Nonisothermal Jet Research Articles

Local optical-parameter distributions in tubular shear flows

Schlieren measurements have been made on the scattering-coefficient distributions in a two-dimensional nonisothermal turbulent air jet.

Semi-preserving development of a slightly heated free swirling jet

The paper formulates the concept of a semi-preserving developing of a free nonisothermal swirling jet. On the basis of experimental data it may be estimated that the semi-preserving conditions are established at the distance x − x0 ≈ (15−20) D. Also, it has been pointed out that self-preservation, which requires the turbulence structure to be similar during decay, may be considered as an asymptotic state of the semi-preserving development achieved in practice at a distance where $\overline{u_r u_{\phi}/ \overline(u_x u_r) \ll 1\cdot 0$.

Stability of a dusty nonisothermal gas jet

Stability of a dusty nonisothermal gas jet

Optical characteristics of turbulent nonisothermal jet flows

Total cross-section distribution and scattering indicatrices for scattering of radiation from an external source on pulsations in dielectric permittivity are calculated in a nonisothermal turbulent jet.

Modeling the field of a passive scalar in a nonisothermal turbulent plane gas jet

On the basis of a second-order correlational model of turbulence and an effective numerical algorithm, the problem of the distribution of thermal characteristics in a plane nonisothermal turbulent gas jet is solved.

The mechanisms of ‘neck-like’ deformation in high-speed melt spinning. 1. Rheological and dynamic factors

In the search for mechanisms responsible for abrupt (‘neck-like’) deformation of polymer jets in high-speed fibre spinning, two groups of factors are analyzed. Kinematics of inertialess jets from Newtonian, Reiner-Rivlin, ‘power-law’ and co-rotational Maxwell fluids are studied. It is shown that the main factor responsible for S-shaped velocity profiles and concentrated deformation (‘necking’), is a positive viscosity gradient along the fluid jet. Elasticity, and non-linear (elongation-rate dependent) viscosity do not admit ‘necking’ under isothermal conditions, and reduce the necking effects produced by temperature-controlled viscosity increase. A similar study of Newtonian jets with inertial, surface tension, gravity and air drag effects, confirmed the controlling role of the viscosity gradient. Inertia, surface tension and air drag slightly reduce necking in non-isothermal jets; gravity exerts a small positive effect. Necking effects modelled by exponentially varying viscosity cannot quantitatively reproduce the experimental observations on high-speed fibre spinning. An additional source of viscosity gradient — stress-induced crystallization — will be discussed in a separate paper.

Gasdynamic structure of a heated submerged subsonic jet

Measurements are made of the radial and axial distributions of the concentration of a small impurity and the temperature and velocity of a nonisothermal turbulent jet. Comparison of experimental and theoretical data shows that they agree well.

Numerical and experimental study of a nonisothermal turbulent jet with a heavy impurity

Temperature and momentum distributions of the carrier phase are determined experimentally and compared to results of numerical calculations using the (k−e) model.

Experimental study of the fine structure of a turbulent diffusion flame of atomized liquid fuel

It has been previously shown that the basic characteristics of combustion of a kerosene flame from a high-velocity pneumatic nozzle are close to those of the diffusion flame of a gaseous fuel. The purpose of this work is to obtain information on the turbulent characteristics of a submerged kerosene-air flame. The main element of the experimental setup for studying the structure of a turbulent nonisothermal twophase jet is the coaxial pneumatic nozzle, through whose central tube TS-1 kerosene was injected, while air was injected through an annular gap 0.3 mm wide. Also measured were such parameters as the dispersity and the volume concentrations of the liquid phase, the concentration of unburned hydrocarbons, oxygen, and reaction products. Measurements of the concentration and the average size of the kerosene drops as well as the concentrations of the components and combustion products show that combustion occurs according to the diffusion mechanism, very close to the manner in which submerged jets of gaseous hydrocarbons fuels burn.

Calculation of the apparent mass of a supersonic gas jet

The authors compute the amount of air ejected from supersonic nonisothermal underexpanded jets. The results are compared with test data.

Coagulation of an aerosol in a laminar coaxial jet

The evolution of the ultrafine coagulating, coalescing aerosol in laminar, isothermal, and nonisothermal coaxial jets was studied in computer “experiments.” Four processes affect the aerosol particle size distribution for both the isothermal and the nonisothermal jets. These are axial and radial convection, Brownian coagulation, and Brownian diffusion. The additional process of thermophoresis is important in the nonisothermal jet. At the particle concentration levels studied, most of the change in aerosol characteristics occurs within axial distances of the order of 100 nozzle diameters. Also, bimodal number and mass density functions are found at the periphery of the jet near the nozzle. Characteristic times for the various processes occurring in the laminar jet are defined and used qualitatively to generalize specific results given in the paper.

Motion of a nonisothermal jet in a field of centrifugal forces

Considerable interest attaches to the study of a jet of viscous liquid in a field of body forces that depend on an axial coordinate. Such flows are realized when slag cotton is obtained by the action on a molten mineral of the centrifugal force of drums rotating in the vertical plane [1]. The behavior of a film of liquid on a rotating cylinder was considered in [2, 3]. The instability of a molten layer and jet separation are explained on the basis of the Taylor mechanism in [4]. In the present paper, a particular solution is given for accelerating nonisothermal jets of a viscous incompressible liquid. This solution is used to explain the dynamics of jet separation from a uniformly rotating drum. The flow stability is analyzed.

Calculations on a turbulent heterogeneous jet entering a half space

Integral equations have been used in calculations on turbulent nonisothermal jets of variable composition escaping into a space filled with air. The calculations are in satisfactory agreement with experiment.

Comparison of several turbulence models for predicting flow patterns within confined jets

AbstractNumerical solutions of the differential equations governing isothermal and nonisothermal confined jets have been obtained for three different models of the turbulence correlation terms. The models used were1) mixing length model2) k‐l model3) k‐e modelA comparison of the predictions with experimental data taken in a confined jet system indicates that in the absence of a measured distribution of the kinetic energy of turbulence at the entrance section the mixing length model provided the best results for the isothermal case. For the nonisothermal jets, however, it was found that the k‐e model gives better prediction than the other two models in spite of the lack of measured distributions for the kinetic energy of turbulence at the entrance.

Calculating turbulent nonisothermal jets

Experimental and calculated data concerned with the propagation of turbulent nonisothermal jets are compared.

Acoustic energy of a nonisothermal jet

The acoustic energy generated because of density (temperature) fluctuations and the energy due to velocity pulsations in nonisothermal jets are examined. A method is proposed to compute the noise intensity in a nonisothermal jet field.

Escape of a turbulent jet under the effect of acoustic perturbations

Results are presented of experimental investigations of the local effect of acoustic oscillations of different frequency and constant intensity on the root part of a nonisothermal axisymmetric subsonic turbulent jet escaping from a gas jet atomizer at a different velocity in the S = 0.053–3.84 range of Strouhaille numbers. Data have been obtained indicating the presence of unstable escape modes of a subsonic turbulent jet in an acoustic field; experimental dependences are presented of the relative aperture of the turbulent jet flowing in an acoustic field as a function of various parameters.

Intensification of heat and mass transport in a free jet with the aid of a mechanical turbulator

In the development of published data on the dynamic problem (IAN SSSR, MZhG [Fluid Dynamics], no. 6, 1966) results are presented from experiments on the discharge of a nonisothermal jet, which characterize the possibility of intensification of the momentum, heat, and mass transfer in the free jet with the aid of a mechanical turbulator.

Turbulent mixing in a system of plane nonisothermal jets

An examination is made of turbulent flow in the main section in an infinite system of plane nonisothermal jets. The results of calculation are compared with experimental data.

Nonisothermal axisymmetric turbulent jet curved by gravity forces

Characteristic of a free turbulent jet which has a material density differing from the density of the surrounding medium is a variation of the momentum along the stream, caused by the action of the Archimedes lift force.