The growth of a vapor bubble in a superheated liquid is controlled by three factors: the inertia of the liquid, the surface tension, and the vapor pressure. As the bubble grows, evaporation takes place at the bubble boundary, and the temperature and vapor pressure in the bubble are thereby decreased. The heat inflow requirement of evaporation, however, depends on the rate of bubble growth, so that the dynamic problem is linked with a heat diffusion problem. Since the heat diffusion problem has been solved, a quantitative formulation of the dynamic problem can be given. A solution for the radius of the vapor bubble as a function of time is obtained which is valid for sufficiently large radius. This asymptotic solution covers the range of physical interest since the radius at which it becomes valid is near the lower limit of experimental observation. It shows the strong effect of heat diffusion on the rate of bubble growth. Comparison of the predicted radius‐time behavior is made with experimental observations in superheated water, and very good agreement is found.

The growth of vapor bubbles in superheated liquids. report no. 26-6

This paper provides an overview of a workshop focused on fundamental experimental and theoretical aspects of soot measurements by laser-induced incandescence (LII). This workshop was held in Duisburg, Germany in September 2005. The goal of the workshop was to review the current understanding of the technique and identify gaps in this understanding associated with experimental implementation, model descriptions, and signal interpretation. The results of this workshop suggest that uncertainties in the understanding of this technique are sufficient to lead to large variability among model predictions from different LII models, among measurements using different experimental approaches, and between modeled and measured signals, even under well-defined conditions. This article summarizes the content and conclusions of the workshop, discusses controversial topics and areas of disagreement identified during the workshop, and highlights recent important references related to these topics. It clearly demonstrates that despite the widespread application of LII for soot-concentration and particle-size measurements there is still a significant lack in fundamental understanding for many of the underlying physical processes.

Laser-induced incandescence : recent trends and current questions

Hydrodynamic and hydromagnetic stability

Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications

Effects of cavitation in a nozzle on liquid jet atomization

The physics of water-in-oil emulsion droplet microexplosion/puffing has been investigated using high-fidelity interface-capturing simulation. Varying the dispersed-phase (water) sub-droplet size/location and the initiation location of explosive boiling (bubble formation), the droplet breakup processes have been well revealed. The bubble growth leads to local and partial breakup of the parent oil droplet, i.e., puffing. The water sub-droplet size and location determine the after-puffing dynamics. The boiling surface of the water sub-droplet is unstable and evolves further. Finally, the sub-droplet is wrapped by boiled water vapor and detaches itself from the parent oil droplet. When the water sub-droplet is small, the detachment is quick, and the oil droplet breakup is limited. When it is large and initially located toward the parent droplet center, the droplet breakup is more extensive. For microexplosion triggered by the simultaneous growth of multiple separate bubbles, each explosion is local and independent initially, but their mutual interactions occur at a later stage. The degree of breakup can be larger due to interactions among multiple explosions. These findings suggest that controlling microexplosion/puffing is possible in a fuel spray, if the emulsion-fuel blend and the ambient flow conditions such as heating are properly designed. The current study also gives us an insight into modeling the puffing and microexplosion of emulsion droplets and sprays.

/pdf/physics-of-puffing-and-microexplosion-of-emulsion-fuel-2fzqsha1xe.pdf

Physics of puffing and microexplosion of emulsion fuel droplets

https://bura.brunel.ac.uk/bitstream/2438/11590/3/Fulltext.pdf

Puffing and micro-explosion of diesel-biodiesel-ethanol blends

Effects of injection parameters and EGR on combustion and emission characteristics of rapeseed oil and its blends in diesel engines

Combustion and emission of rapeseed oil blends in diesel engine

https://bura.brunel.ac.uk/bitstream/2438/17251/1/FullText.pdf

Lionel Ganippa

Papers

Physics of puffing and microexplosion of emulsion fuel droplets

Puffing and micro-explosion of diesel-biodiesel-ethanol blends

Effects of injection parameters and EGR on combustion and emission characteristics of rapeseed oil and its blends in diesel engines

Combustion and emission of rapeseed oil blends in diesel engine

Experimental understanding on the dynamics of micro-explosion and puffing in ternary emulsion droplets