Measurements of fluid/particle correlated motion in the far field of an axisymmetric jet

• Published in: International journal of multiphase flow 1996, Vol.22 (4), p.685-701
• Main Authors: Prevost, F., Boree, J., Nuglisch, H.J., Charnay, G.
• Format: Article
• Language: English
• Subjects: Anemometers; Correlation methods; Flow interactions; Fluids; gas-solid flows; jet flow; Jets; Kinetic theory; Mathematical models; particle-turbulence interaction; Particles (particulate matter); PDA; Relaxation processes; Turbulence; Turbulent flow; two fluid models; Two phase flow
• ISSN: 0301-9322; 1879-3533
• DOI: 10.1016/0301-9322(96)00009-2

Typical features of fluid-particle interaction in the far field of an axisymmetric polydispersed particle laden tube jet were measured and analysed in the present study. Measurements up to 45 jet diameters were obtained by using a phase Doppler anemometer. The statistical properties of four particle size classes were obtained in order to cover a wide range of particle relaxation times. The downstream evolution of the mean longitudinal particle velocity field aandof the particle radial and longitudinal turbulent components is first displayed. We show that a Stokes number based on the time scale of the large “structural” eddies is a relevant parameter to describe the selective influence of the jet flow on the particle mean velocity field. The anisotropy between axial and radial fluctuating velocity of the particles is found to increase with increasing particle relaxation time scale. A method is proposed and validated to determine the statistics of the velocity of the fluid seen by the particles. Measurements are made in the jet far field at x D = 30 . Ejection of solid particles in regions of high outward velocity is detected statistically. The fluid-particle correlations are presented and used to analyse the evolution of particle kinetic stresses. The experimental results confirm that the radial particle turbulent velocity is mainly controlled by the dragging by the fluid turbulence and decreases with increasing particle relaxation time compared to the fluid turbulence integral time scale. In contrast, production by the mean particle velocity gradient and transport terms are important mechanisms affecting the streamwise particle turbulence velocity. These mechanisms are responsible for the increase in the streamwise particle turbulence velocity with increasing particle relaxation time.