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Theory of droplet. Part 1: Renormalized laws of droplet vaporization in non-dilute spraysThe vaporization of a droplet, interacting with its neighbors in a non-dilute spray environment is examined as well as a vaporization scaling law established on the basis of a recently developed theory of renormalized droplet. The interacting droplet consists of a centrally located droplet and its vapor bubble which is surrounded by a cloud of droplets. The distribution of the droplets and the size of the cloud are characterized by a pair-distribution function. The vaporization of a droplet is retarded by the collective thermal quenching, the vapor concentration accumulated in the outer sphere, and by the limited percolative passages for mass, momentum and energy fluxes. The retardation is scaled by the local collective interaction parameters (group combustion number of renormalized droplet, droplet spacing, renormalization number and local ambient conditions). The numerical results of a selected case study reveal that the vaporization correction factor falls from unity monotonically as the group combustion number increases, and saturation is likely to occur when the group combustion number reaches 35 to 40 with interdroplet spacing of 7.5 diameters and an environment temperature of 500 K. The scaling law suggests that dense sprays can be classified into: (1) a diffusively dense cloud characterized by uniform thermal quenching in the cloud; (2) a stratified dense cloud characterized by a radial stratification in temperature by the differential thermal quenching of the cloud; or (3) a sharply dense cloud marked by fine structure in the quasi-droplet cloud and the corresponding variation in the correction factor due to the variation in the topological structure of the cloud characterized by a pair-distribution function of quasi-droplets.
Document ID
19900001074
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Chiu, H. H. (Illinois Univ. Chicago, IL, United States)
Date Acquired
September 6, 2013
Publication Date
September 1, 1989
Publication Information
Publication: NASA, Marshall Space Flight Center, Constitutive Relationships and Models in Continuum Theories of Multiphase Flows
Subject Category
Fluid Mechanics And Heat Transfer
Accession Number
90N10390
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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