The influence of initial stream turbulence on the characteristics of an axisymmetric immersed jet

Results are given of measurement of mean velocity and of velocity fluctuations in an axisymmetric immersed jet at various values of initial turbulence. It is shown that as the initial stream turbulence increases, the length of the entrance section decreases, and that the entrance section practically disappears in a strongly turbulent jet.     

Motion of a spherical heat source in a melting medium

The gravity-induced steady motion of a heat source boring through a solid medium is investigated. It is shown that the temperature of its surface is substantially nonuniform. Expressions are obtained for the maximum values of the radius and velocity of the source at which this temperature attains the assigned maximum allowable value.Moscow State University of Nature Conditioning, Moscow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 5–6, pp. 506–512, November–December, 1994.     

Discharge of a turbulent jet in a monodisperse fluidized bed

The velocity of initial circulation is calculated and explanations are given for the mechanism of jet collapse and the existence of bubble and jet regimes.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 6, pp. 913–918, December, 1982.     

An experimental study of subsonic microjets escaping from a flat nozzle

We have experimentally studied subsonic laminar gas jets escaping from a flat nozzle with dimensions of 83.3 × 3600 μm. Reynolds numbers calculated for the given nozzle height and average flow velocity at the nozzle output edge ranged within 58–154. The working gas was air at room temperature. Distributions of the gas velocity and its pulsation along the jet axis were determined. It is established that the obtained characteristics of laminar subsonic microjets are fundamentally different from those of macroscopic turbulent jets. Based on the results of velocity pulsation measurements, it is shown that a laminar–turbulent flow transition is present and its position is determined.     

Vertical low-head jet in a transverse flow

The action of a turbulent flow on an injected normally low-head axisymmetric jet has been investigated experimentally. Empirical dependences describing the geometry of the jet axis in a transverse air flow have been obtained. It has been shown that the maximum temperature and velocity curves do not coincide; the thermal axis lies lower than the dynamic axis. The expressions obtained describe a change in the axial values of the velocity and the temperature in the direction of propagation of the jet. It has been shown that the attenuation of dimensionless axial parameters in the jet carried away by the transverse flow is more rapid than that in the case of a submerged jet and a wake. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 6, pp. 143–147, November–December, 2005.     

Calculation of weight functions for three-dimensional bodies with cracks

A new algorithm is proposed for the numerical calculation of weight functions used in the determination of stress intensity factors by the finite elements method. The algorithm is based on the method of equivalent volume integration. It is shown that weight functions can be obtained for cracks in three-dimensional bodies with the stress intensity factor averaged over a small section of the crack front. A numerical example demonstrating the usefulness of the algorithm is presented.Moscow. Moscow Physico-Engineering Institute. Translated from Problemy Prochnosti, No. 11, pp. 32–36, November, 1989.     

Temperature field of a submerged steam jet

The results of an experimental investigation and generalization of experimental data concerning the temperature distribution at the initial section of a submerged steam jet flowing out of a convergent nozzle into unbounded space are given.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 3, pp. 487–492, March, 1978.     

Discharge of a plane air jet into a blind pass

The existence of two discharge regimes of a plane jet into a blind pass was established experimentally. It is shown that the initial section is absent in such a jet and the range of the jet is commensurable with its width.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 20, No. 6, pp. 1020–1026, June, 1971.     

Flow and heat transfer in a nonsteady jet generated by large-amplitude gas oscillations

The problem of the velocity field in a jet formed by nonlinear oscillations in a tube is solved. Equations are derived that describe heat transfer to a body placed at the jet axis. These relationships are tested experimentally.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 5, pp. 747–752, May, 1990.     

Circulation motion of a viscous incompressible stream in an extruder channel

An extruder in the form of a rectangular channel completely filled with an incompressible liquid is considered. The upper wall moves at an arbitrary angle to the channel axis. Equations for the circulation velocity and the flow lines in a channel cross section are obtained and studied numerically.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 26, No. 4, pp. 626–629, April, 1974.     

Relationship between average (over time) velocity and longitudinal turbulent pulsation of velocity on the axis of a jet

Results are presented from an experimental study of a submerged axisymmetric jet with different initial conditions. Criteria are found for determining the location of the point with maximum pulsations on the jet axis.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 5, pp. 794–797, November, 1980.     

Pulling of glass microcapillaries: Theory and experiment

An approximate analytical solution is obtained which predicts a microcapillary form during pulling which is close to that observed in experiments.Institute of Mechanics and Biomechanics, Bulgarian Academy of Sciences, Sofia. Insitute for Problems of Mechanics, Russian Academy of Sciences, Moscow. Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 63, No. 6, pp. 722–727, December, 1992.Indices 0, p, and 1 denote R, h, and T referring to the initial section (x=0), heating zone boundary (x=l), and fiber section on the receiving device (x=L).     

Heterogeneous flux formation in plasma pulse deposition

Conclusions Measurements have been made on the trends in the formation of heterogeneous plasma flows in a coaxial plasma accelerator as affected by the design and technological parameters.There are large spreads in the thermokinetic and concentration parameters when the powder is supplied to a cylindrical tube in the accelerator. The optimum heterogeneous-flow organization is obtained in a new plasma accelerator design that provides a uniform particle distribution in velocity and concentration in the cross section of the plasma jet and compression of the plasma cloud along the jet. The powder use factor is increased by a factor 1.3-1.5.An Ar+H₂ mixture as the plasma-forming gas gives high-grade homogeneous coatings with low porosity.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 27, No. 4, pp. 60–66, July–August, 1991.     

Calculation of the characteristics of countercurrent axisymmetric jets

On the basis of analysis and generalization of experimental data, a method is proposed for calculating the parameters of the interaction of two coaxial jets flowing in opposite directions from circular nozzles of different diameters.Notation d, D diameter of the nozzles for the small- and large-diameter jets - density - x, y coordinates - u, U averaged longitudinal component of velocity of the small- and large-diameter jets - L_ax distance between nozzles - q relative impulse - G mass rate of the medium - 2r width of the jet - _i, L_i lengths of the flow zones of the small- and large-diameter jets, where i=1, 2 - range of the jet - 2B distance between corresponding points of lines of maximum velocity of the large-diameter jet Indices 0 initial state - m maximum value - ax value on the axis - d large-diameter jet - y_0.5 distance from the axis to the point at which the velocity is equal to half the velocity on the axis Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 5, pp. 725–729, May, 1989.     

On the oscillations near and at resonance in open pipes

Summary This paper is concerned with resonance oscillations occurring when a piston executes small oscillations on one end of a pipe which is open to the atmosphere at the other end. According to linear theory very large amplitudes of pressure and velocity oscillations in the gas in the pipe result when the piston is oscillated with an angular frequency neara_o/2L, where a_o is the sound velocity of the gas and L the length of the pipe. In the theory of resonators, due to Helmholtz and Rayleigh and discussed in section 1, radiation from the open end is taken into account. Then resonance occurs at a frequency slightly below _o , and amplitudes are still very large, as is shown in section 1. Therefore a nonlinear theory is developed here, analogous to previous work on resonance oscillations in closed pipes. In section 2 the boundary conditions at the open end are formulated based on the fact that the reservoirconditions are constant at inflow but vary at outflow, since the gas issues as a jet. This difference results in a net efflux of energy to be balanced by the work done by the piston. In sections 3–7 a perturbation theory is developed in terms of the characteristics of motion. The pertinent perturbation parameter is suggested by the energy balance. An ordinary differential equation for the first order perturbation in the quasi-steady state is obtained in section 7. In section 8 experimental results are presented together with results obtained from numerical integration of the above mentioned equation. The results, showing a satisfactory agreement, indicate that further experimental investigation on the conditions at the open end are needed.     

Drawing of a free jet by a rotating roll

Viscous fluid flow in the initial section of the contact of a free jet with a rotating roll is considered.Volgograd State Technical University. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 6, pp. 954–959, November–December, 1995.     

Theoretical investigation of the main section of a turbulent circular jet in stalling flow

A solution of the problem is proposed by an integral method. The results of a computation of trajectories, axial velocity, and jet boundaries by the method proposed for different expulsion angles agree with the test data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 1, pp. 5–12, July, 1988.     

Étude des effets d'extrémité et du champ magnétique induit, dans un générateur MHD

In this work, we consider the expansion to infinity of an electro-conducting fluid in a jet tube of constant rectangular section having two of the electrodes applied in the region x 0 of the horizontal boundaries (the x-axis is the axis of the jet tube) and the vertical isolating boundaries. Flow takes place in the presence of an exterior magnetic field applied only in the electrode region.

The mathematical problem, presented in the terms of the distributions, contains two parameters R_M and λ = R_MR_h. By using three Green functions, a repeating process is given from which can be determined all the approximations (in the series according to the power of λ) of the functions of current, electric potential and magnetic field.     

On the law of central shock displacement for an undersaturated jet affected by an obstacle

A generalized dependence of the dimensionless position of the central shock on the dimensionless position of an obstacle relative to the nozzle exit is obtained. The dependence is obtained for M _a =1.0–2.0 and uncalculability n=2.2–6.7 of the jet.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 2, pp. 340–342, February, 1970.     

Velocity field in the initial section of a film flow

The velocity field in the initial section of gravitational film flows has been investigated analytically and experimentally, and a relationship has been obtained for calculating the length of this section.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 6, pp. 913–917, June, 1986.