Fuel-Air Mixing Characteristics of DI Hydrogen Jets

Owston, Rebecca; Magi, Vinicio; Abraham, John

doi:10.4271/2008-01-1041

Cited by 24 publications

(25 citation statements)

References 20 publications

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“…Figure 5 compares the jet penetration of this case as calculated by the current authors work with what reproduced from [13]. It is seen that there is about ~15% higher penetration with the current methodology.…”

Section: Reference Test Casementioning

confidence: 72%

“…As already mentioned, initially a RANS test case was chosen from the literature [13] in order to set a baseline comparison between the current methodology and previously published work by other authors; see Test Case 1 in Table 1. Figure 5 compares the jet penetration of this case as calculated by the current authors work with what reproduced from [13].…”

Section: Reference Test Casementioning

confidence: 99%

“…In order to validate the capabilities of the computational frame work to capture the important characteristics of the underexpanded sonic hydrogen jets a RANS test case was prepared based on computational data from literature [13]. A cylindrical computational grid with 10 cm diameter and 16 cm length containing ~4.0 million hexahedral cells was created.…”

Section: Nozzle-hole Geometry and Gridmentioning

confidence: 99%

“…In order to eliminate hydrogen abnormal combustion modes such as pre-ignition and backfiring [8][9][10], injecting hydrogen directly into the combustion chamber (DI) after intake valves closure (IVC) has been proposed as a more suitable strategy in comparison to port fuel injection (PFI). Furthermore, closed-valve hydrogen DI eliminates issues related to air displacement from hydrogen's need of large injection durations due to its low density [11][12][13][14]. It also provides great flexibility in optimising the engine's mixture formation, performance and emission characteristics through various injection strategies, including timing and duration of injection, injection pressure, injector location and nozzle configurations [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Increasing grid resolution and performing Large Eddy Simulation (LES) was suggested as the way forward to improve the accuracy of numerical predictions. The features of subsonic and sonic under-expanded hydrogen injection were studied by Owston et al [13]. These authors performed RANS simulations of the effect of exit-to-chamber pressure ratio using 'standard' k-ε modelling.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Computational Study of Hydrogen Direct Injection for Internal Combustion Engines

Hamzehloo¹,

Aleiferis²

2013

SAE Technical Paper Series

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Hydrogen has been largely proposed as a possible fuel for internal combustion engines. The main advantage of burning hydrogen is the absence of carbon-based tailpipe emissions. Hydrogen's wide flammability also offers the advantage of very lean combustion and higher engine efficiency than conventional carbon-based fuels. In order to avoid abnormal combustion modes like pre-ignition and backfiring, as well as air displacement from hydrogen's large injected volume per cycle, direct injection of hydrogen after intake valve closure is the preferred mixture preparation method for hydrogen engines. The current work focused on computational studies of hydrogen injection and mixture formation for direct-injection spark-ignition engines. Hydrogen conditions at the injector's nozzle exit are typically sonic. Initially the characteristics of under-expanded sonic hydrogen jets were investigated in a quiescent environment using both Reynolds-Averaged NavierStokes (RANS) and Large-Eddy Simulation (LES) techniques. Various injection conditions were studied, including a reference case from the literature. Different nozzle geometries were investigated, including a straight nozzle with fixed cross section and a stepped nozzle design. LES captured details of the expansion shocks better than RANS and demonstrated several aspects of hydrogen's injection and mixing. Incylinder simulations were also performed with a side 6-hole injector using 70 and 100 bar injection pressure. Injection timing was set to just after inlet valve closure with duration of 6 μs and 8 μs, leading to global air-to-fuel equivalence ratios  typically in the region of 0.2-0.4. The engine intake air pressure was set to 1.5 bar absolute to mimic boosted operation. It was observed that hydrogen jet wall impingement was always prominent. Comparison with non-fuelled engine conditions demonstrated the degree of momentum exchange between in-cylinder hydrogen injection and air motion. LES highlighted details of hydrogen's spatial distribution throughout the injection duration and up to ignition timing. Higher peak velocities were predicted by LES, especially on the tumble plane. With the employed injection strategy, the areas closer to the cylinder wall were richer in fuel than the centre of the chamber close to the end of compression.

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Section: Reference Test Casementioning

confidence: 72%

Section: Reference Test Casementioning

confidence: 99%

Section: Nozzle-hole Geometry and Gridmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Computational Study of Hydrogen Direct Injection for Internal Combustion Engines

Hamzehloo¹,

Aleiferis²

2013

SAE Technical Paper Series

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Progressive strategies to avoid and exploit knock limit for optimal performance and stoichiometric operation of a DI hydrogen engine with high CR at WOT conditions

Hong,

Ji,

Wang

et al. 2024

Fuel

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Numerical modelling of transient under-expanded jets under different ambient thermodynamic conditions with adaptive mesh refinement

Hamzehloo

Aleiferis

2016

International Journal of Heat and Fluid Flow

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The mixing characteristics of highly turbulent under-expanded gaseous fuel jets issued from millimeter-size circular nozzles are important for developing advanced direct injection gaseous-fuelled internal combustion engines. In the present study high-resolution large eddy simulation in conjunction with an adaptive mesh refinement technique was used in order to investigate key mixing characteristics of under-expanded hydrogen and methane jets under various ambient thermodynamics. Penetration rate, volumetric growth and initial transient vortex ring behaviour were investigated under near atmospheric and elevated ambient pressures and temperatures, P ∞ ≈1 bar and 10 bar, T ∞ =296 K and 600 K, using a nozzle pressure ratio of 10. The conditions corresponded to injection strategies ranging from late intake stroke around inlet valve closure to late compression. It was observed that increasing the ambient temperature at constant pressure resulted in increase in both tip penetration and volumetric growth of the under-expanded jets. It was also found that the effect of diffusivity, ratio of specific heats and ambient density must be considered when scaling volumetric growth of under-expanded jets of different gases and/or when issued into different ambient temperatures. Moreover, substantial differences were observed between the transient jet formation of hydrogen and methane fuels. It was found that the embedded shock structures and supersonic annular shear layers played a significant role in the formation and evolution of the transient preliminary and secondary vortex rings. It was also noted that the evolution of the vortex ring influenced significantly the volumetric growth and hence mixing quality of under-expanded jets.

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Fuel-Air Mixing Characteristics of DI Hydrogen Jets

Cited by 24 publications

References 20 publications

Computational Study of Hydrogen Direct Injection for Internal Combustion Engines

Computational Study of Hydrogen Direct Injection for Internal Combustion Engines

Progressive strategies to avoid and exploit knock limit for optimal performance and stoichiometric operation of a DI hydrogen engine with high CR at WOT conditions

Numerical modelling of transient under-expanded jets under different ambient thermodynamic conditions with adaptive mesh refinement

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