Optimization of ejection angles of double-jet film-cooling holes using RBNN model

Lee, Ki‐Don; Choi, Dae-Woong; Kim, Kwang‐Yong

doi:10.1016/j.ijthermalsci.2013.05.015

Cited by 26 publications

(4 citation statements)

References 11 publications

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“…Then, the maximum temperature ( max ) of the cable core and the total cost function (F c ) for the corresponding samples were calculated based on the simulation results, which are also presented in Table 6. Secondly, based on the sample data and calculation results as presented in Table 6, the geometric parameters for the parabolic-type FTB trefoil buried cables ( 1 , 2 , and ) were trained with the radial basis function neural network (RBNN) [19][20][21]. RBNN is a two-layer network with strong ability to approximate objective function and rapid convergence rate, including a hidden layer of radial basis function (RBF) and a linear output layer [19].…”

Section: Laying Parameter Optimization Formentioning

confidence: 99%

Numerical Study of Heat Transfer in Trefoil Buried Cable with Fluidized Thermal Backfill and Laying Parameter Optimization

Quan

et al. 2019

Mathematical Problems in Engineering

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Trefoil buried cable is one of the important cable arrangements for the underground transmission line, and its heat transfer performance is relatively poor. By filling with fluidized thermal backfill material (FTB) around trefoil buried cables, the heat transfer would be efficiently enhanced, while the filling cost should also be considered. In the present study, the heat transfer process in the FTB trefoil buried cables is numerically studied, where the cable core loss and eddy current loss in the cable were coupled for the simulation. The heat transfer performances and ampacities for trefoil buried cables with different back fill materials were analysed and compared with each other. Then, the laying parameters for the parabolic-type FTB trefoil buried cables were optimized with the radial basis function neural network (RBNN) and genetic algorithm (GA). Firstly, it is found that, with FTB material, the maximum temperature in the cable core is obviously reduced, and the cable ampacity is greatly improved as compared with the cables buried around natural soil (NS). Secondly, when compared with flat-type FTB model, the heat transfer rate in the cable with parabolic-type FTB laying method would be slightly reduced, while the FTB amount used for the buried cables is greatly reduced. Finally, as for parabolic-type FTB trefoil buried cables, with proper design of geometric parameters (s1 = 0.290 m, s2 = 0.302 m, and l = 0.3 m with I = 1300 A) for the FTB laying cross section, the overall performance for the cable was optimized.

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Section: Laying Parameter Optimization Formentioning

confidence: 99%

Numerical Study of Heat Transfer in Trefoil Buried Cable with Fluidized Thermal Backfill and Laying Parameter Optimization

Quan

et al. 2019

Mathematical Problems in Engineering

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“…It was demonstrated that the anti-CVP structure formed in the DJFC was tightly associated with the double-jet pitch and the compound injection angle, wherein the former affected the interaction and the latter affected the strength of each branch of the antikidney vortexes. Choi et al [29] and Lee et al [30] carried out an optimization of the DJFC configurations by selecting four variables (spanwise and streamwise distances between film-hole centers, and respective spanwise injection angles) as design variables. The cooling performance was optimized with the increase in the spanwise injection angle, attributed to a wider spanwise spreading of coolant coverage.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Single-Row Double-Jet Film Cooling of a Turbine Guide Vane under High-Temperature and High-Pressure Conditions

et al. 2022

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Single-row double-jet film cooling (DJFC) of a turbine guide vane is numerically investigated in the present study, under a realistic aero-thermal condition. The double-jet units are positioned at specific locations, with 57% axial chord length (Cx) on the suction side or 28% Cx on the pressure side with respect to the leading edge of the guide vane. Three spanwise spacings (Z) in double-jet unit (Z = 0, 0.5d, and 1.0d, here d is the film hole diameter) and four spanwise injection angles (β = 11°, 17°, 23°, and 29°) are considered in the layout design of double jets. The results show that the layout of double jets affects the coupling of adjacent jets and thus subsequently changes the jet-in-crossflow dynamics. Relative to the spanwise injection angle, the spanwise spacing in a double-jet unit is a more important geometric parameter that affects the jet-in-crossflow dynamics in the downstream flowfield. With the increase in the spanwise injection angle and spanwise spacing in the double-jet unit, the film cooling effectiveness is generally improved. On the suction surface, DJFC does not show any benefit on film cooling improvement under smaller blowing ratios. Only under larger blowing ratios does its positive potential for film cooling enhancement start to show. Compared to the suction surface, the positive potential of the DJFC on enhancing film cooling effectiveness behaves more obviously on the pressure surface. In particular, under large blowing ratios, the DJFC plays dual roles in suppressing jet detachment and broadening the coolant jet spread in a spanwise direction. With regard to the DJFC on the suction surface, its main role in film cooling enhancement relies on the improvement of the spanwise film layer coverage on the film-cooled surface.

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“…Nowadays, many researchers focus attention on the film cooling technology, and this has played a major role in cooling the vanes and blades of the turbine front stages which are exposed to a higher firing temperature. Research works of film cooling mainly concentrate on changing the geometries of the film holes (Bunker, 2005; Zhang et al , 2017; Kim and Kim, 2018), placing vortex generators upstream or downstream the holes (Abdala et al , 2016; Chen et al , 2011) as well as combining and arranging the positions of the round holes (Lee et al , 2013; Zhang et al , 2018; Zhu et al , 2018a).…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis on the film cooling mechanisms of elliptical and cylindrical holes with 90° compound angle

Zhang

Xie

Sundén

2020

HFF

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Purpose In this study, numerical simulations are performed to compare the adiabatic film cooling effectiveness and reveal the difference of film cooling mechanisms of two models with the same geometries and cross-section areas of film holes’ exits at three typical blowing ratios (M = 0.5, 1 and 1.5). The two models are an elliptical model and a cylindrical model with 90° compound angle, respectively. Design/methodology/approach Three different cases are considered in this work and the baseline is the model with a cylindrical film hole. The same boundary conditions and a validated turbulence model (realizable k-ε) are adopted for all cases. Findings The results show that both the elliptical and cylindrical models with 90° compound angle can enhance the film cooling effectiveness compared with the baseline. However, the elliptical model performs well at lower blowing ratios and in the near region at each blowing ratio because of the wider width of the film hole’s exit. The cylindrical model with 90° compound angle provides better film cooling effectiveness in the further downstream area of the film hole at higher blowing ratio because of the less lift-off and better coolant coverage in the larger x/D region along the mainstream direction. Originality/value Overall, it can be concluded that although the elliptical and cylindrical models with 90° compound angle have identical hole exits, the different inlet direction and cross-sectional geometry affect the flow structures when the coolant enters, moves through and exits the hole and finally different film cooling results appear.

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Optimization of ejection angles of double-jet film-cooling holes using RBNN model

Cited by 26 publications

References 11 publications

Numerical Study of Heat Transfer in Trefoil Buried Cable with Fluidized Thermal Backfill and Laying Parameter Optimization

Numerical Study of Heat Transfer in Trefoil Buried Cable with Fluidized Thermal Backfill and Laying Parameter Optimization

Numerical Investigation of Single-Row Double-Jet Film Cooling of a Turbine Guide Vane under High-Temperature and High-Pressure Conditions

Comparative analysis on the film cooling mechanisms of elliptical and cylindrical holes with 90° compound angle

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