Development of a Steady-State Experimental Facility for the Analysis of Double-Wall Effusion Cooling Geometries

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Alexander V. Murray ◽  
Peter T. Ireland ◽  
Eduardo Romero
Keyword(s):  
Film Cooling ◽  
High Performance ◽  
Internal Flow ◽  
Experimental Facility ◽  
Computationally Efficient ◽  
Experimental Conditions ◽  
Cooling Effectiveness ◽  
Experimental Heat ◽  
Conventional Cooling ◽  
Double Wall

The continuous drive for ever higher turbine entry temperatures is leading to considerable interest in high performance cooling systems which offer high cooling effectiveness with low coolant utilization. The double-wall system is an optimized amalgamation of more conventional cooling methods including impingement cooling, pedestals, and film cooling holes in closely packed arrays characteristic of effusion cooling. The system comprises two walls, one with impingement holes, and the other with film holes. These are mechanically connected via pedestals allowing conduction between the walls while increasing coolant-wetted area and turbulent flow. However, in the open literature, experimental data on such systems are sparse. This study presents a new experimental heat transfer facility designed for investigating double-wall systems. Key features of the facility are discussed, including the use of infrared thermography to obtain overall cooling effectiveness measurements. The facility is designed to achieve Reynolds and Biot (to within 10%) number similarity to those seen at engine conditions. The facility is used to obtain overall cooling effectiveness measurements for a circular pedestal, double-wall test piece at three coolant mass-flows. A conjugate computational fluid dynamics (CFD) model of the facility was developed providing insight into the internal flow features. Additionally, a computationally efficient, decoupled conjugate method developed by the authors for analyzing double-wall systems is run at the experimental conditions. The results of the simulations are encouraging, particularly given how computationally efficient the method is, with area-weighted, averaged overall effectiveness within a small margin of those obtained from the experimental facility.

Development of a Steady-State Experimental Facility for the Analysis of Double-Wall Effusion Cooling Geometries

2018 ◽  
Author(s):  
Alexander V. Murray ◽  
Peter T. Ireland ◽  
Eduardo Romero
Keyword(s):  
Steady State ◽  
Film Cooling ◽  
High Performance ◽  
Internal Flow ◽  
Experimental Facility ◽  
Computationally Efficient ◽  
Cooling Effectiveness ◽  
Experimental Heat ◽  
Conventional Cooling ◽  
Double Wall

The continuous drive for ever higher turbine entry temperatures is leading to considerable interest in high performance cooling systems which offer high cooling effectiveness with low coolant utilisation. The double-wall system discussed here, is an optimised amalgamation of more conventional cooling methods including impingement cooling, pedestals, and film cooling holes in a more closely packed array characteristic of effusion cooling. The system entails two walls, one with the impingement holes, and the other with the film holes. These are mechanically connected via the bank of pedestal thereby allowing conduction between the walls and increasing coolant wetted area and turbulent flow. However, in the open literature, data — and particularly experimental data — on such systems is sparse. This study presents a newly commissioned experimental heat transfer facility designed to investigate double-wall cooling geometries. The paper discusses some of the key features of the steady-state facility, including the use of infrared thermography to obtain overall cooling effectiveness measurements. The facility is designed to achieve both Reynolds and Biot (to within 10%) number similarity to those seen at engine conditions. The facility is used to obtain overall cooling effectiveness measurements for a circular pedestal, double-wall test piece at three coolant mass-flow conditions with the results presented and discussed. A fully conjugate CFD model of the facility was also developed providing greater insight into the internal flow field. Additionally, a computationally efficient, decoupled conjugate method developed by the authors for analysing such double-wall systems is run at conditions to match the experiments. The results of the simulations are encouraging, particularly given how computationally efficient the method is, with area-weighted, averaged overall effectiveness within a small margin of those obtained from the experimental facility.

Effects of Double Wall Cooling Configuration and Conditions on Performance of Full-Coverage Effusion Cooling

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Nathan Rogers ◽  
Zhong Ren ◽  
Warren Buzzard ◽  
Brian Sweeney ◽  
Nathan Tinker ◽  
...  
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Hole Array ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Full Coverage ◽  
Cooling Hole ◽  
Double Wall

Experimental results are presented for a double wall cooling arrangement which simulates a portion of a combustor liner of a gas turbine engine. The results are collected using a new experimental facility designed to test full-coverage film cooling and impingement cooling effectiveness using either cross flow, impingement, or a combination of both to supply the film cooling flow. The present experiment primarily deals with cross flow supplied full-coverage film cooling for a sparse film cooling hole array that has not been previously tested. Data are provided for turbulent film cooling, contraction ratio of 1, blowing ratios ranging from 2.7 to 7.5, coolant Reynolds numbers based on film cooling hole diameter of about 5000–20,000, and mainstream temperature step during transient tests of 14 °C. The film cooling hole array consists of a film cooling hole diameter of 6.4 mm with nondimensional streamwise (X/de) and spanwise (Y/de) film cooling hole spacing of 15 and 4, respectively. The film cooling holes are streamwise inclined at an angle of 25 deg with respect to the test plate surface and have adjacent streamwise rows staggered with respect to each other. Data illustrating the effects of blowing ratio on adiabatic film cooling effectiveness and heat transfer coefficient are presented. For the arrangement and conditions considered, heat transfer coefficients generally increase with streamwise development and increase with increasing blowing ratio. The adiabatic film cooling effectiveness is determined from measurements of adiabatic wall temperature, coolant stagnation temperature, and mainstream recovery temperature. The adiabatic wall temperature and the adiabatic film cooling effectiveness generally decrease and increase, respectively, with streamwise position, and generally decrease and increase, respectively, as blowing ratio becomes larger.

Influence of Internal Flow on Film Cooling Effectiveness

1999 ◽  
Vol 122 (2) ◽  
pp. 327-333 ◽  
Author(s):  
Gu¨nter Wilfert ◽  
Stefan Wolff
Keyword(s):  
Film Cooling ◽  
Vortex Generator ◽  
Internal Flow ◽  
Thermochromic Liquid Crystal ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Cylindrical Holes ◽  
Flow Configurations ◽  
Inlet Conditions

Film cooling experiments were conducted to investigate the effects of internal flow conditions and plenum geometry on the film cooling effectiveness. The film cooling measurements show a strong influence of the coolant inlet conditions on film cooling performance. The present experiments were carried out on a flat plate with a row of cylindrical holes oriented at 30 deg with respect to a constant-velocity external flow, systematically varying the plenum geometry and blowing rates 0.5⩽M⩽1.25. Adiabatic film cooling measurements using the multiple narrow-banded thermochromic liquid crystal technique (TLC) were carried out, simulating a flow parallel to the mainstream flow with and without crossflow at the coolant hole entry compared with a standard plenum configuration. An impingement in front of the cooling hole entry with and without crossflow was also investigated. For all parallel flow configurations, ribs were installed at the top and bottom coolant channel wall. As the hole length-to-diameter ratio has an influence on the film cooling effectiveness, the wall thickness has also been varied. In order to optimize the benefit of the geometry effects with ribs, a vortex generator was designed and tested. Results from these experiments show in a region 5⩽X/D⩽80 downstream of the coolant injection location differences in adiabatic film cooling effectiveness between +5 percent and +65 percent compared with a standard plenum configuration. [S0889-504X(00)01102-8]

scholarly journals Simulation of Film Cooling Enhancement With Mist Injection

2005 ◽  
Author(s):  
Xianchang Li ◽  
Ting Wang
Keyword(s):  
Film Cooling ◽  
Injection Rate ◽  
Round Hole ◽  
Gas Temperature ◽  
Cooling Effectiveness ◽  
Droplet Dynamics ◽  
Blowing Ratio ◽  
Jet Cooling ◽  
Cooling Enhancement ◽  
Conventional Cooling

Cooling of gas turbine hot section components such as combustor liners, combustor transition pieces, turbine vanes (nozzles) and blades (buckets) is a critical task for improving the life and reliability of hot-section components. Conventional cooling techniques using air-film cooling, impingement jet cooling, and turbulators have significantly contributed to cooling enhancements in the past. However, the increased net benefits that can be continuously harnessed by using these conventional cooling techniques seem to be incremental and are about to approach their limit. Therefore, new cooling techniques are essential for surpassing these current limits. This paper investigates the potential of film cooling enhancement by injecting mist into the coolant. The computational results show that a small amount of injection (2% of the coolant flow rate) can enhance the cooling effectiveness about 30% ∼ 50%. The cooling enhancement takes place more strongly in the downstream region, where the single-phase film cooling becomes less powerful. Three different holes are used in this study including a 2-D slot, a round hole, and a fan-shaped diffusion hole. A comprehensive study is performed on the effect of flue gas temperature, blowing angle, blowing ratio, mist injection rate, and droplet size on the cooling effectiveness with 2-D cases. Analysis on droplet history (trajectory and size) is undertaken to interpret the mechanism of droplet dynamics.

A Three-Dimensional Conjugate Approach for Analyzing a Double-Walled Effusion-Cooled Turbine Blade

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Gladys C. Ngetich ◽  
Alexander V. Murray ◽  
Peter T. Ireland ◽  
Eduardo Romero
Keyword(s):  
Temperature Distribution ◽  
Turbine Blade ◽  
Film Cooling ◽  
Numerical Procedure ◽  
Numerical Approach ◽  
Critical Parameters ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Wall Element ◽  
Double Wall

A double-wall cooling scheme combined with effusion cooling offers a practical approximation to transpiration cooling which in turn presents the potential for very high cooling effectiveness. The use of the conventional conjugate computational fluid dynamics (CFD) for the double-wall blade can be computationally expensive and this approach is therefore less than ideal in cases where only the preliminary results are required. This paper presents a computationally efficient numerical approach for analyzing a double-wall effusion cooled gas turbine blade. An existing correlation from the literature was modified and used to represent the two-dimensional distribution of film cooling effectiveness. The internal heat transfer coefficient was calculated from a validated conjugate analysis of a wall element representing an element of the aerofoil wall and the conduction through the blade solved using a finite element code in ANSYS. The numerical procedure developed has permitted a rapid evaluation of the critical parameters including film cooling effectiveness, blade temperature distribution (and hence metal effectiveness), as well as coolant mass flow consumption. Good agreement was found between the results from this study and that from literature. This paper shows that a straightforward numerical approach that combines an existing correlation for film cooling from the literature with a conjugate analysis of a small wall element can be used to quickly predict the blade temperature distribution and other crucial blade performance parameters.

Experimental and Computational Methods for the Evaluation of Double-Wall, Effusion Cooling Systems

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Alexander V. Murray ◽  
Peter T. Ireland ◽  
Eduardo Romero
Keyword(s):  
Reynolds Numbers ◽  
Coolant Temperature ◽  
Computationally Efficient ◽  
Regular Array ◽  
Cooling Systems ◽  
Experimental Heat ◽  
Turbine Efficiency ◽  
Flow Features ◽  
Wetted Area ◽  
Double Wall

Abstract Further improvements in gas turbine efficiency can be sought through more advanced cooling systems—such as the double-wall, effusion system—which provide high cooling effectiveness with low coolant utilization. The double-wall system, as described here, comprises two walls: one with a regular array of impingement holes and the other with a closely packed, regular array of film holes (characteristic of effusion systems). These walls are mechanically and thermally connected via a bank of pedestals which increase coolant wetted area and turbulent flow features. However, a lack of data exists in the open literature on these systems. This study presents a novel experimental heat transfer facility designed with the intent of investigating flat plate versions of such double-wall geometries. Key features of the facility are presented including the use of recirculation to increase the mainstream-to-coolant temperature ratio and the use of infrared thermography to obtain thermal measurements. Some rig commissioning characteristics are also provided which demonstrate well-conditioned, uniform flow. Both coolant and mainstream Reynolds numbers are matched to engine conditions, with the Biot number within around 15% of engine conditions. The facility is used to assess the cooling performance of four double-wall effusion geometries which incorporate various geometrical features. Both overall effectiveness and film effectiveness measurements are presented at a range of coolant mass flows with conclusions drawn as to preferable features from a cooling perspective. The results from a fully conjugate computational fluid dynamics (CFD) model of the facility are presented which utilized boundary conditions obtained during experimental runs. Additionally, a computationally efficient decoupled conjugate method developed previously by the authors was adapted to assess the experimental geometries with the results comparing favorably.

3D Heat Transfer Assessment of Full-Scale Inlet Vanes With Surface-Optimized Film Cooling: Part 2 — Conjugate CFD Simulations

2019 ◽  
Author(s):  
J. J. Johnson ◽  
J. P. Clark ◽  
R. A. Anthony ◽  
M. K. Ooten ◽  
R. H. Ni ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Side Surface ◽  
Full Scale ◽  
Pressure Side ◽  
Computationally Efficient ◽  
Cfd Simulations ◽  
Experimental Heat ◽  
Cooling Hole ◽  
Cooling Design

Abstract An investigation of the experimental heat transfer and cooling effectiveness for a modern fully-cooled high-pressure turbine (HPT) inlet vane is presented. Conjugate Heat Transfer (CHT) Computational Fluid Dynamics (CFD) is conducted to simulate experiments using thin-film heat-flux gauges on full-scale 3D vanes at engine-representative conditions from Part 1 of this paper. Pressure side (PS) film cooling performance is compared for a baseline and optimized configuration, in which the latter was previously developed using genetic algorithm (GA) optimization. The optimized vane was iterated using hundreds of computationally efficient 3D Reynolds Averaged Navier Stokes (RANS) CFD simulations with a transpiration boundary condition to simulate film cooling. This combination of CFD and GAs determined surface-optimized cooling hole orientations and placement. Steady-state flat plate infrared thermography experiments that followed also determined the best cooling hole shapes to use on different sections of the vane pressure side surface. This ultimately generated the cooling design to be fabricated using realistic materials and experimentally tested in Part 1 and simulated using CHT CFD in the current work (Part 2). Here, spanwise and streamwise heat transfer distributions for the baseline and optimized cooling design are validated against experimental data. 3D CHT CFD results are then assessed at the same conditions, providing relevance and credence to the overall cooling design methods. Ultimately, surface-optimized film cooling designs can be used to reduce the adverse effects of sub-optimal heat distribution on critical high temperature engine parts, increasing the life of the part. Alternatively, such a design could lead to increases in engine efficiency since less cooling air is required from the mainstream per part.

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.

Experimental and Computational Methods for the Evaluation of Double-Wall, Effusion Cooling Systems

2019 ◽  
Author(s):  
Alexander V. Murray ◽  
Peter T. Ireland ◽  
Eduardo Romero
Keyword(s):  
Reynolds Numbers ◽  
Coolant Temperature ◽  
Computationally Efficient ◽  
Regular Array ◽  
Cooling Systems ◽  
Experimental Heat ◽  
Turbine Efficiency ◽  
Flow Features ◽  
Wetted Area ◽  
Double Wall

Abstract Further improvements in gas turbine efficiency can be sought through more advanced cooling systems — such as the double-wall, effusion system — which provide high cooling effectiveness with low coolant utilisation. The double-wall system, as described here, comprises two walls, one with a regular array of impingement holes, the other with a closely-packed, regular array of film holes (characteristic of effusion systems). These walls are mechanically and thermally connected to one another via a bank of pedestals which increase coolant wetted area and turbulent flow features. However, a lack of data exists in the open literature on these systems. This study presents a novel experimental heat transfer facility designed with the intent of investigating flat plate versions of such double-wall geometries. Key features of the facility are presented including the use of recirculation to increase mainstream-to-coolant temperature ratio and the use of infrared thermography to obtain thermal measurements. Some rig commissioning characteristics are also provided which demonstrate well-conditioned, uniform flow. Both coolant and mainstream Reynolds numbers are matched to engine conditions, with Biot number within around 15% of engine conditions. The facility is used to assess the cooling performance of four double-wall effusion geometries which incorporate various geometrical features. Both overall effectiveness and film effectiveness measurements are presented at a range of coolant mass flows with conclusions drawn as to preferable features from a cooling perspective. The results from a fully conjugate CFD model of the facility are presented which utilised boundary conditions obtained during experimental runs. Additionally, a computationally efficient decoupled conjugate method developed previously by the authors was adapted to assess the experimental geometries with the results comparing favourably.

Study of Film Cooling Effectiveness on a Double-Walled Effusion-Cooled Turbine Blade in a High-Speed Flow Using Pressure Sensitive Paint

2019 ◽  
Author(s):  
Gladys C. Ngetich ◽  
Peter T. Ireland ◽  
Eduardo Romero
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
High Speed ◽  
High Porosity ◽  
Pressure Sensitive Paint ◽  
Blade Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Double Wall

Abstract A detailed analysis of film cooling performance on a double-walled effusion-cooled blade is essential for both the coolant consumption optimization and assessment of the film to offer the desired levels of the turbine blade protection. Yet there are hardly any film effectiveness studies on double-wall full-coverage film cooled turbine blades. This paper presents a detailed film cooling effectiveness study over the full surface of a double-walled effusion-cooled high-pressure turbine rotor blade using Pressure Sensitive Paint (PSP). PSP permitted a non-intrusive and conduction-errors-free means of obtaining clean and distinct local distribution of film effectiveness on the blade surface making it possible to extract valuable film cooling effectiveness performance data on the whole blade surface. Three large-scale circular pedestal double-wall blade designs with varying pedestal height, pedestal diameter and cooling hole diameter were tested in a high-speed stationary single-blade linear cascade running at engine-representative Mach and Reynolds numbers. All the blades were tested within a range of representative modern engine coolant mass flow, ṁc to mainstream, ṁg ratios; 1.6% < ṁc/ṁ∞ < 5.5%. High porosity blade exhibited a better flow distribution and was found to consistently perform the best.

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