scholarly journals Прохождение плоской ударной волны через область тлеющего газового разряд

2019 ◽  
Vol 89 (1) ◽  
pp. 42
Author(s):  
Т.А. Лапушкина ◽  
А.В. Ерофеев ◽  
О.А. Азарова ◽  
О.В. Кравченко
Keyword(s):  
Shock Wave ◽  
Stokes Equations ◽  
Wave Structure ◽  
Gas Discharge ◽  
Navier Stokes ◽  
Plane Shock ◽  
Two Dimensional ◽  
Gas Temperature ◽  
Discharge Region ◽  
Navier Stokes Equations

AbstractThe interaction of a plane shock wave ( M = 5) with an ionized plasma region formed before the arrival of a shock wave by a low-current glow gas discharge is considered experimentally and numerically. In the experiment, schlieren images of a moving shock-wave structure resulting from the interaction and consisting of two discontinuities, convex in the direction of motion of the initial wave, are obtained. The propagation of a shock wave over the region of energetic impact is simulated on the basis of the two-dimensional Riemann problem of decay of an arbitrary discontinuity with allowance for the influence of horizontal walls. The systems of Euler and Navier–Stokes equations are solved numerically. The non-equilibrium of the processes in the gas-discharge region was simulated by an effective adiabatic index γ. Based on the calculations performed for equilibrium air (γ = 1.4) and for an ionized nonequilibrium gas medium (γ = 1.2), it is shown that the experimentally observed discontinuities can be interpreted as elements of the solution of the two-dimensional problem of decay of a discontinuity: a shock wave followed by a contact discontinuity. It is shown that a variation in γ affects the shape of the fronts and velocities of the discontinuities obtained. Good agreement is obtained between the experimental and calculated images of density and velocities of the discontinuities at a residual gas temperature in the gas discharge region of 373 K.

scholarly journals Characteristics of a CW HF chemical laser calculated from a simplified two-dimensional model

1986 ◽  
Vol 4 (2) ◽  
pp. 167-181 ◽  
Author(s):  
Zhou Xuehua ◽  
Chen Liyin ◽  
Chen Haitao
Keyword(s):  
Stokes Equations ◽  
Computing Time ◽  
Navier Stokes ◽  
Small Signal Gain ◽  
Small Signal ◽  
Two Dimensional ◽  
Gas Temperature ◽  
Navier Stokes Equations ◽  
Chemical Laser ◽  
Signal Gain

A two-dimensional simplified model of an HF chemical laser is introduced. Using an implicit finite difference scheme, the solution of two adjacent parallel streams with diffusion mixing and chemical reaction is generated. A contour of the mixing and reaction boundary is obtained without presupposition. The distribution of the HF(u) concentrations, gas temperature and the optical small signal gain (αu, J) on the flowing plane (X, Y) are presented. Compared with the solution solved directly from a set of Navier–Stokes equations, the results of these two methods agree with each other qualitatively. The influences of the different velocity, temperature (T0) and composition of the two streams on the small signal gain after the nozzle exit are investigated. It is interesting that for larger J with a fixed u, the peaks of αu, J—T0 profiles move towards higher T0. The computing method is simple and only a short computing time is needed.

scholarly journals Флуктуации плотности и температуры за фронтом ударной волны при воздействии стратифицированного источника энергии

2020 ◽  
Vol 46 (13) ◽  
pp. 27
Author(s):  
О.А. Азарова ◽  
О.В. Кравченко ◽  
Т.А. Лапушкина ◽  
А.В. Ерофеев
Keyword(s):  
Shock Wave ◽  
Wave Front ◽  
Shock Wave Front ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Gas Temperature ◽  
Navier Stokes Equations ◽  
Higher Temperature ◽  
The Impact ◽  
Unstable Plasma

For the conditions obtained in experiments on the interaction of a shock wave with an ionization unstable plasma, a numerical simulation of the impact of a thermally stratified energy source on the shock wave front is performed based on the full Navier-Stokes equations. It has been shown that its curvature, registered in schlieren-images, is associated with a higher temperature of the central layers of the source, and its disappearance is due to the multiple generation of the Richtmayer-Meshkov instabilities, which were obtained in the field of gas density. In addition, it was shown that when the source energy is redistributed into layers, local regions are formed behind the shock wave front with a gas temperature several times higher than the values for a homogeneous source.

A note on the solution of the Navier-Stokes equations for a spherically symmetric expansion into a very low pressure

1973 ◽  
Vol 59 (2) ◽  
pp. 391-396 ◽  
Author(s):  
N. C. Freeman ◽  
S. Kumar
Keyword(s):  
Shock Wave ◽  
Reynolds Number ◽  
Stokes Equation ◽  
Stokes Equations ◽  
Low Pressure ◽  
Navier Stokes ◽  
Spherically Symmetric ◽  
Navier Stokes Equation ◽  
Navier Stokes Equations ◽  
Type Flow

It is shown that, for a spherically symmetric expansion of a gas into a low pressure, the shock wave with area change region discussed earlier (Freeman & Kumar 1972) can be further divided into two parts. For the Navier–Stokes equation, these are a region in which the asymptotic zero-pressure behaviour predicted by Ladyzhenskii is achieved followed further downstream by a transition to subsonic-type flow. The distance of this final region downstream is of order (pressure)−2/3 × (Reynolds number)−1/3.

Direct simulation of transition in an oscillatory boundary layer

1998 ◽  
Vol 371 ◽  
pp. 207-232 ◽  
Author(s):  
G. VITTORI ◽  
R. VERZICCO
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Turbulent Regime ◽  
Two Dimensional ◽  
Temporal Development ◽  
Direct Simulation ◽  
Navier Stokes Equations ◽  
Oscillatory Boundary Layer

Numerical simulations of Navier–Stokes equations are performed to study the flow originated by an oscillating pressure gradient close to a wall characterized by small imperfections. The scenario of transition from the laminar to the turbulent regime is investigated and the results are interpreted in the light of existing analytical theories. The ‘disturbed-laminar’ and the ‘intermittently turbulent’ regimes detected experimentally are reproduced by the present simulations. Moreover it is found that imperfections of the wall are of fundamental importance in causing the growth of two-dimensional disturbances which in turn trigger turbulence in the Stokes boundary layer. Finally, in the intermittently turbulent regime, a description is given of the temporal development of turbulence characteristics.

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