Numerical investigations of the accuracy of conductivity wire-mesh sensors

Abstract

The wire-mesh sensor (WMS) is a promising instrumentation for two-phase flows investigation. Since the WMS is a kind of intrusive sensor, some researchers have focused on its intrusive effects on the measurement results. However, apart from the intrusive effects, the uniform sensitive volume assumption also brings a systematic error. For a WMS, it is assumed that there is a linear relationship between the current received by the receiver wire and the void fraction within a square sensitive volume, of which the side length equals to the lateral distance between two adjacent wires. Since the complexity of the potential field, the uniform sensitive volume assumption brings a systematic error. In order to evaluate this systematic error, a cuboid with zero conductivity was introduced in 9 × 9 WMS potential field simulations. The results indicate that the systematic error caused by the uniform sensitive volume assumption increases in the wire plane axial distance. The wire diameter has little effects on the measurements. However, in view of eliminating the intrusive effects, the wire diameter should be as small as possible. The phenomena of over-shoots and cross-talk, which can be observed in experiments, were explained by the potential field simulation results. With the wire plane axial distance increase, the over-shoots and cross-talk will be exacerbated. Even though the over-shoots and cross-talk can cause a deviation for local void fraction measurements, they would not cause any systematic error for sectional average void fraction measurements in a square cross-section.