Directional sensitivity in 3D fields

If the velocity vector is at an angle в Ф 0 with the wire/sUpport plane (FigUre 3.18), the effective speed detected by the wire is

uf = ux + kuy + huZ

= U1 (cos2 a cos2 в + ksen2a + h1 cos2 asen2e)

where k = yaw factor, h = pitch factor.

Average valUes of h2 provided by the manUfactUrers are shown in the following table:

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Gold-plated probe 1.04

Fiber probe 1.20

In the particUlar case of planar flow (в = 0), one finds the sensitivity of the probe to the angle of yaw EqUation (3.17)

Uf (a) = U (cos2 a + k2sen2a) в = 0

Similarly the sensitivity of the probe at the pitch angle can be found by putting a = 0:

Uf (в) = U (cos2 в + h1sen1e) a = 0