The development of a fast response static pressure instrument for field use

Abstract

A sphere probe with sixteen holes has been developed to measure turbulent fluctuations of static pressure in the atmospheric boundary layer. Wind tunnel tests show that the static pressure error of the probe is limited within ±2 per cent for variations of wind direction from 0º to 35º with the probe axis. The results of field test are summarized as follows. (1) The power spectral shape of static pressure fluctuations shows a –1 power slope at high frequency ranges for 2 ≥ n ≥ 0.05Hz. (2) The wp-cospectrum shows negative values for all frequencies analyzed, while the up-cospectrum shows positive values. (3) Measured coherence and phase between the static pressure, p, and the velocities, u and w, show typically that p is in phase with u for frequencies between 0.005 and 0.1Hz with a root-coherence over 0.8, and p not in phase (ca. 135º) with w for whole frequencies.