To analyze the response of the wall pressure fluctuation in an isolator when the shock train is subjected to a periodic motion at a low frequency,the isolator experiment is conducted in a blow-down supersonic wind tun...To analyze the response of the wall pressure fluctuation in an isolator when the shock train is subjected to a periodic motion at a low frequency,the isolator experiment is conducted in a blow-down supersonic wind tunnel at free stream Mach number of 1.98 under asymmetric incoming flow.Experimental results show that：The isolator effectively isolates the periodic back pressure fluctuation from affecting upstream undisturbed flow;The wall pressure fluctuations are due to the propagation of wave fronts with the second acoustic mode,but they are subjected to an oscillating shock train in the most part of the shock oscillation region;The attenuation of wall pressure fluctuations on the lower wall with thick boundary layer accords with the exponential law,but it fluctuates on the upper wall with thin boundary layer in the shock oscillation region.展开更多
A hybrid central-upwind scheme is proposed. Two sub-schemes, the central difference scheme and the Roets flux difference splitting scheme, are hybridized by means of a binary sensor function. In order to examine the c...A hybrid central-upwind scheme is proposed. Two sub-schemes, the central difference scheme and the Roets flux difference splitting scheme, are hybridized by means of a binary sensor function. In order to examine the capability of the proposed hybrid scheme in computing compressible turbulent flow around a curved surface body, especially the flow involving shock wave, three typical eases are investigated by using detached-eddy simulation technique. Numerical results show good agreements with the experimental measurements. The present hybrid scheme can be applied to simulating the compressible flow around a curved surface body involving shock wave and turbulence.展开更多
In this short note, a new projective equation （Ф = σФ ＋ Ф^2） is used to obtain the variable separation solutions with two arbitrary functions of the （2＋1）-dimensional Boiti-Leon-Manna Pempinelli system （BLM...In this short note, a new projective equation （Ф = σФ ＋ Ф^2） is used to obtain the variable separation solutions with two arbitrary functions of the （2＋1）-dimensional Boiti-Leon-Manna Pempinelli system （BLMP）. Based on the derived solitary wave solution and by selecting appropriate functions, some novel localized excitations such as multi dromion-solitoffs and fractal-solitons are investigated.展开更多
With the help of an improved mapping approach and a linear-variable-separation approach, a new family of exact solutions with arbitrary functions of the （2＋1）-dimensional Nizhnik-Novikov-Veselov system （NNV） is d...With the help of an improved mapping approach and a linear-variable-separation approach, a new family of exact solutions with arbitrary functions of the （2＋1）-dimensional Nizhnik-Novikov-Veselov system （NNV） is derived. Based on the derived solutions and using some multi-valued functions, we find a few new folded solitary wave excitations for the （2＋1）-dimensional NNV system.展开更多
This study demonstrates the potential for shock wave-boundary layer interaction control in air by plasma aerodynamic actuation.Experimental investigations on shock wave-boundary layer interactions control by plasma ae...This study demonstrates the potential for shock wave-boundary layer interaction control in air by plasma aerodynamic actuation.Experimental investigations on shock wave-boundary layer interactions control by plasma aerodynamic actuation are conducted in a Mach 3 in-draft air tunnel.Schlieren imaging shows that the discharges cause the oblique shock to move forward.Schlieren imaging and static pressure probes also show that separation phenomenon shifts backward and the size of separation is enlarged when plasma aerodynamic actuation is applied.The intensity of shock wave is weakened through wall pressure probe.Furthermore,numerical investigations on shock wave-boundary layer interactions control are conducted with plasma aerodynamic actuation.The discharge is modeled as a steady volumetric heat source which is integrated into the energy equation.The input energy level is about 7 kW through discharge process.Results show that the separation phenomenon shifts backward and the intensity of shock is reduced with plasma actuation.These numerical results are consistent with the experimental results.展开更多
In usual cases of significant pressure gradients and strong shocks, the front shock takes a fixed location along the wall, at which separation starts. Usually the rear shock is responding to vortex sheding by its defl...In usual cases of significant pressure gradients and strong shocks, the front shock takes a fixed location along the wall, at which separation starts. Usually the rear shock is responding to vortex sheding by its deflection angle. In consequence main shock and rear shocks are moving whilst front shock is stable. The goal of the measurements presented here is to find out how the k-foot behaves during shock oscillations in the case when front shock is not fixed by the pressure gradient. Unsteady shock behaviour is also investigated when air jet vortex generators （AJVG） are used. Counteraction of the separation is directly related to the influence on unsteady processes in the shock wave induced separation.展开更多
According to the mechanism of the arc plasma heating effect,and from a phenomenological perspective of view,the plasma actuation was simplified as heating energy injected into the supersonic flow field for the numeric...According to the mechanism of the arc plasma heating effect,and from a phenomenological perspective of view,the plasma actuation was simplified as heating energy injected into the supersonic flow field for the numerical research on controlling detached shock of the blunt body in non-center symmetrical positions.Besides,experimental research on the form and strength of detached shock wave control by plasma aerodynamic actuation in non-center symmetrical positions was conducted in a high-speed shock tunnel(M=2).The results showed that the detached distance of shock wave increased and the strength of normal shock wave ahead of the detached shock wave reduced when plasma actuation was applied.The control effect was greatly improved after the magnetic field was applied and the effect of upwind-direction flow was the best one.When the upwind-direction flow was applied with 1000 V voltage actuation,the distance of detached shock wave would increase from 3.4 to 7.6 mm and the time average strength of normal shock wave was weaken by 5.5%.At last,the mechanism of plasma actuation on controlling the detached shock wave was briefly analyzed.展开更多
基金Supported by the National Natural Science Foundation of China(10572059)~~
文摘To analyze the response of the wall pressure fluctuation in an isolator when the shock train is subjected to a periodic motion at a low frequency,the isolator experiment is conducted in a blow-down supersonic wind tunnel at free stream Mach number of 1.98 under asymmetric incoming flow.Experimental results show that：The isolator effectively isolates the periodic back pressure fluctuation from affecting upstream undisturbed flow;The wall pressure fluctuations are due to the propagation of wave fronts with the second acoustic mode,but they are subjected to an oscillating shock train in the most part of the shock oscillation region;The attenuation of wall pressure fluctuations on the lower wall with thick boundary layer accords with the exponential law,but it fluctuates on the upper wall with thin boundary layer in the shock oscillation region.
基金Supported by the National Science Foundation for Post-doctoral Scientists of China(20100481141,201104567)the Natural Science Foundation of Jiangsu Province(BK2011723)the Planned Projects for Postdoctoral Research Foundation of Jiangsu Province(0902001C)~~
文摘A hybrid central-upwind scheme is proposed. Two sub-schemes, the central difference scheme and the Roets flux difference splitting scheme, are hybridized by means of a binary sensor function. In order to examine the capability of the proposed hybrid scheme in computing compressible turbulent flow around a curved surface body, especially the flow involving shock wave, three typical eases are investigated by using detached-eddy simulation technique. Numerical results show good agreements with the experimental measurements. The present hybrid scheme can be applied to simulating the compressible flow around a curved surface body involving shock wave and turbulence.
基金Supported by the Natural Science Foundation of Zhejiang Province under Grant Nos.Y604106 and Y606128the Scientific Research Fund of Zhejiang Provincial Education Department of China under Grant No.20070568the Natural Science Foundation of Zhejiang Lishui University under Grant Nos.KZ08001 and KZ09005
文摘In this short note, a new projective equation （Ф = σФ ＋ Ф^2） is used to obtain the variable separation solutions with two arbitrary functions of the （2＋1）-dimensional Boiti-Leon-Manna Pempinelli system （BLMP）. Based on the derived solitary wave solution and by selecting appropriate functions, some novel localized excitations such as multi dromion-solitoffs and fractal-solitons are investigated.
基金supported by the Natural Science Foundation of Zhejiang Province under Grant No.Y604106the Scientific Research Foundation of Zhejiang Provincial Education Department under Grant No.20070568the Natural Science Foundation of Zhejiang Lishui University under Grant No.KZ08001
文摘With the help of an improved mapping approach and a linear-variable-separation approach, a new family of exact solutions with arbitrary functions of the （2＋1）-dimensional Nizhnik-Novikov-Veselov system （NNV） is derived. Based on the derived solutions and using some multi-valued functions, we find a few new folded solitary wave excitations for the （2＋1）-dimensional NNV system.
基金supported by the National Natural Science Foundation of China(Grant Nos.51276197,51207169,11372352)
文摘This study demonstrates the potential for shock wave-boundary layer interaction control in air by plasma aerodynamic actuation.Experimental investigations on shock wave-boundary layer interactions control by plasma aerodynamic actuation are conducted in a Mach 3 in-draft air tunnel.Schlieren imaging shows that the discharges cause the oblique shock to move forward.Schlieren imaging and static pressure probes also show that separation phenomenon shifts backward and the size of separation is enlarged when plasma aerodynamic actuation is applied.The intensity of shock wave is weakened through wall pressure probe.Furthermore,numerical investigations on shock wave-boundary layer interactions control are conducted with plasma aerodynamic actuation.The discharge is modeled as a steady volumetric heat source which is integrated into the energy equation.The input energy level is about 7 kW through discharge process.Results show that the separation phenomenon shifts backward and the intensity of shock is reduced with plasma actuation.These numerical results are consistent with the experimental results.
基金the UFAST project financed by the European Commission within a cooperation sectorunder number:012226
文摘In usual cases of significant pressure gradients and strong shocks, the front shock takes a fixed location along the wall, at which separation starts. Usually the rear shock is responding to vortex sheding by its deflection angle. In consequence main shock and rear shocks are moving whilst front shock is stable. The goal of the measurements presented here is to find out how the k-foot behaves during shock oscillations in the case when front shock is not fixed by the pressure gradient. Unsteady shock behaviour is also investigated when air jet vortex generators （AJVG） are used. Counteraction of the separation is directly related to the influence on unsteady processes in the shock wave induced separation.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51276197,51207169)
文摘According to the mechanism of the arc plasma heating effect,and from a phenomenological perspective of view,the plasma actuation was simplified as heating energy injected into the supersonic flow field for the numerical research on controlling detached shock of the blunt body in non-center symmetrical positions.Besides,experimental research on the form and strength of detached shock wave control by plasma aerodynamic actuation in non-center symmetrical positions was conducted in a high-speed shock tunnel(M=2).The results showed that the detached distance of shock wave increased and the strength of normal shock wave ahead of the detached shock wave reduced when plasma actuation was applied.The control effect was greatly improved after the magnetic field was applied and the effect of upwind-direction flow was the best one.When the upwind-direction flow was applied with 1000 V voltage actuation,the distance of detached shock wave would increase from 3.4 to 7.6 mm and the time average strength of normal shock wave was weaken by 5.5%.At last,the mechanism of plasma actuation on controlling the detached shock wave was briefly analyzed.
