Optimization Design And Experimental Research Of Differential Pressure Type Air Flow Measurement Device

As we all know,a good and comfortable working environment is crucial for ensuring productivity and improving work efficiency.Airflow velocity or volume is an important indicator for monitoring the environment and ventilation system operation,and therefore,accurate airflow measurement is necessary.The airflow measurement device needs to have accuracy and superior measurement performance that comply with standards,which is currently one of the focuses of instrument technology research.This article focuses on the differential pressure airflow measurement device,including an analysis of the airflow measurement principle,optimization of the device structure using CFD simulation methods,innovative design of the uniformity matrix structure,fitting calculation of cross-sectional average airflow velocity data based on the matrix pressure-taking structure,selection of the device host sensor module,design of gas flow rate temperature and pressure compensation,production of a measurement device prototype,and construction of an airflow measurement experimental testing platform.Performance verification and backpressure compensation experiments are also conducted on the prototype.The main research contents are as follows.（1）Optimization design of hood structure based on CFD simulation of flow field.The analysis uses the differential pressure principle for wind flow measurement,with a flow hood as the measuring device.Based on the distribution of flow field characteristics inside the hood during the measurement process and the differential pressure data of the measuring section,a simulation model for wind flow measurement is established.The numerical simulation of the wind volume measurement process for the square jet nozzle using the existing flow hood device is conducted,and the error source is analyzed.Orthogonal combinations of hood structure parameters are performed to obtain the changing pattern of the flow field under multiple specifications of hood structures,and the influence trend of hood structure parameters on wind flow measurement results is determined.The hood structure scheme with a base diameter of D₂=400mm and a hood length of L=700mm is determined.（2）Design and data processing of the differential pressure uniform velocity matrix.Based on the distribution of airflow pressure on the measuring section of the base,the design scheme of the uniform velocity matrix structure,diameter size,and pressure tapping method are determined.The pressure data processing and average wind speed fitting calculation method corresponding to the circular ring uniform velocity matrix structure are proposed.Using CFD simulation,the impact of the two uniform velocity matrix structures on the flow field is compared,and the measurement errors of the two uniform velocity matrix structures are quantitatively analyzed to achieve accurate acquisition of the section average wind speed.（3）Design of the main unit and experimental testing of the prototype device.Based on the measurement principle and method of the device,data are collected using three independent differential pressure sensors,and real-time correction of the airflow density is achieved by adding temperature and atmospheric pressure sensors,and the temperature and pressure compensation of the airflow measurement results are carried out.An Arduino development board is selected as the control processing module to realize functions such as sensor signal acquisition and calculation,and display of measurement results for the complete device.Based on the design results of each component of the device,a complete prototype of the airflow measurement device is assembled.A small wind tunnel device using an axial fan as the air source is used as the experimental platform to measure the performance of the device prototype,and the measurement results of the device prototype are compared with those of advanced foreign products.A backpressure compensation scheme for the device prototype is also designed,and the backpressure compensation point and compensation coefficient are obtained through experiments,verifying the accuracy of the backpressure compensation results.The highlights and features of this research work are reflected in the optimization of the structure of the airflow measurement device for the square diffuser with the highest measurement demand,as well as the innovation in the design of the uniform velocity matrix structure and the calculation method for multi-point pressure difference data.A prototype device was developed that integrates multi-point measurement,temperature and pressure compensation,and backpressure compensation coefficient correction functions.Experimental results showed that all functions of the prototype device were normal,and the measurement results were controlled within±3%compared to similar advanced measurement devices from abroad,with a wind flow resolution of 1 m³/h and a wind speed resolution of 0.01 m/s.The backpressure compensation experiment yielded a compensation point of approximately 1560 m³/h,and the relative error of the measurement results after compensation for high wind flow was around -2%.