| 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.
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