Energy deposition in boundary gas layer during initiation of nanosecond sliding surface discharge

The process of rapid gas heating in the region of distributed pulsed sliding surface gas discharge (plasma sheet) of nanosecond duration has been studied. The fraction of electric energy converted into heat during the passage of discharge current has been estimated from a detailed analysis of the dynamics of shock wave fields arising upon the initiation of discharge. Experiments are performed in quiescent gases (air, nitrogen, helium) and in supersonic airflows behind a plane shock wave in a shock tube at gas densities within 0.04–0.45 kg/m³ and flow velocities up to 1600 m/s.     

The surface energy deposited into gas during initiation of a pulsed plasma sheet discharge

Gasdynamic perturbations arising during the initiation of a pulsed surface (plasma sheet) discharge have been experimentally studied in a shock tube. The evolution of flow was also numerically simulated within the framework of a thermal energy deposition model. Experimental values of the velocity of perturbations well agree with the results of calculations obtained assuming that about 50% of the energy deposited in the surface layer is converted into heat in the stage of energy supply.     

Turbulent boundary layer in a supersonic diffuser

The one-parameter method of calculating the turbulent boundary layer of a compressible gas with positive axial pressure gradient is analyzed. Theory is compared with experiment. One of the advantages of this method is its simplicity.     

Flow in a turbulent supersonic boundary layer with a heat source

A numerical analysis is made of a turbulent supersonic boundary layer with a heat source for a wide range of heat supplied to the gas. It is shown that the frictional resistance may be reduced appreciably and the efficiency of using a heat conductor to achieve such a reduction is estimated. Pis’ma Zh. Tekh. Fiz. 25, 38–42 (April 12, 1999)     

Velocity profile in a turbulent boundary layer of a supersonic gas stream

A semiempirical equation is proposed for relating the coefficients of molecular and turbulent viscosity in the laminar sublayer and in the transition region. Simple formulas are derived for determining the velocity throughout the boundary layer and the frictional stress at the surface of a plate at various values of the Mach number. The results of calculations are compared with experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 1, pp. 112–120, July, 1972.     

Three-dimensional flow in a supersonic MHD generator with boundary layer separation

A computational experiment is performed in order to estimate the importance of volume gasdynamic effects in an MHD channel with continuous electrodes. Singularities are analyzed of secondary flows arising as a result of nonuniformity of Hall current in the direction of insulating walls. It is demonstrated that, at the initial stage of development of separation flow (during formation of separation bubble on the anode), secondary flows additionally destabilize the anode boundary layer and increase the layer stability at the cathode. In the developed stage of separation, secondary flows contribute to the emergence of separation bubbles in the channel corners. As the MHD effect increases, the cathode separation bubbles merge into a single separation zone.     

An investigation of surface energy input to gas during initiation of a nanosecond distributed surface discharge

The fraction of energy, directly introduced into gas during the initiation of a distributed pulsed surface discharge of the plasma sheet type, is analyzed using the results of investigation of the dynamics of resultant shock waves. Results are given of numerical calculation of development of flow within the model of thermal energy input. It is demonstrated that the experimentally obtained values of the velocity of motion of perturbations agree well with the calculation results assuming that 40 ± 10% of the energy of surface electric discharge of nanosecond duration changes to thermal energy in the stage of energy input, i.e., during the time which is much shorter than 1 μs.     

Laminar boundary layer at a permeable surface

A universal equation for the boundary layer with continuous suction is proposed and solved (to the first approximation) in Crocco variables.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.22, No. 5, pp. 859–865, May, 1972.     

Study on boundary layer transition of a rotating disk

Summary Behaviour of spiral vortices being generated in transition regime of a disk rotating in otherwise undisturbed fluid is experimentally studied in detail. Through visualizations of the transition regime by using close-up camera, new striped flow patterns originating along the axis of spital vortices are found to be ring-like vortices which occur on the surfaces of each spiral vortices. Mechanism of the spiral vortex is clarified by cutting the vortices by strobo slit light. It is also found out experimentally that the phase velocity of the vortices is zero.     

Temperature stratification under suction of the boundary layer from a supersonic flow

A carried out numerical simulation showed that a considerable difference can be achieved between the temperatures of a gas in the boundary layer and a suctioned gas under the gas suction from a turbulent boundary layer in a supersonic flow on a permeable surface. The effect of the Prandtl and Mach numbers of the incident flux on the temperature stratification, which depends on the gas suction intensity, is studied. The stratification is the most pronounced for low-Prandtl-number gases. It was established that, due to laminarization of the boundary layer under an intense gas suction, in the region of the impermeable plate following the permeable wall, the wall temperature drops abruptly.     

Experimental investigation of local heat transfer in a turbulent boundary layer at supersonic speed

The authors present results of an experimental investigation of coefficients of local heat transfer in a turbulent boundary layer over a wide range of M and Re numbers and values of the temperature ratio.     

On the possibility of supersonic pulsed gas jet blocking by transverse discharge

It is established that activation of a pulsed supersonic gas jet by transverse arc discharge can provide the effective blocking (delay) of the neutral gas flow. The delay time is determined by the duration of discharge operation. After the quenching of discharge, a delayed pulse of neutral gas species is formed, the intensity of which increases with the discharge power and can exceed the intensity of pulses observed in the absence of discharge. In addition, an intense pulse of working gas ions is formed that propagates at a velocity exceeding that of the gas flow.     

Spiral vortices in boundary layer transition regime on a rotating disk

Summary Behavior of spiral vortices on a disk rotating in still fluid is studied theoretically and experimentally in detail. A linear stability analysis, in which effects of streamline curvature and Coriolis force are considered, gives a critical Reynolds number at the onset of instability close to the one measured here by using a hot wire probe. Gradient of the vortex axis is determined under a condition of the maximum amplification. Flow patterns in the transition regime are experimentally visualized. The results show that the number of the spiral vortices is 31 or 32 as mean value and the gradient of the vortex axis decreases from 14° to 7° as the local Reynolds number is increased.

---

Spiral-Wirbel im Umschlagbereich der Grenzschicht an einer rotierenden Scheibe

Zusammenfassung Das Verhalten der spiralen Wirbel an einer in ruhender Flüssigkeit rotierenden Scheibe wird theoretisch und experimentell eingehend untersucht. Eine lineare Stabilitätstheorie, in welcher der Einfluß von Krümmung der Stromlinien und Coriolis-Kraft in Betracht gezogen wird, ergibt eine kritische Reynolds-Zahl des Indifferenzpunktes, die gut mit dem mit einem Hitzdrahtgerät gemessenen Wert übereinstimmt. Der Gradient der Wirbelachse wird unter der Bedingung der maximalen Anfachung bestimmt. Der Strömungsvorgang im Umschlagbereich wird experimentell sichtbar gemacht. Dadurch ergibt sich, daß die Anzahl der an der Scheibe auftretenden Wirbel 31 oder 32 im Mittel beträgt, und der Gradient der Wirbelachse mit zunehmender lokaler Reynolds-Zahl von 14° bis zu 7° abnimmt.

---

---

With 12 Figures

---

Dedicated to Professor Dr. Henry Görtler on the occasion of his seventieth birthday     

Neutron generation during pulsed discharge in deuterium

The process of neutron generation during pulsed discharge in inhomogeneous electric field in deuterium has been studied. At a deuterium pressure of several Torr, the generation of neutrons is possible with both deuterated and deuterium-free cathodes.     

Heat and mass transfer as a means of flow mode management in a supersonic boundary layer

This paper continues the studies cycle of flow management simulation methods in boundary layers of compressible gas. The influence of distributed heat and mass transfer on the stability characteristics of supersonic boundary layers is considered at Mach numbers M = 2.0 and 5.35. At high Mach numbers, waves of vortex nature and unstable acoustic oscillations emerge. Resistance to both types of disturbances is studied. Both normal injection, with normal mean velocity, V, being the only nonzero component, and injection at other angles, including tangential with the longitudinal component of mean velocity, U, being the only nonzero component on the wall, are simulated. It is shown that a tangential streamwise injection causes significant flow stabilization in relation to vortex and acoustic modes. This mode management provides thermal protection of the streamlined surface under aerodynamic heating, and is able to expand the laminar flow mode region. Cooled gas injection suppresses vortex disturbances and amplifies acoustic waves, while injected heated gas influences boundary layer stability in the opposite way. The performed studies anticipate that an injection of homogeneous cold gas would be similar to an extraneous heavy gas injection, and that injected heated gas would behave similarly to injected light gas.     

Interaction between a weak oblique shock wave and a turbulent boundary layer in purely supersonic flow

Summary The paper deals with the interaction of a weak oblique shock and a turbulent boundary layer at a flat plate at purely supersonic speeds. Except for a small region where nonlinear transonic effects are of importance analytical expressions for the pressure- and skin friction distributions are derived.With 6 Figures     

Influence of the plasma of a high-frequency barrier discharge on the structure of the dynamic boundary layer on a flat surface

Methods of obtaining a surface high-frequency barrier discharge have been analyzed. The results of investigation of the influence of this discharge on the characteristics of the dynamic boundary layer on a flat surface have been given. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 55–61, January–February, 2008.     

Turbulent boundary layer on a flat plate in a supersonic stream of equilibrium dissociated and ionized gas

A method is described for calculating the turbulent boundary layer on a flat plate in an equilibrium dissociated and ionized supersonic stream. An estimate is made of the effect of ionization on the drag and heat transfer in a stream of air.     

Turbulent boundary layer on a permeable surface with intensive blowing

Results of an experimental investigation of the structure and integrated characteristics of a turbulent boundary layer on a permeable plate in a broad range of blowing intensities ¯j=0.005–0.04 are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 5, pp. 773–779, May, 1976.