GUY NORRIS / LOS ANGELES
General Electric is stepping up development of an innovative combustor concept for future military engines which could solve the problem of reducing emissions without sacrificing performance.
The US Navy has awarded GE a $7.5 million contract to evaluate the trapped vortex combustor (TVC) by August 2005. The work is part of ongoing studies aimed at running an F414-sized engine demonstration test in 2005-06, and parallel plans by the US Air Force to demonstrate a TVC combustor system in an advanced engine around early 2005. The latter test is expected to be part of the last phases of the integrated high performance turbine engine technology (IHPTET) programme.
The TVC differs from a conventional combustor by stabilising the flame within a vortex that is trapped in cavities in the walls of the combustor itself. In current combustors, air swirlers around fuel injectors generate a primary recirculation zone. This zone transports some of the hot combustion products back towards the combustor face and ignites incoming fuel and air as it is mixed in the chamber.
The vortex of the TVC, created by strategically placed air and fuel injection points, allows staged combustion to take place within the cavity while operating in pilot mode. In previous tests at the Air Force Research Laboratory's Propulsion Directorate at Wright-Patterson AFB, a TVC "concept sector" demonstrated up to a 50% improvement in ignition, blowout and altitude relight characteristics. It also showed 40% lower nitrous oxide emissions compared to current military engines, and maintained a combustor efficiency level at or above 99%.
Pratt & Whitney has won an $18.5 million contract Phase III IHPTET contract to design and modify the advanced engine XTC/E67/2, the core of which formed the basis for the Joint Strike Fighter's F135 turbofan. The work, which focuses on modifying the core with advanced components, builds on current tests of the core engine XTC67/1, and the high-performance fan on the XTE67/1.
Source: Flight International
