Mist/Steam Cooling by a Row of Impinging Jets

Li, X.; Gaddis, J. L.; Wang, T.

doi:10.1115/2001-gt-0151

Cited by 9 publications

(15 citation statements)

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“…The overall cooling enhancement ranged from 40% to 300% with the maximum local cooling enhancement being over 800%, which occurred at about 45 o downstream of the inlet of the test section. Li et al [13] reported results of mist/steam cooling with a slot jet on a heated flat surface. Their results showed a 200% cooling enhancement near the stagnation point by adding 1.5% mist (in mass) to the steam flow.…”

Section: Gt2005-69100mentioning

confidence: 99%

“…Models of collisions and coalescences will also be developed and incorporated into the future studies. Li et al modeled the mist cooling [22] using the experimental data from [13] and reported the major contribution for mist cooling enhancement was from the direct contact between droplets and the wall. In this paper, the direct droplet-wall contact heat transfer mechanism is not included, so the cooling results could be probably 50% under predicted.…”

Section: Concerns and Future Researchmentioning

confidence: 99%

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Simulation of Film Cooling Enhancement With Mist Injection

Wang

2005

Volume 3: Turbo Expo 2005, Parts a and B

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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 hotsection 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.

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Section: Gt2005-69100mentioning

confidence: 99%

Section: Concerns and Future Researchmentioning

confidence: 99%

Simulation of Film Cooling Enhancement With Mist Injection

Wang

2005

Volume 3: Turbo Expo 2005, Parts a and B

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“…A promising technology is to enhance film cooling with mist (small water droplets) injection. Based on the aforementioned heat transfer mechanisms, mist can be used in gas turbine systems in different ways, including gas turbine inlet air fog cooling [10], overspray cooling through wet compression in the compressor [11], and airfoils (vanes and blades) internal cooling [12][13][14][15][16]. Recently, Li and Wang [17] conducted the first numerical simulations of air/mist film cooling.…”

Section: Introductionmentioning

confidence: 99%

“…The main objective of this thesis is to elucidate how the mass and dimension of the droplet affect the mist impingement cooling performance over a curved surface with a hole of double chamber model, calculated by CFD. Earlier studies discussed the mist film performance on the blade and combustor of gas turbine [10][11][12][13][14][15]. The model created in the paper looks like a flat with two double chambers, simulating the structure of transition piece.…”

Section: Introductionmentioning

confidence: 99%

Computational Analysis of Droplet Mass and Size Effect on Mist/Air Impingement Cooling Performance

et al. 2013

Advances in Mechanical Engineering

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Impingement cooling has been widely employed to cool gas turbine hot components such as combustor liners, combustor transition pieces, turbine vanes, and blades. A promising technology is proposed to enhance impingement cooling with water droplets injection. However, previous studies were conducted on blade shower head film cooling, and less attention was given to the transition piece cooling. As a continuous effort to develop a realistic mist impingement cooling scheme, this paper focuses on simulating mist impingement cooling under typical gas turbine operating conditions of high temperature and pressure in a double chamber model. Furthermore, the paper presents the effect of cooling effectiveness by changing the mass and size of the droplets. Based on the heat-mass transfer analogy, the results of these experiments prove that the mass of 3 − 3 kg/s droplets with diameters of 5-35 m could enhance 90% cooling effectiveness and reduce 122 K of wall temperature. The results of this paper can provide guidance for corresponding experiments and serve as the qualification reference for future more complicated studies with convex surface cooling.

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“…Furthermore, the continuous evaporation of droplets can last farther into the downstream region where single-phase air film cooling becomes less effective. Based on the aforementioned heat transfer mechanisms, mist can be used in gas turbine systems in different ways, including gas turbine inlet air fog cooling [16], overspray cooling through wet compression in the compressor [17], and airfoils (vanes and blades) internal cooling [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Simulation of Mist Film Cooling at Gas Turbine Operating Conditions

Wang

2006

Volume 3: Heat Transfer, Parts a and B

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Air film cooling has been successfully used to cool gas turbine hot sections for the last half century. A promising technology is proposed to enhance air film cooling with water mist injection. Numerical simulations have shown that injecting a small amount of water droplets into the cooling air improves film-cooling performance significantly. However, previous studies were conducted at conditions of low Reynolds number, temperature, and pressure to allow comparisons with experimental data. As a continuous effort to develop a realistic mist film cooling scheme, this paper focuses on simulating mist film cooling under typical gas turbine operating conditions of high temperature and pressure. The mainstream flow is at 15 atm with a temperature of 1561K. Both 2-D and 3-D cases are considered with different hole geometries on a flat surface, including a 2-D slot, a simple round hole, a compound-angle hole, and fan-shaped holes. The results show that 10%-20% mist (based on the coolant mass flow rate) achieves 5%-10% cooling enhancement and provides an additional 30-68K adiabatic wall temperature reduction. Uniform droplets of 5 to 20 µm are used. The droplet trajectories indicate the droplets tend to move away from the wall, which results in a lower cooling enhancement than under low pressure and temperature conditions. The commercial software Fluent (v. 6.2.16) is adopted in this study, and the standard k-ε model with enhanced wall treatment is adopted as the turbulence model.

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Mist/Steam Cooling by a Row of Impinging Jets

Cited by 9 publications

References 0 publications

Simulation of Film Cooling Enhancement With Mist Injection

Simulation of Film Cooling Enhancement With Mist Injection

Computational Analysis of Droplet Mass and Size Effect on Mist/Air Impingement Cooling Performance

Simulation of Mist Film Cooling at Gas Turbine Operating Conditions

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