| Axial flow fan is a kind of impeller machinery mainly used for pumping,conveying and improving gas energy.It is widely used in petrochemical industry,such as the main fan in catalytic cracking unit,mechanical ventilation tower,oil and gas gathering and transportation process.This paper studies a certain type of carbon steel axial flow fan,which consumes a large amount of electricity and has low operating efficiency in actual working conditions.Therefore,the flow field distribution characteristics and performance curves of the axial flow fan are deeply explored to improve the full pressure efficiency of the axial flow fan,which provides a theoretical reference for the performance optimization of the axial flow fan.In this paper,the numerical simulation of the axial flow fan is carried out to investigate the internal flow characteristics of the axial flow fan and the influencing factors of the fan performance.The effects of different blade structure parameters on the performance of the fan are explored.From the three aspects of blade relative thickness,installation angle and blade tip clearance,the blade is structurally optimized to improve the internal flow and operating efficiency of the fan.The guide vane is constructed after the axial flow ventilation of the motorized blade,which can reduce the radial energy loss of the airflow,improve the interference of the tail vortex on the mainstream area,and improve the wind pressure and operating efficiency of the fan.Explore the effects of rear guide vanes on fan performance and total pressure efficiency.The numerical results show that the pressure surface of the fan blade is positive pressure and reaches the maximum static pressure at the leading edge of the pressure surface.The suction surface of the blade is negative pressure,and the flow separation is gradually formed.Since the tail of the blade exerts a transverse shearing force on the surrounding airflow,there is a de-vortex phenomenon of the impeller wake,which consumes kinetic energy of the gas and reduces the efficiency of the fan.The greater the relative thickness of the axial flow fan impeller,the lower the airflow impact loss of the impeller leading edge.The flow separation phenomenon of the impeller suction surface is improved,and the total pressure and total pressure efficiency of the fan are increased.The larger the blade mounting angle,the lower the impeller circumferential load.The phenomenon of de-vortexing of the impeller wake is improved,and the total pressure and efficiency of the fan are improved.The tip clearance is small,and the static pressure distribution on the impeller pressure surface is reasonable.The impeller has a uniform work,the tip discharge is small,the turbulence intensity at the tip of the blade is low,the flow is relatively stable,and the total pressure and total pressure efficiency of the fan are improved.Under the design flow rate of 18000m~3/h,the comparison of the relative thickness of the fan is 20%,30%,40%,50%of the four sets of blades,of which40%of the fans have the best performance,and the total pressure efficiency is improved by3.05 percentage points before optimization.Comparing the installation angle of the fan to 6sets of blades of 6 degrees,8 degrees,10 degrees and 12 degrees,the performance of the blade mounted angle fan of 12 degrees is the best,and the total pressure efficiency is increased by 2.2 percentage points before optimization.Compared with the fan blade tip clearance of 5mm,10mm,15mm,20mm four sets of blades,the 5mm tip clearance fan has the best performance,and the total pressure efficiency is improved by 3.75 percentage points before optimization.The rear guide vane can reduce the radial energy loss of the airflow,improve the interference of the tail vortex flow to the mainstream area,and improve the full pressure and full pressure efficiency of the axial flow fan.Compared with the rearless guide vane fan,the total pressure of the fan is increased by 12.82.Pa,the total pressure efficiency is increased by 5.73 percentage points.Therefore,through the analysis of the internal flow field of the axial flow fan,the influence of different blade structure parameters and the rear guide vane on the performance of the fan is explored,which provides a valuable reference for the blade design and performance optimization of the axial flow fan. |
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