On-board Dynamic Strain System For Turbine Engine Ground Testing

The Arnold Engineering Development Center (AEDC) testing complex includes more than 50 wind tunnels, test cells, arc heaters, and other specialized test facilities. Of these, 27 units have capabilities that are unmatched in the United States, and 14 are unmatched in the world. These unique facilities pose equally unique testing challenges, including several related to test preparation. A dynamic strain measurement system feasibility demonstrator for turbine engine ground testing applications was developed as the product of a Small Business Innovative Research (SBIR) phase I contract. System specifications include 40 kHz minimum bandwidth, 0-65 degrees C operating temperature, IEEE-1451 ("smart sensor plug and play") compliance, and synchronized sampling per IEEE-1588. The transducer interface for each channel features hardware-configurable bridge completion, an instrumentation amplifier, a remotely configurable antialiasing filter, and a combined A-D/microcontroller on a 5 square inch circuit board. The A-D/microcontroller stores essential transducer information locally and converts the amplified analog signal into digital data. The network interface from 12 transducer channels to the host computer comprises an FPGA and a microprocessor with integral IEEE-1588. Data systems of this type will reduce engine test cell wiring to control room, improve noise immunity, reduce engine installation time, enable faster calibration, and reduce per channel instrumentation cost.