Flow field characteristics in the housing of noncircular gear flowmeter

Abstract

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.In order to find the factors which affect the accuracy of the flow rate measurement, the inner flow characteristics of an oval-gear flowmeter were investigated. Inner flow field was analyzed by using the fluid-structure coupling technique with ADINA-FSI (Fluid-Structure Interactions) module. The results were compared with experimental results such as flow visualization and measurements of flow rate, rpm, and pressure drop. As a result, the pressure on the rotor surface was periodically changed with respect to the rotational angle, from the maximum value of the inlet pressure to the minimum value of the outlet pressure. The rotor tip velocity showed the periodical changes with respect to the rotational angle. The creation, movement, and discharge of vortices were observed by turns around the upper and the lower rotor, which are produced by the rotation of the rotor and the changes in the flow passage area and contour in the housing. Larger pressure difference between the inlet and the exit of the housing showed higher flow rate. The flowmeter used in the present experiment had the precision of 1%, in view of the ppl (pulse per liter) variation as a function of flow rate. The power loss, the difference between the theoretical driving power of the rotor due to the pressure difference and the actual power of the rotor, was increased as the flow rate was increased.