3D-不对称菱形被动式微混合器混合特性

提高微混合器雷诺数的适用范围和混合强度是微混合器设计的发展趋势。本文基于非对称分离重组混合原理设计、制作了一种3D-不对称菱形被动式微混合器,并借助数值分析方法和可视化实验对混合强度和混合状态的变化进行了研究。研究发现:在低Re(0.01~10)范围内,两组分间的混合以扩散混合为主,随着Re的增加,流速对混合强度的影响有一定下降;在较高Re(10~200)范围内,受流速增加的影响,流体间不平衡微流惯性碰撞逐渐成为影响混合的主要因素。此时,混合强度随流速的增加逐渐增强并趋于平稳。对Re在0.01~200内的微混合器展开研究,分析了宽缝比Ws/S、分合角θ、宽厚比H/S等结构尺寸对混合强度的影响。通过综合考虑流体混合强度和通道压降的变化情况,确定最佳通道结构尺寸为Ws/S=0.2、θ=45°、H/S=0.5,此时微混合器的混合强度可维持在78%以上。与传统平面对称分合式混合器相比,设计制作的3D-不对称菱形被动式微混合器混合强度有较大的提高,验证了本文设计结构的有效性。

Mixing characteristics of passive-type micro-mixer with 3D-asymmetrical rhombus

Increasing applicable scope of Reynolds number and mixing strength is development trend of micro-mixer design . A passive-type micro-mixer of 3D-asymmetrical rhombus was designed and manufactured on the basis of asymmetrical separation and reconstruction mixing principle ,and change of mixing strength and mixing state were studied by means of numerical analysis and visualized experiment .Results indicate that in scope of low Re (0 .01~10) ,the mixing between two components is dominated by diffusion mixing ,with increase of Re ,the influence of flow speed on mixing strength decreases to a certain degree ;in higher scope of Re(10~200) ,influenced by increase of flow speed , the inter-fluid imbalance inertia collision becomes the main factor affecting mixing , and mixture strength gradually increases and tends to be stable with increase of flow speed .Take the micro-mixer with Re scope of (0 .01~200) as research object ,influence of structural sizes such as width slit ratio W/s S , divided-compound angle θ, width-to-thickness ratio H/S , etc on mixing strength was analyzed .By taking into consideration of fluid mixing strength and change of passage pressure drop comprehensively ,the optimum structural size of passage was designed as Ws/S=0 .2 ,θ=45° ,H/S=0 .5 ,and mixing strength of micro-mixer can maintain above 78% .Compared with traditional planar symmetrical separation-and-reconstruction mixer , mixing strength of designed passive-type micro-mixer of 3D-asymmetrical rhombus is greatly increased , w hich verifies the effectiveness of the structure .