Abstract
The method for estimating the circulation of optimal vortex ring generated by a pulsating jet flow has been investigated experimentally with PIV measurement. The periodical change of flow rate was conducted by sine curves under the conditions of amplitude Reynolds' numbers Re_0 of 1200〜5040 and Womersley numbers a of 12.5〜24.4. The results indicate that the formation time of the optimal vortex ring can be estimated using the condition which the optimal vortex ring is formed when the propagation velocity of vortex core is equal to the convection velocity of shear layer of jet flow. Each of the velocities is expressed as empirical formulations with pulsating jet conditions. Therefore, the formation time of the optimal vortex ring can be estimated from the pulsating jet conditions, when the circulation of vortex ring stops growing. The circulation of vortex ring estimated using the present method is in good agreement with the measurement data within 5% error. The circulation of vortex ring indicates the local maximum value with a specific Strouhal number.
