Method and results of cavitation testing of a conductive MHD flowmeter

V. P. Bocheninskii - Yu. B. Emelin - A. V. Tananaev - Yu. P. Ushakov

Abstract
New test data are presented pertaining to cavitation in a conductive MHD machine which operates as a flowmeter. The beginning of cavitation is established on the basis of "flow- separation characteristics", by analysis of the acoustic noise, and from measurements of the voltage drop at the electrodes. The electrical parameters are shown to be most sensitive to the beginning of cavitation in a mercury stream. This reveals new possible ways of diagnosing both the onset and the development of cavitation. An equivalent electrical-circuit diagram of an MHD machine is analyzed, with regard to indicating possible causes of anomaly in the V vs Q (voltage drop versus flow rate) characteristics during cavitation. A change in the electrical conductivity of the active medium and in the electrical contact resistance are considered the main causes of cavitation.