Impact of the Temperature of Twin Inclined Tandem Jets on Their Dynamic Interaction With a Cooler Oncoming Crossflow

We deal in the present paper with the commonly known “jets in crossflow” configuration. The interest raised by this configuration comes from its wide application in several fields and from its dependence on numerous parameters. Its well understanding is crucial in the way it helps solve problems in relation with the mixing processes, the heating and cooling performances, the control of fume dispersion, etc... These problems are also faced in small-scale applications like electronic devices cooling or the pulverization of fuel in combustion chambers through infinitely small nozzles, etc... The jets handled in our study are elliptic, aligned in the same direction of the oncoming crossflow, undergoing the same initial conditions and their dimensions are within the micro-scale. In addition to these primer conditions, an injection ratio of R=2 is imposed between the velocities of the jets and the main flow. The jet nozzles adopt a streamwise inclination of 60° and are separated with a distance of three diameters (the little ellipse diameter). The configuration is examined both experimentally by means of the Particle Imagery Velocity (PIV) technique and numerically with the finite volume method. The latter is based on the resolution of the Navier Stokes equations by means of the RSM second order turbulent closure model and a non uniform mesh system that is particularly refined near the injection nozzles. Once validated by confrontation to the experimental data, our numerical model will be generalized by the introduction of further conditions that make it more realistic. A non reactive fume is injected within the jets and a variable temperature gradient is imposed between the jets and the crossflow. Our aim is precisely to evaluate the impact of the introduced temperature gradient on the reigning flow field, and particularly on its dynamic features (the different velocity components).