MEAN VELOCITY 



Consider a hypothetical example of the effect of this nonlinearity when 

 extracting a dc signal in the presence of an ac flow. Assume the ac flow is of 

 low enough frequency so that the steady-state output calibration curve (figs. 4 

 and 5) will hold. For velocities under 1 knot, let the output, e, be given by 



e = K7L/- U^j for (i> U^ > (1) 



e = KW + L/^) for U < -U^ (2) 



e = for -Uj <U <Uj (3) 



where 



K = constant 



U = velocity 



Uj, = threshold velocity 



Let the actual velocity component, U. in the direction of the meter axis be 



U = Vq + IJ„ sin uZ (4) 



where Ug = dc velocity component in direction of meter axis 



(i^ = amplitude of ac velocity component 



Now for the case where L/q > (J^, the meter input and output appear as in 

 figure 6. The mean, or filtered, output e, over one wave cycle can be found from 



A C 2tt 



e=-^ f K(U - Uj,) d(at) + J- [ l«U + ^t' ^^"^^ ^ J~ f ^'^^' " ^T^^^"'^ ^^' 

 B D 



where 



A = sin'^ 



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