Turbofan

About: Turbofan is a research topic. Over the lifetime, 4114 publications have been published within this topic receiving 39490 citations. The topic is also known as: fanjet & turbofan engine.

Turbofan engine bearing support

Abstract: A turbofan engine (20) comprises an engine case (22). A gaspath extends through the engine case (22). A fan (42) has a circumferential array of fan blades (100). A fan case (40) encircles the fan blades (100) radially outboard of the engine case (22). A plurality of fan case vanes (44) extend outward from the engine case (22) to the fan case (40). A front frame assembly (172) includes a plurality of vanes (173) extending radially across the gaspath. A transmission (46) couples a shaft (25) to a fan shaft (132) to drive the fan (42). A bearing assembly (176) couples the shaft (25) to the front frame assembly (172). A bearing support (454) extends aftward and radially inward from the front frame assembly (172) to the bearing assembly (176).

Noise Reduction Potential of Large, Over-the-Wing Mounted, Advanced Turbofan Engines

Abstract: As we look to the future, increasingly stringent civilian aviation noise regulations will require the design and manufacture of extremely quiet commercial aircraft. Indeed, the noise goal for NASA's Aeronautics Enterprise calls for technologies that will help to provide a 20 EPNdB reduction relative to today's levels by the year 2022. Further, the large fan diameters of modem, increasingly higher bypass ratio engines pose a significant packaging and aircraft installation challenge. One design approach that addresses both of these challenges is to mount the engines above the wing. In addition to allowing the performance trend towards large, ultra high bypass ratio cycles to continue, this over-the-wing design is believed to offer noise shielding benefits to observers on the ground. This paper describes the analytical certification noise predictions of a notional, long haul, commercial quadjet transport with advanced, high bypass engines mounted above the wing.

Noise Benefits of Increased Fan Bypass Nozzle Area

Abstract: An advanced model turbofan (typical of current engine technology) was tested in the NASA Glenn 9 by 15 Foot Low Speed Wind Tunnel (9-by 15-Foot LSWT) to explore far field acoustic effects of increased bypass nozzle area. This fan stage test was part of the NASA Glenn Fan Broadband Source Diagnostic Test, second entry (SDT2) which acquired aeroacoustic results over a range of test conditions. The baseline nozzle was sized to produce maximum stage performance for the engine at a high altitude, cruise point condition. However, the wind tunnel testing is conducted near sea level conditions. Therefore, in order to simulate and obtain performance at other aircraft operating conditions, two additional nozzles were designed and tested-one with a +5 percent increase in weight flow (+5.4 percent increase in nozzle area compared with the baseline nozzle), sized to simulate the performance at the stage design point conditions, and the other with a +7.5 percent increase in weight flow (+10.9 percent increase in nozzle area), sized for maximum weight flow with a fixed nozzle at sea level conditions. Measured acoustic benefits with increased nozzle area were very encouraging, showing overall sound power level (OAPWL) reductions of 2 or more dB while the stage thrust actually increased by several percentage points except fro the most open nozzle at takeoff rotor speed where stage performance decreased. These noise reduction benefits were seen to primarily affect broadband noise, and were evident throughout the range of measured sideline angles.

Design, construction, and testing of an aero-engine starter-generator for the more-electric aircraft

Abstract: This study describes the design, construction, and testing of an aero-engine starter-generator and its associated power electronic converter. A high-speed, permanent magnet machine and a dual-channel machine-facing converter with an electrical power offtake rating of 95 kW have been developed for a small civil turbofan application. The study also describes the more-electric architecture into which the machine and converter are integrated and reviews the multi-faceted performance specification, which is a common feature of machines of this type.

Distributed propulsion and turbofan scale effects

Abstract: A coupled aircraft and engine model is used to evaluate the fuel consumption and mission weight of distributed propulsion aircraft. The engine cycle is optimized for the installation to show the ultimate performance of each propulsion alternative. The effect of higher specific fuel consumption for smaller engines is weighed against the potentially lower installation weight and higher integration efficiency of distributed propulsion.