基于CFD的新型布浆器混合室结构

为了进一步改善新型布浆器的布浆性能，设计了单腔式混合室（混合室Ⅰ）、以两组支管为单位的多腔式混合室（混合室Ⅱ）及以单组支管为单位的多腔式混合室（混合室Ⅲ），采用计算流体力学（CFD）方法对混合室内的流动特性进行了模拟。结果表明，单腔混合室内，由于平行射流组各股射流间的强烈干涉作用，导致各股射流向混合室中部聚集，造成出口处质量流量分布呈现中间明显高于两侧的状态。在多腔混合室Ⅱ内，每个混合腔内有两组射流，保证了浆料的良好混合，避免了射流在中部聚集的现象。在多腔混合室Ⅲ内，由于每个混合腔内只有一组支管射流，实现了互补混合过程，混合效果明显好于混合室Ⅰ和混合室Ⅱ。从质量流量分布看，混合室Ⅲ的分布曲线比混合室Ⅰ和混合室Ⅱ的更平缓，其最大偏差仅为0.254%，明显小于混合室Ⅰ的0.538%和混合室Ⅱ的0.294%，更接近于理论混合平均值和期望值。

Study on structure of mixing chamber in new pulp distributor based on CFD

In order to improve performance of pulp distribution of new distributor，three structures of mixing chamber were designed，namely single cavity mixing chamber （mixing chamberⅠ），multicavity mixing chamber with two sets of branch pipes as a unit （mixing chamberⅡ），multicavity mixing chamber with a set of branch pipe as a unit （mixing chamberⅢ），and computational fluid dynamics（CFD） was used to simulate flow characteristic in three mixing chambers. The results showed that in the mixing chamberⅠ，there was strong interference effect between two adjoining jet-flows in a row parallel pipes and jet-flows assembled to central section in mixing chamber. So the mass flow rate out of mixing chamber in center was obviously higher than two sides. In the mixing chamberⅡ，two sets of jet-flow in a mixing chamber could have a good mixture and avoided phenomenon of jet-flows aggregation. In the mixing chamber Ⅲ，there were only two jet-flows of corresponding branch pipe in every mixing chamber and complementary mixture was really realized. From the viewpoint of distribution of mass flow rate out of mixing chamber，the curve of mass flow rate of mixing chamberⅢ was much gentler than mixing chamberⅠ and mixing chamberⅡ. Maximum deviation of mass flow rate to expected value in mixing chamberⅢ was only 0.254%，obviously smaller than 0.538% in mixing chamberⅠand 0.294% in mixing chamberⅡ.