Liquid jet breakup regimes at supercritical pressures

Abstract

Previously, a theory has been presented that explains how discrete vapor-liquid interfaces become diminished at certain high-pressure conditions in a manner that leads to well known qualitative trends observed from imaging in a variety of experiments. Rather than surface tension forces, transport processes can dominate over relevant ranges of conditions. In this paper, this framework is now generalized to treat a wide range of fuel-oxidizer combinations in a manner consistent with theories of capillary flows and extended corresponding states theory. Different flow conditions and species-specific molecular properties are shown to produce distinct variations of interfacial structures and local free molecular paths. These variations are shown to occur over the operating ranges in a variety of propulsion and power systems. Despite these variations, the generalized analysis reveals that the envelope of flow conditions at which the transition from classical sprays to diffusion-dominated mixing occurs exhibits a characteristic shape for all liquid-gas combinations. For alkane-oxidizer mixtures, it explains that these conditions shift to higher pressure flow conditions with increasing carbon number and demonstrates that, instead of widely assumed classical spray atomization, diffusion-dominated mixing may occur under relevant high-pressure conditions in many modern devices.

Transient behavior near liquid-gas interface at supercritical pressure

“…At subcritical pressures, a clear distinction between the liquid and the gas phase exists and the liquid breakup is mainly driven by capillary forces and hydrodynamic instabilities, depending on the fluid properties and configuration of the problem. However, at high-pressure regimes close or above the critical pressure of the new liquid solution, diffusion can become one of the main drivers of the mixing process and a well-defined liquid-gas interface may not be easily identified [1].…”

Development of a Eulerian Multi-Fluid Solver for Dense Spray Applications in OpenFOAM

“…The same research framework applies to the exploitation of unconventional low-grade fuels, e.g., heavy fuel oils which contain even more components with a broad spectrum of physical and chemical properties [11]. Another possibility is to take advantage of the high temperature and pressure conditions and utilize the spray/air mixture at supercritical states to promote diffusive mixing [12][13][14][15][16]. These advances in fuel development require a modeling framework capable of predicting the dynamic behavior of modern fuels.…”

Treatment of long-range interactions arising in the Enskog–Vlasov description of dense fluids

“…The situation is imminent in the phase transition phenomena arising e.g. in fuel droplets [3], molecular distillation [4][5][6], evaporation processes in the laser-solid interaction [7], sonoluminescence [8] and supercritical gas-liquid interface in injecting engines [9][10][11]. The kinetic theory provides an attractive framework which overcomes the closure problem associated with macroscopic quantities, through notion of the distribution function.…”

“…Through the identity(10), the expectation can be estimatedU N C O R R E C T E D P R O O FARTICLEIN PRESS Please cite this article in press as: M. Sadr, M.H. Gorji, Treatment of long-range interactions arising in the Enskog-Vlasov description of dense fluids, J. Comput.…”