Investigation of Cavitation Fields by Application of Comparative Calorimetric Method
M.Margulis, I.M.Margulis (Department of Sonochemistry, N.N. Andreyev Acoustics Institute, Moscow, Russia)
At cavitation regime widespread acoustics methods of acoustic power W determination give unsatisfactory results because of ambiguity of acoustic resistance of bubbly liquid (it ranges stochastically in 100 times!). Absence of common and direct method for measurement of W leads to incompatibility of data obtained by different authors. Only the comparative calorimetric method can be used to determine W absolutely (e.g. in Watts). It is based on continuous registration of temperature T course on time t at the action of ultrasound and the heater. If the curves T(t) are very close, the heater power is considered as an equivalent of the W absorbed in liquid. We have obtained experimentally the conditions at that all irradiated W is absorbed by bubbly liquid, and we can measure all irradiated W also. At these conditions W doesn.t depend on geometry of a vessel and on volume of liquid if size of a vessel and level of liquid are large enough in comparison with a size of cavitation cloud. At these conditions dependence of rate w of typical sonochemical reaction (formation of NO2 ions under action of ultrasound) on acoustics intensity I is linear (decreasing of w at high I is absent). Using this method we worked out the device APM-1 that measures total irradiated and absorbed W with accuracy 3%. The results obtained can be used at calibration of ultrasound equipment, for scientific applications at studying of processes at cavitation regime etc.
Section : 11