Ultrasonic cavitation detection system

Abstract

A forced-excitation ultrasonic cavitation detection system for detecting cavities in rotating machinery such as pumps, water turbines and ducting elements, is composed of an ultrasonic transmitting transducer attached to the outer wall of the test component for transmitting ultrasonic pulses into the test component, and at least one, and preferably a plurality of ultrasonic receiving transducers attached to the outer wall of the test component for receiving the ultrasonic pulses passing through the test component. The ultrasonic transmitting transducer is excited by an ultrasonic pulse generator. An electronic data processing system is provided which is connected to the output of the receiving transducers and is also connected to the ultrasonic pulse generator through a synchronization line. The data processing system is programmed to discriminate as between signals from the receiving transducers due to cavitation in the test component, from other extraneous signals including noise. For this purpose the data processing system includes an algorithm, such as ensemble averaging, time-gating or cross-correlation, each capable of extracting signals due to cavitation from noise signals even of much higher intensity. When there is no cavitation, a maximum signal is received. In the presence of cavitation, as by the presence of vapor or gas bubbles, this interferes with the propagation of the pulses, thus reducing the amplitude of the received signal.