Abstract
Previous work has shown that the k 2 term in the effective cooling velocity equation for inclined hot-wires can become negative under certain probe configurations and wire length-to-diameter ratios. It was hypothesised that this was due to a downwash component of velocity along the wire when prong interference effects were expected to be minimal. Direct measurements of the flow around a typical hot-wire probe using digital particle image velocimetry have shown that this downwash velocity component does exist, leading to negative values of k 2 as calculated from the angle of deviation from the free stream.
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Abbreviations
- d :
-
diameter of hot-wire mm
- k :
-
factor in equation for effective dimensionless velocity for inclined hot-wire
- l :
-
length of hot-wire mm
- Q :
-
effective velocity mm/s
- U :
-
free stream velocity mm/s
- α :
-
angle between free stream and degrees wire normal
- δ :
-
angle through which flow is degrees deflected at working section of wire
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Graham, L.J.W., Soria, J. & Bremhorst, K. Examination of the flow around a hot-wire probe using particle image velocimetry. Experiments in Fluids 19, 379–382 (1995). https://doi.org/10.1007/BF00190254
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DOI: https://doi.org/10.1007/BF00190254