Analysis And Test Of The Flow Field And Aerodynamic Noise Of The Air Cylinder Of Air-Assisted Sprayer

Air-assisted sprayer is a new type of spray application machinery,because of its characteristics of good spraying effect,long range,high efficiency,and was widely used in agricultural plant protection and application of medicine,environmental protection dust haze,industrial dust cooling and other fields.With the increasing speed and flow of the sprayer,the sprayer will produce a large noise in operation,which will have a negative impact on the physical and mental health of personnel,safety and production.Therefore,in this paper,using the theory of computational fluid dynamics and fan noise control methods,we carry out a study on the flow field and noise control of air-assisted sprayers.Experimental studies are conducted to provide effective and feasible solutions to reduce the noise of air-assisted sprayers.The main elements of the work are as follows.(1)A computational model of the air-assisted sprayer simulation is established,and in order to shorten the computation time for fluid simulation,the air-assisted sprayer model is simplified as follows guide leaf,deflector,and blade.Numerical calculations of the blade mounting angle and the shape of the deflector vane are carried out using the RNG k-εmodel,and the simulation shows that the blade mounting angle at 30°～35°,air-assisted sprayers with outlet speeds ranging from 19m/s to 46m/s,with bent deflector blades installed.The ability to reduce airflow energy losses from air-assisted sprayers.(2)Based on the flow field steady-state calculation results,the wide band noise source distribution of the air-assisted sprayer was calculated,and surface acoustic power level clouds were obtained for each component of the air-assisted sprayer.The study shows that the presence of large sound power levels at the top of the air inlet of the air-assisted sprayer and at the leading edge section of the deflector blades.(3)A study of the noise directivity and vibration noise of a air-assisted sprayer using a sound level meter and a vibration noise analysis system.Noise spectrograms and 1/3octave analysis at the monitoring points.The test shows that the peak of pneumatic noise of the air-assisted sprayer occurs at the fundamental frequency and high harmonics.The vibration noise peak occurs at a frequency close to the fundamental frequency of the air-assisted sprayer,indicating the existence of resonance phenomena in the sprayer,at the top of the sprayer inlet.The maximum amplitude at the monitoring point at the three channels was 3.04 d BA,3.02 d BA,1.92 d BA,respectively.(4)By laying noise reduction materials(nitrile rubber,aluminum foam metal,nickel foam metal)in the runners of the wind-fed sprayers,the monitoring points sound pressure level variation and 1/3 octave analysis.Tests show that the use of noise-reducing materials can reduce the aerodynamic noise of air-assisted sprayers to varying degrees,with 5mm thickness of foam Aluminum metal has the best noise reduction,with the sound pressure level monitored at each monitoring point being 2d B lower than that of the original turbine.