Self-ignition and transition to flame-holding in a rectangular scramjet combustor with a backward step

Takahashi, Shuhei; Yamano, Goro; Wakai, Kazunori; Tsue, Mitsuhiro; Kono, Michikata

doi:10.1016/s0082-0784(00)80272-6

Cited by 37 publications

(16 citation statements)

References 5 publications

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“…12 shows the hydrogen mass fractions around the backward-facing step and the cavity. This means that the fast chemical reaction is allowed in the recirculation zone behind the step (Takahashi et al 2000) and in the cavity (Gruber et al 2001). Because the cavity is located downstream of the fuel injection, the penetration depth of the hydrogen in case 2 is smaller than that in case 1.…”

Section: Cavity Flowmentioning

confidence: 99%

“…Therefore, this has become one of the most important issues to be dealt with for future hypersonic airbreathing propulsive systems. Recently, the backward-facing step (Halupovich et al 1999;Mitani and Kouchi 2005;Takahashi et al 2000) and the cavity flameholder Hanson 1998, 2001;Gu et al 2009) are widely used to solve this problem in the scramjet combustor to generate the recirculation zones with low flow velocity which can prolong the residence time of the flow formed in the core region, upstream of the fuel injector, and in the cavity. However, the flameholding mechanisms of these two different geometric models are still not clear enough to design a scramjet engine with the highest possible combustion efficiency, the advantages and differences between their flameholding mechanisms have rarely been compared and discussed in the open literature.…”

Section: Introductionmentioning

confidence: 99%

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Investigation on the flameholding mechanisms in supersonic flows: backward-facing step and cavity flameholder

Huang

Pourkashanian

et al. 2010

J Vis

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As effective devices to extend the fuel residence time in supersonic flow and prolong the duration time for hypersonic vehicles cruising in the near-space with power, the backward-facing step and the cavity are widely employed in hypersonic airbreathing propulsive systems as flameholders. The two-dimensional coupled implicit RANS equations, the standard k-e turbulence model, and the finite-rate/eddy-dissipation reaction model have been used to generate the flow field structures in the scramjet combustors with the backward-facing step and the cavity flameholders. The flameholding mechanism in the combustor has been investigated by comparing the flow field in the corner region of the backward-facing step with that around the cavity flameholder. The obtained results show that the numerical simulation results are in good agreement with the experimental data, and the different grid scales make only a slight difference to the numerical results. The vortices formed in the corner region of the backward-facing step, in the cavity and upstream of the fuel injector make a large difference to the enhancement of the mixing between the fuel and the free airstream, and they can prolong the residence time of the mixture and improve the combustion efficiency in the supersonic flow. The size of the recirculation zone in the scramjet combustor partially depends on the distance between the injection and the leading edge of the cavity. Further, the shock waves in the scramjet combustor with the cavity flameholder are much stronger than those that occur in the scramjet combustor with the backward-facing step, and this causes a large increase in the static pressure along the walls of the combustor.

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Section: Cavity Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation on the flameholding mechanisms in supersonic flows: backward-facing step and cavity flameholder

Huang

Pourkashanian

et al. 2010

J Vis

View full text Add to dashboard Cite

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“…However, with the development of scramjet engine, backward-facing step as the flame holder has drawn more attention in combustor design due to its simple geometry. The backward-facing step can generate recirculation zones with low flow velocity and prolong the residence time of the flow formed in the step corner as discussed by Halupovich et al [8], Takahashi et al [9], and Mitani and Kouchi [10]. Recently, Huang et al [11] have investigated the flameholding mechanism in the combustor.…”

Section: Introductionmentioning

confidence: 99%

Effects of Inflow Mach Number and Step Height on Supersonic Flows over a Backward-Facing Step

Liu

Wang

Guo

et al. 2013

Advances in Mechanical Engineering

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The backward-facing step is practically implicated in many devices, encountering the massive separation flows. In the present study, simulations of supersonic flow over a backward-facing step have been carried out employing both RANS and LES. The simulated results are validated against the experimental data. The results of RANS and LES show a good comparison with the experimental results. Different inflow Mach numbers and expansion ratios are also investigated. The reattachment length decreases with the increase of inflow Mach number. The duct height has a great effect on the flow patterns. The present conclusions are helpful to understand the physics in supersonic separation flows and also provide theory basis for engineering applications.

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“…To solve this problem, some fuel injection techniques have been proposed. The strut [5][6][7][8][9][10][11][12][13][14], the cavity [15][16][17][18], the cantilevered ramp [4], the backward facing step [19][20][21] and the combination [22][23][24][25], whose principle is to generate vorticity in the vicinity of the walls of the combustor. The region forming the vorticity, namely the recirculation zone, has low flow velocity.…”

mentioning

confidence: 99%

Parametric effects on the combustion flow field of a typical strut-based scramjet combustor

et al. 2011

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The flame-holding mechanism in hypersonic propulsion technology is the most important factor in prolonging the duration time of hypersonic vehicles. The two-dimensional coupled implicit Reynolds-averaged Navier-Stokes equations, the shear-stress transport k- turbulence model and the finite-rate/eddy-dissipation reaction models were used to simulate the combustion flow field of a typical strut-based scramjet combustor. We investigated the effects of the hydrogen-air reaction mechanism and fuel injection temperature and pressure on the parametric distributions in the combustor. The numerical results show qualitative agreement with the experimental data. The hydrogen-air reaction mechanism makes only a slight difference in parametric distributions along the walls of the combustor, and the expansion waves and shock waves exist in the combustor simultaneously. Furthermore, the expansion wave is formed ahead of the shock wave. A transition occurs from the shock wave to the normal shock wave when the injection pressure or temperature increases, and the reaction zone becomes broader. When the injection pressure and temperature both increase, the waves are pushed out of the combustor with subsonic flows. When the waves are generated ahead of the strut, the separation zone is formed in double near the walls of the combustor because of the interaction of the shock wave and the boundary layer. The separation zone becomes smaller and disappears with the disappearance of the shock wave. Because of the horizontal fuel injection, the vorticity is generated near the base face of the strut, and this region is the main origin for turbulent combustion. , hypersonic propulsion technology has drawn increasing attention from researchers. However, the flame-holding mechanism in the scramjet combustor cannot satisfy the requirement for cruising a long time in near-space [3] because of the short residence time of the mixture remaining in the supersonic flow, which is in the order of milliseconds [4]. This restricts improvement of the aerodynamic performance of hypersonic vehicles. To solve this problem, some fuel injection techniques have been proposed. The strut [5][6][7][8][9][10][11][12][13][14], the cavity [15][16][17][18], the cantilevered ramp [4], the backward facing step [19][20][21] and the combination [22][23][24][25], whose principle is to generate vorticity in the vicinity of the walls of the combustor. The region forming the vorticity, namely the recirculation zone, has low flow velocity. In this region the fuel mixes with the supersonic flow and the mixture can stay in the scramjet combustor for a long time. Zou et al. [6] have used a newly-proposed partiallyresolved numerical simulation procedure to investigate turbulent combustion in a two-dimensional DLR scramjet engine, and the large-scale turbulence was defined by the temporal filtering. Oevermann [7] has used a two-equation k- turbulence model combined with a stretched laminar

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Self-ignition and transition to flame-holding in a rectangular scramjet combustor with a backward step

Cited by 37 publications

References 5 publications

Investigation on the flameholding mechanisms in supersonic flows: backward-facing step and cavity flameholder

Investigation on the flameholding mechanisms in supersonic flows: backward-facing step and cavity flameholder

Effects of Inflow Mach Number and Step Height on Supersonic Flows over a Backward-Facing Step

Parametric effects on the combustion flow field of a typical strut-based scramjet combustor

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