An experimental and numerical study of particle-laden coaxial jet flows (original) (raw)

On the evolution of particle-laden jet flows - A theoretical and experimental study

23rd Joint Propulsion Conference, 1987

A combined experimental/analytical investigation is being conducted to study the interaction of particles and turbulent fluid flowfields under a wide range of test conditions. As a first step, the developing region of an unconfined axisymmetric turbulent jet with and without glass beads of 105 /*m diam (d} has been addressed for two mass loading ratios, LR = 0.2 and 1.0. A well-defined data set suitable for the validation of two-phase flow models was obtained by using a two-component phase Doppler technique. The theoretical calculations, based on a stochastic Lagrangian treatment along with a two-equation turbulence model for two-phase flows, yield reasonable and encouraging agreement with the measurements.

Evolution of particle-laden jet flows - A theoretical and experimental study

AIAA Journal, 1989

A combined experimental/analytical investigation is being conducted to study the interaction of particles and turbulent fluid flowfields under a wide range of test conditions. As a first step, the developing region of an unconfined axisymmetric turbulent jet with and without glass beads of 105 /*m diam (d} has been addressed for two mass loading ratios, LR = 0.2 and 1.0. A well-defined data set suitable for the validation of two-phase flow models was obtained by using a two-component phase Doppler technique. The theoretical calculations, based on a stochastic Lagrangian treatment along with a two-equation turbulence model for two-phase flows, yield reasonable and encouraging agreement with the measurements.

Numerical simulation of particle laden coaxial turbulent jet flows

Bulletin of the American Physical Society, 2010

Submitted for the DFD10 Meeting of The American Physical Society Numerical simulation of particle laden coaxial turbulent jet flows 1 KUMARAN KANNAIYAN, REZA SADR, Texas A&M at Qatar-The study of coaxial turbulent particle laden jets has been of interest due to its importance in many applications such as industrial burners, and mixing devices. The addition of the second phase to the continuous phase jet can change the already complicated flow pattern and turbulent characteristics of the jets. Albeit the vast research efforts that have been devoted to understand such phenomena, demand for detailed investigation of particle laden flows remains an active area of research. The advent of laser diagnostics has helped to quantify the myriad details of the jet flow fields in more details. In parallel computational fluid dynamics (CFD) can provide additional information by further investigating such flows with an acceptable level of accuracy. In this work, numerical simulations results are presented for the flow and turbulent characteristics of a coaxial jet with and without the dispersed phase. The results are compared with the experimental data measured using Molecular Tagging Velocimetry diagnostic technique. The key objective of this work is to undermine the flow field details that are difficult if not impossible to measure.

Flow field characteristics in the near field region of particle-laden coaxial jets

Experiments in Fluids, 2005

The effects of solid particles on the flow structure in the near field region of a coaxial water jet are investigated non-intrusively using molecular tagging velocimetry. Glass beads of 240 lm and specific gravity SG of 2.46 are used at three volume loadings of c v =0.03, 0.06, and 0.09% in the central water jet with a Reynolds number of 4.1•10 4. Measurements are acquired for four annular to central jet velocity ratios in the range 0.11 £ U o /U i £ 1.15 at downstream distances up to six inner jet diameters and the results are analyzed for the effects of solid particles on the characteristics of flow. It is found that the addition of particles does not affect the mean fluid velocity profile in this region. The results also indicate a small and moderate enhancement of axial turbulent velocity and radial gradients of velocity fluctuations, respectively, due to the presence of particles.

Particle Motion and Turbulence in Dense 2-PHASE Flows

International Journal of Multiphase Flow, 1987

Measurements of particle mean and r.m.s, velocity were obtained by laser-Doppler anemometry in a descending solid-liquid turbulent flow in a vertical pipe with volumetric concentrations of suspended spherical particles of 270/~m mean diameter in the range 0.1-14°/,. Similar measurements were obtained in the flow downstream of an axisymmetric baffle of 50% area blockage placed in the pipe with volumetric concentrations of 3 I0/~m particles up to 8"/0 and of 665/am particles up to 2%. In orcler to enable measurements in high particle concentrations without blockage of the laser beams the refractive index of the particles was matched to that of the carrier fluid. The results show that the particle mean velocity profiles become more uniform and the particle r.m.s. velocity decreases with increasing concentration in both flow cases. The particle mean velocity in the pipe flow also decreases with concentration and the relative velocity, the difference between the particle velocity and the fluid velocity in single-phase flow, decreases with increasing Reynolds number. The length of the recirculation region downstream of the baffle was shorter than in single-phase flow by 11 and 24% for particle concentrations of 4 and 8*/0, respectively. The particle mean velocities were hardly affected by size for concentrations up to 2%, but the r.m.s, velocities were lower with the larger particles.

Numerical Validation of a Coaxial and Confined Jet Flow

Icheap-10: 10th International Conference on Chemical and Process Engineering, Pts 1-3, 2011

The purpose of this study is to investigate experimentally and numerically the flow behavior of a confined coaxial jet flow for two different velocity ratios Ru=0.04 and Ru=0.08. For the experimental analysis a two dimension particle image velocimetry system (2D-PIV) is used to measure the gas behavior in the measurement section. The numerical analysis is developed for four different Reynolds Average Navier-Stokes models: standard k-, k-ω, SST and RSM. The experimental and numerical results are presented in radial profiles in two different axial positions (L/D=3 and L/D=6) in terms of axial mean velocity and turbulence kinetic energy. All turbulence models showed a good qualitatively agreement in relation to the axial mean velocity analysis. However, the turbulence kinetic energy analysis showed that the Reynolds Stress model can better describe the flow behavior in the confined coaxial jet.

Influence of Stokes number on the velocity and concentration distributions in particle-laden jets

Journal of Fluid Mechanics, 2014

The first measurement of the influence of the Stokes number on the distributions of particle concentration and velocity at the exit of a long pipe are reported, together with the subsequent influence on the downstream evolution of these distributions through a particle-laden jet in co-flow. The data were obtained by simultaneous particle image velocimetry (PIV) and planar nephelometry (PN), using four cameras to provide high resolution through the first 30 jet diameters and also correction for optical attenuation. These data provide much more detailed information than is available from previous measurements. From them, a new understanding is obtained of how the Stokes number influences the flow at the jet exit plane and how this influence propagates throughout the jet.