Effect Of Sound Wave On Convective Heat Transfer Characteristics Of Tube Bundle

In this paper,aiming at the optimization of the heat transfer performance of the heat exchanger of the power station boiler,a numerical model of the coupling of sound field,flow field and temperature field is established,and the effect of sound waves on the heat exchange efficiency of the heat exchanger of the power station boiler is studied.The heat exchangers in the boiler are all composed of cylindrical tube bundles,and the flue gas flow through the tube bundles will cause cylindrical circumfluence.Numerical simulation of the flow and convection heat transfer characteristics of a single cylinder,double cylinder and tube bundle under the action of a sound wave.Get the influence of acoustic waves on the surface pressure coefficient C_P,lift coefficient C_DL,drag coefficient C_DF,Strouhal number Sr,and the local Nusselt number Nuθof convective heat transfer.The research results can provide a theoretical research foundation for enhancing convective heat transfer around a cylinder.This research mainly uses the finite element method for simulation calculation.The cylinder parameters in the calculation model refer to the economizer diameter,and the pipe diameter D=40mm is selected.Numerical simulation are carried out on the convective heat transfer of single cylinder,double cylinders in tandem,double cylinders in parallel,and 5×4 tube bundles.The research results show that the effect of sound waves will accelerate the shedding of the vortex around the cylinder and promote the heat transfer on the cylinder surface,but at the same time it will also increase the force on the cylinder surface.In the range of f=20～80Hz and SPL=123～149d B,the Nusselt number Nuθof the local heat transfer on the cylindrical surface increases with the increase of the sound wave frequency,and first increases and then decreases with the increase of the sound pressure level,The best heat transfer sound pressure level is132d B.For the tube row,under given conditions,the best heat exchange tube spacing is the horizontal spacing ratio S_T/D=2.5,and the longitudinal spacing ratio S_L/D=2.At this time,the interference effect between adjacent cylinders is small.Affected by the wake of the front row of cylinders,and the sound wave propagating in the array will have dissipation,the convective heat transfer efficiency of the back row of cylinders in the array will decrease,and the heat transfer efficiency of the front row of cylinders is better than that of the rear cylinder.