风室试验中轴对称排气引射-混合器的引射特性  

Experimental Study on the Entrainment Characteristics of Axisymmetric Eductor by Using Wind Chamber

作　　者：林文进[1] 王炜哲[1] 刘应征[1] 陈汉平[1] 

机构地区：[1]上海交通大学机械与动力工程学院,上海200240

出　　处：《上海交通大学学报》2009年第5期759-762,771,共5页Journal of Shanghai Jiaotong University

基　　金：国防科工委十一五计划资助项目

摘　　要：建立了大尺度引射进气风室试验装置,以精确测量排气引射-混合器的引射流量,采用辅助风机补风以调整并逼近实际引射进口压力,从而提高了引射流量的测量精度,采用3种直径的混合管对轴对称排气引射-混合器的引射流量特性进行对比研究,并结合射流理论对其流动状态加以分析.结果表明:在主流喷管直径一定而混合管直径(D2)不同的条件下,混合管内的流动状态有所不同;当D2=250 mm时,混合管内的流动为过度发展状态,随着主喷管与混合管间距离(a)增大,射流半厚度经扩展后过早附着在混合管壁,其引射系数和引射流量随a值增加而增大,当增至最大值后逐渐减小,随着主流流量的增加,引射流量增大而引射系数变化不大;当D2=300 mm时,混合管内的流动为充分发展状态,随着a值增大,射流半厚度经扩展后在a=300 mm时恰好在混合管出口处附着于混合管壁,其引射系数和引射流量随a值的增幅逐渐变缓;当D2=350 mm时,混合管内的流动为欠发展状态,随着a值增大,射流半厚度经扩展后在混合管出口处仍未附着于混合管壁,引射系数和引射流量随a值增加而增大.A large-scale wind chamber was built in the present study to accurately measure entrainment rate of the ejector at variable mainstream speed. In this experimental rig, an additional blower was used to pump air into the wind chamber until the total pressure inside the wind chamber is equal to environmental atmosphere pressure, by which the accuracy of the entrainment rate measurement is increased. The entrainment rates of three eductors with different diameter of the mixers were experimentally measured; the flow patterns of the eductors were classified by using the jet theory. The experimental results indicate that the flow state differs when mixer diameter D2 varies under the certain main nozzle diameter. When D2 = 250 mm, the flow state of mixer is in an excessive development state, the primary flowing fluid premature- ly attaches the inner wall of the mixer before outlet section, the entrainment flow rate and coefficient quickly reach the maximum point then reduce gradually with the growth of value a. When D2 = 300 mm, the flow state of mixer is in a full development state, the primary flowing fluid properly attaches the inner wall of the mixer at outlet section, the entrainment flow rate and coefficient increase with the growth of value a, then reach the maximum point at-outlet section. When D2 =350 mm, the flow state of mixer is in an underdevelopment state, the primary flowing fluid never attaches the inner wall of the mixer at outlet section, the entrainment flow rate and coefficient increase quickly with the growth of value a.

关 键 词：引射-混合器 引射流量 射流 风室试验 

分 类 号：TK05[动力工程及工程热物理]