Internal characteristics of hydrogen boiling

Study of the internal characteristics of boiling is of great importance in understanding the physics of this complex process; data on internal characteristics may be used for derivation of formulas for integral boiling characteristics (heat-liberation coefficients, critical thermal flux densities). Only a limited number of works have been dedicated to study of boiling of cryogenic liquids over a wide saturation pressure range. In [1] the internal characteristics of nitrogen boiling were studied at pressures from 0.1 to 8 bar, while oxygen was studied from 0.22 to 2 bar. In [2] detachment radius and bubble-detachment frequency were determined for hydrogen boiling over the pressure range 1–11 bar. The present study is dedicated to an examination of internal characteristics of hydrogen boiling over the saturation pressure range from triple point pressure (0.072 bar) to 2.0 bar.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 103–108, July–August, 1976.     

Electrization of dielectric liquids flowing in tubes

The methods of the mechanics of continuous media [1] are used to consider the problem of electrization of dielectric liquids flowing in tubes [2–6]. According to modern ideas [2–6], there is always dissolved in such liquids a slight admixture of an electrolyte, whose molecules in such a dilute solution dissociate to a certain extent into positively and negatively charged ions. On the walls, oxidizing and reducing reactions take place, as a result of which the negative and positive ions, respectively, give up to the wall surplus electrons or take missing electrons from it. Thus, a positive (respectively, negative) total electric charge is induced in the liquid by the flow. We consider in this paper the electrization of a dielectric liquid in laminar flow in a circular cylindrical tube. We find the distribution of the electric charge in the liquid, the maximal electric current, and the dependence of the length over which the distribution of the electric charge in the tube is established on the tube radius, the Debye radius of the liquid, and the Péclet diffusion number.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 41–47, November–December, 1979.We thank V. V. Gogosov for helpful comments made in a discussion of thwe work.     

A collisionless thermal wave in a plasma

Experiments are described on the collisionless propagation of heat in a plasma along the magnetic field. Thermal waves can be propagated in a medium whose thermal conductivity is a power function of the temperature. In a collisionless plasma, where the mean free path of particles is much greater than all typical lengths, in particular the length of the equipment, the heat must be propagated by a different method. Experiments to study this phenomenon showed that heat is propagated along the magnetic field with velocity exceeding that of ion-acoustic velocity (I. A. Velocity), and that the spatial width of the thermal disturbance is much less than the mean free path. Heat is propagated because hot electrons are replaced by cold [1]. Noise was observed experimentally in the vicinity of the ion plasma frequency and an estimate of its intensity was obtained. Theoretical discussion showed that the I. A. Velocity instability which develops at the wave front leads to collective friction of the cold electrons with the ions and makes it possible to find the effective collision frequency. It was also shown theoretically that, in accordance with experiment, noise is localized near _pi, and the level agrees with that obtained experimentally. The phenomenon can be pictured as follows: hot electrons expanding into the region occupied by cold electrons and ions create an electric field. Cold electrons, accelerating in this field, oscillate the I. A. Velocity. This instability leads to heating of the electrons and the appearance of collective friction which forms the heat front.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 1, pp. 51–59, January–February, 1971.     

Average Fluid Flow in the End Regions of a Long Channel Subjected to Rotational Vibration

The average isothermal fluid flow in an elongated parallelepiped that performs rotational vibration is studied experimentally. The structure and intensity of the average flows and the regularities of their transformation with variation of the vibration frequency are investigated. The dimensionless frequency is varied over a wide interval: from extremely low values where the fluid vibration is largely determined by the viscous forces up to high frequencies where the viscosity is important only in relatively thin Stokes boundary layers. The dimensionless complexes that determine the intensity of the average flows over the entire frequency range are found.__________Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, 2005, pp. 37–44.Original Russian Text Copyright © 2005 by Ivanova, Kozlov, and Selin.     

Electric arc in a submerged gas jet

The results of photographic studies of the behavior of an electric arc in a submerged gas jet, using both regular photography and still and cine shadow photography, are presented. The interaction of the arc with the turbulent portion of the jet and the development of disturbances in the arc and the thermal layer around the arc dependent on initial jet velocity are noted. Experimentally obtained values for extent of the arc laminar zone, radius of arc thermal layer, and electric field intensity are compared with calculated values.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 17–23, September–October, 1971.     

Methods of calculation and numerical analysis of conducting-gas flow in high-current electric arcs

The mechanism of conducting-gas acceleration in an electric arc by intrinsic magnetic field was first investigated in [1]. Further theoretical study of this question was associated with the numerical calculation of arcs [2–7]. A more general approach to the solution of the problem was realized in [4], where the finite-difference method was used. Integral calculational models were developed in [5–7]. The present work proposes a modified version of the difference method [4] and a series of integral methods for the calculation of the conducting-gas flow in a high-current electric arc. The development of integral methods is of interest in that they are usually associated with adequate accuracy in determining integral values and values averaged over the cross section by a relatively simple calculation, and also allow the solution of the problem to be obtained in a number of situations when the realization of a difference method is complicated. The results of different calculation methods are compared. The effect of conditions in the initial cross section of the calculation region of the arc on its characteristics is investigated and a numerical analysis of the heating and acceleration of conducting gas is carried out.Translated from Izvestiya Akademiya Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 103–110, September–October, 1978.     

Investigation of the wake of a hypersonic sphere in air by means of an open microwave resonator

The use of an open microwave resonator with plane-parallel mirrors for plasma diagnostics was first proposed in [1]. A resonator with spherical mirrors, which provides better spatial resolution in addition to high sensitivity, was used later [2, 3] to investigate the wake flow of models moving through air at hypersonic velocities. The presence of free electrons in the flow field is caused by ionization processes behind the bow shock and in the model boundary layer in this case. However, only the results of measurements of the density of electrons are presented in [2, 3], and no information is given on another important plasma parameter: the effective collision frequency of electrons with heavy particles. In the present study we use a microwave (8-mm range) resonator for an experimental study of the flow of gas in the wake of a polymer (Kaprolon) sphere traveling through air at hypersonic velocity. The flow is visualized by the schlieren technique. The electron densities and effective collision frequency of electrons with heavy particles are determined as a function of the distance behind the sphere.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 156–160, July–August, 1978.     

The behaviour of field-responsive fluids during shear start-up

The application of an external field (magnetic or electric) to suspensions of particles in a carrier liquid often causes a dramatic increase in the flow resistance. The transient stress response of these systems during the start-up of shear flow was studied as a function of the shear rate, using a system of carbonyl iron particles dispersed in paraffinic spindle oil under magnetic flux densities up to 0.57 T. It was found that initially the stress increased in proportion to the applied strain, reaching a plateau value at a characteristic strain of 0.2. Similar strain dependence of the transient stress behaviour was observed for shear rates spanning the range 0.01 s^–1 to 10 s^–1, suggesting that strain-governed deformation and rupture of the particle aggregates in the fluid was the main contribution to the response. In addition, the steady state flow curves of these fluids were obtained over the shear rate range 0.1 to 100 s^–1.     

The Stress–Strain State of an Elastic Ferromagnetic Medium with an Ellipsoidal Inclusion in a Homogeneous Magnetic Field

A stress–strain problem is solved for an infinite elastic magnetically soft medium with an ellipsoidal inclusion in an external magnetic field. The main characteristics of the stress–strain state and induced magnetic fields in the medium and the inclusion are determined and their distribution over the surface of the inclusion is analyzed     

Stabilization of the unstable steady states of a conducting fluid in an electromagnetic field

The linear disturbance spectrum is determined for the solution with the fluid at rest and its unstable region identified. It is shown that an electric field has a destabilizing effect, while a magnetic field and viscosity affect only the rate of damping of the disturbances and not the actual existence of instability. An example of a feedback regulator that stabilizes two unstable modes is constructed.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.6, pp. 138–142, November–December, 1993.     

Flow of a conductive gas in a circular tube in a strong axiosymmetric magnetic field

The flow of a conductive gas along a channel in an external axiosymmetric magnetic field with a finite value of the magnetogasodynamic parameter N is examined. Numerical flow calculations are performed for a circular tube in such a field. Gas dynamic parameter fields, total pressure losses, and electric current intensities with the presence of transsonic zones and highly compressed regions are determined. Through comparison of the results obtained with linear theory data, the range of applicability of the latter is determined. Of the works dedicated to study of flow in external magnetic fields with N1, we should take note of [1], in which the process of entry of the gas into a transverse magnetic field was examined; [2], which studied one-dimensional transient motion with shock waves; and [3], where mixed flow in a Laval nozzle with an axiosymmetric homogeneous magnetic field was studied. Flow in a circular tube was examined in [4]; but the analysis performed by the characteristic method permitted calculation of only the initial supersonic flow zone. Motion in circular tubes in the presence of an axiosymmetric, magnetic field was studied in the linear formulation in [4, 5].Moscow. Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 145–155, September–October, 1972.     

Theory of plasma acceleration in electric and magnetic fields

The problem of the acceleration of a plasma in crossed electric and magnetic fields under the simplest physical conditions suitable for comparison with experiment is considered. Analytical expressions are obtained for the velocity of the electrons, the value of the resonance acceleration zone, and the increment of the potential of the accelerated plasma.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 14–17, November–December, 1972.     

Parameters of streamer breakdown in xenon

It is known from experiments [1–3] that the velocity of streamers, induced in the center of the interelectrode gap and propagating to the electrodes under conditions when the streamer length is comparable with the distance between the electrodes, increases linearly as the streamer length increases. This relationship is in qualitative agreement with theory [4], Nevertheless, the velocity of streamers starting from the electrodes and propagating in a long interelectrode gap remains practically constant during the whole propagation process [5, 6], In the case of short gaps (2–5 cm), constancy of the velocity is observed during the stage of the process when the length of the streamer is much less (20%) than the length of the gap [7], Since the electric field at its end controls the streamer propagation, the constancy of the streamer velocity indicates that the controlling field is constant under these conditions. A number of theoretical models were proposed in [8–13] which describe uniformly moving anode- and cathode-directed streamers (henceforth called anode and cathode streamers). Comparison of experimental data with the corresponding theoretical model enables one to determine the streamer parameters: the electric field, the charged-particle density, the current density, the channel radius, etc. In the case of an anode streamer in Xe an attempt at such a comparison was made, in particular, in [6]. However, the lack of reliable data on the value of the drift velocity and the diffusion coefficient of electrons in Xe for E/p (10² – 10³) V/cm · mm Hg allowed only rough estimates to be made. In this paper a numerical calculation is made of the drift velocity, the diffusion coefficient of electrons in Xe, and the rate of excitation of Xe atoms in the resonance level in the range of values of E/p (10¹–10³) V cm · mm Hg, and the volt-ampere characteristic of the breakdown is measured under conditions described in [6] (p₀=300 mm Hg and E 10⁴–10⁵ V/cm). Using these results, the formulas for the velocity of anode [12] and cathode [13] streamers, and experimental data [6], the parameters of the streamers studied in [6] are determined.Translated from Zhurnal Prikladnoi Meknaniki i Tekhmcheskoi Fiziki, No. 3, pp. 6–11, May–June, 1976.The authors thank A. T. Rakhimov and A. N. Starostin for useful discussions, and A. V. Markov for help with the experiments.     

End effects in magnetohydrodynamic channels at finite magnetic reynolds numbers

The effects of the magnetic Reynolds number have been examined via the distribution of the magnetic fields induced by the motion of a medium in a rectangular channel with conducting walls in the presence of an inhomogeneous magnetic field; the effects of wall conductivity and geometry of the external field are also examined as regards the distribution of the induced currents, the Joule loss, and the electric and magnetic fields over the cross section. The problem has previously been considered for a channel with insulating walls [1].Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 19–27, May–June, 1971.We are indebted to A. B. Vatazhin for his interest.     

Stability of a radiation-absorbing ionizing shock wave in an electromagnetic field

The linear stability of a radiation-absorbing ionizing shock wave (light detonation waves) in the presence of a uniform electromagnetic field is investigated. The applied electric field is considered to be normal to the wave front and the magnetic field to be parallel to the front and perpendicular to the plane in which perturbations propagate. The medium satisfies a two-parameter equation of state. Analytic stability criteria are obtained. For a perfect gas the effect of the electromagnetic field and radiation on shock wave stability is determined.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 23–30, January–February, 1996.     

The stability of a free rotating layer in an electrically conducting fluid in an axial field

The subject considered is a homogeneous electrically conducting incompressible medium with a current in a homogeneous external magnetic field and bounded by parallel insulating planes normal to the induction vector. When the current is fed by means of a system of coaxial electrodes located on one or both of the insulating planes, regions arise in which the medium is in rotational motion. If the lateral wall is at a sufficient distance from the electrodes, the rotating layer which forms as a result of the interaction of the axial magnetic field and the radial component of the electric current has free lateral boundaries. A study is made of the way in which the Reynolds number for the loss of stability in such a layer depends on the Hartmann number and on the geometric parameter for high values of the Hartmann number and low values of the magnetic Reynolds number.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 166–173, September–October, 1984.     

Parametric instability of a nonuniformly heated horizontal layer of liquid dielectric in a variable electric field

The parametric instability of a nonuniformly heated horizontal layer of liquid dielectric with free isothermal boundaries in a transverse electric field is studied analytically. An instability map is obtained. It is shown that instability can develop at some critical electric field strength which depends on the frequency and is several times greater than the critical strength of the constant electric field.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 5, pp. 184–186, September–October, 1993.     

Estimate of the amplitudes of the fields created by an unsteady gamma source

It is known [1–4] that an unsteady gamma source gives rise to an electromagnetic field in the surrounding space. Most of the studies of the characteristics of such fields have been performed in the approximation which is linear in the field [1–3]. An exception is [4] in which the slowing down of Compton electrons by the electric field is taken into account. It follows from [1, 2] that the characteristic scale of the fields created close to the source is of the order of 3 · 10⁴ V/m. Although this value is appreciably lower than the value of breakdown fields in air, electric discharges are observed [5] in the vicinity of a gamma source, indicating the presence of substantially larger fields. One effect not taken into account in the latter approximation which could lead to an increase in the field is the increase in electron termperature due to the electric field [6]. On the one hand, this decreases the electron mobility and consequently also the conductivity of the system, On the other hand, it is known that the electron attachment coefficient for electronegative molecules strongly affects the characteristics of electric fields and depends on the electron energy. Therefore, the electron balance equation must take account of the dependence of on the electric field through the electron energy, and this leads to a further change in conductivity. We take account of these effects on the shaping of electric fields in air in the vicinity of the source. It is assumed that electron lifetimes are determined solely by their attachment to molecules. This is a good approximation for air pressures near normal [1–3].Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 163–170, July–August, 1976.     

Generation of higher electron cyclotron frequency harmonics in plasma with a beam

We examine nonlinear excitation of the higher electron-cyclotron frequency harmonics for waves propagating perpendicular to an external uniform magnetic field in a Maxwell plasma for the case of low-density electron beam passage through the plasma. It is shown that the nonlinear excitation mechanism leads to the possibility of generating cyclotron harmonics for plasma parameters for which generation does not occur from the linear theory viewpoint. The nonlinear cyclotron harmonic generation increments are calculated for nonlinear scattering by the beam and plasma electrons of the high frequency longitudinal waves excited in the plasma by the beam.Translated from Zhurnal Prikladnoi Mekhaniki Tekhnicheskoi Fiziki, Vol. 10, No. 6, pp. 40–51, November–December, 1969.The author wishes to thank V. N. Tsytovich for posing the problem and for many discussions of the questions touched upon in the article.     

Electrode region of a weakly ionized plasma in chemical equilibrium

The paper is devoted to an analysis of the wall (electrode) region of disturbance of the electric parameters of a weakly ionized plasma, i.e., the region in which the concentrations of the charged particles and the values of the electric field change from the distributions corresponding to the conditions in the undisturbed plasma to the values determined by the boundary conditions on the wall.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 142–153, January–February, 1982.I thank G. A. Lyubimov and G. A. Tirskii for interest in the work and valuable discussions.