Blade pitch

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

Iterative Lifting Surface Method for Thick Bladed Hovering Helicopter Rotors

Abstract: A prescribed-wake, inviscid, incompressible, lifting-surface method using vortex sheets to define the upper and lower blade surfaces is developed to predict the pressure distribution on helicopter blades in hover. Starting with an approximate upper and lower surface vortex sheet strength distribution obtained by using a liftingline/blade-element method, the final strength distribution is computed iteratively by applying the Biot-Savart law. The convergence rate is rapid and reasonably good results can be obtained within three iterations. The method is used to compute the blade pressure distribution in hover for a single-bladed, teetering model helicopter rotor with negligible blade coning. The constant-chord, untwisted blade has a body of revolution tip and is structurally rigid. The results show good agreement with experimental data except very near the blade tip in the trailing-edge region of the upper surface where the effects of the formation of the tip vortex predominate. At spanwise stations inboard of the maximum blade bound circulation, the iterative procedure produces only small changes in the initial two-dimensional blade-element pressure distributions.

Non-co-axial multi-rotor aircraft and attitude control method thereof

Abstract: The present invention relates to a non-co-axial multi-rotor aircraft, which comprises an aircraft body, a power system, a transmission system, a flying control system, and 2N rotor components, wherein N is more than or equal to 2, the power system drives the rotor component to rotate through the transmission system, the flying control system controls the power system to work, every rotor component comprises a rotor and a blade pitch driving mechanism for changing a rotor blade pitch, the flying control system is provided for controlling works of every blade pitch driving mechanism, the transmission system comprises N forward direction transmission mechanisms and N reverse direction transmission mechanisms, the forward direction transmission mechanisms and the reverse direction transmission mechanisms are sequentially and staggedly distributed, and the power system drives the rotors of the N rotor components to rotate along the same direction through the N forward direction transmission mechanisms. With the present invention, technical problems of single driving manner, low aircraft load, short flying time and the like due to application of rotor rotation speed changing to control an aircraft attitude by the existing multi-rotor aircraft are solved.

Turbo engine with propeller(s) for an aircraft with a system for changing the pitch of the propeller

Abstract: A turbo engine includes a system for changing a pitch of blades of a propeller, the system including an annular fluid cylinder with a linear drive and a link mechanism linking the cylinder to the blades of the propeller to change an orientation of the propeller. The annular cylinder of the system can be rigidly mounted on a fixed housing supporting the propeller and internal to it, unlike the blades mounted in an external rotating hub of the propeller, and the link mechanism includes a displacement transfer bearing fixed, on one side, to the mobile part of the cylinder and cooperating, on the other side, with a mechanism linking to the blades of the rotating hub of the propeller.

Friction torque of wind-turbine pitch bearings – comparison of experimental results with available models

Abstract: . Pitch bearings of wind turbines are large, grease-lubricated rolling bearings that connect the rotor blades with the rotor hub. They are used to turn the rotor blades to control the power output and/or structural loads of the turbine. Common actuators turning the blades are hydraulic cylinders or electrical motor–gearbox combinations. In order to design pitch actuator systems that are able to turn the blades reliably without imposing an excessive power demand, it is necessary to predict the friction torque of pitch bearings for different operating conditions. In this paper, the results of torque measurements under load are presented and compared to results obtained using different calculation models. The results of this comparison indicate the various sources of friction that should be taken into account for a reliable calculation model.

Load-receiving arrangement for wind turbine wings

Abstract: The invention relates to a rotor blade (10) of a wind power plant, comprising a rotor blade connection that is joined to a rotor hub (12) of a wind power plant, and a rotor blade tip (13) located at the opposite end of the rotor blade (10). In order to create a rotor blade (10) in which a deflection can be detected with simple means, at least one electrical conductor (20, 21, 22, 23, 24, 26) that begins at the rotor blade connection and extends in the longitudinal direction of the rotor blade and back to the rotor blade connection is laid across the entire length of the rotor blade (10) while a detector (16) which detects the electrical resistance of the conductor (20, 21, 22, 23, 24, 26) is connected to a device evaluating said electrical resistance. The invention is based on the recognition that any deflection of the rotor blade results in the support structure being extended and that said extension modifies the electrical resistance of an electrical conductor when transferred thereto. The degree of deflection of the rotor blade can be inferred from the modification of the electrical resistance because said modification is proportionate to the extension of the conductor, which is proportionate to the deflection of the rotor blade.