Experimental And Numerical Research On Natural Convection Heat Transfer Of Array Of Cylinders Based On Laser Interferometry

The natural convection heat transfer analysis of single cylinder and an array of cylinders are of great significance to the development of industrial fields such as energy and power and high-tech fields such as microelectronic technology.Large lateral shearing interferometer and commercial software ANSYS-Fluent 18.0 are applied to the heat transfer analysis of this study.When the shear amount of the lateral shearing interferometer is large enough,two side-by-side simple fringe patterns similar to double-exposure holographic interference are output.Large lateral shearing interferometer has been widely used in fluid temperature measurement with the advantages of strong antivibration.The rapid development of computational fluid dynamics has promoted the numerical simulation of natural convection heat transfer for complex research objects.The natural convection heat transfer characteristics analyzed in this study are from a vertical array of five cylinders with four flow diverters,three cylinders arranged in a triangular configuration,single cylinder and three cylinders arranged like a triangular configuration.The numerical simulation method is applied to study the natural convection heat transfer from a vertical array of five cylinders with four flow diverters,investigating the influence of flow diverter’s offset angle,the vertical center-to-center separation distance between cylinders,and Rayleigh number on heat transfer.The results show that when the flow diverter’s offset angle isφ=0°,the heat transfer rate of the array is weakened and has no effect on the heat transfer of C1 cylinder.In the case ofφ=15°～60°,with the increasing of the flow diverter angle,the heat transfer rate first increased and then decreased,and the best heat transfer angle isφ=45°.While the center-to-center separation distance increased,the heat transfer rate is increased.Compared with no flow diverters,the heat transfer rate of the array is increased by 20.29%.When center-to-center separation distance is small,the flow diverters weaken the heat transfer rate of each cylinder.The numerical simulation method is applied to study the natural convection heat transfer from three cylinders arranged in a triangular configuration,investigating the influence of center-to-center separation distance and Rayleigh number on heat transfer,and comparing with the natural convection heat transfer of a single cylinder.The difference between the heat transfer of each cylinder is studied.The results show that the heat transfer rate of C3 cylinder increases with the increasing of center-to-center separation distance and Rayleigh number.When the center-to-center separation distance is larger,the heat transfer rate of C3 cylinder is stronger than that of a single cylinder.For C1 and C2 cylinders,the plume flow is inclined to the middle C3 cylinder.Although their local heat transfer is different from that of a single cylinder,the average Nusselt number is basically the same as a single cylinder.Large lateral shearing interferometer is conducted to study the natural convection heat transfer of a single cylinder.Recording the interference picture with the Rayleigh number in the range of 4×10~3～10~4,using the Matlab program to identify the center of the interference fringe,determining the fringe series difference to reflect the temperature field around the cylinder,and obtaining the local Nusselt number and the average Nusselt number of the heated cylinder.The experimental results have been compared with previous results,filling in the experimental data gaps with the Rayleigh number in the range of 10~3～10~4and providing experimental reference.Large lateral shearing interferometer is conducted to study the natural convection heat transfer of three cylinders arranged like a triangular configuration.The shear interference fringes with the Rayleigh number in the range of 10~3～10~4 are obtained,and the local Nusselt number and the average Nusselt number under different working conditions are calculated by analyzing the fringes.The numerical simulation method is applied for comparative heat transfer analysis under the same working conditions,and the influence of each cylinder in the cylinder array on the heat transfer between each other is studied.In summary,this study is intended to provide a reference for practical engineering applications.