Begell House Inc.
Atomization and Sprays
AAS
1044-5110
18
3
2008
INTERACTIONS OF DECELERATING DROPS MOVING IN TANDEM
191-241
10.1615/AtomizSpr.v18.i3.10
Niru
Kumari
School of Mechanical Engineering, Maurice J. Zucrow Laboratories, Purdue University, West Lafayette, IN 47907-2014
John
Abraham
University of St. Thomas
Binary and ternary systems of decelerating drops moving in tandem are numerically studied. The influence of the separation distance between drops, drop size ratio, individual Weber numbers, and Ohnesorge numbers on the transient deformation and breakup of the drops are discussed. Drag coefficients for the drops are also reported. As a point of reference, results for single drops are presented, and the differences between the behavior of a single drop and binary and ternary drops are discussed. It is shown that in binary drops, the trailing drop decelerates slower than the leading one and breaks up slower. Both drops decelerate slower than the isolated drop. In the case of ternary drops, the three drops decelerate slower than the isolated one. The leading drop breaks up fastest followed by the middle one.
EFFECTS OF ELASTICITY ON THE SPRAYING OF A NON-NEWTONIAN FLUID
243-271
10.1615/AtomizSpr.v18.i3.20
Gyo Y.
Park
Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634
Graham M.
Harrison
Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634
The effects of elasticity on spray performance are investigated. In particular, the breakup of liquid filaments exiting the nozzle and the drop size distribution are investigated for a series of low-viscosity polyethylene oxide (PEO) elastic liquids sprayed through a commercially available spray nozzle. Multiple vertical and horizontal positions within the spray are studied. We find that the increase in the elasticity of the moderate to high molecular weight polymer PEO solutions substantially impacts the breakup of liquids exiting the nozzle, reducing the spray angle and the overall coverage of the spray. The vertical distance from the nozzle for the fluid to break up increases with an increase in extensional viscosity. The fluid extensional properties lead to liquid filaments between drops in the non-Newtonian fluids, and these lead to an increase in the average drop size within the spray and also suppress the formation of undesirable fine spray drops.
THREE TYPES OF LINEAR THEORIES FOR ATOMIZING LIQUIDS
273-286
10.1615/AtomizSpr.v18.i3.30
Z. L.
Wang
Institute of Applied Mechanics, Shanghai University, People's Republic of China
Sung P.
Lin
Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, New York
There are three types of linear stability theories that are currently being used to predict the onset of breakup of liquid jets or sheets. Temporal theory, which is most commonly used because of its simplicity, assumes that the disturbance responsible for the breakup grows temporally at the same rate everywhere in space. A less commonly used spatial theory assumes the disturbance grows in space, because the breakup appears to take place in the region downstream of the location where the liquid is introduced. The most complete theory is that of spatiotemporal instability. This theory has not yet been widely applied because of its mathematical and numerical complexity. It is demonstrated here with an example that a flow may be predicted to be neutral according to pure spatial or pure temporal theory, while it is actually stable according to the spatiotemporal theory. The prediction of the latter theory is shown to agree with the numerical solution of the initial value problem.