EVALUATION OF PIV INTERROGATION STRATEGY IN THE INVESTIGATION OF THE LIQUID PHASE VELOCITY IN A BUBBLE COLUMN SECTION

Rodrigo de Lima Amaral¹; Diana Isabel Sánchez Forero¹; Guilherme José de Castilho¹; Sávio Souza Venâncio Vianna¹; Milton Mori¹

¹ UNICAMP

doi:10.20906/CPS/COB-2015-1930

Resumo

Particle image velocimetry (PIV) has become attractive in the investigation of several flow. The processing of PIV images requires a careful selection of interrogation parameters in order to determine the highest correlation peak resulting in a calculation more precise of velocity. This work aims to assess the best PIV interrogation strategy (size and overlap of the interrogation windows) in the investigation of the liquid phase velocity in a bubble column section using the standard cross-correlation. The size and overlap of the interrogation windows were analyzed using correlation coefficient and signal-to-noise ratio (SNR) as quality parameters. Experimental tests were carried out in a water-air system in a cylindrical acrylic column of 1 m high and 141 mm diameter. Rhodamine B as tracer particle, a CCD camera (1376 x 1040 pixels and 12 bits) and a high-pass filter (560 nm) were used. The resolution of the image system was 12 pixels/mm and the investigated area was located from 55.2 cm of the gas distributor. The Nd:YAG (200 mJ) laser system, a lens with focal length of - 10 and a box with slit were used to produce a top-hat profile of light. The results show that different interrogation strategy is required for each gas flow rate in order to increase the correlation coefficient and signal-to-noise ratio.

Palavras-chave: PIV Interrogation; Correlation; Bubble Column; Two-Phase Flow; Signal-to-Noise Ratio