The process of liquid sheet disintegration and break-up into a spray is studied making use of a flat liquid film surrounded by two air streams. The work considers a 2-D liquid film with an aspect ratio of 114 and a liquid velocity between 0.7 and 6.4 m/s (543 less than or equal to Re-L less than or equal to 4963) and an air velocity up to 39 m/s (Re-G less than or equal to 17647), and allows to study the basic phenomena typical of airblast atomisation. The results include the quantification of instability amplitudes, break-up lengths and frequencies for the above-mentioned range of liquid (water) and air flow velocities. Three different experimental techniques are used: back light and laser light sheet illumination, to measure the instability amplitudes, which leads to the liquid film disintegration and the spray formation; strobe light illumination, for the quantification of either break-up lengths and frequencies, and; a laser attenuation technique for frequency measurements and comparison with the visualisation technique. The results quantify the range of application of the different techniques, and include an analysis of the liquid disintegration process as function of the liquid velocity when exposed to different air flow velocities, along with the quantification of break-up lengths, disintegration frequencies and spray angles, and show that the disintegration of the liquid sheet is associated with a periodic process, which is mainly dependent on the absolute air velocity and the air-liquid momentum ratio. Correlations are proposed for liquid sheet break-up length and frequency based on the air-to-liquid momentum ratio. (C) 2002 Elsevier Science Ltd. All rights reserved.