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.

System and method for mounting an aircraft engine

Abstract: A mounting system and method capable of reducing backbone deflection in a high-bypass turbofan engine. The system includes a rigid structure and a linkage mechanism having at least first and second links that are each pivotally connected to the rigid structure and adapted to be pivotally connected to an engine support structure of the aircraft. The first and second links are configured to define a focal point thereof at a location that is a distance from a centerline of the engine of not more than 15% of an inlet diameter at an inlet of the engine, and is located aft of a vector of an inlet load to which the engine is subjected when the aircraft is in a climb maneuver. The location of the focal point is such that a moment of a thrust load of the engine and a moment of the inlet load oppose each other, thereby reducing backbone bending of the engine during the climb maneuver.

Aerothermal Investigation of an Intermediate Turbine Duct

Abstract: Intermediate turbine ducts are used to guide the flow in turbofan engines from the short-radius high-pressure turbine to the large-radius low-pressure turbine. The demand for more efficient and silent jet engines and with a reduced environmental impact requires turbofans with increasingly higher by-pass ratios. Intermediate turbine ducts that could provide a greater radial offset in shorter length would contribute greatly to achieving this goal, especially if they maintained low pressure losses and avoided non-uniformities in the outlet flow that might affect the downstream low-pressure turbine. This thesis presents an experimental study of the flowfield and the heat transfer in an aggressive intermediate turbine duct. The goals of this research were to obtain an understanding of the mechanisms governing the heat transfer in intermediate turbine ducts; and as well, to provide detailed high-quality flow and heat transfer experimental data for CFD validation purposes. The experiments were carried out in a state-of-the-art aggressive intermediate turbine duct with structural struts in a large-scale low-speed turbine facility at realistic engine Reynolds numbers and inlet conditions. For the flow measurements, oil-film visualization, static pressure measurements, 5-hole pressure probe and hot-wire anemometry were used. The heat transfer measurements were performed using a technique based on IR-thermography. The experiments were performed for three different turbine operating points in order to evaluate the effect of inlet swirl on the flow and heat transfer in the duct. The results showed that the stationary flow features arising from the upstream turbine had a large effect on both the flowfield and the heat transfer in the duct. The combination of tip leakage flow and structural struts gave rise to a large vortex with changing relative strength for different inlet swirl. This vortex locally dominated the heat transfer in the neighborhood of the suction side of the vane. Also, counter-rotating vortex pairs near the hub created streaks of low and high heat transfer coefficient that varied ±20% on the hub. For a lower inlet swirl angle, flow separation occurred at the corner between the shroud endwall and the strut pressure side due to the mismatch of the strut and flow angles in the tip leakage region. These flow separations created large circumferential variations in the duct outflow, and significantly modified the flowfield and heat transfer on the endwalls where an increase in the heat transfer coefficient of up to 25% was seen. These and other important effects of the flowfield on the heat transfer distributions have been identified. The results provide valuable insights into duct flow phenomena and how they are coupled to the heat transfer. Together they represent a first step towards understanding the heat transfer phenomena in the duct. The results are already being used to improve design methods in industry. Keywords: Intermediate turbine duct, flowfield measurements, heat transfer measurements.

Enhanced Fan Noise Modeling for Turbofan Engines

Abstract: This report describes work performed by MTC Technologies (MTCT) for NASA Glenn Research Center (GRC) under Contract NAS3-00178, Task Order No. 15. MTCT previously developed a first-generation empirical model that correlates the core/combustion noise of four GE engines, the CF6, CF34, CFM56, and GE90 for General Electric (GE) under Contract No. 200-1X-14W53048, in support of GRC Contract NAS3-01135. MTCT has demonstrated in earlier noise modeling efforts that the improvement of predictive modeling is greatly enhanced by an iterative approach, so in support of NASA's Quiet Aircraft Technology Project, GRC sponsored this effort to improve the model. Since the noise data available for correlation are total engine noise spectra, it is total engine noise that must be predicted. Since the scope of this effort was not sufficient to explore fan and turbine noise, the most meaningful comparisons must be restricted to frequencies below the blade passage frequency. Below the blade passage frequency and at relatively high power settings jet noise is expected to be the dominant source, and comparisons are shown that demonstrate the accuracy of the jet noise model recently developed by MTCT for NASA under Contract NAS3-00178, Task Order No. 10. At lower power settings the core noise became most apparent, and these data corrected for the contribution of jet noise were then used to establish the characteristics of core noise. There is clearly more than one spectral range where core noise is evident, so the spectral approach developed by von Glahn and Krejsa in 1982 wherein four spectral regions overlap, was used in the GE effort. Further analysis indicates that the two higher frequency components, which are often somewhat masked by turbomachinery noise, can be treated as one component, and it is on that basis that the current model is formulated. The frequency scaling relationships are improved and are now based on combustor and core nozzle geometries. In conjunction with the Task Order No. 10 jet noise model, this core noise model is shown to provide statistical accuracy comparable to the jet noise model for frequencies below blade passage. This model is incorporated in the NASA FOOTPR code and a user s guide is provided.

System Noise Assessment of Blended-Wing-Body Aircraft with Open Rotor Propulsion

Abstract: An aircraft system noise study is presented for the hybrid wing–body aircraft concept with open-rotor engines mounted on the upper surface of the airframe. The aircraft chosen for the study is of a size comparable to the Boeing 787 aircraft. It is shown that, for such a hybrid wing–body aircraft, the cumulative effective perceived noise level is about 24 dB below the current aircraft noise regulations of stage 4. Although this makes the design acoustically viable in meeting the regulatory requirements, even with the consideration of more stringent noise regulations in the next decade or so, the design will likely meet stiff competition from aircraft with turbofan engines. The noise levels of the hybrid wing–body design are held up by the inherently high noise levels of the open-rotor engines and the limitation on the shielding benefit due to the practical design constraint on the engine location. Furthermore, it is shown that the hybrid wing–body design has high levels of noise from the main landing gear,...

Fan cowl support for a turbofan engine

Abstract: A fan cowl support for an aircraft having an engine pylon, an engine fan case and an engine fan cowl. The fan cowl support includes a support having a forward end connected to the engine fan case and an aft end connected to the engine pylon. At least a portion of the engine fan cowl is connected to the support.