Topic
Blade pitch
About: Blade pitch is a research topic. Over the lifetime, 5321 publications have been published within this topic receiving 63134 citations.
Papers published on a yearly basis
Papers
More filters
Patent•
17 Sep 1984
TL;DR: In this paper, the authors present a system for adjusting the pitch of the blades of a helicopter's rotor blades by drawing precise positioning feedback signals of a feedback device mounted stationary on the fuselage.
Abstract: Mecanisme de commande et de positionnement des pales d'un helicoptere comportant un arbre de rotor creux (14) pour monter une pluralite de pales de rotor (22) tout en permettant le reglage du pas. control mechanism and positioning the blades of a helicopter having a hollow rotor shaft (14) for mounting a plurality of rotor blades (22) while allowing the pitch adjustment. Un arbre de commande (28) est dispose a l'interieur de l'arbre du rotor, il peut tourner par rapport a celui-ci et est associe a des verins (20) pour les pales, si bien que le pas des pales est modifie lorsque l'arbre de commande tourne par rapport a l'arbre du rotor. A control shaft (28) is disposed inside the rotor shaft, it can rotate relative thereto and is associated with the jacks (20) for the blades so that the pitch of the blades is modified when the control shaft rotates relative to the rotor shaft. Un montage d'engrenage planetaire (44) relie l'arbre de commande a une source d'energie fixee au fuselage de l'helicoptere (10) et, lorsque une entree du montage d'engrenage planetaire est au repos, l'arbre de commande tourne dans la meme direction et a la meme vitesse que l'arbre du rotor afin de maintenir un pas desire. A planetary gear assembly (44) connects the drive shaft to a power source attached to the fuselage of the helicopter (10) and, when an input of the planetary gear assembly is at rest, the shaft command rotates in the same direction and at the same speed as the rotor shaft to maintain a desired pitch. Reciproquement, lorsqu'une entree est placee sur le systeme d'engrenage planetaire, il se produit une rotation relative entre l'arbre de commande et l'arbre du rotor afin de permettre le reglage desire du pas des pales. Conversely, when an entry is placed on the planetary gear system, there occurs a relative rotation between the drive shaft and the rotor shaft to permit the desired adjustment of blade pitch. Le systeme permet de tirer des signaux de retour de positionnement precis des pales d'un dispositif de retour monte de maniere stationnaire sur le fuselage. The system allows to draw precise positioning feedback signals of the blades of a feedback device mounted stationary on the fuselage.
29 citations
Patent•
20 Mar 196829 citations
TL;DR: In this paper, the authors developed a mathematical model of a horizontal axis wind turbine with flexible tower and blades, and examined the effects of pitch angle and blade orientation on the natural frequencies and mode shapes of the wind turbine.
Abstract: In this paper, we develop a mathematical model of a horizontal axis wind turbine (HAWT) with flexible tower and blades. The model describes the flapping flexures of the tower and blades, and takes into account the nacelle pitch angle and structural damping. The eigenvalue problem is solved both analytically and numerically using the differential quadrature method (DQM). The closed-form and numerical solutions are compared, and the precision of the DQM-estimated solution with a low number of grid points is concluded. Next, we examine the effects of pitch angle and blade orientation on the natural frequencies and mode shapes of the wind turbine. We find that these parameters do not incur apparent alteration of the natural frequencies. Then, we examine the linear dynamics of the wind turbine subjected to persistent excitations applied to the tower. We investigate the effects of the pitch angle and blade orientation on the linear vibrations of the wind turbine. We demonstrate that the time response of the cou...
29 citations
Patent•
20 Mar 1989
TL;DR: In this article, a dual counterrotating propeller drive mechanism for a marine propulsion system incorporates a torque splitting device which consists of a differential gear means and a ratio gear means, assigning a selectable fixed fraction of the engine torque to each propeller regardless of power, thrust, and speed conditions.
Abstract: A dual counterrotating propeller drive mechanism for a marine propulsion system incorporates a torque splitting device which consists of a differential gear means and a ratio gear means. The torque splitting device assigns a selectable fixed fraction of the engine torque to each propeller regardless of power, thrust, and speed conditions. The rear one of the two propellers adjusts its rotational speed relative to the front propeller in response to changes in the front propeller's wake and in this way maintains optimum propulsive efficiency over a wide range of operating conditions. Furthermore, precise matching of front and rear propeller parameters for a given application is no longer required.
29 citations
Patent•
28 May 2008TL;DR: A pitch bearing for a wind turbine rotor comprises a rotor hub and at least one rotor blade, the pitch bearing comprising a cylindrical inner bearing ring connectable to a rotor blade of the wind turbines rotor, and an annular reinforcement section for reinforcing the outer bearing ring as mentioned in this paper.
Abstract: A pitch bearing for a wind turbine rotor comprises a rotor hub and at least one rotor blade, the pitch bearing comprising a cylindrical inner bearing ring connectable to a rotor blade of the wind turbine rotor, a cylindrical outer bearing ring connectable to the rotor hub of the wind turbine rotor and an annular reinforcement section for reinforcing the outer bearing ring. The annular reinforcement section adjoins the cylindrical outer bearing ring at its radial outer surface.
29 citations