Numerical investigation of shock train unsteady movement in a mixing duct

Lü, Lei; Wang, Yi; Fan, Xiaoqiang; Yan, Guowei; Pan, Jingwen

doi:10.1016/j.ast.2018.08.027

Cited by 22 publications

(4 citation statements)

References 20 publications

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“…Lu et al. 23 believe that the Ma number and wall pressure distributions of the background flow are the key factors that affect the motion process of the shock train. In order to obtain the continuous distributions of flow parameters, the numerical computations are carried out with steady-state code using the 2D compressible RANS equations to calculate the background flow field.…”

Section: Experimental Facility and Methodsmentioning

confidence: 99%

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Experimental investigation of shock train unsteady movement in a mixing duct

Lü

Wang

Yan

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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The structure and dynamic of the shock train in a mixing duct are investigated experimentally in a supersonic air breathing wind tunnel. High-speed schlieren technique and pressure measurements are utilized for the data acquisition. Nozzle clapboards are applied to separate the incoming flow into upper secondary flow, primary flow, and lower secondary flow. The Mach number of all incoming flows is 2.05, whereas the static pressures between primary and secondary flow stay unmatched. Experimental results indicate that nozzle clapboards lead to complex background waves and mixing layers in the mixing duct. As the throttling valve rotates at a constant speed, two motion patterns alternatively govern the shock train movement, namely jump movement and slow movement. Judging from the path of shock train leading edges, adverse pressure gradient at the wall of background flow induces jump movement, while the slow movement only appears at the zone of favorable pressure gradient. Besides, leading shock structures continuously change in the forward propagation process. Four types of leading shock structures are discovered namely regular reflection, convex-stem Mach reflection, straight-stem Mach reflection, and concave-stem Mach reflection. Based on the numerical results of the background flow field, these special structures are explained theoretically by analyzing the variation of the wavefront Ma contour lines.

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Section: Experimental Facility and Methodsmentioning

confidence: 99%

“…He found that the flow field could be divided into free mixing region and shock train mixing region. Based on Yan's research, Lu et al 23 conducted an unsteady calculation on characteristics of shock train unsteady movement. He displayed the jump motion pattern of the shock train and explained it by analyzing the wall pressure gradient.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of shock train unsteady movement in a mixing duct

Lü

Wang

Yan

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…Li et al [14] used theoretical modeling of the motion of the shock train leading edge in complex background waves, which better predicted the characteristics of the rapid forward propagation of the shock train. Lu Lei [20] studied the RBCC inlet and found that with the back pressure increasing, the forward transmission process of the shock train includes four motion periods. Each motion period contains two motion modes: slow forward transmission and "sudden jump" forward transmission.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Shock Wave Oscillation Suppression by Overflow in the Supersonic Inlet

2022

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With a focus on the shock oscillation phenomenon of a supersonic inlet at a high Mach number, the influence of isolator overflow on shock oscillation is studied in this paper. The shock wave dynamic model with overflow was established by the theoretical method, and the integrated numerical model of internal flow and external flow in the inlet was established too. The theoretical analysis of rate of overflow and overflow position on the flow field is carried out, and the changes of flow field parameters are studied by numerical simulation under different overflow positions. The results showed that both increasing the rate of overflow and setting the overflow gap close to the shock front were beneficial to reducing the flow parameters’ oscillation. In the viscous flow field, the overflow gap restricted the forward development of the local separation region of the shock train system, thus constraining the shock wave movement process, which could significantly reduce the parameter oscillation. In model C with two groups of overflow gaps, pressure oscillations of sampling point PU8 and PL8 were reduced to 29.81% and 30.56% relative to without overflow, and the corresponding rate of overflow was within 3.6%, which indicated that the appropriate overflow gap setting could effectively suppress the self-excited oscillation in the inlet.

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“…In recent years, the unsteady characteristics of shock trains have attracted more attention from researchers (Lu et al, 2018;Wang et al, 2018). Self-excited oscillation is one of the most significant unsteady characteristics.…”

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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Numerical investigation of shock train unsteady movement in a mixing duct

Cited by 22 publications

References 20 publications

Experimental investigation of shock train unsteady movement in a mixing duct

Experimental investigation of shock train unsteady movement in a mixing duct

Investigation of Shock Wave Oscillation Suppression by Overflow in the Supersonic Inlet

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

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