【作者】 翟恩昱；

【导师】 郑加强；

【作者基本信息】 南京林业大学 ， 机械设计及理论， 2012， 博士

【摘要】 植保机械的使用正逐步从提高作业效率、减轻劳动强度向高效、安全、精准等方向发展，喷头作为植保机械的关键部件之一,其结构的合理性决定了药液的雾化效果,而过度磨损会造成喷头结构尺寸和精度改变，导致喷头使用性能达不到要求。论文阐述了液力式扇形雾喷头的磨损对植保机械质量的影响，在分析国内外液力式雾喷头磨损研究的基础上，研究了造成扇形雾喷头磨损的因素，以及磨损对各喷雾指标的影响，利用固液两相流动理论探索了扇形雾喷头磨损特点和磨损规律，模拟仿真了扇形雾喷头内部流场和固体颗粒运动轨迹，并研制了一套液力式雾喷头磨损测试试验系统，测试了磨损对各喷雾性能指标的影响关系，验证了理论分析结果。论文利用固液两相流的流体动力学和颗粒运动动力学等理论分析了液力式扇形雾喷头喷洒时固液两相，尤其是农药中固体颗粒的运动过程和特点，即农药中固体颗粒的运动特性属于稀疏两相流的混合边界层流动；运动速度不仅受到液体曳力uFuvD、压差力uFuvug和重力Fuvw的作用，还应考虑Saffman力uFuvS的影响，建立了完整的扇形雾喷头的液固两相流边界层的数学模型，获得了农药中固体颗粒在扇形雾喷头内表面上的运动轨迹方程。根据扇形雾喷头球头内表面为球形曲面的几何形状特点，分析认为农药固体颗粒的攻角λ不能简单地等同于冲击角度α，针对磨损程度以及与攻角λ和冲击角度α的关系，建立了攻角λ与冲击角度α的关系式。根据分析，农药中固体颗粒在扇形雾喷头内表面的磨损遵循冲蚀磨损的微切削理论和变形磨损理论，建立了可通过测量扇形雾喷头球头尺寸改变，以及农药用量等参数衡量磨损程度的扇形雾喷头磨损率计算公式，依此可制定各种扇形雾喷头的最佳农药用量。通过FLUENT流体动力学软件对扇形雾喷头内部流场和固体颗粒运动轨迹进行了计算机仿真模拟；利用自行研制的喷头磨损测试系统对美国喷雾系统公司的TP11002VB型和德国LU110-05型以及国产SSP13型扇形雾喷头进行了磨损测试，试验数据证明：扇形雾喷头的磨损对流量的影响最为显著；理论分析获得的扇形雾喷头球头尺寸磨损率计算公式符合试验结果；最后，对试验数据进行了回归分析，确定了扇形雾喷头磨损率计算公式中的修正系数、建立了扇形雾喷头流量与磨损时间的关系式和扇形雾喷头在失效期内农药用量的计算公式，验证了可通过检测扇形雾喷头球头尺寸作为判断喷头磨损的失效标准，为预测喷头磨损失效和制定喷头定期检测制度提供基础依据。论文通过研究液力式扇形雾喷头的磨损过程，掌握了喷头磨损规律，可为国家制定液力式喷头失效标准、国内喷头制造企业提供技术支持和喷头使用提供磨损失效检测方法，以及对降低喷头生产、使用成本和防治环境污染均具有非常重要的意义。更多还原

【Abstract】 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.更多还原