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.
