Assessment of miniature Knowles sensor for the measurement of wall pressure

Abstract

The wall pressure fluctuations can be measured using a flush-mounted or a pinhole-mounted sensor construction. Due to signal averaging over the sensor surface [1], a small sensing area is required to minimize the high-frequency spectral attenuation. The pinhole-mounted construction is an effective means to reduce the sensing area. However, even for the pinhole-mounted construction, a miniature pressure sensor is needed to increase the resonance frequency of the pinhole construction. In the present work, two Knowles miniature sensors, model FG-23329-P07, along with Kulite miniature sensors were mounted on a flat plate model for measurement in the Acoustic Wind Tunnel Braunschweig (AWB). Both sensor types were pinhole mounted with a pinhole diameter of 0.5 mm. The wall pressure fluctuations were measured in zero pressure gradients (ZPG) for various flow velocities and also in adverse and favorable pressure gradients (APG, FPG). The mean flow velocities across the boundary layer were obtained using a single-wire hot-wire probe. The one- and two-point statistics of the wall pressure fluctuations measured by the Knowles sensors are analyzed and compared to those measured by the Kulite sensors. Based on the comparison, the performance of the Knowles sensors for the measurement of wall pressure fluctuations is assessed.