吸粮机三级离心风机内部流场的数值模拟

Numerical simulation of internal flow field in three-stage centrifugal fan of grain sucker

为了较好地捕捉多级离心风机内部流动特征,该文以吸粮机使用的三级离心风机为研究对象,应用FLUENT6.3软件对其内部流场进行了整机三维稳态可压缩计算。计算过程中综合考虑了准确性和经济性,以Pro/E系统建立了风机的全流道模型,利用动参考系(moving reference frame,MRF)模型实现了叶轮间流动参数的实时传递,用重整化群(renormalization group,RNG)κ-ε湍流模型、一阶迎风空间离散格式、Roe-FDS(flux difference splitting)通量差分方法实现了该三级离心风机整机的可压缩计算。根据计算结果,得到了风机内部主要区域的压力与速度分布图,通过分析发现风机内部各级叶轮间气体流动速度基本不变,静压力和总压力逐级上升,第1级和第2级叶轮内的流场分布呈对称性,而第3级叶轮内的流场分布呈非对称性。通过对蜗壳内部流场的分析发现了此风机内部流场在蜗壳小端流动不顺畅的设计缺陷,并给出了蜗壳结构的改进意见,为进一步提高风机效率提供了参考。

In order to catch the figure of internal flow field of multi-stage centrifugal fan,centrifugal fan of a pneumatic grain sucker was used as the research object in this thesis,three-dimensional steady and compressible computation was performed for its whole internal flow by using FLUENT 6.3 software.During the course of the calculation,the accuracy and efficiency of computation were overall considered,the model of all channels were built by using Pro/E as a solution domain,the MRF（moving reference frame）method was used to realize real-time transmission of flow parameters among each stage impeller,the RNG（Renormalization Group） k-ε turbulent model and method of Roe-FDS（Roe flux difference splitting）flux difference with first order upwind spatial discrete schemes were used to realize the simulation.According to the result,the distribution diagrams of pressure and velocity in the main area were provided,through analyzing it was found that flow velocity of gas between each impeller maintains the same level,but static pressure and total pressure increase gradually,and except the third impeller,the distribution of flow field in the first and second impeller is mostly symmetrical.Through analyzing the internal flow field of volute,the design defect of this fan that gas could not flow smoothly in the small part of volute was discovered,and the advice for improving volute structure was given,which provides reference for improving the efficiency of the fan.