Two-phase Turbulent Jet Research Articles

The two-phase turbulent jet

Turbulent two-phase axisymmetric jets, in which the volume fraction of the secondary phase is much less than unity, are considered. Emphasis is placed on cases in which the mass fraction of particles is of order unity. The available experimental measurements are examined and it is found that physical arguments and dimensional analysis lead to good correlations of the mean fluid velocity and particle mass flux fields in terms of the initial loading of particles. The jet may be simply described with reference to the momentum transfer between the phases. Two main regions exist: a near field in which essentially no momentum has been transferred between the phases, and a far field in which sensibly all the momentum resides in the fluid phase. Exponential and power law functions of the ratio of the mass density of the particles to that of the suspending fluid at the jet orifice are found to correlate much of the data with the corresponding single phase jet. A relationship for the virtual origins of the far field in terms of the integral invariants of the flow is derived and supported by the measurements.

Numerical calculations of two-phase turbulent round jet

The investigation deals with the effect of suspended particles on the dissipation of turbulence energy. Additional dissipation is hypothesized as caused by the relative velocity between the particles and the fluid, and by structural changes of turbulence. An extended model for the turbulence energy equation is derived and applied to the case of an axially symmetrical free jet. The governing equations are solved numerically, and the results are compared with experimental data. Reasonably good agreement is obtained.

Development of techniques and investigation of turbulence energy at the axis of a two-phase turbulent jet

Development of techniques and investigation of turbulence energy at the axis of a two-phase turbulent jet

Velocity measurements in a two-phase turbulent jet

The motion of oil droplets in a round turbulent air jet is investigated experimentally. Direct information on the droplets' average velocity is obtained by means of a Laser Doppler velocimeter. Average velocity profiles of the droplets are measured along the axis of the jet and transverse to it. The results are compared to the free jet expansion. The jet Reynolds number is in the range 10 4–10 5, the droplets' diameters are 50 μm and below and the volume concentration of the oil in the air is 10 −6. At the jet exit, the air velocity is higher than the droplets' velocity, at the developed region of the jet the droplets' velocity is found to be higher than the free air jet velocity at the same location. In the radial direction, the velocity profiles of the droplets are self similar and the droplets' velocity is lower than the free air jet velocity at the same location. The droplets' velocity decay along the axis of the jet is slower than the air velocity in the free jet and the two-phase jet is narrower than the submerged free air jet at the same exit velocity.

Distribution of Mass, Velocity, and Intensity of Turbulence in a Two-Phase Turbulent Jet

The effect of small liquid droplets on the flow structure of an axially symmetrical turbulent air jet was studied. The flux of the droplets was measured and correlated by a normal-distribution curve with a spreading coefficient of 0.05. Distributions of time-average and fluctuating longitudinal velocities were measured and correlated. In general the two-phase jet is narrower than the single-phase one, with smaller normalized velocity fluctuations. Studies of the spectra and probability density functions indicated that the discontinuous phase causes suppression of turbulence in the dissipation range, namely at high wave numbers. This effect is proportional to the droplets’ concentration in the investigated range.

Closure to “Discussion of ‘Distribution of Mass, Velocity, and Intensity of Turbulence in a Two-Phase Turbulent Jet’” (1971, ASME J. Appl. Mech., 38, pp. 568–569)

Closure to “Discussion of ‘Distribution of Mass, Velocity, and Intensity of Turbulence in a Two-Phase Turbulent Jet’” (1971, ASME J. Appl. Mech., 38, pp. 568–569)

Discussion: “Distribution of Mass, Velocity, and Intensity of Turbulence in a Two-Phase Turbulent Jet” (Hetsroni, G., and Sokolov, M., 1971, ASME J. Appl. Mech., 38, pp. 315–327)

Discussion: “Distribution of Mass, Velocity, and Intensity of Turbulence in a Two-Phase Turbulent Jet” (Hetsroni, G., and Sokolov, M., 1971, ASME J. Appl. Mech., 38, pp. 315–327)

Two-Phase Turbulent Jet Prediction Analysis

A two-phase two-dimensional turbulent jet is examined. While this jet is described by Reichardt’s equation, nevertheless a change in the mixing coefficient Cm is anticipated between the single and the two-phase jets. An experiment to determine this coefficient is discussed and σˆCm, the predicted uncertainty in the measured value of Cm is computed. Quantitative results are presented which can facilitate the design of an experiment for determining Cm to a desired level of accuracy.