Detonation Stabilization in Supersonic Flow: Effects of Suction Boundaries

Cai, Xiaodong; Deiterding, Ralf; Liang, Jianhan; Sun, Mingbo; Dong, Dezun

doi:10.2514/1.j058625

Cited by 4 publications

(4 citation statements)

References 27 publications

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“…To dynamically stabilize the detonation in the engine combustor, Cai et al (2016Cai et al ( , 2019Cai et al ( , 2021 employed a cavity as a flame holder to support an NDW in the supersonic incoming flow and used an expansion wall to attenuate the detonation wave downstream; the opposing effects of the cavity and the expansion wall on the propagation of the detonation wave compete and ultimately equilibrate with each other, which facilitates the stabilization of the NDW in the combustor. Moreover, Cai et al (2020) further attempted to control the propagation of an NDW in a straight channel by setting a series of suction slots behind the detonation front; their numerical results suggested that the dynamic stabilization of the detonation wave can be achieved.…”

Section: Introductionmentioning

confidence: 99%

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Mechanisms of the destabilized Mach reflection of inviscid oblique detonation waves before an expansion corner

2022

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The stabilization of oblique detonation waves (ODWs) in an engine combustor is important for the successful applications of oblique detonation engines, and comprehensively understanding the effects of the inviscid reflection of ODWs on their stabilization and the relevant mechanisms is imperative to overall combustor design. In this study, the flow fields of ODW reflections in a space-confined combustor are numerically studied by solving the two-dimensional time-dependent multispecies Euler equations in combination with a detailed hydrogen combustion mechanism. The inviscid Mach reflections of ODWs before an expansion corner are emphasized with different flight Mach numbers, Ma, and different dimensionless reflection locations, ζ ≥ 0 (ζ = 0: the ODW reflects precisely at the expansion corner; ζ > 0: the ODW reflects off the wall before the expansion corner). Two kinds of destabilization phenomena of the inviscid Mach reflection of an ODW induced by different mechanisms are found, namely wave-induced destabilization at large ζ > 0 for moderate (not very low) Ma and inherent destabilization at any ζ > 0 for low Ma. Wave-induced destabilization is attributed to the incompatibility between the pressure ratio across the Mach stem and its relative propagation speed, which is triggered by the action of the secondary reflected shock wave or the transmitted Mach stem on the subsonic zone behind the Mach stem. Inherent destabilization is demonstrated through an in-depth theoretical analysis and is attributed to geometric choking of the flow behind the Mach stem.

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Section: Introductionmentioning

confidence: 99%

“…Moreover, Cai et al. (2020) further attempted to control the propagation of an NDW in a straight channel by setting a series of suction slots behind the detonation front; their numerical results suggested that the dynamic stabilization of the detonation wave can be achieved.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of the destabilized Mach reflection of inviscid oblique detonation waves before an expansion corner

2022

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“…Hence, it is indeed of great guiding significance for the practical application of detonation engines to explore fundamentally the mechanisms of detonation propagation, stabilisation in expanding combustors with non-uniform supersonic flow. In the present work, the mechanism of self-sustaining detonation propagation with layered velocity in expanding channels is investigated using the dynamic adaptive mesh refinement program AMROC (Adaptive Mesh Refinement in Object-Oriented C++), [37][38][39][40] which has been demonstrated in multiple dimensional detonation simulations 41,42 .…”

Section: Introductionmentioning

confidence: 99%

Effects of velocity shear layer on detonation propagation in a supersonic expanding combustor

Cai

Mahmoudi

2021

Physics of Fluids

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This study investigates the mechanism of detonation propagation in a stoichiometric hydrogen-oxygen mixture with non-uniform flow velocity entering an expanding combustor. For simulation of the detonation propagation, the Navier-Stokes equations with a one-step two-species chemistry model are solved by employing the hybrid sixth-order weighted essentially non-oscillatory centre difference scheme. The self-sustaining mechanism of detonation propagation in an expanding combustor under the action of non-uniform supersonic flow with a velocity shear layer is revealed. The results show that under the influence of velocity shear layer, two different unburned jets are produced behind the detonation front. These jets are induced by the velocity shear layers and the Prandtl-Meyer expansion fan. The two jets interact and mix gradually. The interaction between the mixed unburned jets and highly unstable shear layers creates large-scale vortices that intensify the turbulent mixing of the unburned jets. Meanwhile, the baroclinic mechanism generates numerous vortices on the boundary of the unburned jet. These vortices promote the mixing of the burned and unburned gases, which eventually leads to the rapid consumption of the unburned pockets. The heat released due to the burning of the unreacted pockets behind the detonation wave, supports a self-sustaining propagation of the detonation wave. When the velocity difference among the shear layers increases, the surface fluctuation of the detonation wave increases.

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“…In turbofan and other turbine engines, separation of the gas flow through the engine can dramatically increase engine losses, reducing its efficiency [3]. Similarly, in supersonic ramjet (scramjet) engines for hypersonic aircraft, control of BL separation may be a necessary requirement to maintain an effective shock train and ensure continual sufficient thrust as its growth can have a substantial effect on performance [4][5][6][7]. The aerospace engineer has two methods at their disposal to combat these dramatic effects: (1) careful design and engineering of the shape and composition of the bounding surfaces (the body) or (2) direct control of the fluid flow [8].…”

Section: Introductionmentioning

confidence: 99%

Eliminating Boundary Layer Separation on a Cylinder with Nonuniform Suction

Ramsay

Sellier

2020

International Journal of Aerospace Engineering

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Boundary layer separation negatively influences the performance of aerospace vehicles, for example, by triggering static stall or reducing combustion engine efficiency. Developing effective flow control to delay or eliminate separation is therefore of real use to the field. In this paper, numerical studies were carried out to optimise distributed suction profiles for preventing boundary layer separation on a circular cylinder in the fully laminar regime (Re<188), with the least control effort. Relationships were found between the Reynolds number, the separation angle of the uncontrolled case, and the uniform suction needed to eliminate separation. It was found that for Re>20, the uniform suction required to eliminate separation followed a quadratic profile, as a function of Re. Maximum uniform suction effort was needed at Re=20, requiring a suction coefficient of CQ=49.14 (as a percentage of the free-stream velocity) to eliminate separation. To resolve the best nonuniform suction profile at Re=180, a variety of optimisation studies were performed using the coordinate search method. It was determined that the use of six control segments on each half of the cylinder provided the best control and efficient convergence to the optimal solution. 6-segment nonuniform suction eliminated separation at Re=180 with net suction effort of CQ=13.26 compared to CQ=31.25 for the uniform case. These optimal suction profiles were compared using time-dependent simulations to confirm that both methods eliminate separation when introduced to an already unsteady case. Nonuniform suction eliminated separation faster, though uniform suction was more stable.

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Detonation Stabilization in Supersonic Flow: Effects of Suction Boundaries

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Cited by 4 publications

References 27 publications

Mechanisms of the destabilized Mach reflection of inviscid oblique detonation waves before an expansion corner

Mechanisms of the destabilized Mach reflection of inviscid oblique detonation waves before an expansion corner

Effects of velocity shear layer on detonation propagation in a supersonic expanding combustor

Eliminating Boundary Layer Separation on a Cylinder with Nonuniform Suction

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