The Application Of Double Venturi Effect In Optimization Design Of The Catamaran Averaging

The averaging pitot tube,with high measuring accuracy, simple structure, has been widely applied to the various departments of the national economy. To increase the output pressure difference and improve the measurement precision, the research on the monomer velocity-equalizing tube flowmeter must be improved, we innovative designs a catamaran velocity-equalizing tube flowmeter, which use of the venturi effect between the two test bar and increase the measurement precision. This paper add a venturi tube structure outside the catamaran velocity-equalizing tube flowmeter, forming a double venturi effect, increasing the output pressure difference, improve the flow measurement precision, at the same time have a certain rectification effect.Paper first confirm static pressure and total pressure area by numerical simulation, take the average value on line area as the total pressure and the static pressure value, and then calculate the flow coefficient K. This article verifies that under certain time step, along with the growth of the computation time, flow coefficient K will eventually reach a stable value. Second, change the type of venturi structure dimension, including the back-end section Angle, the front-end and back-end structure (including straight line, spline curve, for chamfering, etc.),11groups of different structure model is established,we will select one model, which can increase output differential pressure to maximum, and at the same time reduce the pressure loss. Calculation results show that the best model average flow coefficient K value is0.325, reduced by42.2%compared to no add of venturi tube. The average pressure loss increased from10.3%to26.6%, in an acceptable range. Flow coefficient variance reduced from6.76‰to5.78‰, flow coefficient stability enhancement. Paper also studies the different space between the test bar. Results show that with the increase of space, the flow coefficient has increased synchronization, when the spacing is20mm the K value is0.383, flow coefficient stability slightly enhanced at the same time. Paper studied the type of venturi structure in the role of the rectifier, the fluid flows through the right-angle bend as the research object, Results show that the type of venturi structure can play the role of rectifier, model2under different speed condition can reduced the demand for straight pipe length by29%. model5under different speed condition can reduced the demand for straight pipe length by35%. Finally we add a rectifier in front of the model2, the calculation results show that after adding rectifier can reduced the demand for straight pipe length by44%, Flow coefficient K value is0.325, but the pressure loss has increased considerably, up to35.8%.