm, with both inline and staggered arrangements, were numerically investigated. The numerical results were validated through various comparison and validation procedures. The best performing pin fin configuration was determined by employing the performance plot: heat transfer per unit volume (or per unit area, if the pin height is constant) versus the energy input reduced to the same parameter as the heat transfer (volume or area). The heat exchanger performance plot showed that, for the investigated flow length, the staggered pin fin configuration performs better when compared to the inline arrangement. In order to prove the industrial applicability of these results, a louvered fin heat exchanger, commonly used as a car radiator, was experimentally investigated. A comparison of the best performing pin fin heat exchanger with the louvered fin model revealed an enhancement in the heat transfer of the pin fin model of 35%.

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.

Numerical Investigation of Heat Transfer in a High Aspect Ratio Double Wall Channel With Pin Fin and Jet Array Impingement

2016 ◽  
Author(s):  
Rui Kan ◽  
Shuqing Tian
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Cfd Simulation ◽  
Cooling Effectiveness ◽  
Pin Fin ◽  
Pin Fins ◽  
Double Wall ◽  
Jet Array

A combined impingement-pedestal geometry for turbomachinery double wall cooling application is studied numerically with the shear stress transport turbulence model. Conjugated CFD simulation is performed to investigate the cooling effectiveness distribution. The configuration consists of a high aspect ratio cooling duct, with jet array impinging onto the pin fin-roughed wall. The jet Reynolds number varies from 8,000 to 80,000, jet-to-target wall spacing is kept constant at Z/Dj=0.8. Three main parameters are investigated, including the jet Reynolds number, pin fin shapes (circular and elongated) and the relative location between jets and pin fins (the jet placed uniformly inside the duct or more densely at the front of the duct). For more detailed investigations, the pin fin diameter and impingement hole diameter are varied independently, and a total of 26 configurations are studied. The results show that the double wall configuration with pin fins significantly increases the heat transfer coefficients, compared to that with only impingement. Non-uniform jet arrangement results in a stronger crossflow and enhances heat transfer on the pins, which brings an increase of cooling effectiveness and more uniform temperature distribution.

Planar Duct Heat Transfer With Turbulence Enhancing Obstacles for Combustor Liner External Cooling

2007 ◽  
Author(s):  
Gordon E. Andrews ◽  
Ibrahim M. Khalifa
Keyword(s):  
Heat Transfer ◽  
Pressure Loss ◽  
Air Cooling ◽  
Test Rig ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Flat Surfaces ◽  
Impingement Jet ◽  
External Cooling ◽  
Combustor Liner

Parallel plate combustor wall cooling was investigated. The combustor air flowed down the gap between two flat surfaces in a low pressure loss configuration. The work was aimed at combustor liner external air cooling for regenerative combustor cooling prior to entering a lean low NOx combustor. The test rig was 152 mm square and the test section was a duct of 152mm width and height of 10 and 5mm with a 152mm length. The experimental investigation involved the measurement of the heat transfer coefficient using the lumped capacity method. together with overall wall cooling effectiveness measurements in a hot duct test rig. The compromise between increased pressure loss and enhanced heat transfer for obstacles in the duct was investigated. It was shown that at coolant flow rates comparable with combustor requirements, adequate wall cooling effectiveness could be achieved using this technique. The cooling effectiveness performance was compared with the alternative technique of impingement cooling using low impingement jet pressure loss.

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