The first 100-kW-class pulse-controlled, nontoxic turbine power unit (TPU) has been built and demonstrated for space transportation flight control system applications. In space transportation vehicles, auxiliary power is used to provide short-duration high power for applications such as thrust vectoring, aerodynamic controls, brakes, and engine throttling. The space shuttle orbiter auxiliary power is provided by hydrazine-fueled auxiliary power units. Unlike the shuttle auxiliary power unit that uses toxic propellants to drive a hydraulic pump, this TPU (see the following photograph) uses nontoxic reactants to drive a generator to produce 270-Vdc electrical power. Applications of the TPU include power for high-horsepower, all-electric actuation systems and for electric-pump-powered hydraulic systems for launch vehicle flight controls.
Brassboard turbine power unit.
The prototype nontoxic TPU includes a shaft-speed turboalternator, gas-cooled foil bearings, a high-reactance permanent magnet generator, and hydrogen and oxygen propellants with catalytic reaction that are pulsed on-off for speed control. A flight unit version is envisioned to be self-cooled using regenerative cooling with prognostic health monitoring and integrated power-processing modules wrapped around the TPU housing. The potential advantages of the new TPU concept include the elimination of toxic propellants, reduced ground processing, improved reliability, and reduced critical failure modes.
The prototype, also known as the brassboard TPU, has been successfully demonstrated with both cold and hot gases (see the final photograph). Cold gases include nitrogen and helium. A laboratory gas generator was used to generate the hot gas by the catalytic reaction of gaseous hydrogen and oxygen. The brassboard TPU has demonstrated 135-kW output with a designed electrical power output of 142 kW. TPU components such as seals and foil bearings have been demonstrated separately in simulated launch environments with no observable wear.
Brassboard turbine power unit, power control and conditioning unit, and laboratory gas generator configured in a test cell for hot gas testing.
The TPU effort is led by the NASA Glenn Research Center with a Lockheed Martin Corporation prime contract and a subcontract with Honeywell for hardware development and testing. The last phase of this task, which is currently underway, is to develop and test a new design brassboard hydrogen/oxygen gas generator with the goal of increased life and performance. The new gas generator will be integrated with the brassboard TPU and tested.
Find out more about exploration systems research at Glenn: http://exploration.grc.nasa.gov
Nang T. Pham, 216–433–6165, Nang.T.Pham@nasa.gov; Clint B. Ensworth, 216–433–6297, Clinton.B.Ensworth@nasa.gov; and Scott R. Graham, 216–977–7123, Scott.R.Graham@nasa.gov
Authors: Nang T. Pham, Clinton B. Ensworth, Scott R. Graham, and Emily R. Groh
Headquarters program office: Exploration Systems
Programs/Projects: Constellation Systems
Last updated: September 14, 2006
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