New Russian Geared Turbofan Could Re-engine the Ruslan

 - May 4, 2012, 2:10 PM
The Kuznetsov PD30 geared turbofan is proposed for the An-124 Ruslan airlifter, and a possible future Russian widebody airliner. (Photo: Vladimir Karnozov)

The Kuznetsov design bureau, part of the United Engine Corporation (ODK), unveiled a new geared turbofan design at the Engines 2000 exhibition in Moscow last month. The PD30 is proposed for an upgrade to the Antonov An-124 Ruslan heavy airlifter, which is currently powered by the Ukrainian Ivchenko Progress D18T. The PD30 could also power Russia’s proposed widebody airliner, known as Airplane 2020.

The PD30 is portrayed as a low-risk project through extensive use of off-the-shelf components and technologies proven on other projects. However, it features many innovations: a high-power (50,000 hp, 99 percent efficiency) reduction gearbox between fan and turbine, wide-chord hollow (honeycomb) fan blades, very-low-emission combustor, mono-crystal blades, blisks in the HP compressor and booster, chevron nozzle, all-composite nacelle, intake and thrust reverser, and Fadec.

When fitted to the An-124-300, the PD30 would develop 29.5 metric tons (65,000 pounds) of thrust for takeoff and 5.7 to 6.2 metric tons (12,560- to 13,670 pounds) when cruising at 11,000 meters (36,000 feet). Low specific fuel consumption (SFC) of 0.535-0.548 lb/lb/hr is achieved through a high bypass ratio (between 7.65 and 8.7), while gas temperatures are kept at 1,433K at maximum continuous power.

By comparison, the D18T series 5 delivers 27.85 metric tons (61,400 pounds) thrust at takeoff and 6.28 metric tons (13,840 pounds) in cruise, with an SFC of 0.541 lb/lb/hr. At 5,140 kg (11,330 pounds), the PD30 weighs 560 kg (1,235 pounds) less than the D18T. Kuznetsov says that the PD30 has a similar performance to the Rolls-Royce Trent series, while running at lower temperatures for higher margins and lower emission levels.

The centerpiece of the PD30 project is the use of a “modified baseline gas generator” from the improved NK32 turbofan that powers the Tupolev Tu-160 strategic bomber. Production of the NK32 was restarted recently, with some 40 engines already manufactured. The fleet leader has logged more than 3,500 flight hours. The modified gas generator is undergoing bench testing, and has so far amassed 1,000 hours. Kuznetsov says its industrial turbine NK36ST that is derived from NK32 has logged 25,000 hours without removal, while running continuously at 1,520K.

Kuznetsov promises low noise through the use of a new low-speed fan with rotational speeds below 340-350 m/sec (1,115-1,148 ft/sec) to comply with upcoming ICAO standards. Levels of NOx, CO and hydrocarbon are two, 10 and 15 times less than ICAO 2004 requirements, respectively, through use of a multi-fuel-injector combustor with a life of 30,000 flight hours before removal. This unit has been tested on industrial engines during an 8,000-hour run.

The reduction gearbox is the most complex part of the project. It uses sliding bearings tried on Kuznetsov’s experimental NK93 propfan. Key technologies come from the 33,000-hp unit developed for the An-70’s D27 powerplant. The hollow blades are considered lower risk since Kuznetsov has already tested elements of their design on the NK56 and NK44 in the late 1980s. The blades will be manufactured at ODK’s new factory in Ufa, which specializes in diffusion soldering.

Kuznetsov has issued manufacturing documentation for the PD30 and expects the engine to be mature enough for series production in four to five years. Should the engine be selected for the Airplane 2020 program, its fuel burn could be lowered through higher bypass ratio and higher gas temperatures.