Liquid Sheet Disintegration and Atomization Process on a Simplified Airblast Atomizer

Abstract

Liquid sheet break-up in coflowing shear flow is the mean by which liquids are atomized in practical injectors for gas turbine combustors. The present study explores experimentally the mechanisms of liquid sheet instabilities and spray formation. Experiments are conducted on four airblast geometries. A high-speed video camera associated with an image processing unit was used to study the liquid sheet instabilities. A microphone and a frequency analyzer were used to track the disintegration frequency. Instability amplitude and disintegration length of the liquid sheet were measured. A two-component Phase Doppler Particle Analyzer was used to characterize the resultant spray. The spatial distribution of the particle size is influenced by the swirling flow field. These experimental results will be used to assess models of fuel sheet instabilities and disintegration.

Experimental Investigation of Breakup of Annular Liquid Sheet in a Hybrid Atomizer

“…Kendall measured the frequency of shell production stroboscopically and the shell diameters optically under stroboscopic illumination using a cathetometer. The atomizer reported by Lavergne et al [12] has a high degree of modularity: variable liquid sheet thickness, variable swirl angle, and variable inner and outer air velocities. They tracked the disintegration frequency using a microphone and a frequency analyzer.…”

Experimental Study of Primary Atomization Characteristics of Sonic Air-Assist Atomizers

“…With increasing ALR, owing to the high-speed aerodynamic interaction, the mist-like droplets (tiny) formed downstream axially in the 70 µm case (Figure 5c,d), whereas some thread-like droplets (bigger) ejecting laterally out of the sheet are visible with 280 µm sheet thickness (Figure 5g,h). The sheet formed was corrugated/wavy in both of the above cases, forming a cellular pattern (not visible here, whose cell size may depend upon the air jet velocity), as well as stretched-sheet/ligament structure in both the spanwise and streamwise direction (also observed in planar sheet configuration [20,21]), which is attributed to the three-dimensional (3D) nature of the annular sheet. The pressure difference, the surface tension effect, and the aerodynamic forces dictate the liquid sheet breakup characteristics, such as breakup length, spray angle, and so on.…”

Primary breakup study of sonic & supersonic air-assist atomizers

“…With increasing ALR, the mist-like droplets (tiny) formed downstream axially in 70 µm case (c & d) whereas some threads-like droplets (bigger) ejecting laterally out of the sheet can be visible with 280 µm sheet thickness ( g & h). The sheet formed was corrugated/wavy in both the above cases forming a cellular pattern (whose cell size may depend upon the jet velocity), as well as stretched-sheet/ligament structure both spanwise and streamwise direction (both observed in planar sheet configuration [15,16]) which is attributed to the three-dimensional (3-D) nature of the annular sheet. The pressure difference and the surface tension effect, and aerodynamic forces dictate the breakup characteristics of the liquid sheet, such as breakup length, spray angle etc.…”