Evaluation and performance enhancement of a pressure transducer under flows, waves, and a combination of plows and waves

The performance of a pressure transducer, with its inlet attached to differ ing hydromechanical front ends, has been evaluated in Row flume and wave fl ume experiments in which laminar and turbulent Rows, and regular progressiv e gravity waves and combinations of hows and waves, were generated. For ste ady laminar Rows, and for waves propagating on quiescent waters, the transd ucer's performance improved when the inlet was at the center and Rush with a large, thin, and smooth circular horizontal end plate. This enhancement i s likely to have been achieved because of the isolation of the pressure inl et from the separated flows and vortices generated by the transducer housin g. Flow disturbances, generated by nearby solid structures, deteriorated th e performance of the pressure transducer. However, its performance could be significantly improved by protecting the pressure inlet by a sturdy, curve d perforated shield. The dynamic pressure error in this case was 2 mb at 10 0 cm s(-1), compared to 8 mb in the absence of the shield. For turbulent fl ows less than 100 cm s(-1), a pair of thin, circular, parallel plates, with a diameter three to four times that of the transducer housing and separati on equal to the housing diameter, led to a much improved horizontal azimuth al response. At this speed the spread in the dynamic pressure, Delta P, was less than 1 mb compared to 6 mb without a plate. Beyond this speed the tra nsducer's horizontal azimuthal response deteriorated faster. For combinatio ns of waves and Rows a relatively small Delta P was found. This result is o f special significance to tidal measurements of coastal waters, in which wa ves propagate on tidal currents.