摘要
为了弥补LNG液舱喷雾预冷运动液滴在同种蒸气中蒸发过程阻力模型的缺失,基于气液界面传热传质理论模型,采用计算流体力学(CFD)方法建立了液滴蒸发模拟模型,对温差为190 K、13<雷诺系数(Re)<4500的液滴蒸发过程开展模拟,得到了液滴阻力计算模型,并从压力、蒸气蒸发速度、分离点研究蒸发液滴的阻力特性。研究结果表明:①压力(p)随Re增大而增大,Re相同时p随来流夹角(φ)的增大先减小后增大,压力到达最小值(p_(min))后逆压造成分离,液滴表面蒸气蒸发速度(v_(2))变化趋势与p基本一致,存在蒸气蒸发速度最小值(v_(2min))。②不同条件下对应的来流夹角(φ_(s)、φ_(v_(2min))和φp_(min))都随Re的增大而减小,由于分离作用且液滴表面受蒸气蒸发影响,使液滴表面切向速度梯度为0对应点的角度(φ_(s-d))小于低温球表面切向速度梯度为0对应点的角度(φ_(s-b)),即Re越大,液滴的分离点越靠前。③液滴压差阻力系数(C_(d-d))和低温球压差阻力系数(C_(d-b))都随φ的增大先减小后增大,且同一工况下C_(d-d)>C_(d-b);由于液滴表面速度梯度(L_(v-d))小于低温球表面速度梯度(L_(v-b)),使C_(dt-d)<C_(dt-b)。结论认为,提出的阻力无量纲关联式C_(dt-d)=9.8Re^(-0.51)、C_(dt-b)=31.4Re^(-0.62),对研究喷雾预冷液滴运动特性、保障预冷安全具有重要价值。
There is no resistance model for the moving droplets in the process of evaporation in the same kind of vapor during spray precooling of an LNG tank.To address this problem,this paper establishes a droplet evaporation simulation model based on the theoretical model of heat and mass transfer at the gas-liquid interface using the computational fluid dynamics(CFD)method.Then,the droplet evaporation process with temperature difference of 190 K and Reynolds number(Re)ranging from 13 to 4500 is simulated.In addition,the calculation model of droplet resistance is established,and the resistance characteristics of droplets in the process of evaporation are studied from the aspects of pressure,vapor evaporating velocity and separation point.And the following research results are obtained.First,the pressure(p)increases with the increase of Re.When Re is the same,p decreases first and then increases with the increase of the inflow included angle(φ).After the pressure reaches the minimum value(p_(min)),the reverse pressure causes separation.The changing trend of vapor evaporating velocity(v_(2))on the droplet surface is basically consistent with that of p,so correspondingly,there is a minimum vapor evaporating velocity(v_(2min)).Second,under different conditions,the corresponding inflow included angles(φs,φv_(2min) andφp_(min))all decrease with the increase of Re.Because of the separation effect and the influence of vapor evaporation on the droplet surface,the angle(φ_(s-d))where the tangential velocity gradient on the surface of droplet is 0 is smaller than the angle(φ_(s-d))where the tangential velocity gradient on the surface of cryogenic sphere is 0.That is to say,the greater the Re,the higher the separation point of the droplet.Third,both the pressure drag coefficient(C_(d-d))of droplet and the pressure drag coefficient(C_(d-b))of cryogenic sphere decrease first and then increase with the increase ofφ,and the former is larger than the latter(C_(d-d)>C_(d-b))under the same working condition.The velocity gradient on
作者
邓佳佳
庹中兰
束露露
夏海山
卢金树
薛大文
雷利
彭辉
DENG Jiajia;TUO Zhonglan;SHU Lulu;XIA Haishan;LU Jinshu;XUE Dawen;LEI Li;PENG Hui(Zhejiang Ocean University,Zhoushan,Zhejiang 316022,China;Guangxi Electrical Polytechnic Institute,Nanning,Guangxi 530007,China;Chuanzhong Division of PetroChina Southwest Oil&Gasfield Company,Suining,Sichuan 629000,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2023年第12期100-109,共10页
Natural Gas Industry
基金
浙江省基础公益研究计划项目“液货舱预冷过程同种过热蒸气中液滴蒸发机理及模型研究”(编号:LY18E090009)。
关键词
LNG
液滴蒸发
强制对流
阻力特性
传热传质
蒸发速度
压力
甲烷
LNG
Droplet evaporation
Forced convection
Resistance characteristics
Heat and mass transfer
Evaporating velocity
Pressure
Methane
