Research On Flow Field Characteristics And Structure Optimization Of Macro-scale Fluid Distribution Manifolds

Fluid distribution manifolds are very common device applied to divert fluids in the industry.The horizontal channel used to evenly distribute the dust-containing airflow configured on the large bag filter in the actual project is a typical application case of macro-scale fluid distribution manifold.Uneven distribution of horizontal channels will directly lead to a reduction in dust removal efficiency and an increase in operating costs,respectively.Therefore,in order to improve the overall performance of such equipment,unequal distribution of flow in macro-scale fluid distribution manifolds needs to be overcome urgently.In this thesis,the flow field characteristics and structural optimization of macro-scale fluid distribution manifolds were studied.Firstly,research on the header shape and overall structure of the fluid distribution manifolds were conducted through theoretical methods,and the main factors affecting the fluid distribution performance of the fluid distribution manifold were obtained;Secondly,by establishing the fluid dynamics numerical model of the fluid distribution manifold,the effects of the inlet Reynolds number,ratio of width to length of the rectangular section of the branch pipe,the area ratio of the manifolds,and the linear tapering angle of the header on the flow distribution performance of the fluid distribution manifold were investigated.The correlation between factors and the uniformity of flow distribution as well as pressure drop were reflected to obtain a reasonable means to improve the uniformity of flow distribution;then,the multi-factors cooperative effects on the flow field characteristics of the fluid distribution manifold were studied by numerical simulation.The degree of importance of the factors was obtained by range analysis method,and the multi-variable non-linear regression model was used to optimize the structure of fluid distribution manifold.Finally,according to the relevant design parameters in the actual project,the original fluid distribution manifold structure was optimized based on the abovementioned optimization model,and the flow distribution performance under different models was studied by setting up a non-optimized and optimized fluid distribution manifold performance model experimental platform,making the accuracy of optimized model verified.The main conclusions and innovations of this thesis are as follows:(1)Theoretical analysis was conducted to research on impact of header shape on fluid distribution manifolds based on overall balance algorithm.In detail,frictional resistance coefficient and local resistance coefficient of manifolds were quantified to obtain that fluid distribution uniformity could be effectively improved by tapering header linearly.Meanwhile,effects of overall structure of manifolds on fluid distribution performance were investigated theoretically based on momentum conservation algorithm and differential control equation of fluid distribution manifolds were compiled,including frictional coefficient and momentum coefficient.At last,eight main influencing factors of fluid distribution performance were concluded,i.e.,length of manifold header(L),cross-sectional diameter of manifold header(D),length of horizontal branch pipe(L_o),cross-sectional diameter of horizontal branch pipe(D_o),number of horizontal branch pipe(N),absolute wall roughness of manifold(K),linear tapering angle of header(θ)and inlet Reynolds number(Re).(2)Effects of inlet Reynolds number,ratio of width to length of the rectangular section of the branch pipe,area ratio of the manifolds,and linear tapering angle of the header on the fluid distribution performance of the fluid distribution manifolds were explored in numerical way.The results showed that at Re=4×10~5~4×10~6,little correlation could be found between fluid distribution uniformity and inlet Reynolds number.There was inverse relationship between ratio of width to length of the rectangular section of the horizontal branch pipe and fluid distribution uniformity,but positive correlation between that and pressure drop of air flow in manifolds was found.When areas of manifolds decreased,air flowing resistance inside manifolds increased evidently and flow distribution uniformity enhanced.As the linear tapering angle of the header increased,air flowing resistance inside manifolds declined slightly and flow distribution uniformity improved.The optimized longitudinal section of header was proved to be triangle.(3)Range analysis method was applied to rank the important degree of influencing factors on fluid distribution uniformity orderly,i.e.,area ratio of manifolds,length of header,absolute wall roughness,length of horizontal branch pipe,inlet Reynolds of manifolds.Optimization model of fluid distribution manifold was obtained by multi-variable non-linear regression model under the cooperative effects of aforementioned influencing factors.(4)By referring to relevant design parameters and the optimization model,the optimal value of area ratio of manifolds was calculated.In the model experiment,the effects of both non-optimized and optimized fluid distribution manifold models on flow field characteristics were researched comparatively.It turned out that optimized fluid distribution manifold model could not only improve fluid distribution uniformity,but also reduced flow resistance to a small extent,which manifested the accuracy of optimization design.