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Diagram of a fan disk Fan disk assembly diagram, showing one blade and attachment hardware Cross section of fan disk Failed fan disk recovered from the center engine of UAL 232. A fan disk is the central hub of a fan in a turbofan engine. Fan blades are attached to the fan disk, which is rotated by a shaft driven by a gas turbine. [1]
A rotor blade produces more lift in the advancing half. As a blade moves toward the direction of flight, the forward motion of the aircraft increases the speed of the air flowing around the blade until it reaches a maximum when the blade is perpendicular to the relative wind. At the same time, a rotor blade in the retreating half produces less ...
Figure 1: Components of a centrifugal fan An external motor belt driven inline centrifugal fan discharging inline to the exterior of a building through a duct. Unlike non-inline/non-concentric impeller casing design with a cutoff blade above, the concentrically symetric cylinder casing and impeller geometry of inline type redirects the outflow around so that it is parallel to the inflow of gases.
A fan is a propeller with a large number of blades. A fan therefore produces a lot of thrust for a given diameter but the closeness of the blades means that each strongly affects the flow around the others. If the flow is supersonic, this interference can be beneficial if the flow can be compressed through a series of shock waves rather than one.
High-pressure gases such as steam can drive a small turbine, and high-pressure liquids can drive a pelton wheel, either of which can provide the rotational drive for a fan. Large, slow-moving energy sources, such as a flowing river, can also power a fan using a water wheel and a series of step-down gears or pulleys to increase the rotational ...
The NK-110, which was tested in the late 1980s, had a contra-rotating propeller configuration with four blades in front and four in back, like the NK-12. Its 190-inch propeller diameter (4.7-metre) was smaller than the NK-12's 220–240 in (5.6–6.2 m) diameter, but it produced a power output of 21,007 hp (15,665 kW), delivering a takeoff ...
Vaneaxial fans – These axial flow fans have a higher pressure capability due to the presence of static vanes. Variable pitch axial fans – The blades on these axial fans are manually adjustable to permit the blade angle to be changed. This allows operation over a much wider range of volume/pressure relationships.
Sikorsky's earliest attempt at a fast compound helicopter with stiff coaxial rotors was the Sikorsky S-69 (XH-59A) flown in the 1970s. Its top speed was over 260 knots but its excessive fuel consumption, vibration and complexity requiring the full-time attention of two pilots led to the program's cancellation. [5]