Experimental investigation on printed circuit sensor performance for two-phase flow measurement in narrow channels

Printed circuit sensors (PCS) have demonstrated promising potential to tackle the challenges in two-phase flow measurement in narrow channels. Sensor geometric configuration, bubble shape and data processing algorithm are crucial factors influencing the measurement uncertainty. In order to promote the application of PCS in narrow channels, an experimental setup with flexibility to adjust the channel gap has been established. The sensors with a variety of electrode pitches are used to measure the volume fraction of ceramic slice with precisely known geometry in different gap sizes. The local void fraction characteristics, as well as the uncertainties of two-phase flow parameters, are assessed in detail. Results show that the uncertainty of local void fraction measurement is primarily affected by two dimensionless parameters: $L^{\ast }$, which is the dimensionless distance to the bubble edge, and $l_e^{\ast }$, the dimensionless sensor electrode pitch. It is recommended to configure the sensor with $l_e^{\ast }=0.6$ to allow for clear distinction between the gas and liquid phases at high spatial resolution. The Maxwell correlation, combined with the noise elimination method, is recommended to derive high-accuracy average void fraction. The relative error of measured average void fraction can be within ± 10 % for most of the cases, provided that the dimensionless bubble thickness $h^{\ast }$ is greater than 0.8. The accuracy of the projected area equivalent bubble diameter and perimeter depends on the ratio of bubble diameter to sensor electrode pitch $d^{\ast }$. The relative error of bubble diameter and perimeter derived from the resolution-enhanced data is mostly within ± 20 % for 1 < $d^{\ast }\le 10$and within ± 10 % for $d^{\ast }>10$.