| With the integrated development of electronic equipment,the volume of its internal cooling fan is gradually miniaturized,and the air volume and air pressure parameters are lower.To solve problems of small flow measurement and automatic flow regulating in the micro fan aerodynamic performance testing system.This paper propose a micro fan aerodynamic performance test technology based on the flow balancing method,analyzes the working principle of this technology,designs the corresponding test device,and conducts the experimental test.The main research contents and results are as follows:(1)Analysis of flow regulation technology principle of flow balancing method.Based on the flow balance method of micro cooling fan aerodynamic performance test device pipeline contains a number of branches composed of flow measurement pipeline and flow balance pipeline two parts.The flow measurement branch and the corresponding flow balance branch switch are complementary.Theoretically,under different flow combinations,the resistance of the whole pipeline system remains unchanged and the working condition of the auxiliary fan remains unchanged.The flow regulation and control of the measurement pipeline can be realized by combine measurement branch switch.In this paper,a flow measurement and balance pipeline system model with laminar flow elements is established,and the characteristics of pipeline flow resistance and the influencing factors of flow regulation error are analyzed.(2)Simulation and experimental study on influencing factors of flow regulation accuracy of flow balance method.The experimental pipeline system containing four flow measurement branches and balance branches is designed and tested;Meanwhile,a physical model of computational simulation was established according to the experimental pipeline parameters and a computer simulation analysis of the flow in the pipe was performed.The results show that,in addition to the resistance of the laminar flow element,there are other parts of the pressure drop has an impact on the flow regulation error.Since the resistance of the laminar flow element has a linear relationship with the flow velocity,while the resistance of the flow in other parts has an approximate quadratic relationship with the flow velocity,resulting in the same overall pressure drop in each branch pipeline,the larger the flow velocity of the branch pipeline,the smaller the proportion of partial pressure drop in the laminar flow element,and the flow velocity is smaller than expected.Therefore,the actual design should use pipeline and valves with large enough inner diameter to reduce the pipeline flow resistance loss and reduce the proportion of pressure drop in the pipeline other than the laminar flow element.(3)Design and development of the flow balance method micro cooling fan aerodynamic performance test system and experimental testing.The experimental test device was designed based on the flow balance method measurement principle,and the design of laminar flow elements with five specifications was completed.The measuring pipe and balance pipe each contain 5 branches and can be combined into29 flow points.The flow calibration of each measurement branch was carried out by using the Sonic nozzle gas flow standard system,and the flow-differential pressure calibration curve was obtained.Repeated experiments have been carried out,and the device has good repeatability.Then the flow regulation performance of the device was tested and the actual miniature fan aerodynamic performance test was performed.Without the installation of the fan,the combined flow regulation error is within ±4%,and the flow resistance of the pipeline outside the laminar flow element has an effect on the flow rate,but the amount of effect is relatively fixed.The results of the miniature fan test show that the fan under test has a certain influence on the flow regulation,but the influence is limited,and the combined flow regulation works normally,which proves the practicality of the method. |
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