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Two-Phase Quality/Flow MeterA quality and/or flow meter employs a capacitance probe assembly for measuring the dielectric constant of flow stream, particularly a two-phase flow stream including liquid and gas components.ne dielectric constant of the flow stream varies depending upon the volume ratios of its liquid and gas components, and capacitance measurements can therefore be employed to calculate the quality of the flow, which is defined as the volume ratio of liquid in the flow to the total volume ratio of gas and liquid in the flow. By using two spaced capacitance sensors, and cross-correlating the time varying capacitance values of each, the velocity of the flow stream can also be determined. A microcontroller-based processing circuit is employed to measure the capacitance of the probe sensors.The circuit employs high speed timer and counter circuits to provide a high resolution measurement of the time interval required to charge each capacitor in the probe assembly. In this manner, a high resolution, noise resistant, digital representation of each of capacitance value is obtained without the need for a high resolution A/D converter, or a high frequency oscillator circuit. One embodiment of the probe assembly employs a capacitor with two ground plates which provide symmetry to insure that accurate measurements are made thereby.
Document ID
19990046087
Acquisition Source
Kennedy Space Center
Document Type
Other - Patent
Authors
Moerk, J. Steven (NASA Kennedy Space Center Cocoa Beach, FL United States)
Youngquist, Robert C. (NASA Kennedy Space Center Cocoa Beach, FL United States)
Werlink, Rudy J. (NASA Kennedy Space Center Cocoa Beach, FL United States)
Date Acquired
August 19, 2013
Publication Date
January 19, 1999
Subject Category
Instrumentation And Photography
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
NASA-Case-KSC-11770|US-Patent-5,861,755
Patent Application
US-Patent-Appl-SN-552456

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