Blade pitch

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

Variable-twist rotor blade controlled by hub pitch angle and rotational speed

Abstract: The twist distribution of torsionally-flexible rotor blades is adjusted by exploiting centrifugal effect on inertial torquers affixed at one or more stations along the blade span. Twist is thereby made to vary passively as a function of rotor speed and hub incidence angle. With inertias of appropriate size and location, the twist variation is such that high rotor efficiency is maintained over a wide range of operating conditions. Satisfactory dynamic behavior of the blade, including cyclic-pitch response and flutter resistance, is simultaneously achieved.

Electric air-driven helicopter

Abstract: A helicopter has a low profile electric motor mounted in each of the rotor blades to drive a cross-flow fan which draws air in through a slot at the leading edge of the blade and forces it out through an opposing slot adjacent the trailing edge of the blade to provide the thrust for rotating the rotor blade. An engine is located in the fuselage of the helicopter for driving an electric generator to produce the electricity supplied to the motors mounted in the blades. In addition, yaw control is achieved without the necessity of tail structure or a tail rotor using a small electric motor driving or absorbing power from the main rotor shaft. Both the yaw control motor and the main rotor shaft tilt together as a rigid unit. Pitch and roll control is achieved without the necessity of aerodynamic surfaces by movement of the main rotor support mast about a gimbal bearing support located above the center of gravity of the helicopter.

Power Input of High-Speed Rotary Impellers

Abstract: This paper presents the results of an experimental investigation of the power input of pitched blade impellers and standard Rushton turbine impellers in a cylindrical vessel provided with four radial baffles at its wall under a turbulent regime of flow of an agitated liquid. The influence of the geometry of the pitched blade impellers (pitch angle, number of blades) and the off-bottom impeller clearance of both high-speed impellers tested on the impeller power input is determined in two sizes of the cylindrical vessel (0.3 m and 0.8 m diameter of vessel). A strain gauge torquemeter is used in the small vessel and a phase shift mechanical torquemeter is used in the large vessel. All results of the experiments correspond to the condition that the Reynolds number modified for the impeller exceeds ten thousand. The results of this study show that the significant influence of the separating disk thickness of the turbine impeller corresponds fairly well to the empirical equations presented in the literature. Both the influence of the number of impeller blades and the blade pitch angle of the pitched blade impeller were expressed quantitatively by means of the power dependence of the recently published correlations: the higher the pitch angle and the number of blades, the higher the values of the impeller power input. Finally, it follows from results of this study that the impeller off-bottom clearance has a weak influence on the power input of the Rushton turbine impeller, but with decreasing impeller off-bottom clearance the power input of the pitched blade impeller increases significantly.

Rotor blade for a wind turbine, method and manufacturing mold for the production thereof

Abstract: A rotor blade and a method and a manufacturing mold for the production of a rotor blade for a wind turbine, which extends longitudinally in the operational state from a blade root area to the connection to a rotor hub of the wind turbine and which is divided into at least two segments for its production, wherein at least one subdivision is provided approximately transverse to its longitudinal extension between the blade root area and the blade tip. The method facilitates and shortens the production of the rotor blade, in particular for a series production and to still provide the completed rotor blade as a familiar uniform rotor blade. In the method, the at least two segments, preferably after they have been at least partially produced or partially produced mainly parallel in time, are interconnected in an integration device.