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Xiangrui Dong - One of the best experts on this subject based on the ideXlab platform.
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spectrum study on unsteadiness of shock wave Vortex ring interaction
Physics of Fluids, 2018Co-Authors: Xiangrui Dong, Yonghua Yan, Yong Yang, Gang Dong, Chaoqun LiuAbstract:Shock oscillation with low-frequency unsteadiness commonly occurs in supersonic flows and is a top priority for the control of flow separation caused by shock wave and boundary layer interaction. In this paper, the interaction of the shock caused by the compression ramp and the Vortex Rings generated by a micro-Vortex generator (MVG) in a supersonic flow at Ma = 2.5 is simulated by the implicit large eddy simulation method. The analysis of observation and the frequency of both the Vortex ring motion and the shock oscillation is carried out. The results show that the shock produced by a compression ramp flow at Ma = 2.5 has a dominant non-dimensional low frequency, which is around St = 0.002, while the Vortex Rings behind the MVG have a dominant high frequency which is around St = 0.038. The dominant low frequency of the shock, which is harmful, can be removed or weakened through the shock-Vortex ring interaction by the Vortex Rings which generate high frequency fluctuations. In the shock and Vortex ring interaction region, a dominant high frequency St = 0.037–0.038 has been detected rather than the low frequency St = 0.002, which indicates that the Vortex ring is stiff enough to break or weaken the shock. This analysis could provide an effective tool to remove or weaken the low frequency pressure fluctuation below 500 Hz, which has a negative effect on the flight vehicle structures and the environmental protection, through the high frequency Vortex generation.Shock oscillation with low-frequency unsteadiness commonly occurs in supersonic flows and is a top priority for the control of flow separation caused by shock wave and boundary layer interaction. In this paper, the interaction of the shock caused by the compression ramp and the Vortex Rings generated by a micro-Vortex generator (MVG) in a supersonic flow at Ma = 2.5 is simulated by the implicit large eddy simulation method. The analysis of observation and the frequency of both the Vortex ring motion and the shock oscillation is carried out. The results show that the shock produced by a compression ramp flow at Ma = 2.5 has a dominant non-dimensional low frequency, which is around St = 0.002, while the Vortex Rings behind the MVG have a dominant high frequency which is around St = 0.038. The dominant low frequency of the shock, which is harmful, can be removed or weakened through the shock-Vortex ring interaction by the Vortex Rings which generate high frequency fluctuations. In the shock and Vortex ring i...
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spectrum study on unsteadiness of shock wave Vortex ring interaction
Physics of Fluids, 2018Co-Authors: Xiangrui Dong, Yonghua Yan, Yong Yang, Gang Dong, Chaoqun LiuAbstract:Shock oscillation with low-frequency unsteadiness commonly occurs in supersonic flows and is a top priority for the control of flow separation caused by shock wave and boundary layer interaction. In this paper, the interaction of the shock caused by the compression ramp and the Vortex Rings generated by a micro-Vortex generator (MVG) in a supersonic flow at Ma = 2.5 is simulated by the implicit large eddy simulation method. The analysis of observation and the frequency of both the Vortex ring motion and the shock oscillation is carried out. The results show that the shock produced by a compression ramp flow at Ma = 2.5 has a dominant non-dimensional low frequency, which is around St = 0.002, while the Vortex Rings behind the MVG have a dominant high frequency which is around St = 0.038. The dominant low frequency of the shock, which is harmful, can be removed or weakened through the shock-Vortex ring interaction by the Vortex Rings which generate high frequency fluctuations. In the shock and Vortex ring interaction region, a dominant high frequency St = 0.037–0.038 has been detected rather than the low frequency St = 0.002, which indicates that the Vortex ring is stiff enough to break or weaken the shock. This analysis could provide an effective tool to remove or weaken the low frequency pressure fluctuation below 500 Hz, which has a negative effect on the flight vehicle structures and the environmental protection, through the high frequency Vortex generation.
Chaoqun Liu - One of the best experts on this subject based on the ideXlab platform.
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spectrum study on unsteadiness of shock wave Vortex ring interaction
Physics of Fluids, 2018Co-Authors: Xiangrui Dong, Yonghua Yan, Yong Yang, Gang Dong, Chaoqun LiuAbstract:Shock oscillation with low-frequency unsteadiness commonly occurs in supersonic flows and is a top priority for the control of flow separation caused by shock wave and boundary layer interaction. In this paper, the interaction of the shock caused by the compression ramp and the Vortex Rings generated by a micro-Vortex generator (MVG) in a supersonic flow at Ma = 2.5 is simulated by the implicit large eddy simulation method. The analysis of observation and the frequency of both the Vortex ring motion and the shock oscillation is carried out. The results show that the shock produced by a compression ramp flow at Ma = 2.5 has a dominant non-dimensional low frequency, which is around St = 0.002, while the Vortex Rings behind the MVG have a dominant high frequency which is around St = 0.038. The dominant low frequency of the shock, which is harmful, can be removed or weakened through the shock-Vortex ring interaction by the Vortex Rings which generate high frequency fluctuations. In the shock and Vortex ring interaction region, a dominant high frequency St = 0.037–0.038 has been detected rather than the low frequency St = 0.002, which indicates that the Vortex ring is stiff enough to break or weaken the shock. This analysis could provide an effective tool to remove or weaken the low frequency pressure fluctuation below 500 Hz, which has a negative effect on the flight vehicle structures and the environmental protection, through the high frequency Vortex generation.Shock oscillation with low-frequency unsteadiness commonly occurs in supersonic flows and is a top priority for the control of flow separation caused by shock wave and boundary layer interaction. In this paper, the interaction of the shock caused by the compression ramp and the Vortex Rings generated by a micro-Vortex generator (MVG) in a supersonic flow at Ma = 2.5 is simulated by the implicit large eddy simulation method. The analysis of observation and the frequency of both the Vortex ring motion and the shock oscillation is carried out. The results show that the shock produced by a compression ramp flow at Ma = 2.5 has a dominant non-dimensional low frequency, which is around St = 0.002, while the Vortex Rings behind the MVG have a dominant high frequency which is around St = 0.038. The dominant low frequency of the shock, which is harmful, can be removed or weakened through the shock-Vortex ring interaction by the Vortex Rings which generate high frequency fluctuations. In the shock and Vortex ring i...
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spectrum study on unsteadiness of shock wave Vortex ring interaction
Physics of Fluids, 2018Co-Authors: Xiangrui Dong, Yonghua Yan, Yong Yang, Gang Dong, Chaoqun LiuAbstract:Shock oscillation with low-frequency unsteadiness commonly occurs in supersonic flows and is a top priority for the control of flow separation caused by shock wave and boundary layer interaction. In this paper, the interaction of the shock caused by the compression ramp and the Vortex Rings generated by a micro-Vortex generator (MVG) in a supersonic flow at Ma = 2.5 is simulated by the implicit large eddy simulation method. The analysis of observation and the frequency of both the Vortex ring motion and the shock oscillation is carried out. The results show that the shock produced by a compression ramp flow at Ma = 2.5 has a dominant non-dimensional low frequency, which is around St = 0.002, while the Vortex Rings behind the MVG have a dominant high frequency which is around St = 0.038. The dominant low frequency of the shock, which is harmful, can be removed or weakened through the shock-Vortex ring interaction by the Vortex Rings which generate high frequency fluctuations. In the shock and Vortex ring interaction region, a dominant high frequency St = 0.037–0.038 has been detected rather than the low frequency St = 0.002, which indicates that the Vortex ring is stiff enough to break or weaken the shock. This analysis could provide an effective tool to remove or weaken the low frequency pressure fluctuation below 500 Hz, which has a negative effect on the flight vehicle structures and the environmental protection, through the high frequency Vortex generation.
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numerical study of micro ramp Vortex generator for supersonic ramp flow control at mach 2 5
Shock Waves, 2017Co-Authors: Yonghua Yan, L Chen, Chaoqun LiuAbstract:An implicit large eddy simulation, implemented using a fifth-order, bandwidth-optimized weighted essentially non-oscillatory scheme, was used to study the flow past a compression ramp at Mach 2.5 and $$\text {Re}_{\theta } = 5760$$ with and without a micro-ramp Vortex generator (MVG) upstream. The MVG serves as a passive flow control device. The results suggested that MVGs may distinctly reduce the separation zone at the ramp corner and lower the boundary layer shape factor. New findings regarding the MVG-ramp interacting flow included the surface pressure distribution, three-dimensional structures of the re-compression shock waves, surface separation topology, and a new secondary Vortex system. The formation of the momentum deficit was studied in depth. A new mechanism was observed wherein a series of Vortex Rings originated from the MVG-generated high shear at the boundary of the momentum deficit zone. Vortex Rings strongly interact with the shock-separated flow and play an important role in the separation zone reduction.
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by the MVG Controlled Ramp Flow at M=2.5
2014Co-Authors: Yonghua Yan, Chaoqun Liu, Xiao Wang, Yonghua Yan XiaowangAbstract:In this paper, the implicitly implemented LES method and fifth order bandwidthoptimized WENO scheme are used to make comprehensive studies on the interaction of Vortex Rings and shock waves of the MVG controlled flow at M=2.5 and Reθ=5760. The kinetic information of the Vortex Rings is carefully studied and provided. The interaction of the streamwise vortices and Vortex Rings are investigated using vorticity and three stages of evolution are found. The study between the oblique shock and Vortex Rings is made on 2-D section analyses, 3-D shock surface investigation and the relation between Vortex ring structure and the interaction. The multilayer shock structure, different shock reflection type, etc are investigated, and characteristics are obtained about the 3-D hump shape of the distorting shock caused by the Vortex ring. Nomenclature MVG = micro ramp Vortex generator M = Mach number Reθ = Reynolds number based on momentum thickness h = micro ramp height δ = incompressible boundary-layer nominal thickness x, y, z = spanwise, normal and streamwise coordinate axes u,v,w = spanwise, normal and streamwise velocity LES = large eddy simulation ∆sring = averaged horizontal distance between Rings Vring,1 = the horizontal component of the velocity of the Vortex ring Vring,2 = the ramp-aligned component of the velocity of the Vortex ring Tring = averaged period of a ring passing ∆sring Stθ = Strouhal number based on inlet momentum thickness θ/(U ∞ Tring) Sth = Strouhal number based on height of MVG h/(U ∞ Tring) Subscript 0 = inlet w = wall ∞ = free stream I
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study on shock wave Vortex ring interaction by the micro Vortex generator controlled ramp flow with turbulent inflow
Aerospace Science and Technology, 2013Co-Authors: Yonghua Yan, Caixia Chen, Chaoqun LiuAbstract:Abstract In this study, we will investigate the interaction between the Vortex Rings and oblique shocks generated by the micro Vortex generatorʼs (MVG) controlled ramp flow at M = 2.5 and Re θ = 5760 . An implicit large eddy simulation method is used by solving the unfiltered form of the Navier–Stokes equations with the 5th order bandwidth-optimized WENO scheme. It shows that the Vortex ring structure generated by MVG is very stable, it does not break down and it keeps its original topology after penetrating the strong shock wave. However, the oblique shocks are broken when they interact with Vortex Rings. The bump on the 3D shock wave surface is observed and its mechanism is explained. The separation zone, which is originally generated by the shock–boundary layer interaction, is significantly reduced due to the Vortex ring–shock interaction.
Lene Vestergaard Hau - One of the best experts on this subject based on the ideXlab platform.
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observation of hybrid soliton Vortex ring structures in bose einstein condensates
Physical Review Letters, 2005Co-Authors: Naomi S Ginsberg, Joachim Brand, Lene Vestergaard HauAbstract:We present the experimental discovery of compound structures comprising solitons and Vortex Rings in Bose-Einstein condensates. We examine both their creation via soliton-Vortex collisions and their subsequent development, which is largely governed by the dynamics of interacting Vortex Rings. A theoretical model in three-dimensional cylindrical symmetry is also presented.
Jeff Steinhauer - One of the best experts on this subject based on the ideXlab platform.
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evidence for an oscillating soliton Vortex ring by density engineering of a bose einstein condensate
Nature Physics, 2009Co-Authors: Itay Shomroni, Elias Lahoud, Shahar Levy, Jeff SteinhauerAbstract:Two intriguing shapes that appear in Bose–Einstein condensates are Vortex Rings and solitons. Experiments now suggest that there can be periodic oscillations between these qualitatively different structures. When two Bose–Einstein condensates collide with high collisional energy, the celebrated matter-wave interference pattern appears1. For lower collisional energies, the repulsive interaction energy becomes significant, and the interference pattern evolves into an array of grey solitons2,3. But the lowest collisional energies, producing a single pair of solitons, have not been probed so far. Here, we report on experiments using density engineering on the healing length scale3,4 to produce such a pair of solitons. We see evidence that the solitons evolve periodically between Vortex Rings and solitons. The stable, periodic evolution is in sharp contrast to the behaviour seen in previous experiments5,6 in which the solitons decay irreversibly into Vortex Rings through the so-called snake instability7,8,9,10,11,12,13. The evolution can be understood in terms of conservation of mass and energy in a narrow condensate.
Victor M Perezgarcia - One of the best experts on this subject based on the ideXlab platform.
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nonlinear quantum piston for the controlled generation of Vortex Rings and soliton trains
Physical Review A, 2013Co-Authors: Florian Pinsker, Natalia G Berloff, Victor M PerezgarciaAbstract:We propose a simple way to generate nonlinear excitations in a controllable way by managing interactions in Bose-Einstein condensates. Under the action of a quantum analog of a classical piston, the condensed atoms are pushed through the trap, generating Vortex Rings infully three-dimensional condensates or soliton trains in quasi-one-dimensional scenarios. The Vortex Rings form due to transverse instability of the shock-wave train, enhanced and supported by the energy transfer between waves. We elucidate in what sense the self-interactions within the atom cloud define the properties of the generated Vortex Rings and soliton trains. Based on the quantum-piston scheme we study the behavior of two-component Bose-Einstein condensates and analyze how the presence of an additional superfluid influences the generation of Vortex Rings or solitons in the other component, and vice versa. Finally, we show the dynamical emergence of skyrmions within two-component systems in the immiscible regime.
