| Fan is conveying gas equipment,which has widely application in the areas of economy departments.From the point of energy transformation,the fan is a machine that can transform the prime mover's mechanical energy into gas's kinetic energy and the pressure.According to the requirements of industry,the fan has variety of forms.The object of research is based on axial flow fan of marine.We mainly discussed how to achieve the numerical simulation and performance improvement of axial flow fan.We tried to develop the numerical simulation firstly,exploring the inner flow field of axial flow fan.In the working range of fan,the original axial flow fan has the performances of sufficient pressure and low efficiency.As we all known,we can achieve the purpose of raising the pressure of axial fan by the way of increasing the installation angle of impeller.In this way,the axial fan can meet the requirements of the total pressure,but with lower internal efficiency and higher power in the flow scope of fan.In the point of volume flow for Qv=24000m3/h,the fan internal power is 7.559kw,which is more than the motor power 7.5kw.Thus,there will be super power over current phenomenon.The research is based on CLARK y profile.The study on profiles contains the following two aspects:the center line forms and the thickness.One method is put forward,that is suitable for the center line of axial fan's profile.From the aspects of improving the axial fan'pressure,triangle discharge method is better than that of shaft.Of course,triangle discharge method is better than the commonly used single arc center line.Profile thickness change is achieved through the airfoil chord length and thickness direction enlarged or reduced in proportion.Appropriate minus the thickness of profile is favorable for axial flow fan,the total pressure and efficiency.Our designing goal is to meeting the pressure required for premise,with the found of improve the efficiency of axial flow fan as far as possible.Due to the higher demand of total pressure of axial fan researched,the commonly used equal circulation and variable circulation method don't fit with this situation any more.So this research proposes an improved variable circulation designing method.The fan blade of guide section of axial flow fan has great influence on fan performance.The original model of stator blade is too little in quantity,and the inlet angle is small,so we improved the guide section.The stator blade is the combination of straight blade and circular plate blade.We increased the inlet angle and number of inlet arc blade,with the result of higher total pressure and efficiency.The above numerical simulations show that the purpose model is better in fan performance,without super current risk.Axial flow fan's total pressure efficiency decreases with the increasing of volume flow.When the volume flow is 21000m3/h,the pressure efficiency is the worst,66.61%.Compared with the original model 1fan,the total pressure increased 138.3Pa,the total pressure efficiency increased by 12.69%.And compared with the original model 2 fan,the total pressure increased 74.42Pa,the total pressure efficiency increased by 14.45%.When the volume flow is 30000m3/h,the pressure efficiency is the best,79.48%.Compared with the original model 1fan,the total pressure efficiency increased 8.066%.And compared with the original model 2 fan,the total pressure efficiency increased 10.56%. |
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