Study On Aerodynamic Noise Of Mechanical Ventilation Cooling Tower

The sharp rise in industrial water consumption will inevitably exacerbate the level of water resource calls,In order to reduce the waste of water resources,cooling tower is used as a core component in industrial waste heat recycling system,gradually widely used in electric power,chemical industry,refrigeration,textile,air conditioning and other fields.In the cooling system,the mechanical ventilation and the wet counter flow cooling tower are mainly selected.However,the operation of large power fan will inevitably lead to noise pollution.This subject is based on the theory of aerodynamic noise and fluid mechanics,and carry out the mechanical ventilation cooling tower for the experiment of Aerodynamic noise research.The following parts are studied in order to reduce the noise of the cooling tower:Study on flow instability of fan in cooling tower.In view of the aerodynamic noise disturbance caused by the cross beam structure at the fan inlet,The experiment is based on Fluent simulation technology,and qualitatively analyzes the flow inside the cooling tower under the two working conditions with or without cross beam structure,analysis of cooling tower fan internal noise source size distribution and export monitoring points of estimated noise spectrum.Then,different kinds of cross beam have been selected to study the influence of aerodynamic noise of the fan.That the leading cross beam structure can reduce the turbulence intensity,make airflow more uniform and reduce the influence of fan tonal noise have been verified.Application of damping net in control of aerodynamic noise of cooling tower fan.Through the design and installation of the damping network,the turbulence noise of the fan is controlled,Under the premise of choosing a kind of porosity damping network,install one layer,two layers,three layers of different combinations,and a total of seven kinds of working conditions.The experimental results show that under the condition of installing second or third layers of damping nets,the effect is better.Application of foam material in control of aerodynamic noise of cooling tower fan.For fan blade surface caused by the unsteady fluctuating pressure fan aerodynamic noise effect,with the feature of foam material,the fan blades are respectively pasted foam and foamed nickel material,exploring the role of foam to reduce the ratio of fan aerodynamic noise effects.The experimental results show that the aerodynamic noise of the fan will be attenuated to a certain extent under the cushioning of the foam material.Study on the cooling tower fan tip clearance effect on aerodynamic noise.In view of the influence of blade tip vortex and blade tip return on the aerodynamic noise of axial flow fan blade in cooling tower.The experiment through the design of fan blades and fan wheel,the distance between the tip of tower from the original 17 mm reduced to 7mm,which can effectively improve effect of tip vortex,reduce the fan noise.