First JTAGG III turboshaft demonstrator engine expected to be tested in mid-2005

Honeywell is preparing to assemble its final set of Joint Turbine Advanced Gas Generator (JTAGG) turboshaft demonstrators - the last element of its involvement in the USA's long-running Integrated High Performance Turbine Engine Technology (IHPTET) initiative.

The initial JTAGG III demonstrator, XTC-97/1, is a two-spool, high power turboshaft that is being developed in partnership with General Electric. The first engine to test is "anticipated in the second quarter of 2005", says Honeywell Propulsion Systems advanced technology director Ron Rich.

The IHPTET work paves the way for the company's involvement in the US government and industry follow-on Versatile Affordable Advanced Turbine Engine effort, he says.

Following a series of rig and component tests, Rich says: "We've done a lot of fit checking on the engine and we are just about ready to commence the formal build for testing at our remote San Tan test site near Phoenix."

Key technologies to be demonstrated in the XTC-97/1 core include a counter-rotating vaneless turbine; a forward-swept splittered rotor and split inducer impeller; a ceramic matrix composite (CMC) combustor liner; a cooled CMC turbine nozzle; monolithic ceramic turbine blades and advanced seals and bearings.

Later builds, which could extend final IHPTET runs into 2006, will include magnetic bearings, adds Rich.

Phase III targets, relative to a 1987 state-of-the-art turboshaft, include a 120% increase in power-to-weight ratio, a 40% lower specific fuel consumption, a 1,000°C increase in turbine inlet temperature, and 35% reductions in both acquisition and maintenance costs.

The targets remain ambitious, particularly given the work still remaining in front of Honeywell to achieve the Phase II targets with the JTAGG II XTC-56/2 demonstrator. Although focused at a lower power bracket and aimed ultimately at the hoped-for funded go-ahead of the US Army's Improved Turbine Engine Programme from around 2007, the demonstrator is being modified for a final series of runs planned for late 2005.

"We did not complete everything we wanted, so we have rematched the first spool to the intermediate second spool, and have improved the high-pressure turbine in terms of single-stage work and heat-transfer loading on the blade and in the whole area around it," says Rich.

In particular, he says the work is focusing on perfecting the company's high-effectiveness advanced turbine blade technology, which is a double-walled turbine blade configuration aimed at helping the core engine to demonstrate higher temperatures at combustion initiation, a higher maximum cycle temperature and more effective control of cooling air in the small blades and vanes.

"Our engine is considerably smaller than those of our counterparts, and some things just don't scale," says Rich.

Honeywell plans to start assembly of the revised XTC-56/2 in the second quarter of 2005 - well after the original January 2001 target date for the demonstration of the Phase II goals.



Source: Flight International