Flow and Thermal Characteristics of Laminar Unsteady Impinging Streams

The pulsating laminar opposing jets are studied numerically in order to investigate the effect of unsteadiness on the mixing characteristics of the resulting flow. Unsteady opposing jets are systematically controlled with respect to their time dependence by imposing arbitrary shapes of unsteadiness onto the system. Three different signals (sinusoidal, triangular and rectangular) are applied and their influences on the mixing index are determined. The effects of the time mean jet Reynolds number, jet-to-jet distance, frequency, amplitude were examined. The numerical results indicate significant mixing index enhancement due to pulsation of the jet flow in comparison with the steady case over a wide range of conditions. In this study mixing index augmentation up to 28% was found which can be due to the existing vortex structures in the flow field.