Influence of different factors on the output power transferred into mediumby ultrasound

The influence of several factors (amplitude of ultrasonic waves, external s tatic pressure, temperature and viscosity of medium) acting, either individ ually or in combination, on the amount of power transferred to a liquid med ium during ultrasonication (power output) was measured by calorimetry. At c onstant amplitude (150 mu m) and pressure (200 kPa), the power output decre ased as the temperature was raised. The effect of temperature could be comp ensated by increasing pressure. The magnitude of the increase in power outp ut due to raising the pressure depended on the pressure range and the treat ment temperature. At all temperatures and pressures studied, the power outp ut increased exponentially when the amplitude was increased linearly. The m agnitude of this power output did not depend on the temperature or pressure of treatment. At 40 degrees C the magnitude of the increase in power outpu t due to increasing the pressure was not influenced by the amplitude of son ic waves. The power output increased as the viscosity of the medium was inc reased. The magnitude of this effect did not depend on the amplitude but on the static pressure. (C) 1999 Elsevier Science B.V. All rights reserved.