Combined Experimental and CFD Investigation of Flat Plate Film Cooling through Fan Shaped Holes

Rouina, Samaneh; Ravelli, Silvia; Barigozzi, Giovanna

doi:10.3390/ijtpp4020007

Cited by 6 publications

(3 citation statements)

References 13 publications

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“…In particular, the velocity field appeared in better agreement. His conclusions were confirmed by Rouina [11], on a fan shaped hole configuration, where a DRSM showed superior performance for the prediction of the adiabatic effectiveness maps, for BR of 1 and 2. More recently, Paysant [12] successfully applied two versions of DRSM models to describe the trajectory and mixing of a 400°C hot jet in an ambient crossflow.…”

Section: Introductionmentioning

confidence: 71%

Towards an Improved Description of Film-Cooling Heat Transfer Through Anisotropic RANS Modeling: A Combined LES/RANS Contribution

Laroche,

Dupuy,

Duchaine

et al. 2023

Volume 7A: Heat Transfer — Combustors; Film Cooling

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This study focuses on the physics and the modeling of the heat transfer taking place within the Penn State 777 shaped hole flow configuration. To do so, a dedicated Large-Eddy Simulation conducted with the AVBP solver is carried out and shows good reproduction of the main flow characteristics observed in terms of features and adiabatic effectiveness. This simulation is then more deeply analyzed to conduct an a priori evaluation of the most current heat flux assumptions used in RANS modeling, being the Prandtl analogy and the Daly Harlow hypothesis. Results obtained for this shaped hole configuration confirm previous ones obtained for cylindrical holes, showing the deficiencies of classical RANS models. In particular, it is shown that the equivalent Turbulent Prandtl number usually fixed at 0.9 is here largely overestimated. The most representative value is indeed around 0.5 in most regions of interest. It is also showed that the diffusion process is not the same in all directions, namely the wall normal and transverse directions turbulent diffusion processes differ. A Reynolds-Stress model simulation using the Elliptic Blending Reynolds-Stress Model developed by Manceau is then conducted, combined with different advanced heat flux models. With this new and more advanced model, obtained results show major improvements compared to state of the art RANS simulation using the k-ω SST along with the Prandtl analogy. In particular, the centerline and the lateral effectiveness profiles are considerably enhanced, exhibiting a more representative lateral spreading. The respective contributions issued by the improved Reynolds-stress description and the heat flux models are eventually analyzed. A modified model for the heat flux formulation is hence suggested in an attempt to provide extra improvement compared to Daly-Harlow formulation. In conclusion, this work strongly advocates for the use of anisotropic models either for turbulent stress modeling or turbulent heat flux modeling for the description of film cooling phenomena at stake.

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Section: Introductionmentioning

confidence: 71%

Towards an Improved Description of Film-Cooling Heat Transfer Through Anisotropic RANS Modeling: A Combined LES/RANS Contribution

Laroche,

Dupuy,

Duchaine

et al. 2023

Volume 7A: Heat Transfer — Combustors; Film Cooling

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show abstract

“…The gas represents continuous single phase for the OIL atomizer, while it is the liquid in the other configurations (OIG, IOG, ACLR, and SACLR), as shown in Figure 2. Tu 1 can be calculated as follows [63,64]: Figure 12 compares the differences in Tu 1 among the tested nozzles. It suggests that the mixing process of the two phases, and consequently the nature of the produced two-phase mixture were possibly affected by the inlet conditions.…”

Section: The Effect Of the Mixing Methods On C Dmentioning

confidence: 99%

The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers

et al. 2020

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Accurate prediction of the discharge coefficient (CD) for internal-mixing twin-fluid (IMTF) atomizers is challenging, the effect of control factors remains inadequately understood, and comparative data on the CD of IMTF atomizers are unavailable. This work presents an experimental study on CD for different IMTF atomizers with a wide range of factors, including the gas-to-liquid ratio (GLR), the inlet-overpressure ratio (∆pmix/pamb), the orifice length-to-diameter ratio (Lo/do), and the liquid viscosity (µL). Five atomizers with different internal-mixing principles were probed on a cold test rig, including the frequently studied outside-in-gas (OIG) and inside-out-gas (IOG) effervescent types, the recently-introduced outside-in-liquid (OIL) and air-core-liquid-ring (ACLR) atomizers, and our new design named the swirling-air-core-liquid-ring (SACLR) atomizer. The results demonstrate that CD is governed mainly by GLR, and reduces if GLR, Lo/do, or µL is increased. An increase in ∆pmix/pamb causes a CD reduction up to ∆pmix/pamb = 0.98, and CD increases for a higher ∆pmix/pamb. Surprisingly, differences in CD amid examined atomizers were found negligible, although the flow visualization inside the orifice showed a significantly different flow character for each one of the atomizers. Finally, a general CD correlation fitting with an R2 ≥0.99 for all the tested nozzles was proposed. The results amend the present knowledge, allow design optimization, and provide flow rate prediction for a variety of IMTF atomizers.

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“…In addition, the heat flux model, which calculates turbulent heat transport based on turbulence model predictions, also has a large influence. Rouina et al [2] compared several turbulence models on a laid-back fan shaped cooling hole to measurements and found that the Reynolds Stress model (RSM) available in Star-CCM+ outperformed all considered two equation eddy viscosity models. From a theoretical perspective, RSMs should have an advantage over common two equation eddy viscosity models.…”

Section: Introductionmentioning

confidence: 99%

Assessment of source term and turbulence model combinations for film cooling in turbines

Müller,

Morsbach

2023

European Conference on Turbomachinery Fluid Dynamics and Thermodynamics

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Modern gas turbines require an active cooling system with fluid taken from the compressor to withstand the high turbine inlet temperature. CFD is a useful tool to estimate the effects of different cooling configurations on the blade aerodynamics and the thermal loads. However, this usually requires resolving every cooling hole with a high number of grid cells. To reduce the computational cost of such simulations, a reduced order model using source terms was implemented in TRACE. Different variants are tested on a cylindrical and a laid back fan shaped cooling hole to address issues with accuracy and grid dependency known from the literature. Additionally, two different turbulence and heat flux model combinations are compared to each other. Overall, a differential Reynolds Stress Model with an algebraic heat flux model combined with the simplest approach to modeling film cooling holes, introducing a constant source term at the wall, provided the best results for the considered geometries and blowing ratios. The different strategies to improve the predictions were only able to provide a benefit for some of the cases, while usually having a detrimental effect in other cases.

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Combined Experimental and CFD Investigation of Flat Plate Film Cooling through Fan Shaped Holes

Cited by 6 publications

References 13 publications

Towards an Improved Description of Film-Cooling Heat Transfer Through Anisotropic RANS Modeling: A Combined LES/RANS Contribution

Towards an Improved Description of Film-Cooling Heat Transfer Through Anisotropic RANS Modeling: A Combined LES/RANS Contribution

The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers

Assessment of source term and turbulence model combinations for film cooling in turbines

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