New development of the turbulent Prandtl number models for the computation of film cooling effectiveness

A numerical study, based on experimental work of Inanli et al. [1] is conducted to understand the heat transfer characteristics of film cooled test plates that represent the gas turbine combustor liner cooling system. Film cooling tests are conducted by six different slot geometries and they are scaled-up model of real combustor liner. Three different blowing ratios are applied to six different geometries and surface cooling effectiveness is determined for each test condition by measuring the surface temperature distribution. Effects of geometrical and flow parameters on cooling effectiveness are investigated. In this study, Conjugate Heat Transfer (CHT) simulations are performed with different turbulence models. Effect of the turbulent Prandtl Number is also investigated in terms of heat transfer distribution along the measurement surface. For this purpose, turbulent Prandtl number is calculated with a correlation as a function of local surface temperature gradient and its effect also compared with the constant turbulent Prandtl numbers. Good agreement is obtained with two-layered k–ϵ with modified Turbulent Prandtl number.

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IMPROVING ADIABATIC FILM-COOLING EFFECTIVENESS BY USING AN UPSTREAM PYRAMID

Computational Thermal Sciences An International Journal ◽

10.1615/computthermalscien.2016016302 ◽

2016 ◽

Vol 8 (2) ◽

pp. 135-146 ◽

Cited By ~ 3

Author(s):

Zineb Hammami ◽

Zineddine Ahmed Dellil ◽

Fadela Nemdili ◽

Abbes Azzi

Keyword(s):

Film Cooling ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness

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Application of the Multiple-Time-Scale Turbulence Model to the Prediction of 2-D Film Cooling Effectiveness

Proceeding of International Heat Transfer Conference 10 ◽

10.1615/ihtc10.1180 ◽

1994 ◽

Author(s):

Jian-ming Zhou ◽

Martha Eva Salcudean ◽

Ian S. Gartshore

Keyword(s):

Turbulence Model ◽

Time Scale ◽

Film Cooling ◽

Multiple Time ◽

Multiple Time Scale ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness ◽

Scale Turbulence

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The Effect of Using Ramps with Trench Cylindrical Holes on Film Cooling Effectiveness

Wasit Journal of Engineering Sciences ◽

10.31185/ejuow.vol3.iss2.37 ◽

2015 ◽

Vol 3 (2) ◽

pp. 15-27

Author(s):

Ahmed A. Imram ◽

Humam K. Jalghef ◽

Falah F. Hatem

Keyword(s):

Numerical Simulation ◽

Film Cooling ◽

Air Injection ◽

Baseline Model ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness ◽

Blowing Ratio ◽

Hot Air ◽

Test Study ◽

Cylindrical Holes

The effect of introducing ramp with a cylindrical slot hole on the film cooling effectiveness has been investigated experimentally and numerically. The film cooling effectiveness measurements are obtained experimentally. A test study was performed at a single mainstream with Reynolds number 76600 at three different coolant to mainstream blowing ratios 1.5, 2, and 3. Numerical simulation is introduced to primarily estimate the best ramp configurations and to predict the behavior of the transport phenomena in the region linked closely to the interaction between the coolant air injection and the hot air mainstram flow. The results showed that using ramps with trench cylindrical holes would enhanced the overall film cooling effectiveness by 83.33% compared with baseline model at blowing ratio of 1.5, also the best overall flim cooling effectevness was obtained at blowing ratio of 2 while it is reduced at blowing ratio of 3.

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Conjugate Heat Transfer and Film Cooling of a Multi-Stage Cooling Scheme

Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C ◽

10.1115/imece2008-69138 ◽

2008 ◽

Author(s):

M. Ghorab ◽

S. I. Kim ◽

I. Hassan

Keyword(s):

Heat Transfer ◽

Film Cooling ◽

Gas Turbines ◽

Conjugate Heat Transfer ◽

Density Ratio ◽

Design Parameters ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness ◽

Multi Stage ◽

Internal Gap

Cooling techniques play a key role in improving efficiency and power output of modern gas turbines. The conjugate technique of film and impingement cooling schemes is considered in this study. The Multi-Stage Cooling Scheme (MSCS) involves coolant passing from inside to outside turbine blade through two stages. The first stage; the coolant passes through first hole to internal gap where the impinging jet cools the external layer of the blade. Finally, the coolant passes through the internal gap to the second hole which has specific designed geometry for external film cooling. The effect of design parameters, such as, offset distance between two-stage holes, gap height, and inclination angle of the first hole, on upstream conjugate heat transfer rate and downstream film cooling effectiveness performance are investigated computationally. An Inconel 617 alloy with variable properties is selected for the solid material. The conjugate heat transfer and film cooling characteristics of MSCS are analyzed across blowing ratios of Br = 1 and 2 for density ratio, 2. This study presents upstream wall temperature distributions due to conjugate heat transfer for different gap design parameters. The maximum film cooling effectiveness with upstream conjugate heat transfer is less than adiabatic film cooling effectiveness by 24–34%. However, the full coverage of cooling effectiveness in spanwise direction can be obtained using internal cooling with conjugate heat transfer, whereas adiabatic film cooling effectiveness has narrow distribution.

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Investigations on the effect of different influencing factors on film cooling effectiveness under the injection of synthetic coolant

Scientific Reports ◽

10.1038/s41598-021-83080-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jianlong Chang ◽

Xinlei Duan ◽

Yang Du ◽

Baoquan Guo ◽

Yutian Pan

Keyword(s):

Film Cooling ◽

Elliptical Hole ◽

Synthetic Jet ◽

Cooling Effect ◽

Flow Structures ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness ◽

Cooling Flow ◽

Cooling Method ◽

Strong Controllability

AbstractBy combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method. Numerical simulations of the synthetic coolant ejected are carried out for analyzing the cooling performance in detail, under different blowing ratios, hole patterns, Strouhal numbers, and various orders of incidence for the two rows of holes. By comparing the flow structures and the cooling effect corresponding to the synthetic coolant and the steady coolant fields, it is found that within the scope of the investigations, the best cooling effect can be obtained under the incident conditions of an elliptical hole with the aspect ratio of 0.618, the blow molding ratio of 2.5, and the Strouhal number St = 0.22. Due to the strong controllability of the synthetic coolant, the synthetic coolant can be controlled through adjusting the frequency of blowing and suction, so as to change the interaction between vortex structures for improving film cooling effect in turn. As a result, the synthetic coolant ejection is more advisable in certain conditions to achieve better outcomes.

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