R. Comesaña Piñeiro1, A. Riveiro2, J. del Val Garcia1

1University of Vigo, Applied Physics Department (SPAIN)
2Centro Universitario de la Defensa, Escuela Naval Militar (SPAIN)
Experimental learning is considered to state a deep approach to learning if accompanied by reflection. Institutions that followed the traditional learning approaches, commonly based on theory lessons, are now demanding new strategies for implementation of the student based learning, where one important branch is the development of practical lessons. The work presented here is a case of practice development to improve concept learning in the field of mechanical engineering and particularly in uncompressible flow machinery. In this field, theoretical lessons addressed the study of cavitation phenomena within the didactic units of rotary pumps and hydraulic turbines.
The importance of cavitation phenomena is beyond all doubt; the more patent practical effects can be observed in the operation of pumps and turbines and the produced damage in their blades, with important consequences in economic terms. Nevertheless, the study of cavitation phenomena is difficult because of the involved unsteady flow phenomena, combined with the reaction of the particular material of the solid surface. Thus, localized induction of hydrodynamic cavitation for observation and learning of the underneath cause-effect connection remains difficult. Therefore, we propose the practical implementation of fast optics to induce localized and controlled cavitation; though the induction mechanism is non-hydrodynamic, bubble collapse and associated shock waves and micro-jets are common to the previously mentioned cases. This method can complement theory lessons and computer simulations to visualize and internalize the cavitation phenomena and practical consequences. Theoretical introduction, experimental set-up and practice development is presented and discussed in this work.