| Autor: |
S.W. Van Sciver, D. Scott Holmes |
| Rok vydání: |
1990 |
| Předmět: |
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| Zdroj: |
Advances in Cryogenic Engineering ISBN: 9781461279044 |
| DOI: |
10.1007/978-1-4613-0639-9_30 |
| Popis: |
A novel flowmeter design has been investigated for the metering of liquid He II bulk flows in small channels. The flowmeter consists of a thin film heater with thin film temperature sensors located upstream and downstream from the heater. The thin film heaters and sensors can be placed on the inside walls of the channel and should not restrict the flow or cause cavitation as do venturi or turbine flowmeters. One mode of operation is to pulse the heater, creating second sound pulses which travel upstream and downstream to the temperature sensors. The Doppler shift in the pulse arrival times can be related to the bulk flow velocity. A second operational mode requires a continuous sinusoidal driving current supplied to the heater to produce second sound and a lock-in amplifier to detect the resulting signal at a temperature sensor either upstream or downstream from the heater. The phase shift of the received signal is related to the bulk flow velocity. The resolution and accuracy of the flowmeter depends upon channel size, heater power, bulk flow velocity and heater-to-detector distance. Limitations due to power requirements and attenuation of second sound by quantized vortices are also discussed. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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