方形小通道内高参数下煤油传热与阻力特性

对外边长为4.6 mm的方形小通道光滑管及底部带有不同强化表面的5根粗糙管试件在高热流密度、高流速、超临界压力条件下进行了煤油的传热、阻力、结焦特性的试验与分析研究,获得了煤油的传热、阻力与结焦特性及主要影响因素;分析了方形粗糙表面强化传热机理及不同粗糙度对煤油传热、阻力与结焦特性的影响,并与相同尺寸方光管的试验结果进行了比较.比较结果表明:5根粗糙管的传热系数为光管的1.4～1.9倍,阻力系数为1.3～3.8倍,2#粗糙管的综合效果最好;在相同条件下,粗糙管的平均壁温明显低于光管;增加管壁粗糙度不仅增强了煤油的换热能力,而且可明显提高结焦发生时的壁面热负荷,使结焦现象大为改善.研究结果对火箭发动机的热防护技术具有重要意义.

Investigation to Heat Transfer and Pressure Drop Characteristics of Kerosene under High Parameter in Square Small Channel

Experimental and analytic investigations to heat transfer, pressure drop and coke characteristics of kerosene are carried out in a square smooth small channel and 5 square small channels with different rough surface at the bottom under conditions of high heat flux, high flow rate and supercritical pressure. The characteristics of heat transfer, pressure drop and coke of kerosene and its main influence factors are revealed, and the enhanced heat transfer mechanism of rough surface and the influence of different roughness are analyzed. A comparison with smooth channel with the same size shows that the heat transfer coefficient of rough surface channel is 1.4 -1.9 times of smooth channel, the friction factors is 1.3-3.8 times, and the average wall temperature of rough surface channel is markedly lower than that of smooth channel under the same conditions, thus rough surface enables to enhance the heat transfer ability of kerosene, as well as the coke heat flux.