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Atomization and Sprays
IF: 1.262 5-Year IF: 1.518 SJR: 0.814 SNIP: 1.18 CiteScore™: 1.6

ISSN Print: 1044-5110
ISSN Online: 1936-2684

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Atomization and Sprays

DOI: 10.1615/AtomizSpr.v7.i1.40
pages 77-95

STRUCTURE OF A NONEVAPORATING SWIRL INJECTOR SPRAY

Douglas A. Feikema
Department of Mechanical and Aerospace Engineering, Propulsion Research Center, The University of Alabama in Huntsville, Huntsville, AL 35899
Richard Eskridge
NASA Marshall Space Flight Center, Huntsville, AL 35812
John J. Hurt
NASA Marshall Space Flight Center, Huntsville, AL 35812

ABSTRACT

The structure of a dense-liquid, swirl-injector, hollow-cone spray operating in atmospheric pressure conditions has been investigated using strobe photography, phase Doppler particle anemometry, (PDPA), and mechanical liquid collection methods. Image-processed strobe photographs and measurements of drop velocity, drop size, and liquid mass flux in the dense spray of a pressure-swirl, hollow-cone liquid oxygen (LOX) simulant injector are reported, as well as analysis resulting from these measurements. Since combusting liquid sprays depend on the liquid dispersion rates and the size and distribution of the drops, the liquid mass distribution is important in evaluating the performance of a liquid rocket engine spray. The objective of this study was to determine the drop velocity, the drop size and distribution, the liquid mass distribution within the spray, and a possible relationship to the internal flow of the injector. The results demonstrate that accurate mass flux measurements can be made with the PDPA but only within the discrete droplet regions of the dense spray, which for the present conditions occurs between 20 and 30 injector exit diameters from the injector exit. The measured mean drop size is approximately 330 μm in the dense portion of the spray, which is considerably less than the predicted analytic mean diameter of 1150 μm. The breakup mechanism used to derive the analytic mean drop size expression is qualitatively correct, but it overpredicts the mean drop size because the method does not account correctly for injection-induced turbulence within the liquid sheet and wind-induced secondary breakup, which are important in high-velocity liquid atomization. The results reaffirm that the conical liquid sheet thickness is an important parameter in drop size determination.