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Stabilized flow in capillary-type closed viscometer
1National Research Laboratory of Metrology, 10-4, 1-Chome, Kaga, Itabashi-ku, Tokyo, Japan.
The Review of Scientific Instruments
|March 1, 1980
Summary
A feedback circuit significantly reduces gas flow variations in a capillary viscometer from 1% to 0.1%. This system enhancement improves flow stability for precise measurements in scientific applications.
Area of Science:
- Fluid Dynamics
- Control Systems Engineering
Background:
- Capillary-type closed viscometers are susceptible to gas flow variations.
- Nonlinear transmission in worm mechanisms causes flow instability.
- Understanding and mitigating these variations is crucial for accurate measurements.
Purpose of the Study:
- To reduce periodic variations in gas flow through a capillary.
- To analyze the dynamical properties of the flow control system.
- To identify factors contributing to flow instability.
Main Methods:
- Implementation of a feedback circuit using a pressure gauge and pump motor.
- Application of the Laplace transform method for dynamical analysis.
- Experimental investigation of gas flow in a capillary viscometer.
Main Results:
- Gas flow variations were reduced from 1% to 0.1% peak-to-peak width.
- The feedback circuit effectively stabilized the main gas flow.
- Low pressure, long guide tubes, and high amplifier gain were identified as causes of instability.
Conclusions:
- The developed feedback system significantly enhances gas flow stability in capillary viscometers.
- Dynamical analysis provides insight into the causes of flow instability.
- Optimizing system parameters can further improve measurement precision.
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