Near-Field Simulations of Film Cooling with a Modified DES Model

Yu, Feiyan; Yavuzkurt, Savas

doi:10.3390/inventions5010013

Cited by 6 publications

(4 citation statements)

References 37 publications

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“…At M = 0.5, the overall distributions of the components of the turbulence intensities are downsized compared with those at M = 1.0. When the pulsation of 36 Hz was applied to the flow, the values of u rms around the coolant core increased, and the change in the contour is attributed to the periodic change in the blowing ratio, as shown in Equation (10), resulting in periodic variations in the injection velocity of the coolant. The values of w rms around the wall increase in Figure 10c.…”

Section: Turbulence Statisticsmentioning

confidence: 99%

“…They showed that standard RANS models failed to predict η accurately due to the assumption of isotropic turbulence. Yu and Yavuzkurt (2020) modified the DES model by carrying out the correlation for anisotropic eddy viscosity to obtain better film cooling simulations [10]. They stated that their modified model improved the spreading of the coolant in the spanwise direction compared to the original DES model.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Bulk Flow Pulsation on Film Cooling Involving Compound Angle

Baek

Ahn

2022

Energies

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The main flow could be unsteady in flow fields of film cooling for several reasons such as flow interactions between the rotor and the stator in the turbine. Understanding the characteristics of the film-cooling flow with an unsteady flow is important in the design of gas turbines. The effects of 36-Hz pulsations in the main flow on the streamwise velocity distributions, turbulence statistics, and temperature fluctuations in the film-cooling flow from a cylindrical hole with an orientation angle are investigated by numerical methods. Large-eddy simulation (LES) results match the experimental data with an acceptable accuracy, whereas the Reynolds-averaged Navier–Stokes simulation (RANS) results show large deviations with the experimental data and the LES results. Under 36-Hz pulsations, the URANS results predict a weaker streamwise velocity of the coolant jet that blocks the main flow compared with the LES. With 36-Hz pulsations at the time-averaged blowing ratio of 0.5, urms, the root mean squared fluctuating velocity in the streamwise direction around the coolant core increased due to intensive mixing, and vrms, the root mean squared fluctuating velocity in the wall-normal direction, increased along the trajectory of the injected coolant. Moreover, wrms, the root mean squared fluctuating velocity in the spanwise direction, increased around the wall compared to those at a steady state. The dimensionless temperature fluctuations increased in the region of the core of the coolant compared with those at a steady state. When the orientation angle was 30°, the distribution of the results moved in the z-direction; however, the overall trend was similar to that of a simple angle.

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Section: Turbulence Statisticsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Bulk Flow Pulsation on Film Cooling Involving Compound Angle

Baek

Ahn

2022

Energies

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“…In recent years, film cooling problems were attempted to be solved using the hybrid RANS/large eddy simulation (LES) [16] or the LES [17], which exhibits a higher accuracy but considerably larger computational cost compared to that of the RANS. In the simulation of the film cooling through the hybrid LES or LES, the film cooling effectiveness was better predicted than that in the RANS [16,17]. Moreover, using the instantaneous flow field obtained by the LES, the flow structures that were not visible in the RANS could be identified [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Film Cooling Involving Compound Angle Holes: Comparative Study of LES and RANS

Baek

Ahn

2021

Processes

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A large eddy simulation (LES) was performed for film cooling in the gas turbine blade involving spanwise injection angles (orientation angles). For a streamwise coolant injection angle (inclination angle) of 35°, the effects of the orientation angle were compared considering a simple angle of 0° and 30°. Two ratios of the coolant to main flow mass flux (blowing ratio) of 0.5 and 1.0 were considered and the experimental conditions of Jung and Lee (2000) were adopted for the geometry and flow conditions. Moreover, a Reynolds averaged Navier–Stokes simulation (RANS) was performed to understand the characteristics of the turbulence models compared to those in the LES and experiments. In the RANS, three turbulence models were compared, namely, the realizable k-ε, k-ω shear stress transport, and Reynolds stress models. The temperature field and flow fields predicted through the RANS were similar to those obtained through the experiment and LES. Nevertheless, at a simple angle, the point at which the counter-rotating vortex pair (CRVP) collided on the wall and rose was different from that in the experiment and LES. Under the compound angle, the point at which the CRVP changed to a single vortex was different from that in the LES. The adiabatic film cooling effectiveness could not be accurately determined through the RANS but was well reflected by the LES, even under the compound angle. The reattachment of the injectant at a blowing ratio of 1.0 was better predicted by the RANS at the compound angle than at the simple angle. The temperature fluctuation was predicted to decrease slightly when the injectant was supplied at a compound angle.

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“…Detached Eddy Simulation (DES) is a reasonable alternative as it implements both LES and RANS for tackling high speed and complicated flow [26]. Such a hybrid approach was applied to resolve the structure of film-flow interaction with mainstream flow [27,28]. The capability of the high-fidelity CFD approaches such as LES and DES has been demonstrated in many applications.…”

Section: Introductionmentioning

confidence: 99%

Comparative Numerical Study of the Influence of Film Hole Location of Ribbed Cooling Channel on Internal and External Heat Transfer

Jeon

Son

2021

Energies

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The influence of film-hole position on internal and external heat transfer was investigated using Computational Fluid Dynamics (CFD). A simplified geometry of an integrated configuration of a ribbed channel, film hole and mainstream passage is modeled to represent a turbine internal and external cooling scheme. The proposed configurations with nine different positions of film holes are parameterized to conduct a series of CFD calculations at a target blowing ratio of 0.8, 1.1 and 1.7. Since the present study is taking a comparative approach, CFX with SST models is applied as a primary tool and the results are compared with Fluent solver for selected cases (total 36 cases). Among the proposed nine positions, the film holes located in the separated flow region of a ribbed channel showed considerable enhancement in film effectiveness with minimum reduction and potential improvement in internal heat transfer. The finding offers a design opportunity to enhance internal as well as external heat transfer.

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Near-Field Simulations of Film Cooling with a Modified DES Model

Cited by 6 publications

References 37 publications

Effects of Bulk Flow Pulsation on Film Cooling Involving Compound Angle

Effects of Bulk Flow Pulsation on Film Cooling Involving Compound Angle

Large Eddy Simulation of Film Cooling Involving Compound Angle Holes: Comparative Study of LES and RANS

Comparative Numerical Study of the Influence of Film Hole Location of Ribbed Cooling Channel on Internal and External Heat Transfer

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