共查询到20条相似文献,搜索用时 15 毫秒
1.
I. A. Znamenskaya I. E. Ivanov E. Yu. Koroteeva D. M. Orlov 《Moscow University Physics Bulletin》2012,67(6):541-545
This study concerns the effect of the zone of a plane surface energy deposition on a gas-dynamic flow with a shock wave of M = 2.3–2.7 in a channel with a rectangular cross section. The source of the pulsed energy is a distributed sliding nanosecond discharge that develops in an approximately 1-mm-thick layer on a surface of 100 × 30 mm2. The results of a 3D numerical simulation of the problem on the basis of the Navier-Stokes equations for a compressed gas are presented and compared with the experimental shadow images. 相似文献
2.
S. M. Aulchenko V. P. Zamuraev I. A. Znamenskaya A. P. Kalinina D. M. Orlov N. N. Sysoev 《Technical Physics》2009,54(3):343-353
A way of effectively affecting the gasdynamic structures of a transonic flow over a surface by means of instantaneous local
directed energy deposition into a near-surface layer is proposed. Experimental investigations into the influence of a pulsed
high-current nanosecond surface discharge of the “plasma sheet” type on gas fast flow with a shock wave near the surface are
carried out. The self-localization of energy deposition into a low-pressure region in front of the shock wave is described.
Based on this effect, a facility for automated energy deposition into a dynamic region bounded by the moving shock front can
be designed. The limiting value of the specific energy deposition on the surface in front of the shock wave is found. With
the help of the direct-shadow method, an unsteady quasi-two-dimensional discontinuous flow arising when a plasma sheet is
initiated on the wall in a flow with a plane shock wave is studied. By numerically solving the two-dimensional nonstationary
equations of gas dynamics, the influence of the energy of a pulsed nanosecond discharge, which is applied in the frequency
regime, on the aerodynamic characteristics of a high-lift profile is investigated. It is ascertained that the energy delivered
to the gas before the closing shock wave in a local supersonic region that is located in the neighborhood of the profile contour
in zones extended along the profile considerably decreases the wave drag of the profile. 相似文献
3.
U.?Yusupaliev 《Bulletin of the Lebedev Physics Institute》2009,36(8):239-244
Using an ionization sensor, it was found that weakly ionized plasma with an ionization degree larger than 10?6 is formed under exposure to UV radiation of a high-current pulsed electric discharge in gas (air, nitrogen, xenon, and krypton) at atmospheric pressure at a distance of ~1.2–2.5 cm from the discharge boundary. It was shown that the structure of such discharge includes, in addition to the discharge channel, a dense shell and a shock wave, also a region of weakly ionized and excited gas before the shock wave front. The mechanism of discharge expansion in dense gas is ionization and heating of gas involved in the discharge due to absorption of the UV energy flux from the discharge channel and the flux of the thermal energy transferred from the discharge channel to the discharge shell due to electron thermal conductivity. 相似文献
4.
U. Yusupaliev 《Bulletin of the Lebedev Physics Institute》2009,36(8):245-251
Using an ionization sensor, it was found that weakly ionized plasma with an ionization degree larger than 10−6 is formed under exposure to UV radiation of a high-current pulsed electric discharge in gas (air, nitrogen, xenon, and krypton)
at atmospheric pressure at a distance of ∼1.2–2.5 cm from the discharge boundary. It was shown that the structure of such
discharge includes, in addition to the discharge channel, a dense shell and a shock wave, also a region of weakly ionized
and excited gas before the shock wave front. The mechanism of discharge expansion in dense gas is ionization and heating of
gas involved in the discharge due to absorption of the UV energy flux from the discharge channel and the flux of the thermal
energy transferred from the discharge channel to the discharge shell due to electron thermal conductivity. 相似文献
5.
在20 kV/40 kJ的重复频率压裂系统实验平台上,对大水泥岩样进行了电脉冲水中放电压裂实验。为了模拟井下实际工况,实验时将放电电极装入带有射孔的绝缘套管。水中脉冲放电时岩样中产生定向冲击压力波,冲击波作用于岩层使其产生裂缝。实验结果表明,冲击波通过绝缘套管作用于岩样时有一定的能量损失,部分冲击波压力会施加于绝缘套管,绝缘套管在整个实验期间没有发生形变,电脉冲放电对套管损伤作用极小,重复压裂冲击波会通过射孔在岩样上形成一定规模的微裂缝。去掉绝缘套管后,裸电极作用于岩样造缝效果会更好,裂缝明显的呈现对称规则。 相似文献
6.
A. A. Vorob'ev E. K. Zavadovskaya V. A. Starodubtsev B. V. Fedorov 《Russian Physics Journal》1977,20(2):171-176
Conclusions In high-resistance solid dielectrics (with resistances of 1012 · cm or higher, when they are irradiated with electron beams, spontaneous electric discharges are observed while the irradiation is occurring. The discharges occur at defects in the surface and develop in the layer within which the charged particles are distributed.When the charged particles are distributed in the surface or near-surface layer of the dielectric, the discharge may be initiated close to the charged surface by a grounded metal needle, even some time after the irradiation. After long storage and self-dis charge of the surface layer of the irradiated dielectric or compensation of the surface charge, discharge of the charge stored in the depth of the dielectric can occur by scratching the surface or pricking it with a needle. When the charge lies deep inside the dielectric, a brush discharge occurs when a strong shock is applied to the surface of the dielectric using a grounded needle.In all the above cases initiation of an electric discharge in the solid dielectric occurred by mechanoelectrical phenomena of direct conversion of mechanical energy into electrical energy with a high field strength. These phenomena occur in solid dielectrics with a defect structure.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 40–46, February, 1977. 相似文献
7.
The characteristic of surface arc plasma included millisecond and microsecond actuation in supersonic flow is investigated both experimentally and numerically. In the experiment, the discharge characteristic of surface arc plasma in quiescent air and supersonic flow is recorded. The stable oblique shock could be observed with millisecond actuation. And the unstable compressive wave could be also observed with microsecond actuation. In the numerical investigation, plasma actuation is defined as a source term with input power density from discharge V–I characteristic, which is expected to better describe the influence of heating process. The numerical results are coincident with experimental results. In order to confirm the capability of surface arc plasma actuation to control supersonic flow, experimental investigations on control shock induced by ramp and separation of boundary layer induced by impinging shock are performed. All the results demonstrate the control effect of surface arc plasma actuation onto supersonic flow. 相似文献
8.
Aerodynamic actuation characteristics of radio-frequency discharge plasma and control of supersonic flow 下载免费PDF全文
《中国物理 B》2019,(2)
In this paper, aerodynamic actuation characteristics of radio-frequency(RF) discharge plasma are studied and a method is proposed for shock wave control based on RF discharge. Under the static condition, a RF diffuse glow discharge can be observed; under the supersonic inflow, the plasma is blown downstream but remains continuous and stable.Time-resolved schlieren is used for flow field visualization. It is found that RF discharge not only leads to continuous energy deposition on the electrode surface but also induces a compression wave. Under the supersonic inflow condition, a weak oblique shock wave is induced by discharge. Experimental results of the shock wave control indicate that the applied actuation can disperse the bottom structure of the ramp-induced oblique shock wave, which is also observed in the extracted shock wave structure after image processing. More importantly, this control effect can be maintained steadily due to the continuous high-frequency(MHz) discharge. Finally, correlations for schlieren images and numerical simulations are employed to further explore the flow control mechanism. It is observed that the vortex in the boundary layer increases after the application of actuation, meaning that the boundary layer in the downstream of the actuation position is thickened. This is equivalent to covering a layer of low-density smooth wall around the compression corner and on the ramp surface, thereby weakening the compressibility at the compression corner. Our results demonstrate the ability of RF plasma aerodynamic actuation to control the supersonic airflow. 相似文献
9.
The potential of using the Euler equations to numerically simulate the evolution of localized energy deposition zones interacting with a normal shock in quiescent air and in a supersonic channel flow is demonstrated. Simulation results are compared with available experimental data for an optical discharge in quiescent air and with results calculated for a supersonic flow using the Navier-Stokes equations with allowance for real gas effects. The possibility of predicting gasdynamic effects using the T- and q-models of energy deposition for perfect gas is justified. The variation of the gasdynamic structure and flow parameters near an energy deposition zone developing in a quiescent medium and interacting with a normal shock is analyzed in detail for different energy deposition powers. 相似文献
10.
A. L. Aleksandrov I. V. Schweigert 《Journal of Experimental and Theoretical Physics》2010,110(5):845-850
A surface glow discharge in a gas flow is of particular interest as a possible tool for controlling the flow past hypersonic aircrafts. Using a hydrodynamic model of glow discharge, two-dimensional calculations for a kilovolt surface discharge in nitrogen at a pressure of 0.5 Torr are carried out in a stationary gas, as well as in a flow with a velocity of 1000 m/s. The discharge structure and plasma parameters are investigated near a charged electrode. It is shown that the electron energy in a cathode layer reaches 250–300 eV. Discharge is sustained by secondary electron emission. The influence of a high-speed gas flow on the discharge is considered. It is shown that the cathode layer configuration is flow-resistant. The distributions of the electric field and electron energy, as well as the ionization rate profile in the cathode layer, do not change qualitatively under the action of the flow. The basic effect of the flow’s influence is a sharp decrease in the region of the quasineutral plasma surrounding the cathode layer due to fast convective transport of ions. 相似文献
11.
In the present paper, a physical model is proposed for reducing the
problem of the drag reduction of an attached bow shock around the
nose of a high-speed vehicle with on-board discharge, to the problem
of a balance between the magnetic pressure and gas pressure of plane
shock of a partially ionized gas consisting of the environmental gas
around the nose of the vehicle and the on-board discharge-produced
plasma. The relation between the shock strength and the
discharge-induced magnetic pressure is studied by means of a set of
one-fluid, hydromagnetic equations reformed for the present purpose,
where the discharge-induced magnetic field consists of the electron
current (produced by the discharge)-induced magnetic field and the
partially ionized gas flow-induced one. A formula for the relation
between the above parameters is derived. It shows that the
discharge-induced magnetic pressure can minimize the shock strength,
successfully explaining the two recent experimental observations on
attached bow shock mitigation and elimination in a supersonic flow
during on-board discharge [Phys. Plasmas 9 (2002) 721 and
Phys. Plasmas 7 (2000) 1345]. In addition, the formula
implies that the shock elimination leaves room for a layer of
higher-density plasma rampart moving around the nose of the vehicle,
being favourable to the plasma radar cloaking of the vehicle. The
reason for it is expounded. 相似文献
12.
A possibility of conversion electron Mössbauer spectroscopy for determining the gas molecular state is shown. For acceleration of gas interaction with active surface the thin iron layer enriched with 57Fe was applied on aluminum foil and gas discharge is used. 相似文献
13.
Based on the experimental data and the energy balance of the cylindrically symmetric Z-pinch in gas, a nonlinear differential equation for the plasma filament (layer) radius was derived. From this equation, for the instant of the filament detachment from the discharge chamber wall, the dependence of the initial filament compression rate on the initial discharge and gas parameters was determined, which was compared with experimental data obtained by us and other researchers. It was shown that the dependence found is in agreement with experimental data within measurement error. 相似文献
14.
T. Letardi S. Bollanti P. Di Lazzaro F. Flora N. Lisi C. E. Zheng 《Il Nuovo Cimento D》1992,14(5):495-507
Summary Some limitation problems for gas discharge excimer lasers, when scaled to a high pulsed energy output with high repetition
rate are discussed. As an example, we present some experimental results obtained with an X-ray preionized (10×10×100) cm3 active volume, low-repetition-rate-operated gas discharge XeCl laser system.
ENEA student.
ENEA guest. 相似文献
15.
E. A. Kralkina P. A. Nekliudova V. B. Pavlov K. V. Vavilin 《Moscow University Physics Bulletin》2014,69(1):92-95
This paper presents the results of investigating the power absorption mechanism of an inductive RF discharge plasma. Dependences of the frequency of elastic electron collisions with inert gas atoms (helium, neon, argon, and krypton) on the pressure are given. In the frequency range of 3 × 106–3 × 107 s?1, an equivalent plasma resistance and the power input into the plasma are determined by the values of collision frequency and electron density within a skin layer and do not depend on the type of gas within the limits of experimental error. Upon reaching the electron temperature of ~1 eV, the energy of the main part of electrons lies in the range of Ramsauer’s minimum for elastic cross section. This leads to a decreasing elastic-collision frequency in heavy inert gases as compared to helium. 相似文献
16.
V. S. Zuev 《Journal of Russian Laser Research》1998,19(1):23-94
A photodissociation laser with pumping by radiation of open sources, namely, a strong shock wave in a noble gas and a high-current discharge, both immersed in a laser working substance, is discusse. Theoretical and experimental results on a photodissociation laser of 250 kJ pulse energy are presented. 相似文献
17.
N. A. Gerasimov V. V. Kuchinskiy V. S. Sukhomlinov S. V. Sukhomlinov 《Technical Physics》2007,52(7):831-838
The effect of the familiar Rayleigh mechanism of energy release in an elastic medium (which plays an important role, in particular, in gas discharge plasma) on the structure of a running shock wave (SW) is considered in the general case in the 1D approximation. The equation describing the propagation of the SW in this case is derived. An analytic solution to this equation is obtained for small values of the parameter characterizing the properties of the medium. The type of the solution for different signs of this parameter and for its values modulo equal to unity is analyzed. It is found that, for positive values of this parameter, a SW in the form of a step is suppressed in such a medium and degenerated into a perturbation in the form of a hump. On the contrary, for negative values of the parameter, the SW is enhanced. It is found that a stationary solution exists in the system of coordinates associated with the SW propagation in a medium with the Rayleigh energy release mechanism only if the boundary of the medium lies downstream from the shock layer. The position of this boundary corresponds to the so-called critical energy supply and the local Mach number is equal to unity at this point. For a positive value of the parameter of the medium with the Rayleigh energy release mechanism, the equation of propagation has no stationary solution for any position of the boundary of the medium upstream from the shock layer when the value of the parameter exceeds a certain limiting value. The results make it possible to analyze the features of SW propagation in a weakly ionized gas discharge plasma. 相似文献
18.
B. M. Brzhozovskii S. G. Gestrin E. P. Zinina V. V. Martynov 《Technical Physics》2017,62(12):1856-1862
The properties of a low-pressure combined gas discharge initiated in a resonator chamber near the surface of a metal workpiece subjected to the superposition of high electromagnetic and electrostatic fields have been studied. It has been shown that, when a constant potential is applied to the workpiece, a layer forms on its surface in which positive ions or electrons (depending on the sign of the potential) accelerate to an energy as high as several hundred electronvolts. The interaction between accelerated particles and the workpiece causes the liberation of heat in the surface layer, which is sufficient for its complete melting. If the applied potential is positive, a hardening nanostructure arises on the workpiece surface. The physical parameters of the combined gas discharge have been estimated. 相似文献
19.
G. E. Norman V. V. Stegailov A. V. Timofeev 《Journal of Experimental and Theoretical Physics》2011,113(5):887-900
The system of equations of motion of dust particles in a near-electrode layer of a gas discharge has been formulated taking
into account fluctuations of the charge of a dust particle and the features of the nearelectrode layer of the discharge. The
molecular dynamics simulation of the system of dust particles has been carried out. Performing a theoretical analysis of the
simulation results, a mechanism of increasing the average kinetic energy of dust particles in the gas discharge plasma has
been proposed. According to this mechanism, the heating of the vertical oscillations of dust particles is initiated by induced
oscillations generated by fluctuations of the charge of dust particles, and the energy transfer from vertical to horizontal
oscillations can be based on the parametric resonance phenomenon. The combination of the parametric and induced resonances
makes it possible to explain an anomalously high kinetic energy of dust particles. The estimate of the frequency, amplitude,
and kinetic energy of dust particles are close to the respective experimental values. 相似文献
20.
Dreizin E. Trunov M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1993,21(6):619-624
The properties of a novel, pulsed, high-current gas discharge with minimized energy losses are investigated. The discharge provides a highly concentrated energy flux that can be used to treat metal surfaces and to form thin surface layers with desirable properties. A theoretical treatment of the formation of the discharge is presented, and the limitations on its voltage and interelectrode separation length are considered. Experiments are carried out to test the theoretical predictions of the discharge parameters. The experimental results show that more than 80% of the energy input to the discharge from the power supply is delivered to the metal surface 相似文献