Experimental investigation of free falling water film characteristics

Flow of gravitationally thin falling liquid films over outer cylindrical surfaces with or without concurrent gas or steam flow is of major importance at applied thermal hydraulics. A 1.5 m stainless steel circular tube test section has been set up so as to thoroughly collect film data by means of needle contact probes. Water in ambient pressure is freely falling along the outer wall of the test section cylinder at temperatures in the range 300 to 350 K and volumetric flow in the range between 1 and 3 Lmin-1. Signal acquisition circuitry records the time when probe-tips are in the film and the time when tips are out, for various tip to cylinder distances. Statistical processing of the collected data provides experimental results for the film thickness distribution, the mean film thickness, the film wave frequency and the film celerity, which are further compared to similar theoretical and experimental data in the existing literature.