【作者】 周海燕；

【导师】 李树君； 杨学军；

【作者基本信息】 中国农业机械化科学研究院 ， 机械设计及理论， 2009， 博士

【摘要】 风机在植保机械上的应用非常广泛,风机的性能直接影响到风送式植保机械的射程、药液雾化性能、雾滴穿透能力及防飘移性能,由于风机的性能很难从理论上推导出,主要通过试验来确定,因此风机性能测试系统对于风送式植保机械的研究和开发非常重要。本论文研制出植保机械用离心风机、轴流风机的出气性能测试系统,为植保机械专用风机的设计和选用提供了必要手段。1、本文按照GB/T1236-2000《工业通风机用标准化风道进行性能试验》研制了植保机械用风机性能测试系统,分别用于测试离心风机和轴流风机,实现试验过程自动化,自动调节工况、采集、处理试验数据,生成试验报告,绘制风机有因次和无因次性能曲线。轴流风机测试装置采用三相异步电动机驱动,0-3000r/min变频调速,功率18.5kW;离心风机测试装置采用永磁电动机驱动,功率3kW,0-8000r/min无级调速;测控系统硬件主要由微型计算机、PLC、传感器、二次仪表等组成;其中PLC、步进电机、行程开关、位移传感器实现了风门开度的闭环控制;测控系统软件采用VB开发,全面支持Windows XP、图形界面、操作简单、使用方便。经实际测试结果表明该系统精度高、重复性好、性能稳定、自动化程度高,大大缩短了试验时间。2、本文在对孔板、文丘里管和V型锥三种节流装置理论分析的基础上,首次应用二维轴对称模型对三种节流装置的永久性压力损失、可靠性、来流适应能力等进行数值模拟分析,缩短了研究周期,节省研究费用,最终确定本测试系统采用V型锥节流装置测量流量。3、本文在理论分析的基础上,依据实测数据,在国内首次应用CFD对植保机械风机不同工况进行模拟分析,探讨了试验过程中管道内静压、湍流强度以及气流速度的变化规律:逐渐关闭风门过程中,静压增大,节流装置前后的压差减少;节流装置前气体的湍流强度增大,节流装置后的湍流强度减小;管道内同一位置处气流速度逐渐减少。为风机性能测试系统差压信号采集位置提供理论依据。4、本文在风机性能测试系统中,国内首次采用理论分析与实测数据拟合相结合的方法,最终确定应用最小二乘法拟合风机性能曲线,根据不同测试数据,性能曲线拟合次数3、4、5、6次可选,使拟合曲线接近风机的真实性能曲线。更多还原

【Abstract】 The fan is widely used on the plant protection machinery and its performance affects the spray range directly, the performance of liquid atomization, the droplet penetrability as well as the anti-drift performance of the plant protection machinery. The performances of the fan are mainly determined from performance tests because it is very difficult to be inferred theoretically. In this paper the outlet performance testing system was developed for centrifugal fan and axial flow fan on the plant protection machinery. It provided the necessary means for the selection and the designing of the fans especially used on plant protection machinery, as well as it could enhance the performance of the plant protection machinery.1. In this paper fan performance testing system for centrifugal fan and axial fans was developed according to GB/T1236-2000 Industrial fans-Performance testing using standardized airways. In this system it can achieve test automation, automatic adjustment of operating conditions, automatic acquisition and processing test data, automatic test report generation and automatic drawing dimension and non-dimension fan performance curve. The permanent magnetism electric motor is used in the centrifugal fan testing equipment, the speed range is 0-8000r/min and the power is 3kW. While the axial fan test unit is equipped with the three-phase asynchronous electric motor, the speed range is 0-3000r/min and the power is 18.5kW. The automatic fan testing system is made up of microcomputer, PLC, sensor and secondary instruments etc. The PLC, stepper motor, limit switch and position sensor are used to adjust operating conditions in closed loop. The software was developed with VB and the system supports Windows XP comprehensively. The operation is simple and easy with using of graphical interface. It was showed from the test results that the system is of high accuracy, good repeatability and stable performance. It is high degree of automation and greatly reduces the experimental time. 2. In this paper numerical simulation analysis of the permanent pressure loses, the long-term reliability, the adaptability etc. of three kinds of throttling gear the orifice, the venturi tube and V taper were done for the first time with using 2d axial symmetry model based on the theoretical analysis of them. And finally it was determined V taper was used in the testing system. It could reduce the research cycle, save research expense with this method.3. In this paper the different operating modes of the fan on the plant protection machinery were simulated with CFD based on theoretical analysis and test data for the first time. It also discussed the change orderliness of static pressure, turbulence intensity and gas velocity during the testing process. During the closing process of the air throttle, the static pressure increases gradually and the pressure difference between before and after throttling gear reduces; the turbulence intensity increases before the throttling gear, but reduces gradually after the throttling gear; the stream velocity reduces gradually. It will provide the basis to determine the collecting position of pressure difference signal for the fan performance testing system.4. It was the first time to combine theoretical analysis and test data fitting method in the fan performance test system in this paper.Finally it was determined by least squares method, the fitting curve was 3,4,5,6 times optional fitting curve depending on the test data, which could fit the authenticity fan curve well.更多还原