Design, development, and validation of concepts for generating passive pulsation in cooling nozzles

Efficient liquid cooling systems in cutting and chipping processes are essential to remain below the temperature limits of the cutting tool and materials. Impinging jet cooling near the processing location is a widely employed technique for this purpose. The cooling effect can be optimized using a pulsating cooling fluid to improve heat transfer, via a periodic renewal of the hydrodynamic and thermal boundary layer.

This study focuses on a cooling nozzle which generates a passive jet excitation, without an electric motor or any valve system. Four different nozzle design mechanisms for the jet excitation were developed and tested with respect to their passively generated pulsation. Strouhal number, pressure fluctuation and pulsation amplitude were measured. A Strouhal number close to 0.2 was achieved with one excitation mechanism. The Strouhal number achieved by the other mechanisms was above 0.1.