Experimental and numerical analysis of turbulent opposed impinging jets

A fundamental study of two turbulent, directly opposed impinging jets in a stagnant ambient fluid, unconfined or uninfluenced by far-field walls, is p resented. By experimental investigation and numerical modeling the fundamen tal characteristics of direct impingement of two turbulent axisymmetric rou nd jets under seven different geometrical and flow-rate configurations (L* = L/d = {5, 10, 20}, where L is nozzle to nozzle separation distance and d is nozzle diameter, and Re = rhoU(0)d/mu = {1500, 4500, 7500, 11000}, where rho is fluid density, mu is dynamic viscosity of fluid, and U-0, is averag e initial velocity of fluid) are discussed. Flow visualization and velocity measurements performed using various laser-based techniques have revealed the effects of Reynolds number Re and dimensionless nozzle to nozzle separa tion V on the complex flow structure. Similarity analysis of the initial fr ee-jet development and developing radial jet found Re = 11 x 10(3) and L* = 20 as the only case where the freejets exhibit a self-preserving developme nt. However, the jets show significant growth with axial and radial distanc e for Re = 7.5 X 10(3) and L* = 20. All other experimental cases show littl e or no axial growth as a result of shorter development length. When used t o simulate the present flow, the standard k-epsilon turbulence model showed little disagreement between computed and experimental mean velocities and poor predictions as far as the jet growth rates are concerned.