| Fan performance test is an indispensable part of design, manufacture and inspection of fans. At present, many fan manufacturers and research facilities perform tests primarily depend on manual operation, and there are some problems, such as large labor and inefficiency. In order to realize an automatic testing procedure, virtual instruments technology is adopted in the design and development on the testing system of the fan performance in this thesis.At first, the overall structure of the system was designed according to GB 1236-2000. The testing system is composed of fan driving system, standardized airway, measurement and control system. To meet the requirements of different fans, four sets of standard airways with different diameters were designed in this paper. Flow control valve and its actuator were designed to automatically adjust the working condition of the fan. In addition, to analyze the radial velocity distribution of the flow field, the propelling equipment of hot-wire anemometer were developed.Meanwhile, the software and hardware of the measurement and control system were designed in detail. The hardware of the system mainly includes the selection of sensors and data acquisition card. The software part of the system is based on Lab VIEW. Module programming and component-oriented process were adopted to realize the functions of automatic adjustment of working condition, automatic acquisition of signal, data automatic analysis, performance curves automatic drawing and test report automatic generation. By connecting to the database, the system can also realize the functions of data storage, query and modification.To reasonably design the structure of testing device, CFD method was applied in this thesis to perform numerical simulations on the inner flow field of the device. Numerical simulation combined with theoretical analysis were used to discuss the obstructing effect of the bearing seat on the outlet airflow of axial fan, and changes in the fan performance curves were studied based on the different distances between bearing seat and outlet section. The result may provide a basis for the proper design of the distance between bearing seat and outlet section.Meanwhile, the influence of co-rotating louver valve and bi-rotating louver valve on the inner flow field of the air duct were studied and the distribution of velocity, pressure, streamline and turbulence kinetic energy were studied and compared. Besides, the flow characteristics of the two valves were also compared, and the result may provide a reference for the improvement of flow regulating device.At last, to make an experimental verification of the testing system, the original design scheme was simplified and a miniature-testing device was set up. The performance of an axial fan was tested and performance curves were plotted. The testing device worked stably and reliably in the commissioning process, which can meet the requirements of automatic control and data acquisition. |
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