Effect of the angle of attack of a rectangular vortex generator on the heat transfer in a parallel plate flow

2016 ◽  
Author(s):  
Assadour Khanjian ◽  
Serge Russeil ◽  
Daniel Bougeard ◽  
Charbel Habchi ◽  
Thierry Lemenand
Keyword(s):  
Heat Transfer ◽  
Parallel Plate ◽  
Angle Of Attack ◽  
Vortex Generator

Optimal Position of Rectangular Vortex Generator for Heat Transfer Enhancement in a Flat-Plate Channel

2017 ◽  
Author(s):  
Tariq Amin Khan ◽  
Wei Li ◽  
Zhengjiang Zhang ◽  
Jincai Du ◽  
Sadiq Amin Khan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Numerical Simulations ◽  
Flat Plate ◽  
Heat Transfer Enhancement ◽  
Angle Of Attack ◽  
Vortex Generator ◽  
Transfer Enhancement ◽  
Optimal Position ◽  
Plate Channel

Heat transfer is a naturally occurring phenomenon which can be greatly enhanced by introducing longitudinal vortex generators (VGs). As the longitudinal vortices can potentially enhance heat transfer with small pressure loss penalty, VGs are widely used to enhance the heat transfer of flat-plate type heat exchangers. However, there are few researches which deal with its thermal optimization. Three dimensional numerical simulations are performed to study the effect of angle of attack and attach angle (angle between VG and wall) of vortex generator on the fluid flow and heat transfer characteristics of a flat-plate channel. The flow is assumed as steady state, incompressible and laminar within the range of studied Reynolds numbers (Re = 380, 760, 1140). In the present work, the average and local Nusselt number and pressure drop are investigated for Rectangular vortex generator (RVG) with varying angle of attack and attach angle. The numerical results indicate that the heat transfer and pressure drop increases with increasing the angle of attack to a certain range and then decreases with increasing angle of attack. Moreover, the attach angle also plays an importance role; a 90° attach angle is not necessary for enhancing the heat transfer. Usually, heat transfer enhancement is achieved at the expense of pressure drop penalty. To find the optimal position of vortex generator to obtain maximum heat transfer and minimum pressure drop, the data obtained from numerical simulations are used to train a BRANN (Bayesian-regularized artificial neural network). This in turn is used to drive multi-objective genetic algorithm (MOGA) to find the optimal parameters of VGs in the form of Pareto front. The optimal values of these parameters are finally presented.

Study on Enhanced Heat Transfer and Structural Optimum for Combination Vortex Generator in Spiral Channel

2014 ◽  
Vol 501-504 ◽  
pp. 2338-2343
Author(s):  
De Fan Qing ◽  
Ya Long Zhang ◽  
Sheng Xue Liu ◽  
Cui Fang Wang
Keyword(s):  
Heat Transfer ◽  
Delta Wing ◽  
Orthogonal Experiment ◽  
Angle Of Attack ◽  
Vortex Generator ◽  
Normal Structure ◽  
Simulation Method ◽  
Elliptical Cylinder ◽  
Inlet Temperature ◽  
Array Configuration

The array configuration of delta wing and elliptical cylinder vortex generator in the spiral surface channel was studied. By changing the assembly distance s, the triangle wing vortex generator angle of attack α, the elliptical cylinder vortex generator angle of attack β to research the heat transfer and resistance properties under different working conditions. The research model as follow: the heat-medium is water-vapor [H2, the cold medium of flow is air, Steam temperature is 400K and air inlet temperature is 293K, the Reynolds number ranging from 4000 to 7000.The optimum structure was determined by using numerical simulation method and orthogonal experiment method. The result shows the optimization structure of the combination vortex generator: α=45°, β=45°, s=90mm. Compared with the normal structure, the heat transfer enhancement comprehensive effect of the optimization structure raised about 36.2%~47.6%.

Numerical Investigation of Entropy Generation in the Case of a Finned Oval Tube With a Punched Longitudinal Vortex Generator in Form of Delta Winglet

2006 ◽  
Author(s):  
J. Herpe ◽  
D. Bougeard ◽  
S. Russeil ◽  
B. Baudoin
Keyword(s):  
Heat Transfer ◽  
Entropy Production ◽  
Entropy Generation ◽  
Heat Exchangers ◽  
Angle Of Attack ◽  
Flow Characteristics ◽  
Vortex Generator ◽  
Longitudinal Vortex ◽  
Entropy Generation Rate ◽  
Oval Tube

In order to improve the performance of compact heat exchangers engineers and researchers explore different passive techniques of flow manipulation. Among them one can find the delta wing shaped longitudinal vortex generator. In order to assess the optimal shape of finned tube heat exchangers, the engineer has at disposal many coefficients, such as the Colburn factor j and friction factor f. In the present paper the second law of thermodynamics is introduced to explore the flow and thermal field generated by punched longitudinal vortex generators shaped as winglets around an oval tube. The winglets are in common flow up configuration near the leading edge of the fin. Not only the heat transfer and fluid flow characteristics are studied, but also the local irreversibility methodology is applied to predict the two components of entropy generation rate: the one caused by direct dissipation and the other due to heat transfer. The flow velocity and temperature are numerically determined by solving the Navier-Stokes and energy equations with a finite volume method. The local entropy production is then calculated with the use of available information from the solved flow and thermal fields. This paper is based on Chen works. He has studied the flow characteristics for such a geometrical configuration. But here the fin efficiency is supposed to be equal to the unity. The influence of the angle of attack of winglets on the entropy production is studied. Three elemental configurations are displayed. Each one corresponds respectively to an angle of attack β equal to 20°, 30° and 45°. The minimal entropy principle is adopted to evaluate a global heat exchanger build up as a pile up of elemental component.

AN EXPERIMENTAL STUDY OF ENHANCEMENT OF FORCED CONVECTION HEAT TRANSFER FROM PARALLEL PLATE FINS WITH CUTS

Equipment ◽  
2006 ◽  
Author(s):  
E. N. Pis'mennyi ◽  
V. A. Rogachev ◽  
A. M. Terekh ◽  
Georgiy Polupan ◽  
I. Carvajal-Mariscal ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Forced Convection ◽  
Parallel Plate ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Forced Convection Heat Transfer

Heat transfer enhancement using second mode self-oscillating structures

2019 ◽  
Vol 30 (7) ◽  
pp. 3827-3842
Author(s):  
Samer Ali ◽  
Zein Alabidin Shami ◽  
Ali Badran ◽  
Charbel Habchi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Flow Regime ◽  
Vortex Generator ◽  
Reynolds Numbers ◽  
Content Type ◽  
Laminar Flow Regime ◽  
Second Mode

Purpose In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs). Design/methodology/approach Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers. Findings For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG. Practical implications The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones. Originality/value The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.

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