商用乘骑式草坪割草车刀盘流场及动力学特性的研究

【作者】 张雷；

【导师】 王华坤；

【作者基本信息】 南京理工大学 ， 机械设计及理论， 2009， 硕士

【摘要】 本文研究的是一种商用乘骑式草坪割草车,这种割草车主要用于大中型草坪的草坪修剪与维护,要求具有良好的机械性能和草坪修剪质量。其中切割刀盘的设计是一种关键的技术,本文重点开展对刀盘内流场的特性分析,以此作为优化设计刀盘结构的理论依据。本文研究的草坪割草车采用的是三把旋转刀片的单刀盘结构,工作时内部气流复杂,建立良好的流场特性至关重要。文中首先对刀盘与刀片进行3D设计,然后对截面流场中刀片周围流场以及刀盘内部流场应用Fluent进行建模仿真。通过改变刀片的相关角度,对计算数据进行分析研究流场特性,得到刀片角度变化对气流影响的规律。同样在刀盘内流场分析中,通过不同的刀盘模型构造不同的流场进行建模仿真,得到模型Ⅱ具有更好流场特性的结论。文中还对两种不同的刀盘模型壳体应用ANSYS进行动力学特性分析,对刀盘壳体进行了模态分析,证明刀片旋转的不平衡惯性力对刀盘产生简谐激励,并重点分析了两刀盘壳体模型的简谐响应,得到共振频率以及对坐标轴的变形响应,证明得到刀盘壳体模型Ⅱ提高了刀盘的结构强度和工作频率的合理性。更多还原

【Abstract】 This Article investigated the commercial riding lawn-mower which is used for trimming and maintenance for the large and medium-size of grass lawn. The lawn-mower requires good mechanical properties and quality of grass cutting, and the design of deck is the key of its producing technology. This article focused on the analysis of flow field in the mower deck, and used the analysis as the basis for the deck structure-improving study.The deck of lawn mower investigated in this paper has three rotating blades. When it is working there would be a complicated flow field in the deck. So it is important to structure a good deck for the good internal flow filed. This article firstly designed deck and blades in 3D software. Then stimulated the flow filed around blade of cross-section and in the deck by Flunet, and analyzed the characteristic of flow field depend on the data from changing angles of blades. Finally the article gets the regularity of the blade’s influence for airflow patterns. After the comparison of simulation between the internal flow field of model I and model II, the conclusion is that model II with a better character for airflow patterns.This article also analyzed the model dynamics of model I and model II by ANSYS, and proved that the unbalance force by rotating blades generated sinusoidal excitation to deck. Focusing on the harmonic response, the article analyzed the deformation of the resonant frequency and confirmed that model II has a better dynamics character.更多还原