Control of pseudo-shock oscillation in scramjet inlet-isolator using periodical excitation

Su, Weiyi; Chen, Yun; Zhang, Fengrui; Tang, Piao-Ping

doi:10.1016/j.actaastro.2017.10.040

Cited by 31 publications

(4 citation statements)

References 28 publications

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“…The effects of cavity depth on shock train structure was studied by Kumar and Vaidyanathan [9] who showed that the strength of the shock train system decreases with an increase in the depth of the cavity. Su et al [10] controlled the pseudo-shock oscillation in a scramjet inlet-isolator by applying periodical excitation. Vanstone et al [11,12] proposed a simple physics-based model for the prediction of shock-train location.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation of pseudo shock structure in a convergent–long divergent duct

Mousavi

Kamali

Sotoudeh

et al. 2021

Computers & Mathematics with Applications

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In this paper, the Pseudo shock structure in a convergent-long divergent duct is investigated using large eddy simulation on the basis of Smagorinsky-Lilly, Wall-Adapting Local Eddy-Viscosity and Algebraic Wall-Modeled LES subgrid models. The first objective of the study is to apply different subgrid models to predict the structure of Lambda form shocks system, while the ultimate aim is to obtain further control of the shock behavior. To achieve these goals, the dynamic grid adaption and hybrid initialization techniques are applied under the 3D investigation to reduce numerical errors and computational costs. The results are compared to the existing experimental data and it is found that the WMLES subgrid model results in more accurate predictions when compared to the other subgrid models. Subsequently, the influences of the divergent section length with the constant ratio of the outlet to throat area and, the effects of discontinuity of the wall temperature on the flow physics are investigated. The results indicate that the structure of compressible flow in the duct is affected by varying these parameters. This is then further discussed to provide a deeper physical understanding of the mechanism of Pseudo shock motion.

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Section: Introductionmentioning

confidence: 99%

Large eddy simulation of pseudo shock structure in a convergent–long divergent duct

Mousavi

Kamali

Sotoudeh

et al. 2021

Computers & Mathematics with Applications

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“…The position and structure of the shock train remained stable when the backpressure was low, but oscillations emerged when the backpressure was high. To suppress the oscillation, they used a periodic jet to manipulate the cowl reflected shock wave (Su et al, 2018). Even when the incoming flow is uniform, the structure of the shock train may be asymmetric.…”

Section: Introductionmentioning

confidence: 99%

Experimental study and analysis of shock train self-excited oscillation in an isolator with background waves

Hou

Chang

Kong

et al. 2020

J. Zhejiang Univ. Sci. A

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A study of shock train self-excited oscillation in an isolator with background waves was implemented through a wind tunnel experiment. Dynamic pressure data were captured by high-frequency pressure measurements and the flow field was recorded by the high-speed Schlieren technique. The shock train structure was mostly asymmetrical during self-excited oscillation, regardless of its oscillation mode. We found that the pressure discontinuity caused by background waves was responsible for the asymmetry. On the wall where the pressure at the leading edge of the shock train was lower, a large separation region formed and the shock train deflected toward to the other wall. The oscillation mode of the shock train was related to the change of wall pressure in the oscillation range of its leading edge. The oscillation range and oscillation intensity of the shock train leading edge were affected by the wall pressure gradient induced by background waves. When located in a negative pressure gradient region, the oscillation of the leading edge strengthened; when located in a positive pressure gradient region, the oscillation weakened. To find out the cause of self-excited oscillation, correlation and phase analyses were performed. The results indicated that the instability of the separation region induced by the leading shock was the source of perturbation that caused self-excited oscillation, regardless of the oscillation mode of the shock train.

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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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Control of pseudo-shock oscillation in scramjet inlet-isolator using periodical excitation

Cited by 31 publications

References 28 publications

Large eddy simulation of pseudo shock structure in a convergent–long divergent duct

Large eddy simulation of pseudo shock structure in a convergent–long divergent duct

Experimental study and analysis of shock train self-excited oscillation in an isolator with background waves

Eliminating Boundary Layer Separation on a Cylinder with Nonuniform Suction

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