Instrumentation Systems for a Continuous Flow Turbine Rotor

The design and testing of instrumentation systems for the measurement of steady and unsteady turbine blade surface pressure and boundary layer condition for a turbine stage operating at design Mach and Reynolds numbers is presented. The boundary layer condition is monitored by an array of suction and pressure surface heated thin-film gauges. This paper describes the desigo of a forty channel constant temperature bridge to drive these gauges. The bridge fits into the centre of a sub-shaft driven by the turbine wheel. The amplified bridge output is transferred from the rotor via an array of light emitting diodes. The surface pressure is recorded by unpackaged pressure transducer chips laid into the surface of the blade. This paper also describes the circuitry necessary to drive these transducers. The position of these circuits and the transmission method are the same as those used for the thin film gauges. Both systems have a bandwidth sufficient for the resolution of vane-blade interactions.