摘要近年来，随着船舶能效设计指数的推广，船用设备的节能日益受到关注，换热设备的传热强化问题已越来越引起重视。本文以此作为研究背景，采用实验研究的方法，对脉动流强化换热问题开展了深入研究。实验系统脉动源采用往复泵，工质为水，流动状态是层流或过渡流工况，雷诺数范围在2000≤Re≤9000范围。86822
首先，搭建了的脉动流强化换热实验台架，探究了不同表面结构、不同脉动参数变量(脉动频率和脉动振幅)与换热效果的关系。实验中，数据采集系统可对脉动流参数的精确控制和数据的实时采集、存储，并且自行设计了满足脉动频率和振幅要求的往复泵。
往届实验研究表明：1。在矩形平板通道中，Re=2406、A=0。12Mpa、f=1。08Hz工况下，换热效果比稳态流下提高了160%；在周期性变化的矩形凹槽通道中，Re=2406、A=0。12Mpa、f=1。08Hz工况下，换热效果比稳态流下提高了200%;2。在相同雷诺数和脉动振幅条件下，随着脉动频率的变化，对流换热性能呈现逐渐减小或者先增大后减小的态势，存在一个最佳脉动频率；在实验工况范围内，脉动振幅与对流换热强化效果正相关；3。周期性凹槽通道的整体换热性能要优于平板通道。上述结果表明：在层流和脉动流态下，脉动流可有效强化对流换热性能。
然后，在板式换热器实验中，研究了脉动流和稳态流下的换热性能对比，探究了脉动振幅、脉动频率与其换热特性之间的关系。实验结果表明，随着雷诺数的增大，无论稳态流动或是脉动流动下板式换热器的总传热系数呈现增大的现象，换热增强因子呈现逐渐降低的态势；同时，在各雷诺数条件下，随着脉动频率的增大，换热增强因子出现了先减小后增大的现象，最低值出现在脉动频率f=0。66Hz附近，换热增强因子的最大值为1。598，出现在雷诺数Re=3774、脉动频率f=0。55Hz附近。
毕业论文关键词： 脉动流;强化换热;换热器;
Abstract In recent years, along with the promotion of ship energy efficiency design index, the energy saving in marine equipment have been got increasing concern and the heat transfer enhancement of marine heat exchangers have been attracted more attention。 Based on above the background information, this thesis adopts the method of experimental study and conducts a deep explore the issues of heat transfer enhancement of pulsating flow。 The pulsation source in experimental system using reciprocating pump , the working fluid is water, the flow state is laminar or transitional flow conditions and Reynolds number is in the range of 2000≤Re≤9000。
Firstly, an experimental bench of the the pulsating flow strengthening heat transfer is built, which is to explore the relationship between the different surface structures, different pulse parameters (Reynolds number, the pulsating frequency, pulsating amplitude) and the effect of heat exchange。 During the experiment, the data collection system can achieve precise control of the parameters and real-time collection and storage of data。 Moreover, a self-designed reciprocating pump to meet the requirements of the pulsation frequency and amplitude。 Meanwhile, design the three layer structure of heat sink chamber, including heating copper , a heat sink compartment cover and heat sink chamber base。 Besides, the surfaces of the heating copper are the rectangular flat plate flow and periodic variation of the rectangle groove channel。
The previous studies are as follows: 1。 In the rectangular plate channel, under the condition of Re = 2406, A = 0。12Mpa, f = 1。08Hz, the effect of heat transfer is improved by 160% than the steady-state flow。In the the rectangular groove channel with periodical change, under the condition of Re = 2406, a = 0。12Mpa, f = 1。08Hz, the effect of heat transfer is increased by 200% than in steady-state flow; 2。 Under different conditions of the Reynolds number and the pulsation amplitude, with the changing of pulse frequency, the efficiency of convective heat transfer presents the tendency of gradual decrease or increase first and then decrease, there is an optimum pulse frequency。 In the experimental range of operating conditions, the pulsation amplitude and the effect of the heat transfer enhancement is a positive correlation; 3。 Overall, the heat transfer efficiency in periodic groove channel is superior to the flat channel。 These results show that: under the condition of laminar and pulsating flow, the pulsating flow can be effectively enhanced the efficiency of heat transfer。 脉动冷却系统的实验研究:http://www.youerw.com/jixie/lunwen_116216.html