Session: 21-02: Wet Steam

Paper Number: 153354

Investigation of Liquid Film Atomization From the Trailing Edge of an Airfoil in a High-Speed Flow- Effect of Trailing Edge Thickness 

Liquid film atomization from trailing edges is found in numerous applications. These include air blast atomization in pre-filming type fuel injectors and shedding from airfoils. The trailing edge geometry significantly influences the breakup of the liquid sheet and the formation of droplets. This study investigates the effect of trailing edge thickness on liquid sheet breakup and droplet formation using NACA0012 airfoils with rounded trailing edges of 0.5 mm, 1.0 mm, and 2.0 mm, in high-speed airflow of up to 175 m/s. Water was introduced on the airfoil surface through 26 holes, each 0.5 mm in diameter and spaced 1 mm apart. These holes were located at 65 mm upstream of the trailing edge along the 100 mm chord length. Three liquid flow rates, i.e., 1.4 cm³/(s·cm), 2.0 cm³/(s·cm), and 2.6 cm³/(s·cm) were tested. A variety of experimental techniques were implemented to analyze liquid film breakup and droplet behavior. High-speed video imaging captured the accumulation of liquid, ligament formation, and breakup at the trailing edge. Microscopic high-speed imaging was used to observe droplet behavior at downstream locations, covering different atomization regimes until the completion of secondary breakup. Phase Doppler Interferometry provided insights into droplet dynamics in the pitchwise direction at 70 mm downstream of the trailing edge, while Laser Diffraction spectroscopy measured droplet mean diameters. The results showed notable differences across different trailing edge thicknesses. However, all followed a general trend of decreasing ligament length and droplet mean diameter with increasing air velocity. Interestingly, the 1.0mm trailing edge thickness airfoil showed the shortest ligament lengths and smallest equivalent droplet mean diameters at all measurement locations downstream of the trailing edge

Presenting Author: Safiullah Safiullah University of California Irvine

Presenting Author Biography: Dr. Safiullah is a Post-Doctoral Researcher at the University of California Irvine Combustion Laboratory (UCICL). He completed his PhD from Hiroshima University, Japan in 2021. His research focuses on the sprays, atomization and optical diagnostics for Flow Visualization and Combustion

Authors:

Safiullah Safiullah University of California Irvine
Vince Mcdonell University of California Irvine
Soichiro Tabata Mitsubishi Heavy Industrues
Shigeki Senoo Mitsubishi Heavy Industries