Large eddy simulation of fluid injection under transcritical and supercritical conditions

Wei, Wu; Xie, Maozhao; Jia, Ming

doi:10.1080/10407782.2016.1214485

Cited by 19 publications

(3 citation statements)

References 35 publications

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“…Early numerical simulations of cryogenic fluids by Zong et al 40 revealed the strong density stratification effects around the jet (near the injection) which act like solid boundaries and dampen the radial oscilla-tions while amplifying the axial oscillations. Later, numerical simulations by other researchers have also confirmed the density stratification effects [42][43][44][45] . In the work of Li et al 56 there is further analysis of the influence of the injection temperature on the density gradient development.…”

Section: Density Gradients and Suppression Of Turbulencementioning

confidence: 73%

Unpicking the interplay of turbulence, diffusion, and thermophysics in cryogenic jets at supercritical pressures

et al. 2021

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Cryogenic supercritical fluids represent an intriguing category of fluids that combine mechanical and thermophysical properties of both ultra low temperature conditions as well as phenomena taking place well above the critical point. Recent research has demonstrated that it is a common misconception to consider the supercritical state as one homogeneous state. Instead these fluids consist of two to four liquid and gas like phases, each with their own unique characteristics. In our work we investigate numerically single specie cryogenic fluid jets -initially at subcritical temperatureswhich are injected into a supercritical environment (both the pressure and temperature exceed the thermodynamic critical state). For the investigation, a new solver namely "CoolFoam" has been developed which is designed for compressible non-isothermal two-fluid simulations where diffusive transport of heat and/or mass are accounted for. Real fluid thermodynamics are modelled using a polynomial fitting approach developed in our previous work. We introduce also a new phase characterisation framework based on the association of phases with specific temperature ranges (rather than using a single line like the Widom line) which allowed us to better identify similarity effects between the various conditions. We analyse the inter-dependence of the underlying phenomena: density gradient and diffusive mass transport (molecular and thermo(Soret)-diffusion) and turbulence. We also compared supercritical N 2 with subcritical liquid and gas jets to highlight potential differences with respect to how these jets behave. We find that the jet dynamics are largely dictated by the thermodynamic transition of the injected fluid and the associated variation in thermophysical properties. Recently new evidence relevant to the behaviour of cryogenic jets has been produced based both on numerical and experimental efforts. Banuti has presented a detailed thermo-

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Section: Density Gradients and Suppression Of Turbulencementioning

confidence: 73%

Unpicking the interplay of turbulence, diffusion, and thermophysics in cryogenic jets at supercritical pressures

et al. 2021

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Section: Resultsmentioning

confidence: 99%

“…Moreover, the increased solubility of ambient gas into droplets makes it easier for the gas-liquid mixing layer to enter the combustible concentration range, which shortens the preparation of the fuel-gas mixture. [36][37][38] For the twin-spray collision in Figure 5(a), the mean difference of ignition delay time between different ambient pressures is 0.14 ms, which is shorter than that of the single free spray. The reason is mainly that under the supercritical condition, the smaller mean free molecular path and surface tension reduce the impact of ambient resistance on the post-collision development.…”

Section: Ignition Characteristicsmentioning

confidence: 99%

Experimental study on the combustion and soot emission of twin-spray collision at various collision angles and injection pressures under marine engine’s conditions

Xia

Zhang

Wang

et al. 2023

International Journal of Engine Research

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In a large-bore marine engine, the larger cylinder diameter and space correspond to more fuel injection in a limited time of each working cycle. The fuel injection of multiple injectors can achieve fast atomization and homogeneous fuel-gas mixing performance, which is liable to cause the spray collision problem, but the twin-spray collision phenomenon is rarely observed and studied. Therefore, this work aims to explore the effect of various collision angles (60°, 90°, 120°, and 150°) and injection pressures (60, 100, 140, and 180 MPa) on the combustion and soot emission of twin-spray collision process. Based on a large-bore constant volume chamber and two optical diagnostic techniques, the ignition delay time, initial ignition location, flame collision structure, and soot emission luminosity are obtained in a reactive atmosphere. The results show that near the collision point, there exists a fan-shaped flame structure. Due to the mutual entrainment from twin sprays, the ignition delay time of twin-spray collision is shorter than that of single free spray. As a result, at the constant diesel injection mass, the soot emission intensity of twin-spray collision becomes higher. With the collision angle increasing, the ignition delay time becomes shorter, and the initial ignition location gradually moves upstream, while the soot emission intensity becomes higher. The time integrated natural luminosity difference between 60 and 180 MPa gradually decreases and then reverses. Moreover, the wider collision angle also makes the ignition delay time less sensitive to the injection pressure.

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Supercritical combustion instabilities of oxygen/kerosene mixture in a swirl coaxial injector

Li,

Shi,

Wang

et al. 2024

Applied Thermal Engineering

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Large eddy simulation of fluid injection under transcritical and supercritical conditions

Cited by 19 publications

References 35 publications

Unpicking the interplay of turbulence, diffusion, and thermophysics in cryogenic jets at supercritical pressures

Unpicking the interplay of turbulence, diffusion, and thermophysics in cryogenic jets at supercritical pressures

Experimental study on the combustion and soot emission of twin-spray collision at various collision angles and injection pressures under marine engine’s conditions

Supercritical combustion instabilities of oxygen/kerosene mixture in a swirl coaxial injector

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