Strange attractors and chaotic dynamics in boiling flows

The present work represents a first attempt to use the methods of the nonlinear dynamics theory to analyze experimental results of a two-phase flashing flow. The experiments were performed on a Freon-113 flow visualization loop. The temporal void fraction fluctuations following the onset of boiling were studied using the methods of nonlinear dynamics and deterministic chaos theory. The experimental void fraction time series was used to reconstruct a finite-dimensional phase-space picture of the sampled two-phase flow data. The asymptotic properties of the system, such as the positive Lyapunov characteristic exponents, which are a measure of how chaotic the system is, and topological characteristics such as the attractor's topological dimension, were obtained from the picture. The void fraction formation as a consequence of boiling initiation/flashing was shown to represent under specific experimental conditions, a chaotic deterministic process.