Output shaft torque is a very useful parameter for health and usage monitoring, as well as electronic control, of turboshaft engines. Magnetoelastic polarized band technology is a novel method of torque sensing that provides a wireless signal while maintaining superior torsional stiffness, low mass, and packaging flexibility. Although this technology has been successfully proven in many automotive and industrial applications, its use to date has been limited to average torque measurement and niche production volumes. The objective of this project is to prove the feasibility of a magnetoelastic non-contact torque sensor for turboshaft and turboprop engine applications, with the specific goal of achieving a repeatable signal having large bandwidth from actual measurements on an engine output shaft. This test program is intended to demonstrate enhanced performance as compared with existing torque sensor systems, which more often than not present a heavy compromise among the desired resolution, bandwidth, and packaging. The significant weight and cost reductions, and long-term rotorcraft safety enhancements that can be achieved by the U.S. Navy through this new torquemeter make it well worth evaluating. This initial proveout is intended to provide the basis for a Phase II project to commercialize the technology for various military and commercial gas turbine engine applications.
Benefits: Torque is one of the most fundamental parameters used to analyze and control the performance of rotating machinery. Although all gas turbine engines generate mechanical torque at certain individual stages, turboshaft (and turboprop) engines are particularly well-suited for analysis of their system performance through torque monitoring due to the fact that they provide mechanical power through an output shaft. By demonstrating the feasibility, in hardware, of a magnetoelastic non-contact torque sensor for gas turbine engine output shafts that provides a high bandwidth signal, the following benefits are anticipated: Far greater flexibility in packaging layout of the engine output shaft assembly h Improved torsional stiffness and output signal resolution with respect to existing strain gauge and phase shift torque sensors h Elimination of compliant torsion bar used in existing phase shift torque sensors, with a consequent weight and cost reduction h Lower torque sensor system and output shaft assembly physical length and mass h Improved ability to detect, and eventually prevent, potentially hazardous engine transient events such as flutter, surge, and stall h Improved HUMS capability during engine operation h Improved controllability of engine torque balancing in dual engine configurations h Enhanced capability for diagnostics in helicopter flight testing programs, especially airframe-engine matching and drive system dynamics The commercial implications of a successful high bandwidth torque sensor development program are significant. Truly non-contact, robust, accurate torque measurement for a variety of vehicle and industrial applications has been an elusive goal for many years. The advent of magnetoelastic polarized band technology, in combination with recent improvements in magnetic field sensor technology, suggest the strong possibility that at last reliable torque measurement, including that of transient events, is a real prospect for machine designers across many fields. Such a development could be put to use successfully in such varied applications as automotive engine control for reduced emissions, power control of helicopter engines and rotors, and tool condition monitoring in CNC machining centers. Due to the fact that there are literally millions if not billions of rotating shafts in the field that could benefit from integrated torque sensing, the ramifications of a successful program for U.S. military and industrial applications are exceptionally broad indeed.
Keywords: Torque sensors, Wireless instrumentation, gas turbine engine , Magnetoelastic torque sensors, instrumentation
