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.

Assembly for mounting a turbine engine to a pylon

Abstract: An assembly is provided for mounting a turbofan engine to a pylon. The turbofan engine includes a fan section and an engine core. The mounting assembly includes a fan case, a first mount and a second mount. The fan case is configured to house the fan section of the turbofan engine. The first mount is connected to the fan case, and configured to mount the fan case to the pylon. The second mount is connected to the fan case, and configured to mount the fan case to the pylon.

Comprehensive Report of Fan Performance from Duct Rake Instrumentation on 1.294 Pressure Ratio, 806 FT/SEC Tip Speed Turbofan Simulator Models

Abstract: A large scale model representative of an advanced ducted propulsor-type, low-noise, very high bypass ratio turbofan engine was tested for acoustics, aerodynamic performance, and off-design operability in the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel. The test was part of NASA s Advanced Subsonic Technology Noise Reduction Program. The low tip speed fan, nacelle, and un-powered core passage were simulated. As might be expected, the effect of stall management casing treatment was a performance penalty. Reducing the recirculating flow at the fan tip reduced the penalty while still providing sufficient stall margin. Two fans were tested with the same aerodynamic design; one with graphite composite material, and the other with solid titanium. There were surprising performance differences between the two fans, though both blades showed some indication of transitional flow near the tips. Though the pressure and temperature ratios were low for this fan design, the techniques used to improve thermocouple measurement accuracy gave repeatable data with adiabatic efficiencies agreeing within 1 percent. The measured fan adiabatic efficiency at simulated takeoff conditions was 93.7 percent and matched the design intent.

Effects of forward velocity and acoustic treatment on inlet fan noise

Abstract: Flyover and static noise data from several engines are presented that show inlet fan noise measured in flight can be lower than that projected from static tests for some engines. The differences between flight and static measurements appear greatest when the fan fundamental tone due to rotor-stator interaction or to the rotor-alone field is below cutoff. Data from engine and fan tests involving inlet treatment on the walls only are presented that show the attenuation from this treatment is substantially larger than expected from previous theories or flow duct experience. Data showing noise shielding effects due to the location of the engine on the airplane are also presented. These observations suggest that multiringed inlets may not be necessary to achieve the desired noise reduction in many applications.

Development of a Preliminary Weight Estimation Method for Advanced Turbofan Engines

Abstract: The present work focuses on preliminary weight estimation methods that enable the feasibility studies of novel aero engines. The key contributions can be found in the analysis of the existing preliminary weight estimation methods, the development of a new preliminary weight estimation method and the study on the feasibility of a Geared Turbofan (GTF) engine. In more detail, the existing preliminary weight estimation methods are examined in the first part of the thesis, aiming to define their suitability for current turbofan engines, but also for future engine arrangements. For this purpose, they are examined not only quantitatively, to verify their accuracy, but also qualitatively to figure out if they are able to reflect the key thermodynamic and design parameter variations on weight. Apart from NASA WATE no method achieves either the required accuracy, or simulates the weight trends. Realising the need for a more accurate, robust, flexible and extensible method, a new ”component based” method that performs basic component design to estimate engine weight, is devised. Its accuracy is verified by comparing the whole engine weight prediction and estimated component design against the publicly available data of two major turbofan engines and the weight predictions of existing weight estimation methods. ATLAS, the tool based on the above method was used to estimate weight over a range of Bypass Ratio (BPR) and Turbine Entry Temperature (TET) values for a Direct Drive Turbofan (DDTF) and a GTF two spool arrangement, reaching the following conclusions: • The adjustments of Low Pressure Turbine (LPT) number of stages or geometry are not sufficient, if high stage isentropic efficiency values are targeted at high BPR values • For the examined engine model, with the given weight estimation methodology, the weight reduction, when a gearbox is introduced at a DDTF, depends on the reduction of LPT stages, with the other components having negligible impact. However, it should be noted that a constant fan diameter was assumed for both configurations. A fan loss model and more detailed weight estimation of frames, shafts and control and accessories is required to verify this conclusion. • The comparison of a DDTF and a GTF engine is representative only if the cycles corresponding to the installed performance optima are considered.

Aerodynamic design and performance testing of an advanced 30 deg swept, eight bladed propeller at Mach numbers from 0.2 to 0.85

Abstract: The increased emphasis on fuel conservation in the world has stimulated a series of studies of both conventional and unconventional propulsion systems for commercial aircraft. Preliminary results from these studies indicate that a fuel saving of from 15 to 28 percent may be realized by the use of an advanced high speed turboprop. The turboprop must be capable of high efficiency at Mach 0.8 above 10.68 km (35,000 ft) altitude if it is to compete with turbofan powered commercial aircraft. An advanced turboprop concept was wind tunnel tested. The model included such concepts as an aerodynamically integrated propeller/nacelle, blade sweep and power (disk) loadings approximately three times higher than conventional propeller designs. The aerodynamic design for the model is discussed. Test results are presented which indicate propeller net efficiencies near 80 percent were obtained at high disk loadings at Mach 0.8.