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Breakup of Droplets in an Accelerating Gas FlowA study of droplet breakup phenomena by an accelerating gas flow is described. The phenomena are similar to what propellant droplets experience when exposed to accelerating combustion gas flow in a rocket engine combustion zone. Groups of several dozen droplets in the 100-10 750-micron-diameter range were injected into a flowing inert gas in a transparent rectangular nozzle. Motion photography of the behavior of the droplets at various locations in the accelerating gas flow has supplied quantitative and qualitative data on the breakup phenomena which occur under conditions similar to those found in large rocket engine combustors. A blowgun injection device, used to inject very small amounts of liquid at velocities of several hundred feet per second into a moving gas stream, is described. The injection device was used to inject small amounts of liquid RP-1 and water into the gas stream at a velocity essentially equal to the gas velocity where the group of droplets was allowed to stabilize its formation in a constant area section before entering the convergent section of the transparent nozzle. Favorable comparison with the work of previous investigators who have used nonaccelerating gas flow is found with the data obtained from this study with accelerating gas flow. The criterion for the conditions of minimum severity required to produce shear-type droplet breakup in an accelerating gas flow is found to agree well with the criterion previously established at Rocketdyne for breakup in nonaccelerating flow. An extension of the theory of capillary surface wave effects during droplet breakup is also presented. Capillary surface waves propagating in the surface of the droplet, according to classical hydrodynamical laws, are considered. The waves propagate tangentially over the surface of the droplet from the forward stagnation point to the major diameter. Consideration of the effects of relative gas velocity on the amplitude growth of these waves allows conclusions to be made regarding rates of the droplet breakup processes and total time of the breakup process.
Document ID
19990076149
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Dickerson, R. A.
(North American Aviation, Inc. Canoga Park, CA United States)
Coultas, T. A.
(North American Aviation, Inc. Canoga Park, CA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1966
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
AIAA Paper 66-611
Meeting Information
Meeting: Propulsion Joint Specialist Conference
Location: Colorado Springs, CO
Country: United States
Start Date: June 13, 1966
End Date: June 17, 1966
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
CONTRACT_GRANT: NASw-16
Distribution Limits
Public
Copyright
Other

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