开放式奶牛舍扰流风机扩散器性能参数优化

Optimization of Diffuser Parameters of Mixing Flow Fans in Open Dairy House

为了提高奶牛舍夏季扰流风机的降温效果,在不改变扰流风机外形尺寸以及叶片形状的条件下,通过数值模拟以及现场实验的方法,优化扰流风机扩散器性能参数来提高风机性能。选取扩散器的开合角为90°、120°、150°和180°,以及扩散器的长度为150、250、350、450、550、650 mm,利用CFD数值模拟建立了24种扩散器扰流风机的几何模型,以扰流风机性能、距扰流风机轴心0.5~1.0 m处的流场速度分布以及气流不均匀系数为评价指标,优化了扰流风机扩散器开合角和长度。结果表明,150°/250 mm扩散器使得扰流风机的风量提高了3.80%,能效比增加11%,轴心速度较大,且气流均匀性较好。

In summer,the mixing flow fans（ MMF） are usually used to reduce the heat stress in dairy cows. In order to improve the cooling effect of mixing flow fans（ MMF） in summer open dairy house,numerical simulation and field experiment were adopted to optimize the performance of MMF,without changing the dimensions and blade shape. Totally 24 geometry models of MMF with diffusers of different angles（ 90°,120°,150° and 180°） and different lengths（ 150 mm,250 mm,350 mm,450 mm,550 mm and 650 mm） were established for CFD simulation,and the angles and lengths of diffuser were optimized by taking the fan performance,wind speed distribution in the distance of 0. 5 ~ 1. 0 m from MMF axial and non-uniform coefficients as evaluation indexes. In this thesis,the diffuser angle 90° was taken as an example,the best diffuser length of the diffuser angle 90° was elected according to the fan rotation speed distribution and the diffuser effect of overall calculated filed. The analysis of other diffusers angles（ 120°,150° and 180°） used the same methods. The angle and length of the diffusers（ 90° /450 mm,120° /350 mm,150° /250 mm） were better to improve the MMF air flow and flow field uniformity,making use of analysis the jet length and average axial velocity. Finally,according to the simulation and experimental results,the 150° /250 mm diffuser increased the wind quantity and efficiency ratio by 3. 80% and 11% respectively, and led to greater axial velocity and better non-uniform coefficients. This improvement provides a theoretical basis for facility agriculture equipment while reducing production costs.