Study On Enhanced Heat Transfer Of Pulsating Fluid Flow In Convergent-Divergent Tube

With the continuous depletion of fossil energy and energy consumption caused by environmental pollution and ecological damage has been the concern of all countries,in order to alleviate the energy shortage situation,efficient and reasonable utilization of heat energy and waste heat recovery,researchers have attached great importance to research on heat transfer enhancement of heat transfer equipment.In this paper,the pulsating flow and the convergent-divergent tube are used simultaneously to achieve the compound heat transfer enhancement,and the parameters that affect the heat transfer performance of the convergent-divergent tube under the pulsating fluid flow in tube was optimization researched,such as the average velocity of inlet,the divergent segment-convergent segment ratio of the convergent-divergent tube,the rib height of the convergent-divergent tube,the pulsation amplitude and the pulsation frequency,the optimization parameters which influence the heat transfer performance for convergent-divergent tube of pulsating fluid flow in tube were obtained.The main work of this paper and the results of the study are as follows:1)The reasonable mathematical model was established,and the software Fluent was used to numerical simulate the solving region of two-dimensional physical model of the zoom tube,the heat transfer performance of the convergent-divergent tube that were influence by the pulsating flow in tube and the comprehensive evaluation criterion of heat transfer performance was established.Under the condition of pulsating flow,the comprehensive heat transfer performance of the convergent-divergent tube is evaluated.2)The heat transfer and drag characteristics of the convergent-divergent tube of pulsating flow in tube were numerically studied by Fluent.The influence of five parameters on the heat transfer and drag characteristics were been analyzed,such as the average velocity of inlet u_s,the divergent segment-convergent segment ratio?of the convergent-divergent tube,the rib height e of the convergent-divergent tube,the pulsation amplitude A and the pulsation frequency f,and the influence of the above five parameters on the comprehensive heat transfer performance of the convergent-divergent tube under the fluid pulsation condition are measured synthetically by the comprehensive evaluation criterion of the heat transfer performance.3)The five parameters such as the average velocity of inlet u_s,the divergent segment-convergent segment ratio?of the convergent-divergent tube,the rib height e of the convergent-divergent tube,the pulsation amplitude A and the pulsation frequency f were optimization researched by the orthogonal test method,the results show that:the primary and secondary sequence of the influence of the comprehensive heat transfer performance of the convergent-divergent tube under the fluid pulsation condition is A>u_s>?>f>e,the optimization combination parameters of the comprehensive heat transfer performance of zoom tube underthefluidpulsationconditionwereobtained,whichis A=0.95,f=10Hz,?=1,e=0.7mm,u_s=1.3m/s.At the same time,the heat transfer characteristics of the convergent-divergent tube under the pulsating flow condition are studied experimentally,and the accuracy of the numerical simulation is verified by comparing the error between the experimental value and the simulation value.