The Three-Dimensional Jet-Jet Impingement Flow in a Closed-End Cylindrical Duct

Experimental and theoretical studies are reported on the three-dimensional jet-jet impingement flow in a closed-end cylindrical duct with two 60-deg side inlets. The measurements were made using the laser-Doppler velocimeter. The Reynolds number based on the air density, duct diameter, and bulk velocity was 2.6 × 10⁴. The governing partial differential equations were solved numerically with the k–ε turbulence model. The flow field was characterized in terms of the mean velocity and turbulence intensity components, the swirl intensity, the stagnation points, and the mass flow bifurcated into the head region and was found to be weakly dependent on the head height. Simple geometrical expressions were deduced and were found to effectively estimate the stagnation points and the optimal head height. Furthermore, the dependence of the mass flow into the head region on the head height was found to parallel the dependence of the combustion efficiency and flame stability on the head height.