Gas Turbine Dynamic Dynamometry: A New Energy Engineering Laboratory Module

Abstract

To integrate energy topics into STEM curricula, an archive of "Energy Engineering Laboratory Modules" (EELMs) is being developed by collaborating faculty and students at the Milwaukee School of Engineering (MSOE). EELMs facilitate spiral insertion of energy engineering experiments into college and high school STEM courses. By making innovative use of inexpensive equipment, EELMs facilitate near-ubiquitous accessibility to energy curricula, even for instructors with limited resources.Gas turbines are paramount to modern energy production and transportation, and this critical technology will continue its prominence as we pursue a renewable energy future. Exposure to gas turbines through hands-on experiments could provide meaningful content for a range of STEM courses. However, prohibitively expensive commercially available educational test stands preclude gas turbine experiments from all but specialized engineering programs. Moreover, even if gas turbine hardware is available, specialized dynamometer and data acquisition equipment are needed to evaluate performance. Alternatively, virtual laboratories can offer rich simulated experiences to promote learning, but they lack the stimulating tactile and tangible learning experiences applied experiments provide.We describe a method to accurately measure and predict the mechanical power output of a gas turbine using the rational inertia of the turbine's spinning components and friction in its bearings as the load. The turbine's time response to Dirac load inputs and its no-load responses to compressed air input over a range of pressures are measured. This technique, called dynamic dynamometry, requires only an inexpensive optical tachometer, a digital video recorder, and free image capture software for data acquisition. Turbine power-versus-angular-velocity curves are produced, which can be used for design, additional analysis, and teaching. An additional benefit of this technique is that turbine rotational inertia is determined independently of knowing the rotor's geometry. So, the experiment can be completed without dismantling the turbine; or, if desired, the measured rotational inertia can be independently verified by disassembling the turbine to measure internal component geometry and mass.