Abstract：
In this paper, a new calibration device for an air flow sensor of the VAV terminal unit is designed. Multi-aperture air outlets are designed to meet the calibration requirements of the air flow sensor in a variety of measurement range. The device can calibrate the air flow sensors of different types of VAV terminal unit by a movable flow rectifier without repeating the design of a different calibration pipeline. The Raspberry PI is used to design the high-performance GUI interface and controlling algorithm to achieve a one-button intelligent calibration. The air flow sensors in three different types of VAV terminal units are used to calibrate the experiment. After testing, the differential pressure value measured by the air flow sensor can accurately measure the air flow within the accuracy of 5% after the formula conversion. The conversion from differential pressure values to air flow values requires precise calibration in order to establish an accurate air flow equation, and here the calibration device plays a key role. The negative effect caused by the distance between the flow rectifiers and the VAV terminal unit is discovered. In other words, the distance between the inlet flow rectifier and the air inlet of VAV terminal unit should be kept as close as possible, or within a range of 2~3 cm. Moreover, the distance between the air outlet of VAV terminal unit and the middle-flow rectifier should be kept as close as possible; otherwise, any slight gap will cause a huge error in the calibration result. The research contributes to the further study of airflow sensing technology through the conversion and calibration of differential pressure measurements to accurate air flow values.
摘要：
在本文中,设计了一种新的VAV终端单元空气流量传感器校准装置。多孔径出风口是为了满足空气流量传感器在各种测量范围内的校准要求而设计的。该装置可以通过可移动的流量整流器校准不同类型的VAV终端单元的空气流量传感器，而无需重复不同校准管道的设计。利用RaspberryPI设计高性能GUI界面和控制算法,实现一键式智能标定。三种不同类型的VAV终端单元中的空气流量传感器用于校准实验。测试后,空气流量传感器测得的压差值经公式转换后可准确测量空气流量的精度在5%以内。从压差值到空气流量值的转换需要精确的校准，以便建立准确的空气流量方程，在这里，校准装置起着关键作用。发现了由整流器和VAV终端单元之间的距离引起的负面影响。换句话说,进气整流装置与变风量终端的进气口之间的距离应尽可能靠近,或在2~3厘米的范围内。此外，变风量终端出风口与中流整流器之间的距离应尽可能靠近；否则，任何微小的间隙都会导致校准结果的巨大误差。该研究通过将压差测量值转换和校准为精确的空气流量值，有助于进一步研究气流传感技术。
