气-气混合器的数值模拟及优化设计研究

Numerical Simulation and Optimization Design of a Gas Mixer

设计了一种体积小、压降低的新型气-气混合器,用于实现燃气与空气的均匀混合。利用Fluent数值模拟的方法研究了有导流板和无导流板两种情况下气-气混合器内的流场分布及混合效果,发现无导流板时混合器内存在一个旋涡区,混合器出口截面上的混合不均匀度S=0.0536,空气在混合器中的总压降为960 Pa,空气与燃气进气压差为1164 Pa;有导流板时混合器内存在两个旋涡区,混合器出口截面上的混合不均匀度S^(*)=0.0454,空气在混合器中的总压降为1109 Pa,空气与燃气进气压差为1143 Pa。结果表明增设导流板后的气-气混合器整体压降增加约150 Pa左右,但混合效果更优,可实现均匀混合。对于有导流板的混合器结构,随着空气流量增加,压降增长十分显著,混合不均匀度随空气流量的增加而先下降后增长,燃气流量对压降及混合效果影响均不大。

A new type of gas mixer with small volume and low pressure drop was designed to realize homogeneous mixing.The flow field distribution and mixing nonuniformity of the gas mixer with and without baffles were studied by numerical simulation.There was only one vortex region in the mixer without baffles,but two vortex zones in the mixer with baffles.For the gas mixer with and without baffles,the mixing nonuniformities were 0.0536 and 0.0457,the total air pressure drops were 960 Pa and 1109 Pa,and the pressure differences between air inlet and gas inlet were 1164 Pa and 1143 Pa,respectively.Owing to the baffles,the overall pressure drop increased about 150 Pa,and mixing nonuniformity was small enough to achieve the desirable mixing effect.For the mixer with baffles,the pressure drop increased significantly with the increase of the air flow rate,and the mixing nonuniformity decreased first and then increased with the increase of the air flow rate.The gas flow rate had little influence on the pressure drop and mixing effect.