Scramjet to ramjet transition in a dual-mode combustor with fin-guided injection

Aguilera, Camilo; Yu, Kenneth H.

doi:10.1016/j.proci.2016.06.113

Cited by 40 publications

(6 citation statements)

References 10 publications

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“…However, the reciprocating propagation of flame and combustion oscillation occur frequently under this configuration, which may directly reduce the engine performance and significantly shorter the life cycle. The phenomenon of flame flashback has been observed in many ground experiments, [11][12][13] and its causes are widely analyzed.…”

Section: Introductionmentioning

confidence: 99%

Effects of cavity parameters on flame flashback phenomenon in a supersonic crossflow with a cavity flameholder

Tang

Zhao

Wang

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part G:

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In this paper, the cavity parameters of length-to-depth ratio, aft ramp angle, and nitrogen throttling positions are numerically studied by a Large Eddy Simulation (LES) combined with the Flamelet/Progress Variable (FPV) model, to investigate the inducing factors and formation mechanism of flame flashback. These numerical studies are validated and compared to our previous experiments. It can be observed from both the calculated and experimental flow field that the larger length-to-depth ratio, sharper aft ramp angle, and nitrogen throttling closer to the cavity strengthen the mixing of fuel wake and promote the jet penetration depth. Meanwhile, the separation of the boundary layer downstream of the cavity can be induced by the shear layer, acoustic oscillation, as well as nitrogen throttling. And the above favorable prerequisites enhance the heat release nearby, while the reverse pressure gradient causes the enlargement of the boundary layer separation in turn. Under this positive feedback, thermal choking is formed and drives the reverse propagation of the high-temperature flame. It is concluded that the downstream boundary layer separation induced by the changes of the cavity parameters is a prerequisite for the flame flashback, and the formation of the thermal choking is the main reason for the flame flashback.

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Section: Introductionmentioning

confidence: 99%

Effects of cavity parameters on flame flashback phenomenon in a supersonic crossflow with a cavity flameholder

Tang

Zhao

Wang

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…The scramjet mode corresponded to cavity shear-layer-stabilized combustion, and the flame of the ramjet mode was combined with cavity shear-layer-and recirculation-stabilized combustion. In addition, many researchers have focused on subsonic and supersonic combustion modes in dual-mode scramjet engines [14,15]. The current research has focused on the flame stabilization mode under a fixed equivalence ratio, but there is little research on the switching process between different flame stabilization modes.…”

Section: Introductionmentioning

confidence: 99%

Combustion Modes and Unsteady Characteristics during the Condition Transition of a Scramjet Combustor

et al. 2021

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To investigate the combustion modes and unsteady characteristics during the condition transition of a scramjet combustor, a series of experiments were carried out under the condition of Mach 2.52 supersonic incoming flow, the corresponding stagnation pressure and temperature of which were 1.6 MPa and 1486 K, respectively. A fuel supply system that could dynamically adjust the injection pressure was adopted to simulate the condition transition stage of a scramjet. Based on the advanced combustion diagnosis technique, the transient chemiluminescence image and the wall pressure were recorded during the whole combustion process. Three typical modes of turbulent combustion occurred when the injection pressure drop gradually increased. The jet flame was stable after the condition transition when the injection pressure drop was relatively low. An unstable combustion phenomenon accompanied by intermittent local extinction and reignition could be found near the blowout limits. With a further increase in the injection pressure drop, the flame was blown out quickly during the transition process. In addition, the flame development characteristics during condition transition under stable combustion mode and the effect of injection pressure drop were studied in detail. During the process of switching between the two conditions, the area and light intensity of the flame decreased over time, and the wall pressure was accordingly reduced. As the increase in injection pressure dropped, the intensity of chemical reactions deceased obviously and the transition time became longer.

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“…For another reason, if combustion is considered, well-posed penetration of fuel can alleviate the heat destruction on the combustor wall 10 . Moreover, proper heat release distribution, which seriously relies on lift-off of fuel jet, is the key to a successful mode-transition in dual-mode ramjet/scramjet combustors 11 . Therefore, lift-off of fuel injection from the supersonic streamwise vortex is the core evaluation in the design of combustors.…”

Section: Introductionmentioning

confidence: 99%

Two-stage growth mode for lift-off mechanism in oblique shock-wave/jet interaction

Yu,

He,

Zhang

et al. 2020

Preprint

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The lift-off characteristics of supersonic streamwise vortex in oblique shock-wave/jet interaction (OS/JI for short), extracted from a wall-mount ramp injector in scramjet, is studied through Large-eddy simulation method. Shocked helium jet is deformed into a pair of streamwise vortex with a co-rotating companion vortex showing the lift-off characteristic immediately after shock. Based on the objective coordinate system in frame of oblique shock structure, it is found that the nature of three-dimensional lift-off structure of a shockinduced streamwise vortex is inherently and precisely controlled by a two-stage growth mode of structure kinetics of a shock bubble interaction (SBI for short). The striking similar structures between OS/JI and SBI support the proposition that the lift-off of streamwise vortex is the result of a underlying two-dimensional vortical motion. By considering the first stage impulsive linear growth rate, an improved vortex propagation model suitable for SBI is proposed and validated. The lift-off phenomena of both numerical OS/JI case in this paper and wall-mounted ramp injector cases in literature are well explained under the two-stage structure kinetics model of SBI. This model further predicts that for higher free stream Mach number (M > 5), increasing ramp compression shows little effect on elevating streamwise vortex while evident lift-off may occur for lower Mach number (M < 3.5), which offers the new way for preliminary design of streamwise vortex-based ramp injector in scramjet.

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Scramjet to ramjet transition in a dual-mode combustor with fin-guided injection

Cited by 40 publications

References 10 publications

Effects of cavity parameters on flame flashback phenomenon in a supersonic crossflow with a cavity flameholder

Effects of cavity parameters on flame flashback phenomenon in a supersonic crossflow with a cavity flameholder

Combustion Modes and Unsteady Characteristics during the Condition Transition of a Scramjet Combustor

Two-stage growth mode for lift-off mechanism in oblique shock-wave/jet interaction

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