Blade pitch

About: Blade pitch is a research topic. Over the lifetime, 5321 publications have been published within this topic receiving 63134 citations.

Wind tunnel performance results of swirl recovery vanes as tested with an advanced high speed propeller

Abstract: Tests of swirl recovery vanes designed for use in conjunction with advanced high speed propellers were carried out at the NASA Lewis Research Center. The eight bladed 62.23 cm vanes were tested with a 62.23 cm SR = 7A high speed propeller in the NASA Lewis 2.44 x 1.83 m Supersonic Wind Tunnel for a Mach number range of 0.60 to 0.80. At the design operating condition for cruise of Mach 0.80 at an advance ratio of 3.26, the vane contribution to the total efficiency approached 2 percent. At lower off-design Mach numbers, the vane efficiency is even higher, approaching 4.5 percent for the Mach 0.60 condition. Use of the swirl recovery vanes essentially shifts the peak of the high speed propeller efficiency to a higher operating speed. This allows a greater degree of freedom in the selection of rpm over a wider operating range. Another unique result of the swirl recovery vane configuration is their essentially constant torque split between the propeller and the swirl vanes over a wide range of operating conditions for the design vane angle.

Helicopter type vehicle

Abstract: The invention discloses a helicopter type vehicle having coaxial counter rotating propellers above the cabin of the vehicle, each propeller being fixed in pitch as opposed to conventional helicopter propellers which vary in pitch during rotation of the propeller. The counter rotating propellers provide lift for lifting the vehicle from the surface, and forward thrust on the vehicle is developed by shifting the center of gravity of the vehicle to tilt the axis of rotation of the propellers with the shifting of the center of gravity of the vehicle being accomplished in at least one instance, by mounting the propeller drive motors adjacent the respective propellers and rotating the motors bodily about the axis of rotation of the propellers.

Systems and methods for testing a wind turbine pitch control system

Abstract: Certain embodiments of the invention may include systems and methods for testing a wind turbine pitch control system (200). According to an exemplary embodiment of the invention, a method for testing a wind turbine pitch control system is provided. The method can include measuring tangential acceleration (At) (114) of a wind turbine rotor (102), determining pitch angle of one or more turbine blades (104, 106, 108), and predicting torque applied to the one or more turbine blades (104, 106, 108) based at least in part on the tangential acceleration (At) (114) and the pitch angle.

Variable pitch turbofan engine

Abstract: A turbofan engine is provided with an actuator for varying the fan pitch angle by rotating individual fan blades within apertures in an associated fan disc. The actuator includes a shaft, a sleeve circumscribing the shaft, and a casing receiving both the shaft and the sleeve. Means between the casing and the blade shank rotate the blade (to change its pitch) in response to relative rotation between the casing and the shaft. In order to lock the fan blades in selected pitches between pitch changes, a pitch lock is provided which utilizes a locking piston and a thrust collar cooperating respectively with the casing and the shaft and incorporating interlocking releasable teeth. The locking piston is biased by spring means into a locking relationship with the thrust collar so that if pressure is lost in a main actuating cylinder (within which both the locking piston and an actuator piston are disposed), a fail-safe pitch locked status is assumed by the fan. In order to sense the pitch angle, means are provided for reading the axial position of the actuator piston and, hence, the pitch angle of the fan at any given instant.