| The artificial rainfall simulation system can simulate natural rainfall intensity and raindrop size by adjusting the pressure of work.But in certain pressure range the droplet diameter of existing rigid artificial rain nozzle decreased with the increasing of pressure while the actual rainfall changes conversely.This paper is devoted to develop a flexible variable nozzle whose diameter will increase when pressure increases,so that the droplet diameter closes to natural raindrop diameter.The main research results are as follows:(1)In the design requirements of nozzle diameter with working pressure self-adjusting,in this paper,according to the position of nozzle and flexible variable nozzle,designed the flexible nozzle variable nozzle,flexible pipe nozzle,variable cross-section nozzle,three nozzle structures.Analyzed the conical nozzle,streamline nozzle and conical nozzle and streamline square nozzle four nozzle structures.Finally determine the structure was flexible variable conical nozzle.(2)According to the nozzle structure and the working characteristic of flexible nozzle determined the elastic parameters of nozzle.From the fluid domain and solid domain solution two aspects elaborated the flow solid coupling of the solving process,combined with the single variable method to determine the elastic parameters of nozzle were as follows:400 taper Angle,thickness 5mm,4mm,cylindrical length 6mm.(3)Using one way fluid-solid coupling simulated elasticity of flexible nozzle in the inlet pressure 100kPa,150kPa,200kPa,250kPa and 300kPa,rubber elastic modulus 2MPa,the nozzle diameter 1mm,2mm,3mm,4mm and 5mm.Using Cook.Woodley average calculated droplet diameter of spraying raindrop diameter calculations raindrop size,then using Excel fitted spray nozzle diameter,working pressure and raindrop diameter curve fitting,by comparing the different degree of curve fitting to determine the diameter of the spray nozzle diameter,working pressure,and the rain.The relationship between raindrop diameter and the nozzle diameter was power function.The relationship between presser and raindrop diameter was power function also.The relationship between working pressure and the diameter of nozzle was linear.Setting the relationship of a spray nozzle diameter,working pressure,and the rain of the diameter was power function.(4)Experimental verification.The three samples of 2mm,3mm and 4mm diameter and elastic modulus of the material to 2MPa were made,then tested the flow rate of them in the working pressure of 200kPa,250kPa and 300kPa,and compared the simulated data of flow rate.The error between testing data and simulated data was within 10%,so the nozzle of the simulation model was reasonable. |
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