Large-Eddy simulation of an impinging heated jet for a small nozzle-to-plate distance and high Reynolds number

Grenson, Pierre; Deniau, Hugues

doi:10.1016/j.ijheatfluidflow.2017.09.014

Cited by 21 publications

(20 citation statements)

References 28 publications

(44 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to circumvent these limitations, several numerical simulations have been initiated. Especially, wall-resolved LES [33][34][35][36][37][38][39][40] and direct numerical simulation (DNS) [41][42][43][44][45][46][47] have been carried out in order to complement experimental results and then to gain further insights into the subtle mechanisms of heat transport and fluid flow dynamics in impinging jet cooling. In this regard, Hattori and Nagano [43] provided a comprehensive DNS dataset of fluid flow and heat transport properties for a plane non-inclined impinging jet at Re j = 9120 and different jet-to-plate spacings.…”

Section: Introductionmentioning

confidence: 99%

“…In the first study, the authors analyzed the role of unsteady processes on the wall heat transfer, while in the latter study, the influence of Mach number, Reynolds number and ambient temperature on the velocity and temperature was examined. Recently, Grenson and Deniau [38] performed a wall-resolved LES of a heated impinging jet at Re j = 60,000 in order to analyze the fundamentals of flow and heat transfer in impinging jets under higher Reynolds numbers. Based on the analysis of instantaneous flow topology, turbulent quantities and probability functions, this investigation revealed that hot spots of high convective heat transfer related to unsteady separation and streak-like structures are linked to the secondary peak in the Nusselt number distribution.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Near-Wall Thermal Processes in an Inclined Impinging Jet: Analysis of Heat Transport and Entropy Generation Mechanisms

Ries

Klingenberg

et al. 2018

Energies

View full text Add to dashboard Cite

In this work, near-wall thermal transport processes and entropy generation mechanisms in a turbulent jet impinging on a 45 ∘ -inclined heated surface are investigated using a direct numerical simulation (DNS). The objectives are to analyze the subtle mechanisms of heat transport in the vicinity of an inclined impinged wall, to determine the causes of irreversibilities that are responsible for the reduction of performance of impingement cooling applications and to provide a comprehensive dataset for model development and validation. Results for near-wall thermal characteristics including heat fluxes are analyzed. An entropy production map is provided from the second law analysis. The following main outcomes can be drawn from this study: (1) the location of peak heat transfer occurs not directly at the stagnation point; instead, it is slightly shifted towards the compression side of the jet, while at this region, the heat is transported counter to the temperature gradient; (2) turbulent thermal and fluid flow transport processes around the stagnation point are considerably different from those found in other near-wall-dominated flows and are strongly non-equilibrium in nature; (3) heat fluxes appear highly anisotropic especially in the vicinity of the impinged wall; (4) in particular, the heated wall acts as a strong source of irreversibility for both entropy production related to viscous dissipation and to heat conduction. All these findings imply that a careful design of the impinged plate is particularly important in order to use energy in such a thermal arrangement effectively. Finally, this study confirms that the estimation of the turbulent part of the entropy production based on turbulence dissipation rates in non-reacting, non-isothermal fluid flows represents a reliable approximate approach within the second law analysis, likewise in the context of computationally less expensive simulation techniques like RANS and/or LES.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Near-Wall Thermal Processes in an Inclined Impinging Jet: Analysis of Heat Transport and Entropy Generation Mechanisms

Ries

Klingenberg

et al. 2018

Energies

View full text Add to dashboard Cite

show abstract

“…In particular, they observed how the Nusselt number rises with increasing Mach number, where the cause to this phenomenon was attributed to the larger fluctuations present in the flow. In contrast to the aforementioned compressible numerical investigations, Grenson & Deniau (2017) used a compressible LES code where, despite their low Mach number (M a ≈ 0.064), the molecular viscosity µ and the thermal conductivity κ of the fluid were not assumed constant and varied as a function of the temperature. For such a low Mach number setup, it seems an a-priori a reasonable assumption to neglect these variations in the flow properties (such as in Aillaud et al 2016;Wilke & Sesterhenn 2017), but in this article we show how there are other factors to be considered in addition to the Mach number, which indicate the relevance of flow compressibility.…”

Section: Introductionmentioning

confidence: 99%

Compressibility and variable inertia effects on heat transfer in turbulent impinging jets

Otero-Pérez

Sandberg

2020

J. Fluid Mech.

View full text Add to dashboard Cite

This article shows the importance of flow compressibility on the heat transfer in confined impinging jets, and how it is driven by both the Mach number and the wall heat-flux. Hence, we present a collection of cases at several Mach numbers with different heat-flux values applied at the impingement wall. The wall temperature scales linearly with the imposed heat-flux and the adiabatic wall temperature is found to be purely governed by the flow compression. Especially for high heat-flux values, the non-constant wall temperature induces considerable differences in the thermal conductivity of the fluid. This phenomenon has to date not been discussed and it strongly modulates the Nusselt number. In contrast, the heat transfer coefficient is independent of the varying thermal properties of the fluid and the wall heat-flux. Furthermore, we introduce the impingement efficiency, which highlights the areas of the wall where the temperature is influenced by compressibility effects. This parameter shows how the contribution of the flow compression to raising the wall temperature becomes more dominant as the heat-flux decreases. Thus, knowing the adiabatic wall temperature is indispensable for obtaining the correct heat transfer coefficient when low heat-flux values are used, even at low Mach numbers. Lastly, a detailed analysis of the dilatation field also shows how the compressibility effects only affect the heat transfer in the vicinity of the stagnation point. These compressibility effects decay rapidly further away from the flow impingement, and the density changes along the developing boundary layer are caused instead by variable inertia effects.

show abstract

“…Therefore, in a previous study, a technique of flux reconstruction at the interface of conforming grids has been developed. Based on the application of noncentered spatial schemes at the block interface and the use of ghost cells, the technique allowed us to successfully perform massively parallel aerodynamic and aeroacoustic computations of jet flows …”

Section: Introductionmentioning

confidence: 99%

“…Based on the application of noncentered spatial schemes at the block interface and the use of ghost cells, the technique allowed us to successfully perform massively parallel aerodynamic and aeroacoustic computations of jet flows. [14][15][16][17] In the present study, a flux reconstruction technique for the interface of nonconforming grids is proposed. The technique, derived from the method developed for conforming grids, 12 is based on the application of noncentered schemes at the grid interface.…”

Section: Introductionmentioning

confidence: 99%

A technique of flux reconstruction at the interfaces of nonconforming grids for aeroacoustic simulations

Bras

Deniau

Bogey

2019

Numerical Methods in Fluids

Self Cite

View full text Add to dashboard Cite

Summary A flux reconstruction technique is presented to perform aeroacoustic computations using implicit high‐order spatial schemes on multiblock structured grids with nonconforming interfaces. The use of such grids, with mesh spacing discontinuities across the block interfaces, eases local mesh refinements, simplifies the mesh generation process, and thus facilitates the computation of turbulent flows. In this work, the spatial discretization consists of sixth‐order finite‐volume implicit schemes with low‐dispersion and low‐dissipation properties. The flux reconstruction is based on the combination of noncentered schemes with local interpolations to define ghost cells and compute flux values at the grid interfaces. The flow variables in the ghost cells are calculated from the flow field in the grid cells using a meshless interpolation with radial basis functions. In this study, the flux reconstruction is applied to both plane and curved nonconforming interfaces. The performance of the method is first evaluated by performing two‐dimensional simulations of the propagation of an acoustic pulse and of the convection of a vortex on Cartesian and wavy grids. No significant spurious noise is produced at the grid interfaces. The applicability of the flux reconstruction to a three‐dimensional computation is then demonstrated by simulating a jet at a Mach number of 0.9 and a diameter‐based Reynolds number of 4×105 on a Cartesian grid. The nonconforming grid interface located downstream of the jet potential core does not appreciably affect the flow development and the jet sound field, while reducing the number of mesh points by a factor of approximately two.

show abstract

Large-Eddy simulation of an impinging heated jet for a small nozzle-to-plate distance and high Reynolds number

Cited by 21 publications

References 28 publications

Near-Wall Thermal Processes in an Inclined Impinging Jet: Analysis of Heat Transport and Entropy Generation Mechanisms

Near-Wall Thermal Processes in an Inclined Impinging Jet: Analysis of Heat Transport and Entropy Generation Mechanisms

Compressibility and variable inertia effects on heat transfer in turbulent impinging jets

A technique of flux reconstruction at the interfaces of nonconforming grids for aeroacoustic simulations

Contact Info

Product

Resources

About