基于CFD的文丘里施肥器收缩与扩散段结构优化

Structure Optimization of Contrsction and Diffusion Section of Venturi Fertilizer Based on CFD

为了研发新型文丘里施肥器,提高其吸肥性能,使之适应不同工况的进出口压差,讨论了相同喉管进出口直径之比λ的条件下,得到最佳收缩段与扩散段的结构组合方案。本文采用solidworks2016、CFD软件,对14种不同模型进行建模并计算分析。研究不同组合形式结构的吸肥量q、肥液比δ、肥液浓度γ、吸肥效率η,4个指标以及流场压力、速度、湍动能、流线分布,综合评价吸肥性能的优越性。结果表明:①压差与吸肥量呈现幂函数的关系,压差越大吸肥量越大,但是增大的趋势越来越缓慢,压差与吸肥效率呈现指数函数的关系,压差越大,吸肥效率越小,减少的趋势越来越平缓;②喇叭口收缩段与流线型扩散段结构方案对比同系列产品,吸肥量最大提高80%,肥液浓度随压差变化最稳定,对不同工况适应性最强;③在相同的工况下,喇叭口收缩段与流线型扩散段结构方案,在喉管附近产生的真空度最大、压力最小、速度最大,产生旋涡区所对应的中心截面上平均湍动能最小,最有利于吸肥;综合吸肥性能与流场分析,最优的组合形式为喇叭口收缩段与流线型扩散段。

In order to develop a new Venturi fertilizer, improve its ability to absorb fertilizer and adapt it to different conditions of inlet and outlet pressure differential, the optimal structure combination scheme of contraction and diffusion section is discussed under the same ratio of inlet and outlet diameters. In this paper, the solidworks 2016 and CFD software were adopted to model and calculate 14 different models. The four indexes, including fertilizer absorption amount, fertilizer-liquid ratio δ, fertilizer concentration γ and fertilizer efficiency η, and other indexes, including flow field pressure, velocity, turbulent kinetic energy and the streamline distribution, of different structure combination forms are studied to comprehensively evaluate the fertilizer absorption performance. The results show that:① there is a power function relationship between the pressure difference and the amount of fertilizer absorption. The larger the pressure difference is, the larger the amount of fertilizer absorption is, but the trend of increase is slower and slower.② compared with the same series of products, the structural scheme of bell-bottom contraction section and streamlined diffusion section shows that the maximum fertilizer absorption is increased by 80%, the concentration of fertilizer liquid changes most stable with the pressure difference, and it has the strongest adaptability to different working conditions.③ under the same working conditions, the structural scheme of bell inlet contraction section and streamlined diffusion section generates the maximum vacuum, minimum pressure and maximum velocity near the throat, and the average turbulent kinetic energy on the central section corresponding to the vortex zone is the minimum,which is most conducive to fertilizer absorption. Based on the analysis of fertilizer absorption performance and flow field,it can be found that the optimal combination is bell-bottom contraction section and streamline diffusion section.