Application of piezoelectric film in cavitation research

A research program was conducted at the St. Anthony Falls Laboratory to investigate impulse pressures caused by the collapse of transient cavitation bubbles. The impulsive pressures associated with vibratory as well as hydrodynamic cavitation were measured. Both a stationary specimen subjected to vibratory cavitation and a hydrofoil of NACA 0015 section were instrumented with custom-made pressure transducers using polyvinylidene fluoride (PVDF) piezoelectric polymer film. These transducers provided in situ measurement of impulse pressures. A practical application of this measurement technique was demonstrated in testing the viability of air injection as a means of mitigating cavitation erosion. The high sensitivity, minimal thickness, high frequency response, high spatial resolution, and low cost of the piezoelectric transducers point to their applicability in a wide range of field measurements.