【作者】 王超；

【导师】 苏峰华； 袁熙；

【作者基本信息】 华南理工大学 ， 材料工程（专业学位）， 2021， 硕士

【摘要】 管式机油冷却器在各类车辆上应用广泛,随着铜价上涨和“轻量化、环保性与优化成本”的驱动下,用铝管式机油冷却器代替铜管式机油冷却器是汽车行业发展的趋势。本文使用理论分析、有限元分析和试验结合的方法,对铝管式机油冷却器的生产工艺以及力学和换热性能进行研究。本文第一部分(第二章)对高频感应加热工艺进行研究,并以材料非线性物理特性为基础进行电磁-热耦合分析表明,仿真升温数据与试验结果的相对误差在4%以内。通过研究铝管式机油冷却器上的涡流分布和体积损耗分布发现,涡流符合线圈投影规律,并且管端和焊接法兰距离线圈最近的部位容易熔蚀。对设计的新型锥形线圈与平面线圈的加热效果进行对比发现,平面线圈容易引起管端熔蚀而锥形线圈容易引起焊接法兰熔蚀。研究锥度和电流大小对线圈加热效果的影响,得出最优的锥度为56.9°,对应的3.35匝线圈结构为C3-3.35,该线圈在保证不发生熔蚀的前提下焊接时间为15.5 s。以C3-3.35线圈为基础进一步对导磁体结构进行研究,发现由于较大的后端磁感线收集面积和较小的导磁体前端面积,圆锥鸭嘴形导磁体能将能量尽可能集中在钎料附近,对铝管式油冷器的加热效果最好。导磁体相对于焊接法兰的距离对焊接效果的影响较大,最终得到最优的距离为4 mm,该线圈具有较好的温度分布和生产效率,将焊接时间从最初的22.3s缩减到了6.5 s。本文第二部分(第三章)对铝管式机油冷却器的整体热力学性能进行计算流体力学(CFD)仿真分析,先对局部结构进行特定条件仿真,并记录温差和压降数据。然后将翅片区域简化为多孔介质,并得到与局部结构压降和温差相同的等效阻力系数和等效孔隙率。将上述参数代入到整体多孔介质模型中进行仿真并与试验数据进行对比,发现换热量和压降的相对误差在-5%以内。以油流量84 g/s为例,铝管式机油冷却器的换热性能比铜管式的高16.1%,同时压降增加了47.3%。本文第三部分(第四章)对铝管式机油冷却器在力学性能方面进行了爆破静压强度和高低压脉冲性能分析,爆破静压强度试验值在6.18-6.65 MPa之间,并且高低压脉冲试验在1.5 MPa下进行了100000次循环。结果表明,铝管式机油冷却器满足使用标准。更多还原

【Abstract】 Tubular oil cooler is widely used in all kinds of vehicles.Because of more expensive of cooper and the requirement of “lightweight,environmental protection and optimization cost”,the replacement of cooper tubular oil cooler with aluminum tubular oil cooler is development trend in automobile industry.In this paper,the production process of aluminum tubular oil cooler was studied and optimized,as well as its mechanical properties and heat transfer performance,by combining theoretical analysis,finite element analysis and a serious of experiment tests.In the first part(chapter 2),the heating process of high-frequency induction heating was studied,and the electromagnetic-thermal coupling analysis was carried out on the base of the nonlinear physical properties of the material.The results showed that the relative error of temperature between the simulation and test results was less than 4%.By studying the eddy current distribution and volume loss distribution on the aluminum tubular oil cooler,it was found that the eddy current agreed well with the projection law of the coil,and the pipe end and the flange from the nearest part of the coil is prone to erosion.Compared with the heating effect of the new conical coil and the plane coil,it is found that the plane coil is easy to cause the pipe end erosion and the conical coil is easy to cause the flange erosion.The effect of taper and current on the heating effect of the coil was studied and the results showed that the optimum taper was 56.9° corresponding to the 3.35 turns coil structure being C3-3.35.As this coil was applied,the welding time was 15.5 s without the occurrence of erosion.Based on the C3-3.35 coil,the structure of the magnetic conductor was further studied.Because of its large back-end magnetic inductance line collection area line collection area and small front-end area of the magnetic conductor,the energy was concentrated as much as possible near the solder for likeduckbill magnetizer.Thus,the heating effect of aluminum tubular oil cooler was the best as the like-duckbill magnetizer was applied.The distance between the magnetizer and the flange had a great influence on the welding effect.Finally,the optimal distance is 4 mm,which had good temperature distribution and production efficiency.The welding time was reduced from the initial 22.3 s to 6.5 s.In the second part(chapter 3),the overall thermodynamic performance of the aluminum tubular oil cooler was analyzed by Computational Fluid Dynamics(CFD)simulation.Firstly,the local structure was simulated under certain conditions to record the temperature difference and pressure drop data.Then the finned region was simplified to the porous medium,and the equivalent drag coefficient and equivalent porosity were obtained which were the same as the pressure drop and temperature difference of the local structure.The above parameters were substituted into the whole porous medium model for simulation and compared with the test data.It was found that the relative error of heat transfer and pressure drop was within-5%.For example,the oil flow rate of 84 g/s,the heat transfer performance of aluminum tubular oil cooler was 16.1% higher than that of cooper tubular oil cooler,and the pressure drop by 47.3%at the same time.The third part(chapter 4)analyzed the mechanical properties of aluminum tubular oil cooler.The test value of static pressure strength was between 6.18-6.65 MPa.In addition,the appearance of the aluminum tubular oil cooler kept intact as it was tested at high pressure pulse1.5 MPa for 10000 times.The results showed that the aluminum tubular oil cooler meet the standard for application.更多还原