The Structure Optimal Design Method Of Averaging Pitot Tube Based On CFD Simulation

Through the real-time monitoring of air volume on the central air conditioning system, timely adjust the operating status of each device in accordance with the change of air volume parameters, could save large amounts of energy consumption. Central air conditioning system air volume measuring requires measuring device could be capable of measuring real-time monitoring of air volume, with high accuracy, easy to install and use, the use of the process bring low pressure loss, and cheap price, while, the existing instrumentation is hard to meet so many requirements of the central air conditioning system air volume measurement. The averaging pitot tube has the characteristics of simple structure, cheap, easy to install and low pressure loss, it is suitable for central air conditioning system air volume measurement. But owing to the limit of the working principle and structure of the averaging pitot tube, there are some deficiencies, it needs to be optimized according to the characteristics of central air conditioning system.Out of the averaging pitot tube optimization needs, this paper analyzes the working principle of the averaging pitot tube, and points out the working principle differences between the averaging pitot tube and the pitot tube flowmeter, and combines streamline figures to analyze the characteristics of various cross-sectional shapes of the averaging pitot tube. In order to study the impacts of the averaging pitot tube equivalent diameter De, the static pressure hole angle θ and the average wind speed v on the flow coefficient, this paper designs CFD numerical simulation experiment according to the orthogonal theory. In this study, three different turbulence models including the Standard k-ε model, Standard k-co model and LES model are used for numerical simulation. By numerical comparison it is found that the LES model gives good agreement with experimental. Then, according to the conclusions of previous study and the actual need of the central air conditioning system air volume measurement, proposed pentagonal cross-sectional shape of the outline of the averaging pitot tube. In the design optimization process, the angle of the facing flow angle, the shape of the facing flow edge, the shape and length of the back flow edge, and the size and shape of the pressure tapping are studied respectively, by the means of CFD numerical simulation. Finally, set the averaging pitot tube air volume test experiment platform to study the actual test performance of the optimized pentagon averaging pitot tube, found that at low flow rates, the flow coefficient is still able to maintain a high stability.