【作者】 李伟；

【导师】 湛含辉；

【作者基本信息】 湖南工业大学 ， 机械设计及理论， 2007， 硕士

【摘要】 二次流是流体力学中的一种常见现象,国内外对二次流理论与实验研究已经取得一些成果,并已应用在航空、生物工程、水处理、防洪、生态环境保护和膜分离等高技术领域,而且取得了较为显著的效益。为此,本文从实验和理论推导两个方面对二次流进行深入研究,研究内容包括以下几个方面:⑴建立以直径Φ300有机玻璃材料制成的离心剪切二次流实体模型,利用激光测速仪测试模型内流速分布,通过数据拟合分析,在模型内充满整个搅拌槽内的四个相同的循环二次流场。⑵重现常见的二次流(迪恩涡,泰勒涡和戈特勒涡)特征系数的推导过程。然后,总结相关规律,在能量方程伯努利方程中引进新变量二次流能量h f概念,在此基础上推导出离心剪切二次流系数(L)和二次流特征系数(Z )。⑶将离心剪切二次流理论应用于混凝沉降;比较普通流场和离心剪切二次流混凝沉降效果;实验结果表明:离心剪切流场混凝沉降絮体凝聚快、絮体多、颗粒大且密实、沉降速度快,混凝效果是普通流场5～10倍。⑷运用相似放大理论,运用弗鲁德准则和雷诺准则,对离心剪切流场相似放大,在放大后的模型中进行混凝沉降反应,结果与放大前相近。更多还原

【Abstract】 The secondary flow is a familiar phenomena in the hydrodynamics . The theory of secondary flow has used in lots of high tech fields, such as aviation, bioengineering, water-treatment, preventing or controlling flood ,environment protecting , film separating and so on , which makes great success. So, we use the way of experiment and theory to study the secondary flow. The research work has been accomplished with the following achievements :(1)We build the testing model of centrifugal secondary flow field whose diameter is 300mm. By means of the Laser Dopper Velocimeter (LDV, SCD-21) measure and analyze the velocity distributing in the model . with the analyse of experiment data , we find that there are four circulation secondary flow field .( 2 ) Analyzing and validating the familiar secondary flow coefficient, such as Dean vortex, Taylor vortex and G?rtler vortex, we summarize the secondary flow coefficient . Then, we define a new variable h f in the Bernoulli equation . Based on it, we will get the coefficient of centrifugal shear ( L) and the coefficient of secondary flow (Z ) .(3)Making the centrifugal shear secondary flow theory appliance in coagufloccule and comparing the result of general flow field,the experiment data indicate that floccule agglomerate quickly whose amount is large ,and the sedimentation is rapid , floccule particles are tight. In a word ,the result is as 5～10 times as the general cogufloccuation .(4)Using the Froude rule and Reynolds rule in similitude magnifying theory, we magnify the model of centrifugal shear secondary flow field .Through coagu-flocculation indoors experiments and corresponding resemble magnifying experiments, the result indicate that it approach to indoors experiment .更多还原