Application of algebraic anisotropic turbulence models to film cooling flows

Li, Xueying; Ren, Jing; Jiang, Hongde

doi:10.1016/j.ijheatmasstransfer.2015.07.098

Cited by 21 publications

(4 citation statements)

References 41 publications

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“…Li et al [77] employed the algebraic anisotropic turbulence model to improve the prediction of the turbulent eddy viscosity and the scalar diffusivity in the RANS equations. They found that the anisotropic turbulence model more efficiently and accurately predicted the 3D centerline and lateral film cooling effectiveness as well as the flow field at various flow conditions compared to the experimental results.…”

Section: Turbulence Modelingmentioning

confidence: 99%

Numerical Analysis of Film Cooling Performance of Micro Holes and Compound Angle Sister Holes

Alsalam¹

2021

Preprint

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In the present research, micro holes and compound angle sister holes have been numerically investigated as two different techniques to enhance the cylindrical hole cooling performance, which suffers from a low cooling performance at high blowing ratio. The numerical analysis is performed over a flat plate model to assess the film effectiveness and the associated flow field at low and high blowing ratios. The performance assessment of the discrete round micro hole with a 200 µm diameter reveals that the micro hole yields the best cooling performance at low blowing ratios, and there is nearly 30% increase in the overall film cooling effectiveness compared to that of the round macro hole. The flow field results demonstrate the presence of a Counter-Rotating Vortex Pair (CRVP) at a smaller size and less strength, thus, contributed to better spanwise spreading of the coolant jet and lateral film cooling effectiveness. Micro holes present an improvement in the lateral film cooling effectiveness at high freestream turbulence intensity and high blowing ratios. Computational evaluation of the CFD prediction capability of the sister holes cooling effectiveness using five RANS turbulence models has been carried out as well as an assessment of the effects of the near-wall modeling on the predicted lateral effectiveness. The turbulence models used are realizable k-epsilon, standard k-epsilon, RNG k-epsilon, Reynolds stress model, and Spalart-Allmaras model. It is generally found that realizable k-ε combined with the enhanced wall treatment provides the best prediction of the numerical results in comparison to the experimental measurements at a low blowing ratio while an underprediction of the lateral performance is found at a high blowing ratio from all examined turbulence models. The compound angle upstream sister holes (CAUSH) have been proposed as a novel and simple design of the cooling hole whereas the numerical results have shown a notable increase in both centerline and lateral effectiveness for all tested compound angles at all blowing ratios. The anti-counter rotating vortices pair (ACRVP) structure generated from the compound angle upstream sister holes has actively controlled the flow field and maintained the coolant jet fully attached to the plate surface while restraining the coolant lift-off at high blowing ratios. Finally, the influence of the compound angle sister holes streamwise location on the thermal and flow field performance has also been analyzed, whereas three locations: upstream, midstream, and downstream are examined. It is found that the midstream and downstream locations offered a considerable increase in the cooling effectiveness, which is very much dependent on the blowing ratio and the area downstream of the cooling holes. In addition, the optimum centerline effectiveness is obtained by the downstream location, while the best lateral effectiveness is attained through the midstream location.

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Section: Turbulence Modelingmentioning

confidence: 99%

Numerical Analysis of Film Cooling Performance of Micro Holes and Compound Angle Sister Holes

Alsalam¹

2021

Preprint

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“…where τ is the turbulence time scale, which is typically defined as τ = k/ε and C θ is the constant of the model and is equal to 0.3 [11] or 0.25 [35]. Suga et al [36] carried out modifications on the model by defining the model coefficient, C θ , as a function of turbulent stress.…”

Section: Turbulent Heat Flux Modelsmentioning

confidence: 99%

Application of higher-order heat flux model for predicting turbulent methane-air combustion

Ershadi

Rajabi-Zargarabadi

2021

THERM SCI

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The present study addresses a new effort to improve the prediction of turbulent heat transfer and NO emission in non-premixed methane-air combustion. In this regard, a symmetric combustion chamber in a stoichiometric condition is numerically simulated using the Reynolds averaged Navier-Stokes equations. The Realizable k-? model and Discreate Ordinate are applied for modeling turbulence and radiation, respectively. Also, the eddy dissipation model is adopted for predicting the turbulent chemical reaction rate. Zeldovich mechanism is applied for estimating the NO emission. Higher-order generalized gradient diffusion hypothesis (HOGGDH) is employed for predicting the turbulent heat flux in turbulent reactive flows. Results show that the HOGGDH model is capable of predicting temperature distribution in good agreement with the available experimental data. Comparison of the results obtained by the simple eddy diffusivity (SED) and HOGGDH models shows that applying the HOGGDH significantly improves the over-prediction of NO emission. Finally, the average turbulent Prandtl number for the non-premixed methane-air combustion has been calculated.

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“…The solution was of second order accuracy. The algebraic anisotropic turbulence model AASF AAEV realizable k-e [30] was used as the turbulence model which was proposed by the authors and was proved to be better for the prediction of film cooling.…”

Section: Computational Setup and Validationmentioning

confidence: 99%