A scramjet heat exchanger for future hypersonic vehicles such as a reusable satellite launcher or global reach cruise missile has been successfully tested by Pratt & Whitney.
The test success means the exchanger could be used on the US Air Force's Waverider scramjet engine demonstrator vehicle, expected to fly in 2007. The 152mm (6in)-wide, 762mm-long carbon-carbon composite heat exchanger plate was "flown" in a windtunnel at Mach 6.5. Using an anti-oxidation coating system, the exchanger survived the test undamaged at United Technologies' research centre in Connecticut.
Mounted in the scramjet rig's combustor it was exposed to gases at 2,200C (4,000F) and was simultaneously cooled by the engine's JP-7 aviation fuel flowing through it.
"The idea behind it is to reduce the weight. The composite heat exchanger is 35% lighter than a metallic baseline system with similar performance," says P&W's advanced materials and structures for hypersonics programme manager, Ravi Nigam.
Future research will see the exchanger's size and speed increased for it to become useful for a space or long-range atmospheric vehicle. For these purposes, the exchanger could be many metres long. The exchanger's carbon-carbon composite material could also be used for a hypersonic vehicle's scramjet exhaust nozzle, leading edges and control surfaces. The test was part of NASA's Next Generation Launch Technology programme.#
ROB COPPINGER / LONDON
Source: Flight International