Intrinsic Errors in Pressure‐Hole Measurements
作者:
R. I. Tanner,
A. C. Pipkin,
期刊:
Transactions of the Society of Rheology
(AIP Available online 1969)
卷期:
Volume 13,
issue 4
页码: 471-484
ISSN:0148-6055
年代: 1969
DOI:10.1122/1.549147
出版商: The Society of Rheology
数据来源: AIP
摘要:
A convenient way of measuring normal thrusts on fluid‐immersed surfaces is by use of a pressure gauge attached to a hole in the surface. With viscoelastic fluids exhibiting normal stress effects, it is shown that a systematic error exists, independent of hole size, but dependent on wall shear stress. Experiments were made in an open channel with various holes from132in. to14in. diameter, and also with an18in. wide slot. Errors were small with 30P silicone fluid, but with two viscoelastic solutions errors were alwaysnegativeand of the order of 25% of the first normal stress difference. No significant difference has been seen yet between sharp‐edged holes of different sizes or between holes and slots. A theoretical treatment for plane creeping flow over a deep slot predicts that the error is negative, independent of slot width, and 25% of the first normal stress difference. Some implications for normal stress measurements are considered.
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