Experimental investigation of textural atomization processes : application to cavitating flows

Abstract : Textural atomization designates the mechanism of drop peeling from the interface of a free liquid flow. This mechanismis controlled by the characteristics of the flow issuing from the injector and manifests at its vicinity. Almost uninvestigated,textural atomization is a rapid phenomenon, implies very small ligamentary structures and produces a mist of fine droplets.The work of this thesis is an experimental investigation of a textural atomization process observed on flows issuing fromcavitating injector. Three academic transparent atomizers are used and optical diagnostics are implemented: LDV (LaserDoppler Velocimetry) and PDPA (Phase Doppler Particle Analyzer) to describe the internal flow and the spray, respectively,and still imaging at high spatial resolution or high-speed imaging for the internal and external flows. A first observation revealsa strong link between the cavitation regime and the textural atomization process. An analysis implying the measurementof the variability of the internal flow and of the atomization process quantifies this link. Here, the atomization process isdescribed by the measurement of its scale distribution. Associated with the concept of equivalent system, this multi-scaleanalysis returns a mathematical expression for the investigated atomization process. This result is unprecedented. Completedby a mathematical description of the spray drop-diameter distribution, it offers a new support to build a model of ligamentaryatomization processes presented in this work and that connects ligament size and deformation to the drop populations. Thesefine analyses provide a better knowledge of the investigated atomization process. For instance, we learn that, at fixed flowrate, the height of the inlet pipe feeding the orifice has no influence on the atomization process. Furthermore, a criterion hasbeen established to identify the smallest ligament deformation scale implied in the drop production.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-02284934
Contributor : Abes Star <>
Submitted on : Thursday, September 12, 2019 - 12:05:47 PM
Last modification on : Friday, September 13, 2019 - 1:21:39 AM

File

fakhryabuzahra2.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02284934, version 1

Citation

Fakhry Abuzahra. Experimental investigation of textural atomization processes : application to cavitating flows. Fluid Dynamics [physics.flu-dyn]. Normandie Université, 2019. English. ⟨NNT : 2019NORMR028⟩. ⟨tel-02284934⟩

Share

Metrics

Record views

81

Files downloads

5