Observation of mixing and combustion processes of H2 jet injected into supersonic streamwise vortices

Sunami, Tetsuji; Scheel, Frithjof

doi:10.1007/978-3-540-27009-6_140

Cited by 5 publications

(2 citation statements)

References 8 publications

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“…This parameter is of particular interest in examining the streamwise vorticity eects on neareld mixing, where the circulation of the streamwise vortices predominantly aects the largescale convective mixing through the interaction between the streamwise vortices and fuel jet, as reported in References [10,11].…”

Section: Streamwise Vortex Circulationmentioning

confidence: 99%

“…2), in particular, are capable of generating streamwise vortices to enhance fuel/air mixing in the core ow, incurring minimum inuence of uid compressibility [9], in contrast to the other methods which supply fuel without producing strong vorticity. Experimental and numerical studies have been conducted extensively at JAXA Kakuda Space Center in order to investigate the eects of streamwise vortices introduced by hypermixers on fuel mixing and combustion enhancement [10,11]. These preceding studies were conducted 3 with primary focus on the fundamental physics of supersonic mixing and combustion due to hypermixer injectors, aiming to apply this type of injector to the scramjet combustor.…”

Section: Introductionmentioning

confidence: 99%

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Physical Insight into Fuel/Air Mixing with Hypermixer Injectors for Scramjet Engines

Ogawa

Kodera

2015

Journal of Propulsion and Power

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Ecient mixing of fuel and air is a major objective for the successful operation of scramjet engines, where the supersonic combustion process must occur within an extremely short time frame in the hypersonic ight. This paper presents the insights gained into the key design factors and underlying mechanism for fuel/air mixing enhancement with streamwise vortices introduced by alternating wedges called hypermixers. The results of a parametric numerical study and sensitivity analysis suggest that: Narrow spanwise intervals between the alternating wedges and large fuel/air equivalence ratios are benecial for eective mixing, while higher total pressure recovery is associated with shallower ramp angles and lower fuel/air equivalence ratios.Higher fuel penetration is achieved with steeper ramp angles and higher fuel/air equivalence ratios. Streamwise vortex circulation increases with wider spanwise spacing and steeper ramp angles, but eective mixing enhancement is observed only in the latter case.

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Section: Streamwise Vortex Circulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Physical Insight into Fuel/Air Mixing with Hypermixer Injectors for Scramjet Engines

Ogawa

Kodera

2015

Journal of Propulsion and Power

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Shockwave effects on supersonic combustion using hypermixer struts

Hiejima

Oda

2020

Physics of Fluids

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This study describes combustion features due to streamwise vorticity when using hypermixer struts at Mach numbers of 2.5 and 3.5. Two types of struts are used with hydrogen fuel (at an equivalence ratio of 0.4) injected at sonic speed from the trailing edges of the struts. To study the effects of shockwaves on streamwise vorticity formation and supersonic combustion for an alternating-wedge strut, the intersection point at which the shockwaves cross the central axis is varied by changing the length of the strut. When the incident shock is near the trailing edge of the strut, boundary-layer separation occurs on the ramp of the strut due to pressure increase near the strut and subsonic combustion occurs on the basis of this separation. Conversely, when the incident shock is far from the trailing edge of the strut, a streamwise vortex is generated by the strut and supersonic combustion caused by this vortex makes it effective at entraining fuel into itself. Each flame structure obtained here unquestionably differs in its combustion mode. For a separation-resistant strut, the results show that a streamwise vortex with the required circulation can be induced behind the strut without separation. Moreover, the combustion depends strongly on the incident shockwaves in that the combustion efficiency is not subject to the mixing efficiency because the moderate combustion originates near the point at which the formed streamwise vortex interacts with the shockwaves. Therefore, because an ignition point with moderate combustion can detach from its trailing edge, with a separation-resistant strut, it is possible to control the combustion and avoid an excessive heat load.

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Effects of fuel injection speed on supersonic combustion using separation-resistant struts

Hiejima

Nishimura

2021

AIP Advances

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This paper describes the improvement in combustion efficiency achieved using streamwise vorticity and fuel injections when using hypermixer struts at high Mach numbers. The effects of fuel injection conditions on combustion were investigated using numerical simulations of chemical reactive flows with a detailed reaction mechanism. Hydrogen fuel was injected from the trailing edges of a separation-resistant strut. Fuel injection at sonic speeds led to an enhancement in efficiency with an increased injection angle at Mach number 2.5, but this improvement was not observed at Mach number 3.5. It was found that hydrogen accumulated in the vortex core because of the strong circulation generated from the strut at high Mach numbers. With fuel injection at speeds exceeding the sonic speed, the efficiency increased, and it improved further with an increasing injection angle. From the results, an important indicator for combustion enhancement was derived from the streamwise vortex circulation, fuel injection velocity, and inflow Mach number. To increase the combustion efficiency using the strut, the indicator value should exceed a threshold. This is crucial for ensuring effective fuel consumption during combustion. These findings provide useful insights into a good design of hypermixer struts in supersonic combustion.

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Observation of mixing and combustion processes of H2 jet injected into supersonic streamwise vortices

Cited by 5 publications

References 8 publications

Physical Insight into Fuel/Air Mixing with Hypermixer Injectors for Scramjet Engines

Physical Insight into Fuel/Air Mixing with Hypermixer Injectors for Scramjet Engines

Shockwave effects on supersonic combustion using hypermixer struts

Effects of fuel injection speed on supersonic combustion using separation-resistant struts

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