选择性激光熔化成形点阵结构及其沸腾传热特性

Selective laser melting forming lattice structures and their boiling heat transfer characteristics

选择性激光熔化(selective lasermelting,SLM)技术具有高度的加工灵活性,能够成形高表面积-体积比的点阵结构,用于强化池沸腾传热。本文主要研究单胞构型、梯度以及SLM成形特性对点阵结构样品强化传热效果的影响。使用CuSn10粉末成形出尺寸为15mm×15mm×15mm、孔隙率为59.82%~62.10%、侧表面轮廓算术平均偏差(Ra)为11.6~15.5μm的点阵结构样品,样品表面存在粉末黏结,可提供大量潜在汽化核心;使用去离子水进行池沸腾传热实验,得出两种单胞构型点阵结构的起始沸腾点(104~105℃)和临界热流密度(86.7~110.2W/cm^2),发现不同单胞构型的点阵结构在沸腾传热过程中有不同的气泡逃逸和液体补充通道;成形出两种下层孔小、上层孔大的梯度点阵结构,将其沸腾传热曲线与均匀点阵结构进行对比,结果表明梯度结构对不同阶段沸腾传热的传热条件有着不同的影响。

Selective laser melting (SLM) provides great geometrical freedom for forming lattice structure,which can be applied to pool boiling heat transfer enhancement with its high surface area-volume ratio.This paper aims to explore the effect of cellular unit,gradient and SLM formability on the heat transfer of lattice structure samples.Lattice structure samples are formed using CuSn10 powder with size of 15mm× 15m×15mm,porosity of 59.82%-62.10% and side surface arithmetic mean deviation (Ra) of 11.6- 15.5μm.There is powder adhesion in surface of the samples,which can provide a large number of vaporized cores.Pool boiling heat transfer of water is investigated for samples and boiling point of 104- 105℃ and critical heat flux(CHF) of 86.7-110.2W/cm^2 are obtained,which shows the cellular unit has important influence on bubble departure and liquid replenishment pathways during boiling heat transfer.Two kinds of gradient structures are formed with small holes in the lower part and large holes in the upper part.In comparison with uniform lattice structures,the gradient structures show different heat transfer curves,which reveals that gradient has different effects on the heat transfer conditions of boiling heat transfer at different stages.