Numerical and experimental study of a double jet inclination variation on its dynamic evolution within a crossflow

• Published in: Heat and mass transfer 2009-10, Vol.45 (12), p.1597-1616
• Main Authors: Radhouane, A., Bournot, H., Mahjoub Said, N., Mhiri, H., Le Palec, G.
• Format: Article
• Language: English
• Subjects: Computational methods in fluid dynamics; Engineering; Engineering Thermodynamics; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Heat and Mass Transfer; Industrial Chemistry/Chemical Engineering; Instrumentation for fluid dynamics; Original; Physics; Thermodynamics; Thick shear flows; Turbulent flows, convection, and heat transfer
• ISSN: 0947-7411; 1432-1181
• DOI: 10.1007/s00231-009-0535-4

This paper deals with the dynamics of the flowfield resulting from the interaction of twin inclined elliptic jets with an oncoming crossflow. It will particularly focus on the impact of the initial streamwise inclination angle of the emitted jets on the different flow dynamic features. This particular side of the question is of an extremely high interest as it allows a better understanding of the mixing of the different interacting flows. A well understanding of this mechanism is likely to enable us to control the jets’ trajectories, expansion, confinement, etc. all these processes are in tight relationship with the atmospheric pollution and the pollutants’ dispersion which are nowadays alarming questions needing urgent constraining measures and viable solutions. The consideration of the question was first carried out experimentally by means of the particle image velocimetry (PIV) technique in order to track the evolution of the jets among the environing flow. The second step of this work consisted in the numerical simulation of the same configuration by solving the Navier-Stokes equations with the finite volume method and the Reynolds stress model (RSM) second-order turbulent model. The use of this particular model is in itself a new contribution in the “jets in crossflow” examination; and its merit comes from its high ability to detect the shear stresses that are precisely determinant in the mixing enhancement. The efficiency of this model was proved in our work by the satisfying matching of the numerical results and the experimental data. Once the validation obtained, we enhanced our model by introducing a temperature gradient between the interacting flows and by injecting a non reactive fume through the jet nozzles. We also varied the initial angle of the emitted jets in order to evaluate the impact of this parameter on some dynamic characterizing features such as the global jets’ plumes, the windward and the leeward jets’ spread, the size, the location and the magnitude of the reverse flow region, the penetration and the deflection of the jets’ trajectories, the mass entrainment of the discharged pollutants from the jets’ nozzles, some of the shear stress components, etc. a thorough description of these parameters is likely to well characterize the exact progression of a given particle contained within the jets (in the case of the polluted jets) which will help us find the adequate way to control it.