基于变环量方法的农用轴流风机设计及性能优化

Expansion of the operation range of agricultural axial flow fans based on the variable circulation method

随着农业设施养殖空气过滤装置使用的普及,对高压农用轴流风机的需求也随之提升。为了提高农用轴流风机的气动性能并扩大工作压力范围,利用变环量设计理论,通过风洞试验和数值模拟,对风机叶片进行了重新设计。旨在改变现有叶片轮毂处结构形式,改善农用轴流风机内部流态,达到提升农业轴流风机气动性能和扩大稳定运行范围的目的。该研究以0.91 m农用轴流风机尺寸及目标风量为设计参数,利用变环量方法设计了一款叶片。通过单因素和响应面分析方法,研究了轮毂直径d、安装角α和叶片数n结构参数对风机性能和流场的影响。最佳工艺参数为d=260 mm,α=-0.369°,n=4片。数值模拟结果表明,优化后的轴流风机性能优于设计轴流风机,扩大了高压区稳定运行范围。样机试验测试表明,在高压(120 Pa)下,优化风机相较于原型轴流风机的风量提高了163%(达到18 710.99m3/h),能效比提高了18.9%(达到1.94 m3/(h·W))。该研究证明了变环量在农用轴流风机设计中的可行性,结构参数的优化可进一步降低风机的内部涡流。优化后的轴流风机减少了内部流场的二次流,提高了叶片的做功能力,改善了风机的气动性能,确保轴流风机在农业应用中能够更高效地实现空气流通与调控。

With the increased usage of air filtration and deodorization devices in livestock houses,the demand of agricultural axial flow fans with higher pressure has been raised.To improve the aerodynamic performance of an agricultural axial fan and expand its operating range,a new axial fan was developed using the theory of variable circulation method design via wind tunnel experiments and numerical simulations.The purpose is to change the structural form at the hub of the existing blade to improve the internal flow pattern of the agricultural axial fan,so as to achieve the purpose of improving the aerodynamic performance of the agricultural axial fan and expanding the range of stable operation.In this paper,a new agricultural axial flow fan is designed using the variable circulation method with 0.91m agricultural axial flow fan size and target airflow as design parameters.Secondly,the structural parameters at the hub of the axial fan are optimized by combining the simulation results of the flow field of the designed fan.Factors such as hub diameter d,the placement angleαand the number of moving blades n are analyzed individually,revealing the basic law of the influence of the changes of these factors on the performance of the fan,and the influence of the changes of each factor on the internal flow field of the fan is observed in combination with post-processing.using the better intervals for each factor derived from the one-factor optimisation results,the ventilation volume Q and the energy efficiency ratio N were selected as response values,and a response surface simulation study was carried out for the hub diameter d,the placement angleα,and the number of moving blades n.The response surface simulation study was carried out for the hub diameter d,the placement angleα,and the number of moving blades n.The response surface functional equations were obtained and the better parameter combinations were determined.The correctness of the functional model is further verified by observing the flow field characteristics and external characteristics through post-processing.Finally,the optimised impeller was fabricated by 3D printing technology and wind tunnel tests were conducted,and the results of the actual tests further confirmed the accuracy of the optimisation results.The numerical simulation results of the study show that the optimum combination of these parameters is d=260 mm,α=-0.369°,and n=4 pieces.Experimental test results show that the optimized axial fan performance is better than initial axial fans.On the high-pressure level(120 Pa),the ventilation volume Q of agricultural axial fan increased by 163%,and the energy efficiency ratio N increased by 18.9%.This study proves the feasibility of the variable circulation method in the design of high-pressure agricultural axial flow fan,and the optimization of structural parameters can further reduce the internal vorticity of the fan.The optimized axial fan reduced the secondary flow in the internal flow field,increased the work capacity of the blades,and improved the aerodynamic performance of the fan,ensuring that the axial fan can achieve air circulation and regulation more efficiently in agricultural applications.