Numerical study on convective flow and heat transfer in 3D inclined enclosure with hot solid body and discrete cooling

2020 ◽  
Vol 30 (10) ◽  
pp. 4649-4659 ◽  
Author(s):  
Ali S. Alshomrani ◽  
S. Sivasankaran ◽  
Amer Abdulfattah Ahmed
Keyword(s):  
Heat Transfer ◽  
Convective Flow ◽  
Energy Transport ◽  
Numerical Study ◽  
Three Dimensional ◽  
Thermal Engineering ◽  
Content Type ◽  
Nusselt Numbers ◽  
Inclination Angles ◽  
Inclined Enclosure

Purpose This study aims to deal the numerical simulation on buoyant convection and energy transport in an inclined cubic box with diverse locations of the heater and coolers. Design/methodology/approach The left/right walls are cooled partially whereas the other walls are kept adiabatic. In the left/right walls, three different locations of the cooler are examined, whereas heater moves in three locations in the middle of the enclosed box. The governing models are numerically solved using the finite-element method. Findings The simulations are done on several values of the Rayleigh number and cavity inclination angles and different locations of the heater and coolers. The results are presented in the form of streamlines, isosurfaces and Nusselt numbers for different values of parameter involved here. It is recognized that the inclination of the box and the locations of the coolers strongly influence the stream and energy transport inside the enclosed domain. Research limitations/implications The present investigation is conducted for steady, laminar, three-dimensional natural convective flow in a box for different locations of cooler and tilting angles of a cavity. The study might be useful to the design of solar collectors, room ventilation systems and electronic cooling systems. Originality/value This work examines the effects of different locations of cooler and tilting angles of a cavity on convective heat transfer in a 3D cavity. The study is useful for thermal engineering applications.

Numerical Study of Air Forced Convection in a Rectangular Channel Provided With Ribs

2010 ◽  
Author(s):  
O. Manca ◽  
S. Nardini ◽  
D. Ricci
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Numerical Study ◽  
Flow Direction ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
Three Dimensional Model ◽  
Orthogonal Direction ◽  
Inclination Angles

Heat transfer enhancement technology has the aim to develop more efficient systems as demanded in many applications, like heat exchangers for refrigeration, automotives, process industry, solar heater etc.. Convective heat transfer may be enhanced passively by adopting different solutions. A possibility for increasing the heat transfer is to employ rough surfaces. When a fluid flows in a channel, ribs break the laminar sub-layer and create local turbulence, due to flow separation and reattachment between consecutive ribs, which reduce thermal resistance and augment heat transfer. This behaviour overcomes the effect linked to the increased heat transfer area due to the ribs. However, higher friction losses are expected and turbulence must be created only in the region very close to the heat transferring surface and the core flow should not be unduly disturbed. In this paper a numerical investigation is carried out on air forced convection in a rectangular channel with constant heat flux applied on the bottom and upper external walls. Properties of fluid are considered temperature-dependent and flow regime is turbulent. The investigation is accomplished by means of the commercial code Fluent. A three-dimensional model is developed in order to study the effect of the angle between the fluid flow direction and the ribbed surfaces. In fact, secondary turbulence is promoted in the orthogonal direction to the channel longitudinal axis. Three different inclination angles of the ribbed surfaces have been considered and the channel is provided with rectangular ribs. Simulations have shown that Nusselt numbers as well as the pressure drops increase as the inclination angles increase.

Aerodynamic performance enhancement of an Airfoil using trapezoidal vortex generators

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rawad Himo ◽  
Charbel Bou-Mosleh ◽  
Charbel Habchi
Keyword(s):  
Performance Enhancement ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Dynamic Simulations ◽  
Content Type ◽  
Inclination Angles ◽  
Drag Ratio

Purpose Flow separation on wings, blades and vehicles can be delayed or even suppressed by the use of vortex generators (VG). Numerous studies, documented in the literature, extensively describe the performance of triangular and rectangular VG winglets. This paper aims to focus on the use of non-conventional VG shapes, more specifically an array of trapezoildal-perforated VG tabs. Design/methodology/approach In this study, computational fluid dynamic simulations are performed on an inline array of trapezoidal VG with various dimensions and inclination angles, in addition to considering perforations in the VG centers. The methodology of the present numerical study is validated with experimental data from the literature. Findings The performance and the associated flow structures of these tested non-conventional VG are compared to classical triangular winglets. For the proposed non-conventional trapezoidal VG, at the onset of stall, a 21% increase of lift over drag on the airfoil is observed. The trapezoidal VG enhancement is also witnessed during stall where the lift over drag ratio is increased by 120% for the airfoil and by 10% with respect to the triangular winglets documented in the literature. Originality/value The originality of this paper is the use of non-conventional vortex generator shape to enhance lift over drag coefficient using three-dimensional numerical simulations.

Numerical study of liquid jet impingement flow and heat transfer of a cone heat sink

2019 ◽  
Vol 29 (11) ◽  
pp. 4074-4092 ◽  
Author(s):  
Zhiguo Tang ◽  
Hai Li ◽  
Feng Zhang ◽  
Xiaoteng Min ◽  
Jianping Cheng
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Sink ◽  
Numerical Study ◽  
Cone Angle ◽  
Jet Impingement ◽  
Bottom Edge ◽  
Content Type ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer

Purpose The purpose of this paper is to explore the flow and heat transfer characteristics of the jet impingement onto a conical heat sink and evaluate the ability of heat transfer enhancement. Design/methodology/approach A numerical study of the flow and heat transfer of liquid impingement on cone heat sinks was conducted, and transition SST turbulence model was validated and adopted. The flow and thermal performances were investigated with the Reynolds number that ranges from 5,000 to 23,000 and cone angle that ranges from 0° to 70° in four regions. Findings Local Nusselt numbers are large, and pressure coefficients drop rapidly near the stagnation point. In the conical bottom edge, a secondary inclined jet was observed, thereby introducing a horseshoe vortex that causes drastic fluctuations in the curves of the flow and heat transfer. The average Nusselt numbers are higher in a conical protuberance than in flat plates in most cases, thus indicating that the heat transfer performance of jet impingement can be improved by a cone heat sink. The maximum increase is 13.6 per cent when the cone angle is 60°, and the Reynolds number is 23,000. Originality/value The flow and heat transfer behavior at the bottom edge of the cone heat sink is supplemented. The average heat transfer capacity of different heat transfer radii was evaluated, which provided a basis for the study of cone arrays.

Numerical Study on the Effect of Inner Tube Position on Heat Transfer Process in Self-Recuperative Radiant Tube

2011 ◽  
Vol 228-229 ◽  
pp. 676-680 ◽  
Author(s):  
Ye Tian ◽  
Xun Liang Liu ◽  
Zhi Wen
Keyword(s):  
Heat Transfer ◽  
Transfer Process ◽  
Numerical Study ◽  
Flame Temperature ◽  
Three Dimensional ◽  
Mathematic Model ◽  
Heat Transfer Process ◽  
Bulk Temperature ◽  
Radiant Tube ◽  
Peak Value

A three-dimensional mathematic model is developed for a 100kw single-end recuperative radiant tube and the simulation is performed with the CFD software FLUENT. Also it is used to investigate the effect of distance between combustion chamber exit and inner tube on heat transfer process. The results suggest that the peak value of combustion flame temperature drops along with the increasing of distance, which leads to low NOX discharging. Also radiant tube surface bulk temperature decreases, which causes radiant tube heating performance losses.

Numerical Simulation of Gas Flow and Heat Transfer in Cross-Wavy Primary Surface Channel for Microtubine Recuperators

2005 ◽  
Author(s):  
H. X. Liang ◽  
Q. W. Wang ◽  
L. Q. Luo ◽  
Z. P. Feng
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Gas Turbine ◽  
Numerical Study ◽  
High Reliability ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Flow And Heat Transfer ◽  
High Heat Transfer ◽  
The Cross

Three-dimensional numerical simulation was conducted to investigate the flow field and heat transfer performance of the Cross-Wavy Primary Surface (CWPS) recuperators for microturbines. Using high-effective compact recuperators to achieve high thermal efficiency is one of the key techniques in the development of microturbine in recent years. Recuperators need to have minimum volume and weight, high reliability and durability. Most important of all, they need to have high thermal-effectiveness and low pressure-losses so that the gas turbine system can achieve high thermal performances. These requirements have attracted some research efforts in designing and implementing low-cost and compact recuperators for gas turbine engines recently. One of the promising techniques to achieve this goal is the so-called primary surface channels with small hydraulic dimensions. In this paper, we conducted a three-dimensional numerical study of flow and heat transfer for the Cross-Wavy Primary Surface (CWPS) channels with two different geometries. In the CWPS configurations the secondary flow is created by means of curved and interrupted surfaces, which may disturb the thermal boundary layers and thus improve the thermal performances of the channels. To facilitate comparison, we chose the identical hydraulic diameters for the above four CWPS channels. Since our experiments on real recuperators showed that the Reynolds number ranges from 150 to 500 under the operating conditions, we implemented all the simulations under laminar flow situations. By analyzing the correlations of Nusselt numbers and friction factors vs. Reynolds numbers of the four CWPS channels, we found that the CWPS channels have superior and comprehensive thermal performance with high compactness, i.e., high heat transfer area to volume ratio, indicating excellent commercialized application in the compact recuperators.

A Numerical Study of Heat Transfer and Flow Structure in Channels With Miniature V Rib-Dimple Hybrid Structure on One Wall

2018 ◽  
Author(s):  
Peng Zhang ◽  
Yu Rao ◽  
Yanlin Li
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Hybrid Structure ◽  
Transfer Enhancement ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Flow Mixing

This paper presents a numerical study on turbulent flow and heat transfer in the channels with a novel hybrid cooling structure with miniature V-shaped ribs and dimples on one wall. The heat transfer characteristics, pressure loss and turbulent flow structures in the channels with the rib-dimples with three different rib heights of 0.6 mm, 1.0 mm and 1.5 mm are obtained for the Reynolds numbers ranging from 18,700 to 60,000 by numerical simulations, which are also compared with counterpart of a pure dimpled and pure V ribbed channel. The results show that the overall Nusselt numbers of the V rib-dimple channel with the rib height of 1.5 mm is up to 70% higher than that of the channels with pure dimples. The numerical simulations show that the arrangement of the miniature V rib upstream each dimple induces complex secondary flow near the wall and generates downwashing vortices, which intensifies the flow mixing and turbulent kinetic energy in the dimple, resulting in significant improvement in heat transfer enhancement and uniformness.

Effect of Periodic Imposed Heat Flux on Three-Dimensional Natural Convection in a Partially Heated Cubical Enclosure

2016 ◽  
Vol 831 ◽  
pp. 83-91
Author(s):  
Lahoucine Belarche ◽  
Btissam Abourida
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Cubical Enclosure ◽  
Simplec Algorithm ◽  
Volume Method

The three-dimensional numerical study of natural convection in a cubical enclosure, discretely heated, was carried out in this study. Two heating square sections, similar to the integrated electronic components, are placed on the vertical wall of the enclosure. The imposed heating fluxes vary sinusoidally with time, in phase and in opposition of phase. The temperature of the opposite vertical wall is maintained at a cold uniform temperature and the other walls are adiabatic. The governing equations are solved using Control volume method by SIMPLEC algorithm. The sections dimension ε = D / H and the Rayleigh number Ra were fixed respectively at 0,35 and 106. The average heat transfer and the maximum temperature on the active portions will be examined for a given set of the governing parameters, namely the amplitude of the variable temperatures a and their period τp. The obtained results show significant changes in terms of heat transfer, by proper choice of the heating mode and the governing parameters.

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