The Development of Extremely-Compact Static Pressure Probe for the Simultaneous Measurement of Pressure and Velocity in the Turbulent Flows

A new static pressure probe was developed to improve the space resolution and the measurement accuracy of the combined probe for the simultaneous measurement of the static pressure and the velocity in turbulent flows. The external diameter of the static pressure tube is 0.3 mm and its internal diameter is 0.2 mm. There are 8 static pressure holes on the wall of the static pressure tube and their diameters are 0.1 mm. The MEMS microphone is used as the pressure sensor and embedded inside the flare of the static pressure tube. The diameter of the MEMS microphone is 2.54 mm and has the wide range flat frequency response. The measurement results by the new static pressure probe in the two-dimensional turbulent jet show that the measurement accuracy of the static pressure probe is sufficient and the seven-thirds power law is clearly observed in the power spectra of the fluctuating pressure measured at the position of a half width of the mean velocity distribution in the cross-streamwise direction apart from the jet center line. In addition, the yaw angle characteristics of this new pressure probe shows that the measurement accuracy of the static pressure has less dependency on the yaw angle of the probe to the flow direction than the one of the previous static pressure tube (its external diameter is 0.5 mm). From these results, it is found that the new static pressure probe is effective for the measurement of static pressure in turbulent flows and useful to improve the space resolution and the measurement accuracy of the combined probe for the simultaneous measurement of the velocity and the static pressure. By using this static pressure tube, the space resolution of the combined probe is reduced approximately 40%. Further, by combing two X-type hot-wire probes with the new pressure probe, the simultaneous measurement of three velocity components and static pressure is realized.