Application of Second Moment Closure and Higher Order Generalized Gradient Diffusion Hypothesis to Impingement Heat Transfer

Bazdidi–Tehrani, Farzad; Rajabi-Zargarabadi, Mehran

doi:10.1139/tcsme-2008-0007

Cited by 5 publications

(4 citation statements)

References 24 publications

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“…The temperature distributions predicted by the SED model give a higher gradient specially in the center of combustion chamber, (r/D < 0.02). This means that the SED model fails to capture the heat diffusion in high temperature region [20,22,23]. However, lower temperature gradients have been predicted by the HOGGDH model in the same region.…”

Section: Resultsmentioning

confidence: 98%

“…where equation ε H is the heat eddy diffusivity, ε M -the momentum eddy diffusivity. Assuming a 2-D flow on a flat plate, ε M and ε H are defined [23]:…”

Section: Turbulent Prandtl Numbermentioning

confidence: 99%

“…In previous studies various algebraic models (SED, GGDH, HOGGDH) have been performed for modelling turbulence heat flux in flows such as, the heat transfer of impinging jet [23], cooling flows [24][25][26] and pipe flows [27]. Results of previous studies show that using higher order algebraic models lead to increase of prediction accuracy of temperature distribution, especially in areas with severe (high) gradients.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 98%

“…where equation ε H is the heat eddy diffusivity, ε M -the momentum eddy diffusivity. Assuming a 2-D flow on a flat plate, ε M and ε H are defined [23]:…”

Section: Turbulent Prandtl Numbermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Ershadi

Rajabi-Zargarabadi

2021

THERM SCI

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“…Owing to the dependence of algebraic heat flux models to Reynolds stresses, it is reasonably expected that their coupling with a second moment closure (SMC) model is more suitable for predicting complex thermal fields [15]. Some researchers have recently applied different explicit algebraic models (for example, generalized gradient diffusion hypothesis, GGDH, and higher-order GGDH, HOGGDH) for turbulent heat fluxes in a complicated heat transfer field such as obstacle [15], impingement [16] and film cooling flows [17]. They have reported that these models could perform well due to the reasonable prediction of turbulent heat flux components near a wall.…”

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confidence: 99%

Implicit algebraic model for predicting turbulent heat flux in film cooling flow

Rajabi-Zargarabadi

Bazdidi–Tehrani

2009

Numerical Methods in Fluids

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SUMMARYThe present study addresses a new effort to improve the prediction of turbulent heat flux in the film cooling flow by applying the implicit algebraic flux (IAF) model of Rogers et al. A three-dimensional symmetry case is investigated using a film hole length-to-diameter ratio of 1.75 and an injection angle of 35 • . The low Reynolds number second moment closure (SMC) model with a wall-reflection term is employed for simulating the turbulent flow field right up to the wall. Results obtained from the IAF model are compared with two other algebraic turbulent heat flux models, namely, the simple eddy diffusivity (SED) with a constant turbulent Prandtl number and the generalized gradient diffusion hypothesis (GGDH). Comparisons of the turbulent heat flux components calculated by these models show that the major difference appears in the streamwise turbulent heat flux. These models demonstrate a significant effect on the prediction of film cooling effectiveness. The SED model with a constant prescribed value for the turbulent Prandtl number fails to predict the cooling air spreading in the lateral direction while by employing the GGDH and IAF models, the spreading of the cooling air and the decay of the effectiveness in the core region are reasonably predicted. A combination of the SMC and IAF models for simulating the turbulent flow and heat transfer is capable of predicting the streamwise and lateral film cooling effectiveness in very good agreement with the available experimental data.

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Second-order modeling of non-premixed turbulent methane-air combustion

Ershadi

Zargarabadi

2021

J. Cent. South Univ.

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Application of Second Moment Closure and Higher Order Generalized Gradient Diffusion Hypothesis to Impingement Heat Transfer

Cited by 5 publications

References 24 publications

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

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

Implicit algebraic model for predicting turbulent heat flux in film cooling flow

Second-order modeling of non-premixed turbulent methane-air combustion

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