Blade pitch

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

Comparison of individual pitch and smart rotor control strategies for load reduction

Abstract: Load reduction is increasingly seen as an essential part of controller and wind turbine design. On large multi-MW wind turbines that experience high levels of wind shear and turbulence across the rotor, individual pitch control and smart rotor control are being considered. While individual pitch control involves adjusting the pitch of each blade individually to reduce the cyclic loadings on the rotor, smart rotor control involves activating control devices distributed along the blades to alter the local aerodynamics of the blades. Here we investigate the effectiveness of using a DQ-axis control and a distributed (independent) control for both individual pitch and trailing edge flap smart rotor control. While load reductions are similar amongst the four strategies across a wide range of variables, including blade root bending moments, yaw bearing and shaft, the pitch actuator requirements vary. The smart rotor pitch actuator has reduced travel, rates, accelerations and power requirements than that of the individual pitch controlled wind turbines. This benefit alone however would be hard to justify the added design complexities of using a smart rotor, which can be seen as an alternative to upgrading the pitch actuator and bearing. In addition, it is found that the independent control strategy is apt at roles that the collective pitch usually targets, such as tower motion and speed control, and it is perhaps here, in supplementing other systems, that the future of the smart rotor lies.

Aeroelastic Considerations For Rotorcraft Primary Control with On-Blade Elevons

Abstract: Replacing the helicopter rotor swashplate and blade pitch control system with on-blade elevon control surfaces for primary flight control may significantly reduce weight and drag to improve mission performance. Simplified analyses are used to examine the basic aeroelastic characteristics of such rotor blades, including pitch and flap dynamic response, elevon reversal, and elevon control effectiveness. The profile power penalty associated with deflections of elevon control surfaces buried within the blade planform is also evaluated. Results suggest that with aeroelastic design for pitch frequencies in the neighborhood of 2/rev, reasonable elevon control effectiveness may be achieved and that, together with collective pitch indexing, the aerodynamic profile power penalty of on-blade control surface deflections may be minimized.

Helicopter with a gyroscopic rotor and rotor propellers to provide vectored thrust

Abstract: A model helicopter creates lift using rotor propellers mounted to the rotor arms of a gyroscopic rotor assembly. A controller converts front-back, and left-right inputs into speed control signals used to vary the speeds of the rotor propellers at selected positions of the rotor assembly as it rotates. The varying speed of the rotor propellers at selected rotor positions produces thrust vectors at those positions. The resultant thrust vector determines the direction of the helicopter's flight and enables it to pitch and roll in response to the front-back and left-right inputs. The rotor assembly can have two or more rotor arms, each with a propeller. The helicopter provides left-right yaw control with a yaw propeller on the helicopter body. Electric motors, or motors using other conventional power and speed control methods, can be used to drive the rotor and yaw propellers. Power and speed control signals can be transferred to the rotor motors via commutators on the helicopter body and rotor assembly that make electrical contact as the rotor assembly rotates.