Turbulent Heat Transfer Over a Moving Surface Due to Impinging Slot Jets

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Himadri Chattopadhyay ◽  
Ali Cemal Benim
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Vertical Direction ◽  
Surface Velocity ◽  
Plate Motion ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Moving Surface ◽  
Surface Motion ◽  
Surface Movement

In the present paper, turbulent heat transfer characteristics of submerged slot jets impinging on a moving surface at a constant temperature up to a Reynolds number of 50,000 have been studied. The turbulent flow field was resolved using the realizable k-ɛ model due to Shi et al. [1995, “A New k-ɛ Eddy-Viscosity Model for High Reynolds Number Turbulent Flows-Model Development and Validation,” Comput. Fluids, 24, pp. 227–238] after rigorously establishing the adequacy of the model by comparison with large-eddy simulation data. A periodic element from a jet-bank configuration was chosen in the direction of the surface movement. The distribution of heat transfer on impinging surface is found to be significantly affected by the plate motion. However, the mean velocity distribution along vertical direction in the stagnation region is not affected by the plate motion. With increasing surface motion, the initial symmetric distribution changes to an inclined-S type pattern in the direction of the surface movement up to a certain level of surface velocity and the average heat transfer reduces. When the surface motion crosses this level, the net heat transfer starts increasing. The amount of heat transfer was found to be linked with the level of turbulent kinetic energy close to the impingement surface. The surface velocity at which the heat transfer reaches the value corresponding to the fixed surface value increases with increasing Reynolds number.

Turbulent Heat Transfer Over a Moving Plate Due to Impinging Slot Jets

2010 ◽  
Author(s):  
Himadri Chattopadhyay ◽  
Ali Cemal Benim
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Vertical Direction ◽  
Surface Velocity ◽  
Plate Motion ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Mean Velocity ◽  
Surface Motion ◽  
Surface Movement

In the present paper, turbulent heat transfer characteristics of slot jets impinging on a moving surface up to a Reynolds number of 50,000 have been studied. The turbulent flow field was resolved using the realizable k-ε model due to Shi et al. (1995) after rigorously establishing the adequacy of the model by comparison with large-eddy simulation data. A periodic element from a jet-bank configuration was chosen in the direction of the surface movement. The distribution of heat transfer on impinging surface is found to be significantly affected by the plate motion. However, the mean velocity distribution along vertical direction in the stagnation region is not affected by the plate motion. With increasing surface motion, the initial symmetric distribution changes to an inclined-S type pattern in the direction of the surface movement up to a certain level of surface velocity and the average heat transfer reduces. When the surface motion crosses this level, the net heat transfer starts increasing. The amount of heat transfer was found to be linked with the level of turbulent kinetic energy near the impingement region. The surface velocity at which the heat transfer reaches the value corresponding to the fixed surface value increases with increasing Reynolds number.

scholarly journals Turbulent Heat Transfer From a Slot Jet Impinging on a Flat Plate

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Dahbia Benmouhoub ◽  
Amina Mataoui
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Flow Field ◽  
Skin Friction ◽  
Velocity Ratio ◽  
Surface Velocity ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Jet Velocity

The flow field and heat transfer of a plane impinging jet on a hot moving wall were investigated using one point closure turbulence model. Computations were carried out by means of a finite volume method. The evolutions of mean velocity components, vorticity, skin friction coefficient, Nusselt number and pressure coefficient are examined in this paper. Two parameters of this type of interaction are considered for a given impinging distance of 8 times the nozzle thickness (H/e = 8): the jet-surface velocity ratio and the jet exit Reynolds number. The flow field structure at a given surface-to-jet velocity ratio is practically independent to the jet exit Reynolds number. A slight modification of the flow field is observed for weak surface-to-jet velocity ratios while the jet is strongly driven for higher velocity ratio. The present results satisfactorily compare to the experimental data available in the literature for Rsj ≤ 1.The purpose of this paper is to investigate this phenomenon for higher Rsj values (0 ≤ Rsj ≤ 4). It follows that the variation of the mean skin friction and the Nusselt number can be correlated according to the surface-to-jet velocity ratios and the Reynolds numbers.

Investigation of MHD RANS Modeling Base on DNS Database Under the Advanced Blanket Design Conditions Utilized Molten Salt

2014 ◽  
Author(s):  
Naoki Osawa ◽  
Yoshinobu Yamamoto ◽  
Tomoaki Kunugi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Turbulence Model ◽  
Turbulent Channel Flow ◽  
Turbulent Heat Transfer ◽  
Navier Stokes ◽  
Turbulent Heat ◽  
Mhd Turbulence ◽  
Rans Modeling ◽  
Heat Transfer Degradation

In this study, validations of Reynolds Averaged Navier-Stokes Simulation (RANS) based on Kenjeres & Hanjalic MHD turbulence model (Int. J. Heat & Fluid Flow, 21, 2000) coupled with the low-Reynolds number k-epsilon model have been conducted with the usage of Direct Numerical Simulation (DNS) database. DNS database of turbulent channel flow imposed wall-normal magnetic field on, are established in condition of bulk Reynolds number 40000, Hartmann number 24, and Prandtl number 5. As the results, the Nagano & Shimada model (Trans. JSME series B. 59, 1993) coupled with Kenjeres & Hanjalic MHD turbulence model has the better availability compared with Myong & Kasagi model (Int. Fluid Eng, 109, 1990) in estimation of the heat transfer degradation in MHD turbulent heat transfer.

Turbulent Heat Transfer Computations for Rearward-Facing Steps and Sudden Pipe Expansions

1985 ◽  
Vol 107 (1) ◽  
pp. 70-76 ◽  
Author(s):  
A. M. Gooray ◽  
C. B. Watkins ◽  
Win Aung
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Dynamic ◽  
Turbulence Models ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Streamline Curvature ◽  
Recirculating Flow ◽  
Moderate Reynolds Number ◽  
Entire Flow

Results of numerical calculations for heat transfer in turbulent recirculating flow over two-dimensional, rearward-facing steps and sudden pipe expansions are presented. The turbulence models used in the calculation are the standard k – ε model and the low-Reynolds number version of this model. The k – ε models have been improved to account for the effects of streamline curvature and pressure-strain (scalar) interactions including wall damping. A sequence of two computational passes is performed to obtain optimal results over the entire flow field. The presented results consist of computed distributions of heat transfer coefficents for several Reynolds numbers, emphasizing the low-to-moderate Reynolds number regime. The heat transfer results also include correlations of Nusselt numnber for both side and bottom walls. The computed heat transfer results and typical computed fluid dynamic results are compared with available experimental data.

scholarly journals Computation of Turbulent Heat Transfer on the Walls of a 180 Degree Turn Channel With a Low Reynolds Number Reynolds Stress Model

2002 ◽  
Author(s):  
D. L. Rigby ◽  
A. A. Ameri ◽  
E. Steinthorsson
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Reynolds Stress ◽  
Low Reynolds Number ◽  
Reynolds Stress Model ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Stress Model ◽  
Generalized Gradient ◽  
Low Reynolds

The Low Reynolds number version of the Stress-ω model and the two equation k-ω model of Wilcox were used for the calculation of turbulent heat transfer in a 180 degree turn simulating an internal coolant passage. The Stress-ω model was chosen for its robustness. The turbulent thermal fluxes were calculated by modifying and using the Generalized Gradient Diffusion Hypothesis. The results showed that using this Reynolds Stress model allowed better prediction of heat transfer compared to the k-ω two equation model. This improvement however required a finer grid and commensurately more CPU time.

Large Eddy Simulation of Turbulent Heat Transfer Around a Circular Cylinder in Crossflow

2007 ◽  
Author(s):  
Sung-Eun Kim ◽  
Hajime Nakamura
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Large Eddy Simulation ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Heat Transfer Characteristics ◽  
Eddy Simulation ◽  
Flow And Heat Transfer ◽  
Large Eddy

Large eddy simulation has been carried out of turbulent flow and heat transfer around a circular cylinder in crossflow at three subcritical Reynolds numbers (Re = 3,900, 10,000, 18,900) where the flow and heat transfer characteristics change rapidly with the Reynolds number. The computations were carried out using a second-order-accurate finite-volume Navier-Stokes solver that permits use of arbitrary unstructured meshes. A fully implicit, non-iterative fractional-step method was employed to advance the solution in time. The subgrid-scale (SGS) turbulent stresses and heat fluxes were modeled using the dynamic Smagorinsky model. The LES predictions were found to be in good agreement with the experimental data of Hajime and Igarashi (2004). The salient features of turbulent heat transfer in subcritical regime such as the laminar thermal boundary layer and the rapid increase with Reynolds number both in the mean and the r.m.s. Nusselt number in the separated region are closely reproduced by the predictions. The numerical results confirmed that the heat transfer characteristics are closely correlated with the structural change in the underlying flow with the Reynolds number.

Augmented Heat Transfer in a Rectangular Channel With Permeable Ribs Mounted on the Wall

1994 ◽  
Vol 116 (4) ◽  
pp. 912-920 ◽  
Author(s):  
Jenn-Jiang Hwang ◽  
Tong-Miin Liou
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Thermal Performance ◽  
Rectangular Channel ◽  
Area Ratio ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Open Area ◽  
Number Range ◽  
Solid Type

Turbulent heat transfer and friction in a rectangular channel with perforated ribs arranged on one of the principal walls are investigated experimentally. The effects of rib open-area ratio, rib pitch-to-height ratio, rib height-to-channel hydraulic diameter ratio, and flow Reynolds number are examined. To facilitate comparison, measurements for conventional solid-type ribs are also conducted. Laser holographic interferometry is employed to determine the rib permeability and measure the heat transfer coefficients of the ribbed wall. Results show that ribs with appropriately high open-area ratio at high Reynolds number range are permeable, and the critical Reynolds number of initiation of flow permeability decreases with increasing rib open-area ratio. By examining the local heat transfer coefficient distributions, it is found that permeable ribbed geometry has an advantage of obviating the possibility of hot spots. In addition, the permeable ribbed geometry provides a higher thermal performance than the solid-type ribbed one, and the best thermal performance occurs when the rib open-area ratio is 0.44. Compact heat transfer and friction correlations are also developed for channels with permeable ribs.

Sign in / Sign up

Export Citation Format

Share Document