Spray in Crossflow: Dependence on Weber Number

Abstract

This paper describes an experimental investigation of the spray created by Jet A fuel injection from a plate containing sharp edged orifice 0.018in.(457μm) in diameter and L∕D ratio of 10 into the crossflow of preheated air (555K) at elevated pressure in the test section (4atm) and liquid to air momentum flux ratio of 40. A two component phase Doppler particle analyzer was used for measuring the characteristics of the spray. The Weber number of the spray in crossflow was varied between 33 and 2020 and the effect of Weber number on spray properties was investigated. It was seen that the shear breakup mechanism dominates at Weber number greater than about 300. Droplets’ diameters were found to be in the range of 15–30μm for higher values of Weber numbers, while larger droplets (100–200μm) were observed at Weber number of 33. Larger droplets were observed at the periphery of the spray. The droplet velocities and diameters were measured in a plane 30mm downstream of the orifice along the centerline of the spray at an incoming airflow Mach number of 0.2. The droplets reach a maximum of 90% of the flow velocity at this location. The velocity of the droplets in the directions perpendicular to the airflow direction is higher at the periphery of the spray possibly due to the presence of larger droplets there. The rms values of the droplet velocities are highest slightly off the centerline of the spray due to the presence of vortices and shear layers around the liquid jet. The data presented here improve the understanding of spray formation processes, and provide benchmark data for computational fluid dynamics (CFD) code validation.