Study on Wear Characteristics and Failure Pridiction of Flat-fan Nozzles
|School||Nanjing Forestry University|
|Course||Mechanical Design and Theory|
|Keywords||Flat-fan nozzles Erosion wear Solid-liquid two-Phase flow Solidpesticide particles Wear rate Failure standard|
The development trends are referred to high efficiency and safety and precisionon the pesticide applying machines from improving work efficiency and reducing thelabor intensity. Firstly, the influences of the wear of the hydraulic flat-fan spraynozzles on the quality of spraying facilities were discussed. Secondly, according to thestudy status of the hydraulic spray nozzles wear both at home and abroad. Factorswhich influence the flat-fan nozzles wear and the effect of the performanceparameters by wear were discussed. Finally, the wear characteristics and wearbehavior of the flat-fan spray nozzles were studied, and a set of the experimentalset-up system for measuring spray nozzles wear was developed and manufactured.Based on the theory of fluid dynamics and particles dynamics, the solid pesticideparticles’ properties on its motion in the solid-liquid two-Phase flow of the flat-fannozzles were analyzed. The properties on its motion is belong to mixed flow of theboundary-layer in the dilute solid-liquid two-Phase flow; The main forces that theparticles bears include liquid drag forceuFuvuuvD, pressure gradient forceFg, gravity forcewand Saffman forceuFuvSin the process of motion.The relationship impact angle on the spherical surface and that on the plane werediscussed according to the actual shape on the spherical-top of flat-fan nozzlesorifices. And the mathematical model of boundary-layer in the solid-liquid two-phaseflow of the flat-fan nozzles, the motion equation of the particles in the solid-liquidtwo-phase flow on the inner surface of the flat-fan nozzles.Based on the erosion wear theory of micro-cutting and energy dissipation, thetwo wear rate equations were established, the one was the relationship between usagetimes and the spherical-top configuration parameters of the flat-fan orifices, anotherwas the relation between wear rate and pesticides consumption.The kinematic velocity and Trajectory of the particles and the inner flow in theflat-fan nozzles by the computational fluid dynamics（CFD）simulation. In order toverify the theoretical analysis of the results, the test bench for measuring spraynozzles wear is to be built, the TP11002VB flat-fan nozzles of Spraying SystemsCompany U.S.A and LU110-05flat-fan nozzles of Germany were selected. The testdata verify that wear greatly influence flow of spray nozzles, it is compatible whichthe experiment data and the theoretical analysis of the results. The correctioncoefficient of the wear rate formula is determined by regression analysis, and itsapplicability was verified.The results of study could be application with the failure prediction and todevelop the failure standard for regular examination of the flat-fan nozzles.