基于现场总线和智能变送器的风洞气流参数测量系统研制

Development of measurement system of airflow parameters in wind tunnel based on fieldbus and intelligent transducers

准确测量来流雷诺数对于研究一些对雷诺数变化敏感的流动现象十分重要,为了得到较为准确雷诺数需要测量来流速度、温度和环境大气压等气流参数。本研究基于带Hart通信协议的智能变送器以及数字式振筒气压仪,在低速风洞中实现了一套简单实用的气流参数采集系统。其中,主机和差压、温度变送器之间通过Hart适配器相连接,并通过串口以Hart协议实现通信;而数字式振筒气压仪与计算机之间则直接通过串口实现通信。在系统开发过程中对Hart协议进行了解析和测试。在该系统气流参数采集的基础上,实现了来流雷诺数实时精确的计算,并对比了因温度和气压波动导致的雷诺数计算差异对旋成体大迎角雷诺数效应研究的影响,从而进一步说明了发展该系统的重要性。

The accurate measurement of freestream Reynolds numbers is very important for studying several Re-dependent flows. In order to obtain more accurate Reynolds numbers, the airflow parameter, such as airflow speed, temprature, and atmospheric pressures should be measured. Therefore, a data acquisition system for airflow parameters was implemented in a low speed wind tunnel, which was based on intelligent transducers with Hart protocol and vibrated atmospheric pressure instrument. The host computer connected the differential pressure transducer and temperature transducer with a Hart adapter, and implemented Hart communication by a serial port COM1. The atmospheric pressure instrument was communicated directly with a host computer by another serial port COM2. During the development of the system, the Hart communication protocol was interpreted and evaluated. Finally, a calculation on freestream Reynolds number was carried out in terms of various airflow tempratures and atmospheric pressures, and the difference for the Reynolds numbers caculated was used to study the effect on the Reynolds numbers dependence of flows over a slender body.