NASA turns up the heat on cooperative turbofan research

 - May 6, 2008, 5:00 AM

Two NASA-industry partnerships could produce tangible benefits for aircraft operators in the near term. The turbofan engine research is being conducted by NASA Glenn Research Center in Cleveland as part of its aerospace propulsion and power program, the same division that Williams International teamed up with to develop the 700-lb-thrust FJX2 turbofan. A variant of that Williams engine, the EJ22, will power the Eclipse 500, which is expected to take its maiden flight this summer.

Under the aerospace propulsion and power program umbrella are eight projects: oil-free turbine engine technology; ultra-safe propulsion; smart efficient components; higher-operating-temperature components; pulsed-detonation engine technology; zero CO2 research; revolutionary aeropropulsion concepts; and fundamental noise. While most of those projects won’t produce benefits for at least 10 years, two–oil-free turbine engine technology and higher-operating-temperature components–are close to developing commercial products.

The oil-free project, which is a partnership between Williams International and NASA, aims to put foil air-bearing technology in commercial use by the end of 2006. Contingent on funding, a precious commodity at the space agency, the project team expects to test this technology on a core FJX2 engine in June 2004, after which Williams would take the ball and work on certification.

The theory behind the air-bearing technology is that oil-free engines would eliminate many of the maintenance problems encountered by aircraft operators today. Simplified design and reduced maintenance would yield lower operating costs and greater reliability. Additionally, the environment would benefit due to the elimination of oil emissions and oil disposal.

NASA’s project team is applying enabling technology advances in foil bearings, solid lubricant coatings and modeling to design, fabricate and test an oil-free turbine engine. This will be accomplished by scaling up the foil-bearing technology recently demonstrated in a turbocharger, though the actual turbofan application will involve more complex systems and dynamic issues than those encountered in the turbocharger.

Feeling the Heat

Another NASA project team is tasked with developing technologies that will increase the temperature limits of many propulsion components, reducing cooling requirements and improving engine efficiency. But according to project manager Carol Ginty, the higher-operating-temperature components program has taken a detour. Due to funding constraints, the project has been redirected to first demonstrate a coating that will reduce wear to low-temperature engine components, after which the team will work with higher-temperature coatings.

As it stands, the project team is now testing two different coatings at the University of Cincinnati–one developed by NASA personnel and the other by project partner Rolls-Royce Allison. Ginty told AIN that both coatings are performing well in preliminary testing.

Next month the NASA team will test the two coatings on an inlet guide vane to see if they meet or exceed the goal to double low-temperature engine component life. These tests will be conducted at NASA Glenn.

Performance aside, other deciding factors in which coating is ultimately chosen by Rolls-Royce for a commercial application is how much the coating costs to produce and apply, as well as ease of application. Ginty would not comment on what the coating’s ingredients are, nor how it is applied to components.

Next summer, the program team plans to begin survivability tests on high-temperature polymer coatings. If the test results pan out as predicted, those coatings could allow turbine engine combustion chambers to be 35 percent lighter than existing burner cans.