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Multifractality of drop breakup in the air-blast nozzle atomization process
1East China University of Science and Technology, P.O. Box 272, Shanghai 200237, People's Republic of China. wxzhou@ecust.edu.cn
Summary
This study reveals the multifractal characteristics of droplet breakup during air-blast atomization. A novel random multifractal model accurately describes the drop-size distribution, highlighting intrinsic randomness in spray formation.
Area of Science:
- Fluid Dynamics
- Multiphase Flow
- Atomization Processes
Background:
- Air-blast nozzle atomization is crucial for processes like combustion and spray drying.
- Understanding droplet breakup dynamics is key to optimizing these applications.
- The complex, scale-invariant nature of atomization suggests multifractal analysis is applicable.
Purpose of the Study:
- To investigate the multifractal properties of droplet breakup in air-blast atomization.
- To develop and validate a theoretical model for characterizing droplet size distribution.
- To analyze the spatial distribution and randomness of droplets in the spray.
Main Methods:
- Application of the multiplier method to analyze multifractal spectra (f(alpha) curves).
- Measurement of droplet size distribution using a dual particle dynamic analyzer.
- Development of a random multifractal model with a triangularly distributed multiplier.
Main Results:
- Remarkable agreement between the experimental and model-predicted left side of the multifractal spectra.
- Identification of negative fractal dimensions, indicating fluctuations in spatial drop distribution.
- Demonstration of intrinsic randomness in the spatial concentration distribution of droplets.
Conclusions:
- The proposed random multifractal model effectively characterizes droplet breakup in air-blast atomization.
- Negative fractal dimensions signify inherent sample-to-sample variability in drop spatial distribution.
- The study confirms the presence of momentary fluctuations and randomness in the spray zone.