Response of hot-wire anemometry to transient flow induced by weak pressure waves
When a pressure wave propagates in a stationary fluid, the fluid flow is accelerated from zero to a certain value. Although hot-wire anemometry is among the most reliable measurement techniques for small-amplitude and high-frequency fluctuations of velocity or mass flow rate (mass flux), few reports...
Saved in:
Published in | Experiments in fluids Vol. 65; no. 4 |
---|---|
Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Berlin/Heidelberg
Springer Berlin Heidelberg
01.04.2024
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | When a pressure wave propagates in a stationary fluid, the fluid flow is accelerated from zero to a certain value. Although hot-wire anemometry is among the most reliable measurement techniques for small-amplitude and high-frequency fluctuations of velocity or mass flow rate (mass flux), few reports on their response to step accelerations from zero velocity exist. In this study, the response of hot-wire anemometry operated in constant temperature mode (HW-CTA) to an accelerated flow with an initial flow velocity,
U
, to
U
+
Δ
u
, where
Δ
u
is the increase in flow velocity due to a pressure wave, was investigated. In the experiments, the opening valves generated a pressure wave in a pipe with a radius of 50 mm. The velocity signals measured by HW-CTA and flush-mounted pressure transducer were compared for several values of
U
and
Δ
u
. A non-negligible dead time and increased time constant were found in the signal measured by HW-CTA when compared with those measured by the pressure transducer for
U
=
0
, whereas a negligible delay was observed for
Re
U
>
0.2
U
>
0.5
m
/
s
.
Re
U
is the wire Reynolds number based on
U
and the hot-wire diameter. Finally, it was revealed that the sum of the dead time and time constant corresponded to the flow transitions from natural to forced convection.
Graphical abstract |
---|---|
ISSN: | 0723-4864 1432-1114 |
DOI: | 10.1007/s00348-024-03779-z |