Browse Prior Art Database

Cavitation Energy Monitoring for Ultrasonic Cleaner

IP.com Disclosure Number: IPCOM000106461D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Munce, AC: AUTHOR [+2]

Abstract

Disclosed is a new sensor to provide a direct measure of the energy in the cavitation bubbles within an ultrasonic cleaner. Devices in prevalent use today measure the energy in the cavitation bubbles indirectly based on rms-averaged pressure fluctuations; and, thus, for critical applications involving potential damage to delicate parts, the proposed PVF sub 2 sensor provides better feedback to control power levels.

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Cavitation Energy Monitoring for Ultrasonic Cleaner

      Disclosed is a new sensor to provide a direct measure of the
energy in the cavitation bubbles within an ultrasonic cleaner.
Devices in prevalent use today measure the energy in the cavitation
bubbles indirectly based on rms-averaged pressure fluctuations; and,
thus, for critical applications involving potential damage to
delicate parts, the proposed PVF sub 2 sensor provides better
feedback to control power levels.

      In an ultrasonic cleaner operating at 50 kHz, the wavelength of
the pressure fluctuation is approximately 3 cm.  The cavitation
bubbles upon collapse are approximately 0.1 mm to 1 mm in diameter.
This difference in length scales can be exploited to develop a sensor
which is capable of measuring both the cavitation portion and the
standard ultrasonic portion of the pressure fluctuations in the
fluid.  On a device with multiple pressure sensing elements, each of
which have a length scale of approximately 3 mm or less, the average
pressure signal from two closely spaced elements will be equal to the
average ultrasonic pressure fluctuations because they are spaced
closer than a quarter of a wavelength.  The difference between the
signals from two closely spaced elements would represent a
differential pressure associated with the cavitation bubble collapse.
One possible configuration for this type of device is shown in the
Figure.

      The differential measurement represents the cavitation
pressure, if the two pressure sensing elements are matched well
enough in conversion factor (from pressure to voltage) and if a
cavitation bubble strikes only one of the sensing elements at a...