Numerical simulation of high pressure release and dispersion of hydrogen into air with real gas model

Khaksarfard, Reza; Kameshki, Mohammad Reza; Paraschivoiu, Marius

doi:10.1007/s00193-010-0260-4

Cited by 43 publications

(29 citation statements)

References 8 publications

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“…The specific effect of a real gas EoS for the current flow is under on-going study by the current authors and it will be discussed in a future publication. Nevertheless, it has been shown by [38] that for P 0 <100 bar (i.e. relevant to the current study) an ideal gas EoS would produce acceptable temperatures in under-expanded hydrogen jets.…”

Section: Mach Reflection Recirculation Zonementioning

confidence: 75%

“…It is believed that due to the negative Joule-Thomson coefficient of hydrogen, the temperature profile very close to the nozzle exit may not be predicted accurately by the ideal gas equation of state (EoS) employed here. As it has been presented by some researchers [38,41], for hydrogen jets with extremely high injection pressures (P 0 >>100 bar) using a real gas EoS like Redlich-Kwong, resulted in capturing a higher temperature than that of ambient just after the Mach disk. The specific effect of a real gas EoS for the current flow is under on-going study by the current authors and it will be discussed in a future publication.…”

Section: Mach Reflection Recirculation Zonementioning

confidence: 96%

“…Recently large eddy simulation (LES) was employed to investigate under-expanded methane and nitrogen jets [13,35]. However, very limited experimental and computational studies are available in the literature on under-expanded hydrogen and methane jets and specifically with respect to applications in DI gaseous engines [36][37][38][39][40][41]. Recently, the authors of the present paper used LES to investigate the near-nozzle shock structure and mixing characteristics of highly under-expanded hydrogen and methane jets with NPR=8.5-70 issuing from a circular nozzle into a low ambient pressure (P ∞ ≈1 bar) [14,42].…”

Section: Present Contributionmentioning

confidence: 99%

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Gas dynamics and flow characteristics of highly turbulent under-expanded hydrogen and methane jets under various nozzle pressure ratios and ambient pressures

Hamzehloo

Aleiferis

2016

International Journal of Hydrogen Energy

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The current study used large eddy simulations to investigate the sonic and mixing characteristics of turbulent under-expanded hydrogen and methane jets with various nozzle pressure ratios issued into various ambient pressures including elevated conditions relevant to applications in direct injection gaseous-fuelled internal combustion engines. Due to the relatively low density of most gaseous fuels such as hydrogen and methane, DI requires high injection pressures to achieve suitable mass flow rates for fast in-cylinder fuel delivery and rapid fuel-air mixing. Such pressures typically form an under-expanded fuel jet past the nozzle exit. Test cases of hydrogen injection with nozzle pressure ratio (NPR) of 10 issued into quiescent air with pressure P ∞ ≈1, 5 and 10 bar were simulated. Direct comparison between hydrogen and methane jets with NPR=8.5 and P ∞ ≈1 was also made. The effect of ambient pressure on features of transient development of the nearnozzle shock structure and tip vortices (vortex ring) was investigated. It was observed that at constant NPR, higher ambient pressure resulted in slightly faster formation of the Mach reflection and shorter Mach disk settlement time. Different mechanisms were observed between hydrogen and methane with regards to transient formation of their initial tip vortex rings. It was found that the initial transient tip vortices of hydrogen jets may also contribute to the flow instabilities at the boundary of the intercepting shock and, unlike for methane, promote fuel-air mixing before the Mach reflection. It was also shown that the nearnozzle shock structure was only affected by NPR regardless of the ambient pressure. Furthermore, no flow recirculation zone was found just downstream of the Mach disk, a finding comparable to all previous experimental investigations. Also, it was observed that a locally richer mixture was created for jets with higher NPR or with higher ambient pressure at constant NPR. Based on the results of the current study, correlations were proposed for the shock cell spacing and jet tip penetration of highly under-expanded jets issued from millimetre-size circular nozzles.

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Section: Mach Reflection Recirculation Zonementioning

confidence: 75%

Section: Mach Reflection Recirculation Zonementioning

confidence: 96%

Section: Present Contributionmentioning

confidence: 99%

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Gas dynamics and flow characteristics of highly turbulent under-expanded hydrogen and methane jets under various nozzle pressure ratios and ambient pressures

Hamzehloo

Aleiferis

2016

International Journal of Hydrogen Energy

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“…Consequently, considerable efforts have been made in recent years to develop reliable numerical frameworks (e.g., Banholzer et al 2017;Hamzehloo and Aleiferis 2016a;Velikorodny and Kudriakov 2012;Vuorinen et al 2013;Mohamed and Paraschivoiu 2005;Bonelli et al 2013;Khaksarfard et al 2010).…”

Section: 44 Page 2 Of 10mentioning

confidence: 99%

Mixing characterization of highly underexpanded fluid jets with real gas expansion

et al. 2018

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We report a comprehensive speed of sound database for multi-component mixing of underexpanded fuel jets with real gas expansion. The paper presents several reference test cases with well-defined experimental conditions providing quantitative data for validation of computational simulations. Two injectant fluids, fundamentally different with respect to their critical properties, are brought to supercritical state and discharged into cold nitrogen at different pressures. The database features a wide range of nozzle pressure ratios covering the regimes that are generally classified as highly and extremely highly underexpanded jets. Further variation is introduced by investigating different injection temperatures. Measurements are obtained along the centerline at different axial positions. In addition, an adiabatic mixing model based on non-ideal thermodynamic mixture properties is used to extract mixture compositions from the experimental speed of sound data. The concentration data obtained are complemented by existing experimental data and represented by an empirical fit.

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“…Challenges resulting from the direct injection of gaseous fuels at high pressure ratios are the gas dynamics of the near-nozzle flow structure, the gaseous jet penetration and the fuel-oxidizer mixing. These fluid dynamic aspects are accompanied by strong pressure and temperature changes leading to non-negligible real-gas effects, see, e.g., Khaksarfard et al [7] and Bonelli et al [8]. In Fig.…”

Section: Introductionmentioning

confidence: 99%

Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

Traxinger

Banholzer

Pfitzner

2018

2018 AIAA Aerospace Sciences Meeting

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A numerical framework implemented in the open-source tool OpenFOAM is presented in this work combining a hybrid, pressure-based solver with a vapor-liquid equilibrium model based on the cubic equation of state. This framework is used in the present work to investigate underexpanded jets at engine-relevant conditions where real-gas effects and mixture induced phase separation are probable to occur. A thorough validation and discussion of the applied vapor-liquid equilibrium model is conducted by means of general thermodynamic relations and measurement data available in the literature. Enginerelevant simulation cases for two different fuels were defined. Analyses of the flow field show that the used fuel has a first order effect on the occurrence of phase separation. In the case of phase separation two different effects could be revealed causing the single-phase instability, namely the strong expansion and the mixing of the fuel with the chamber gas. A comparison of single-phase and two-phase jets disclosed that the phase separation leads to a completely different penetration depth in contrast to single-phase injection and therefore commonly used analytical approaches fail to predict the penetration depth.

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Numerical simulation of high pressure release and dispersion of hydrogen into air with real gas model

Cited by 43 publications

References 8 publications

Gas dynamics and flow characteristics of highly turbulent under-expanded hydrogen and methane jets under various nozzle pressure ratios and ambient pressures

Gas dynamics and flow characteristics of highly turbulent under-expanded hydrogen and methane jets under various nozzle pressure ratios and ambient pressures

Mixing characterization of highly underexpanded fluid jets with real gas expansion

Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

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