【作者】 吕杰；

【导师】 修吉平；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2009， 硕士

【摘要】 本论文针对目前汽车空气质量流量计产品的检测系统低端,系统功能不完善,检测精度较低的现状,提出了研制一种可产生任意连续可调气体流量、功能齐全、性能稳定、装备结构简单、操作安全、流量标准、检测精度高的风洞气体流量检定系统。该系统应用于汽车空气质量流量计生产检测部门,以及气体质量流量和体积流量测量场合。本文在分析了目前常用气体流量标准装置的优缺点和风洞流量测量发展现状,以及现有风洞空气质量流量计检定试验系统的基础上,首先对风洞气体流量检定系统做了总体技术规划,介绍了系统的机械结构设计、硬件和软件设计,然后对系统实验数据进行分析,说明了系统调试过程中遇到的问题和解决方法,介绍了系统的抗干扰措施,最后对系统的整体设计和功能做了总结。对风洞流量发生装置进行了研究,包括机械结构设计和控制系统设计。机械结构设计分为管道、阻尼器、加热部分和机箱结构布局设计等。控制系统设计分为数据采集、风速控制、加热控制、通讯控制等模块设计,这些模块都由硬件和软件支持。风洞气体流量检定系统产生标准气体流量。计算机通过变频器和风机控制管道内气体风速,皮托管和各种传感器采集管道内气体的差压、温度、湿度、表压、大气绝压等信号,同时待检测的空气质量流量计也输出电压信号,这些信号经过信号调理电路输入数据采集器,再通过RS-485接口输入计算机,经过计算得出气体密度、质量流量、体积流量和管道风速等数据。通过分析,用测线流量法求得平均质量流量,计算机对空气质量流量计进行校准。在检测过程中,用户根据需要可随时通过加热模块控制管内气体温度。系统考虑湿度对流量的影响,精度更高,能够检测较高温度下空气质量流量计的工作性能和温漂情况,功能齐全。测试结果表明,该系统可产生连续任意可调的气体流量,管道内气体风速范围为0～35m/s,质量流量可达到500kg/h(内径62mm条件下),用户设定的流量最久可在10s内稳定得到,系统检测精度可达到土1%,可对空气质量流量计进行校准,有很好的可靠性和稳定性。更多还原

【Abstract】 The wind tunnel air flow testing and calibrating system is designed to test the automobile air flow meter. In our country, the testing system which is used to test air flow meter is imperfect in the related factory. At present, the function of the air flow meter testing system in our country is single, not to say the accuracy. The system can only test air flow meter. If the air flow meter doesn’t attain the designated standard, this sensor will be discarded. And the measuring accuracy is not good. So it is necessary to develop a new system which can produce adjustable air flow continuously and have whole function. The system must be stable and easy to use.In this thesis, the merit and shortcoming of the commonly used gas flow calibration facilitys and the present situation of wind tunnel flow measurement is analyzed. And then the technology planning of the project is given. Then the mechanical design, software and hardware of the system are introduced. The result of the experiment is analyzed. Then the process of debugging and antijamming measure is introduced. At last, the whole thesis is summarized.The system is described from two aspects, mechanical design and control system design. Mechanical design is combined by pipeline design, structure layout design of the case, and so on. The control system design is consists of data collection, wind speed control, heating control and communication control, and so on.The system can produce standard air flow.Computer controls the transducer and suction fan.Use pitot and sensors to pickup the signal of temperature, humidity, atmospheric pressure, and so on. At the same time, the air flow meter is also measuring the air flow. After the signal processing circuit, the data is collected by data acquisition and transmitted to computer by RS-485. The computer calculates the density, flow and the speed of the air. And the computer calibrates the air flow meter. Humidity is taken into account. So the system is more accurate. And the system has high temperature measurement function.The air speed of the system can attain 35m/s, and the mass flow can achieve 500kg/h (at the situation of 62mm inner diameter). The system can be stable in 10 seconds after the user input the air flow. The detection precision can achieve±1%. The reliability and stability of the system is good.更多还原