Prediction of opposing turbulent line jets discharged laterally into a confined crossflow

Abstract

A numerical study is presented for the mixing of opposing heated line jets discharged normally or at an angle into a horizontal cold cross-flow in a rectangular channel. The k- ε turbulence model is adopted and the simulation is performed for the jet-to-cross-flow momentum flux ratio ranging from 0.42 to 5.42 and the incident angle from 60° to 90°. The results show that there is a strong recirculation near the downstream region of the nozzle opening, and the temperature field behaves like a deflected plume. The turbulent kinetic energy is high in the region where the vertical velocity gradient is steep. The vertical temperature profiles can be expressed as the self-similar forms. Correlations for the jet temperature and velocity trajectories, the penetration and circulation depths, the jet half-width, and the reattachment point are derived in terms of the momentum flux ratio, the downstream distance and the incident angle. As compared to the case of a one-side line jet, the opposing jets will hinder the vertical penetration but increase the horizontal velocity when the jets impinge on each other. Better thermal mixing can be achieved at higher momentum flux ratio and incident angle.