Empirical and theoretical analysis of the stability of an air-assisted atomising annular liquid sheet

Author(s):

Daniel Duke, Laboratory for Turbulence Research in Aerospace and Combustion, Monash University , Damon Honnery and Julio Soria, Laboratory for Turbulence Research in Aerospace and Combustion, Monash University

 Abstract: 

A novel application of a correlation-based measurement technique combined with high speed magnified imaging is employed to measure the interfacial stability properties of an air-assisted atomising annular liquid sheet in the near-nozzle region prior to sheet break-up. Comparison between theoretical stability analysis and such empirical data for the atomisation of liquid sheets has been extremely limited due to the challenging complexities of undertaking measurements in the near-nozzle region where the instabilities amplitudes are extremely small. Using this new technique, extraction of the spatial wave numbers (frequencies), wave speeds and spatial growth rates of the initial instabilities can be extracted with sufficient precision and accuracy to permit a comparison with stability analysis models. Variations in the stability properties are investigated against variation in the liquid and air-assisted co-flow momentum. It is further demonstrated that within the region of approximately one sheet thickness from the nozzle exit, the growth of the initial instability is approximately linear. A whole volume-of-fluid linear stability analysis, solving the Orr-Sommerfeld equations, is thus undertaken in order to permit comparison with empirical data in the near-nozzle region. Some improved agreement between empirical and theoretical analysis is observed, permitting a more rigorous analysis of the use of stability analysis as an analytic tool for sprays.

 

 

Download Full Paper:

ILASS2010-104.PDF

Presented at:

ILASS-AMERICAS 2010

Contact Name:

Daniel Duke, Laboratory for Turbulence Research in Aerospace and Combustion, Monash University

Email:

daniel.duke@eng.monash.edu.au

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