Estimation of in-tube oil film thickness using electrical capacitance tomography

In air/oil lubrication system, the flow pattern of intube air/oil flow is of great impact to the transportation efficiency. Among all the flow parameters, flow pattern and oil film thickness are of most interested to the researchers and operators. In the transportation tube, small amount lubrication oil is blew by the high-speed compressed air, which results in the formation of a small thickness oil film along the circumference. Therefore, online estimation of oil film thickness is a challenging job. In this paper, the application of electrical capacitance tomography to monitor the in-tube air/oil flow has been introduced. The measurements are made from an externally mounted electrode array that made of FPC board, which will not interfering the on-going air/oil flow. Both average and distributed oil film thickness can be calculated from the capacitance images. Experimental results show that the ECT system can provide satisfactory on-line flow pattern monitoring and oil film thickness estimation.