Flex Circuit Sensor Array for Surface Unsteady Pressure Measurements

Abstract

Introduction T HE acquisition of high-fidelity, high-frequency response surface pressure measurements are of interest to experimentalists in gas-turbine aeromechanical research because these data provide a means to measure indirectly the unsteady aerodynamic loading acting on an airfoil. Airfoils are typically (traditionally) instrumented from commercially available miniature pressure transducers that are flush mounted to the airfoil to prevent the transducer from aerodynamically disturbing the flow. Cavities are machined into the airfoil to accommodate the transducers, and trenches are machined to route the lead wires away from the transducer.1−5 The main difficulty in the use of traditional transducers for high spatial resolution comes from the congestion and interference caused by the cavities and trenches required for each sensor location and the number of locations desired. A high spatial resolution array of high-frequency pressure transducers was designed and fabricated that eliminates most of the difficulty associated with having a large concentration of transducers in a given area. Two pressure sensor arrays were applied to the suction and pressure surfaces of two inlet guide vanes (IGVs) of a transonic research compressor to measure the unsteady loading distribution induced by the passage of the bow shocks and the potential field emanating from the downstream rotor.