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Aviation History
1997
1997 - 0445.PDF
INDUSTRY UCI works on shock treatment GUY NORRIS/LOS ANGELES ANEW technique for reducing the exhaust noise of jet engines for supersonic aircraft is being de veloped by a team at die University of California, Irvine (UCI), led by the concept's inventor, Professor Dimitri Papamoschou. Work on die noise-suppression concept, known as theMach Wave Eliminator, is being supported by NASA, and has attracted interest from Boeing, General Electric and McDonnell Douglas. So-called Mach waves are shock waves formed by turbulent eddies in the exhaust of engines such as those under study for the next-genera tion High-Speed Civil Transport (HSCT). The high-energy eddies create a ballistic effect, akin to that of gaseous bullets, which generate much of the engine noise. Papamoschou's technique in volves eliminating the wave by slowing the eddies to subsonic speeds. Two main methods are under test, involving adjustment of the "co-flow" around the core of the engine. "It is really akin to the fan stream in a turbofan engine. By selecting, or changing, the proper ties of the fan stream we can elimi- Mach wave elimination options ^Combustion Option B il 1 1 11 \ M AM ~H ,'f/Ifl >#M: ^•Increased fan pressure ratio n fan stream FLIGHT nate the Mach waves," he says. "It is a trade-off between the speed and heat of the stream," he explains. One technique involves heating up the co-flow, either by injecting core air or by combustion in the co-flow stream itself. The other is to increase the pressure ratio of the fan, thereby increasing co-flow velocity. In either case the moving air molecules in the co- flow mix more readily with die core flow of the exhaust, , reducing shear stress between the two flows and reducing violent eddy interac tion and velocities. Preliminary results from tests on a 1/1 OOth-scale model jet in a UCI laboratory have yielded up to 1 OdB noise reductions, using both tech niques. "To really prove the con cept, we have to move to NASA or an industrial partner and do larger- scale tests," says Papamoschou. Changes to proposed HSCT engines already in early develop ment would be relatively modest, although an increase in pressure ratio might entail a two-stage fan. The team stresses that the sys tem would only be required for take-off, and would weigh far less than the large ejector/mixer de signs planned as the best means of achieving Stage 3 compliance. The penalty for fuel or hot-core air injection is expected to result in a 0.5% increase in fuel consump tion averaged over the entire flight. Other possibilities include use of die system in only the lower hemi sphere of the engine exhaust, or a combination of the Mach Wave Eliminator and a smaller ejector.Q AlliedSignal wins $100 million GECAS APU/avionics deal GE CAPITAL Aviation Ser vices (GECAS) has selected AlliedSignal Aerospace to supply auxiliary-power units (APUs) and avionics for up to 80 Airbus In dustrie A320s which the US leas ing company plans to buy, in a deal worth around $100 million. The agreement means that GECAS is likely to be one of the first customers for AlliedSignal's new 131-9[A] APU, although some aircraft may be delivered with the existing 36-300-4 unit, de pending on operator preference. AlliedSignal Commercial Av ionics Systems, meanwhile, will supply enhanced ground-proximi ty warning systems, forward-look ing windshear-detection radars and traffic-alert and collision- avoidance systems for the aircraft. Also included in the deal are communications and navigation equipment and solid-state flight- data and cockpit-voice recorders, says AlliedSignal. GECAS ordered AlliedSignal equipment worth S700 million in April, for up to 254 Boeing 737s. J Meggitt to equip VClOs for RVSM MEGGITT AVIONICS HAS won a contract to supply solid-state liquid-crystal-display altimeters and air- data computers to enable Vickers VC10 transports of the Royal Air Force to meet North Atlantic reduced vertical-separation minima (RVSM), which are to be implemented this year. The first of 35 shipsets will be delivered to prime contractor British Aerospace in April. The UK company sees "major opportunities in the military-transport and business-jet markets" for its RVSM retrofit upgrade, says Peter O'SuIIivan, Meggitt Avionics sales and marketing director. NEWS IN BRIEF • JAL CHOOSES BEA Japan Airlines QAL) has se lected BE Aerospace's (BEA) MDDS inflight entertain ment system for installation on three Boeing 747-400s which are due for delivery to the Japanese carrier in 1998. The airline is also consider ing retrofitting the system on its 747-300/400 fleet, accord ing to Wellington, Florida- based BEA. • HUNTING CHINA APPROVAL The Civil Aviation Admini stration of China (CAAC) has approved Hunting Avi onics & Accessories to carry out repair and overhaul of aircraft avionics for Chinese airlines. The approval fol lows moves by the CAAC to ban provision of support ser vices for Chinese carriers by unapproved maintenance companies* • LEADING-EDGE LUNN Lunn Industries has deliv ered its first batch of Boeing 767 leading-edge slat core assemblies to Port Mel bourne, Australia-based Rockwell ASTA. Lunn, a subsidiary of Alcore of the USA, has a $2.7 million Iife- of-programme contract, cov ering the supply of the honeycomb cores. • COOL TORNADO IMI Marston has won a £1.5 million (S2.5 million) con tract to supply pre-coolers as part of the mid-life update of the Royal Air Force's Panavia Tornado GR4s. Deliveries to the British Aerospace Mili tary Aircraft division will continue until the year 2001, says Wolverhampton, UK- based IMI. • MOVEX CLARIFICATION Flight Intel-national has been asked to point out that Speedwing is marketing Intentia's Movex Aviation maintenance support soft ware (Flight International, 8- 14 January, PI 9). FLIGHT INTERNATIONAL 29 January - 4 February 1997 27
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