New Method to Correct Energy Losses of Wire-Mesh Sensor Data

Capacitance wire-mesh sensor is a multielectrode instrument for the measurement of multiphase flows. Since it was originally designed to measure fluids with no or very small conductivities, the sensor may suffer from energy losses when used to measure mixtures with conductivity greater than 100 µS/cm. Consequently, when derived flow parameters are estimated from WMS raw data, unphysical results may be obtained, i.e. negative phase fraction. Threshold methods are commonly employed to cut-off such negative values. However, such approaches work well only for flow regimes where the phases are almost binary, e.g. stratified flows. For this reason, we present a new arrangement and a new method to correct energy losses of a capacitance WMS, which generates reliable data also for complex phase fraction distributions. In the new arrangement, an additional transmitter wire is placed outside the flow domain forming external flow-independent crossing-points. Thus, the change in readings of the external crossing points are used to estimate the loss factor of each receiver wire, which in turn are employed to compensate the energy loss of each local measurement. Experimental and numerical results suggest that the new method is fundamental to expand the conductivity range of capacitance WMS and to measure complex flow structures, i.e. emulsions, foam, ionic tracers, etc. In the examples presented in this paper, deviations of some local measurements were reduced from the range of 20% to less than 3.3%.