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.

Cascade reverser without blocker doors

Abstract: A translating cowl composed of two sub-structures forms the thrust reverser for a turbofan engine. The two sub-structures form the rear part of a nacelle, are translatable, and have operative and inoperative modes of operation. The operative mode is used for direct or reverse thrust operation of the engine and the inoperative mode is used for access to the engine.

Convertible aircraft engine

Abstract: A convertible aircraft engine, capable of turboshaft and/or turbofan modes of operation, is provided in a configuration that combines certain components to permit variation in bypass flow to match engine airflows with the mode of engine operation. The provided components permit the engine to decrease the power requirements of the engine's forward fan when the engine is operated in the turboshaft mode. To permit a decrease in fan power requirements, the fan is split into an outer portion and an inner portion separated by a rotating shroud. Airflow into the fan's outer portion is controlled with a part span inlet guide vane and an outlet guide vane. The guide vanes can be used to lessen the load on the outer portion of the fan while the inner portion continues to accelerate and compress a normal airflow into an engine compressor for supplying the engine's core. The power normally used to drive the fan outer portion is used instead to power a transfer shaft in the turboshaft mode.

Military Jet Engine Acquisition: Technology Basics and Cost-Estimating Methodology

Abstract: : Good cost estimates contribute significantly to an effective acquisition policy. RAND has a long history of producing cost-estimating methodologies for military jet engines. Two of RAND's more recent studies of turbine engine costs are Nelson (1977) and Birkler, Garfinkle, and Marks (1982). This report updates those earlier studies by incorporating cost and technical data on recent engine development and production efforts. We analyzed this information and produced a set of parametric relationships to estimate turbofan engine development costs, development schedules, and unit production costs. In this analysis, we have extended and improved upon earlier RAND analyses in two key ways: The previous RAND studies grouped turbojet and turbofan engines into the same population. To provide a more homogeneous population, we focused exclusively on parametric relationships for turbofan engines in this study (because pure turbo-jet engines are largely no longer used in modern aircraft). In the previous studies, it was often not clear how the data from a particular engine family was treated. In our analysis, we treat each model (or "dash number") as a separate observation. We explicitly consider how derivative engines relate to first-of-a-kind engines.

Controlled fan stream flow bypass

Abstract: A turbine engine component of a turbofan engine (10) fitted with a bypass air valve (20) includes at least one turbine engine component having a surface (31) with at least one aperture (37), said turbine engine component located from between a bypass fan duct (32) and a turbine exhaust nozzle (24) of the turbofan engine (10) The bypass air valve (20) includes a liner concentrically disposed about the turbine engine component and parallel to a centerline (30) of the turbofan engine (10) The liner has a surface including at least one aperture (42) and at least one impermeable region (44) Means are provided for actuating the liner about the turbine engine components The flow transfer location (34) comprises an area proximate to a turbine exhaust stream flow (28)