Ultrasonic cavitation detection system

• US 5,235,524 A
• Filed: 04/02/1990
• Issued: 08/10/1993
• Est. Priority Date: 04/02/1990
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: Rockwell International Corporation
• Inventors: Barkhoudarian, Sarkis
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): Ramirez, Ellis B.
• Application Number:
  US07/502,945
• Time in Patent Office: 1,226 Days
• Field of Search: 364/506, 364/508, 364/555, 364/560, 364/574, 364/575, 73/587, 73/590, 73/168, 367/141, 128/660.01
• US Class Current: 702/39
• CPC Class Codes: F04D 29/669 especially adapted for liquid pumps F04D29/18 takes precedence
• CPC Class Codes: G01N 29/032 by measuring attenuation of acoustic waves

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.

Claims

1. A forced-excitation ultrasonic cavitation detection system which comprises

a turbomachine,

an ultrasonic transmitting transducer attached to the outer wall of said turbomachine for transmitting ultrasonic pulses into said turbomachine,

an ultrasonic pulse generator for forced excitation of said ultrasonic transmitting transducer,

a plurality of ultrasonic receiving transducers attached to the outer wall of said turbomachine, for receiving the ultrasonic pulses passing through said turbomachine, and

an electronic data processing system for processing signals from said receiving transducer and programmed to discriminate signals due to cavitation in said turbomachine from other extraneous signals including noise, to thereby indicate the level of cavitation in said turbomachine corresponding to the intensity of the signals due to cavitation,

said ultrasonic pulse generator connected to said data processing system through a synchronization line.

2. The cavitation detection system of claim 1, employing a plurality of said ultrasonic transmitting transducers attached to the outer wall of said turbomachine and spaced from each other and from said receiving transducers.

3. The cavitation detection system of claim 1, said turbomachine including pumps, turbines, and ducts.

4. The cavitation detection system of claim 1, said ultrasonic pulse generator employs a frequency substantially higher than the background hydrodynamic or structural noise spectrum.

5. The cavitation detection system of claim 1, wherein said data processing system employs an algorithm to process the received signals and to indicate the level of cavitation in said turbomachine corresponding to the intensity of the signals due to cavitation and discriminating from said other extraneous signals.

6. The cavitation detection system of claim 5, said algorithm comprising ensemble averaging.

7. The cavitation detection system of claim 5, said algorithm comprising time-gating.