Home Books eBooks Journals References & Proceedings Authors, Editors, Reviewers A-Z Product Index Awards
ICLASS 94<br>Proceedings of the Sixth International Conference on Liquid Atomization and Spray Systems

ISBN:
978-1-56700-019-1 (Print)
978-1-56700-445-5 (Online)

SECONDARY BREAK-UP OF LIQUID DROPLETS: EXPERIMENTAL INVESTIGATION FOR A NUMERICAL DESCRIPTION

W. Samenfink
Universitat Karlsruhe (TH) Karlsruhe, Germany

M. Hallmann
Universitat Karlsruhe (TH) Karlsruhe, Germany

A. ElsaBer
Universitat Karlsruhe (TH) Karlsruhe, Germany

S. Wittig
Universitat Karlsruhe (TH) Karlsruhe, Germany

Abstract

In order to analyze secondary break-up of single droplets usually image-forming systems are used. These allow detailed time-resolved investigations of the droplet deformation and disintegration processes. However, in real sprays, due to a superposition of multiple droplets of different sizes and due to high volume fluxes in the center of the spray, the use of image-forming systems is problematical. For that reason, experimental results are in genera] not comparable to the results of numerical computations. Therefore, in the present study a Phase-Doppler-Anemometer (PDA) is used for the spray analysis, knowing the limitations of the system measuring non-spherical droplets. This PDA-system provides a very good spatial resolution of the data and allows detailed comparisons between measured data and numerical calculations.

For the experiments a rectangular flow duct made of acrylic glass is used, so an excellent accessibility for all optical measuring systems is obtained. By a full analysis of the experimental data, areas are detected, where due to secondary break-up non-spherical droplets occur and consequently the droplet size cannot be determined correctly. Therfore, a criterion is developed to determine a demarcation of these areas. Considering this criterion, comparisons of the experimental results with numerical calculations are carried out. The calculations using a new developed break-up model reveal a significant improvement by the use of break-up correlations in contrast to calculations where secondary break-up is not taken into account.