An Ultrasonic Measurement Research Of Low Gas Flow Rate In Large Space

The accurate measurement of low gas flow rate in large space has always been a technical problem which must be urgently solved in industrial sector. At present, these major measurement methods, including the method of hot wire anemometer and pitot tube method, etc., are limited to its large size space, low flow rate and small pressure gap. Therefore, when they work, they are subject to various restrictions.The measurement equipment which is targeted on low gas flow rate in large space is designed in this paper. Based on this objective, the research is conducted in the following steps:(1). The rate-measuring method of time gap is chosen due to the large space and low flow rate,then based on this method, a complete set of ultrasonic measuring system which can be used to conduct acute check in the wind tunnel is designed. Meanwhile, the influences on several different frequency of ultrasonic transducers brought to the measuring of rate are explored, and the error of its results is also analyzed, thus picking up the ultrasonic transducer which is fit to its frequency according to different rang of wind speed.(2). Having finished the acute check, the property of this system in a complex environment (for example, the transmission pipeline of coal powder in thermal power plant)is further tested. At last, through this experiment it is proved that this equipment can worked normally in a complex environment and meet the requirement for accuracy.(3). In the outside where there is natural wind, the property of this system is further evaluated, and its results had demonstrated that the low gas flow rate in large space can be acutely measured by this system. When the speed of natural wind is more than 2m/s, the result of this system matches that of the hot wire anemometer; while when the speed of natural wind is less than 2m/s, there is huge deviation between the results possibly because of the error of hot wire anemometer itself.