西交热工基础第11章对流换热1

温度相差1度时、每单位壁面面积上、单位时间内所传递的热量Р如何确定h及增强换热的措施是对流换热的核心问题Р热工基础 Fundamentals of Thermodynamics and Heat TransferР6/41Р影响对流换热的因素Р流动起因(The cause of motion)РForced convectionРMixed convectionРNatural convectionР热工基础 Fundamentals of Thermodynamics and Heat TransferР7/41Р流体流动状态(The flow regimes)РLaminar flowРTurbulent flowР流体力学实验:一滴红墨水滴到流体中Р热工基础 Fundamentals of Thermodynamics and Heat TransferР8/41Р换热表面几何因素(The geometric factors)Р形状(shape)Р相对位置(relative position)Р表面粗糙情况(surface roughness)Р尺度(scale)Р内流(internal flow)Р外流(external flow)Р换热过程有无相变(phase change)РBoiling, condensationР热工基础 Fundamentals of Thermodynamics and Heat TransferР9/41Р流体的物性(The thermophysical properties)Р前4类影响因素构成将对流换热进行分类的基架,流体的物性将通过一个特殊的无量纲数来专门予以反映Р热工基础 Fundamentals of Thermodynamics and Heat TransferР10/41Р对流换热的分类(classification)