scholarly journals High-resolution simulation of film cooling with blowing ratio and inclination angle effects based on hybrid thermal lattice Boltzmann method

2021 ◽  
pp. 286-286
Author(s):  
Yanqin Shangguan ◽  
Xian Wang ◽  
Fei Cao ◽  
Yandan Zhu
Keyword(s):  
Heat Transfer ◽  
High Resolution ◽  
Inclination Angle ◽  
Coherent Structure ◽  
Lattice Boltzmann ◽  
Film Cooling ◽  
Blowing Ratio ◽  
Inclination Angles ◽  
Boltzmann Method ◽  
Thermal Lattice Boltzmann

A series of high-resolution simulations on film cooling with varying blowing ratios and inclination angles are carried out by using in-house code based on hybrid thermal lattice Boltzmann method. Three blowing ratios ranging from 0.2 to 0.8 and four inclination angles from 15? to 60? are chosen for the simulations. The evolutionary mechanism of coherent structure in three domains of film-covering region is studied from the view of space and time. Besides, the influencing mechanism of blowing ratio and inclination angle on flow and heat-transfer features of film cooling is uncovered. Results show that hairpin vortex, hairpin packet and quasi-stream-wise vortex appearing in rotating domain play a key role in heat-transfer process of film cooling. The strong ejection, sweep and vortex rotation resulted from these vortices enhance the convective heat transfer. It is also found that the size of coherent structure varies significantly with blowing ratio and its integral form shows a strong dependence on inclination angle. Moreover, inclination angle of coolant jet has a significant impact on turbulence fluctuation intensity. The influence of blowing ratio on the attachment of coolant film and film-cooling performance is more obvious than that of inclination angle. It is believed that all of these are related closely to the variation of stream-wise and wall-normal jet velocity in the case of various blowing ratios and inclination angles.

A Numerical Study on the Effect of Hole Inclination Angle With Imperfection on Film Cooling Effectiveness

2019 ◽  
Author(s):  
Taha Rezzag ◽  
Bassam A. Jubran
Keyword(s):  
Inclination Angle ◽  
Film Cooling ◽  
Numerical Study ◽  
Vortex Pair ◽  
Dimensionless Temperature ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Laser Percussion Drilling ◽  
Inclination Angles ◽  
Lift Off

Abstract The present study numerically evaluates the influence of hole inclination angle with a hole imperfection on film cooling performance. Here, the hole imperfection due to laser percussion drilling is modelled as a half torus. Three hole inclination angles were investigated: 35°, 45° and 55°. Furthermore, every case was evaluated at three blowing ratios: 0.45, 0.90 and 1.25. Each case is compared to a baseline case where the hole imperfection is absent. The results indicate that the hole inclination angle has a strong influence on the film effectiveness performance when a hole imperfection is present. Centerline effectiveness plots reveal a maximum effectiveness deterioration of 89% for a blowing ratio of 0.90 in the vicinity of the hole exit. Dimensionless temperature contours show that the jet produced in the presence of an imperfection is much more compact causing the counter rotating vortex pair to be closer to each other. This enhances the jet to lift off from the plate.

Lattice Boltzmann Simulation of Flow and Heat Transfer Characteristics in a Symmetrically Bifurcated Microchannel

2004 ◽  
Author(s):  
Keqiang Xing ◽  
Yong Tao
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann ◽  
Constant Heat Flux ◽  
Lattice Boltzmann Model ◽  
Straight Tube ◽  
Lattice Boltzmann Simulation ◽  
Flux Boundary Conditions ◽  
Boltzmann Method ◽  
Thermal Lattice Boltzmann ◽  
Transfer Problems

The lattice Boltzmann method (LBM) as a relatively new numerical scheme has recently achieved considerable success in simulating fluid flows and associated transport phenomena. However, application of this method to heat transfer problems has been at a stage of infancy. In this work, a thermal lattice Boltzmann model is employed to simulate a two-dimensional, steady flow in a symmetric bifurcation under constant temperature and constant heat flux boundary conditions. The bifurcation effects on the heat transfer and fluid flow are investigated and comparisons are made with the straight tube. Also, different bifurcation angles are simulated and the results are compared with the work of the other researchers.

Lattice Boltzmann Simulation of Flow and Heat Transfer Characteristics in a Symmetric Bifurcation

2005 ◽  
Author(s):  
K. Q. Xing ◽  
Y.-X. Tao
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann ◽  
Passive Scalar ◽  
Heat Fluxes ◽  
Lattice Boltzmann Model ◽  
Lattice Boltzmann Simulation ◽  
Flux Boundary Conditions ◽  
Constant Wall Heat Flux ◽  
Boltzmann Method ◽  
Thermal Lattice Boltzmann

The lattice Boltzmann method (LBM) originates from the discrete kinetic theory and has been applied for simulation of various kinds of fluid flows under different conditions. In this paper, a passive-scalar-based thermal lattice Boltzmann model is employed to simulate the steady flow in a symmetric bifurcation channel under constant wall heat flux boundary conditions. The bifurcation effects on the heat transfer and fluid flow are thoroughly investigated under different Reynolds numbers, wall heat fluxes and bifurcation angles. The results are compared with the commercial software output. A useful discussion about how to transfer from lattice units to actual physical units is also presented.

Lattice Boltzmann Method for Combined Natural Convection Surface Radiation in Open Cavity

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Ayoub Msaddak ◽  
Mohieddine Ben Salah ◽  
Ezeddine Sediki
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Lattice Boltzmann Method ◽  
Inclination Angle ◽  
Lattice Boltzmann ◽  
Surface Radiation ◽  
Surface Emissivity ◽  
Boltzmann Method

Lattice Boltzmann method (LBM) is performed to study numerically combined natural convection and surface radiation inside an inclined two-dimensional open square cavity. The cavity is heated by a constant temperature at the wall facing the opening. The walls normal to the heated surface are assumed to be adiabatic, diffuse, gray, and opaque while the open boundary is assumed to be black at ambient temperature. A Bathnagar, Gross and Krook (BGK) collision model with double distribution function (D2Q9-D2Q4) is adopted. Effects of surface radiation, inclination angle, and Rayleigh number on the heat transfer are analyzed and discussed. Results are presented in terms of isotherms, streamlines, and Nusselt number. It was found that the presence of surface radiation enhances the heat transfer. The convective Nusselt number decreases with increasing surface emissivity as well as with Rayleigh number, while the total Nusselt number increases with increasing surface emissivity and Rayleigh number. The inclination angle has also a significant effect on flow and heat transfer inside the cavity. However, the magnitude of total heat transfer decreases considerably when open cavity is tilted downward.

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