Blade pitch

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

Adaptive Pitch Control of Variable-Speed Wind Turbines

Abstract: The aerodynamic efficiency of a variable-speed wind turbine operating in Region 2, or below-rated wind speeds, is greatly affected by the identification of accurate parameters for the controller. In particular, the power coefficient (Cp) surface must be well known for optimal efficiency to be achieved with a constant-gain controller. However, adaptive control can overcome the inefficiencies caused by inaccurate knowledge of the Cp surface. Previous work focused on adaptive torque gain control to cause a variable-speed turbine to operate, on average, at the tip-speed ratio λ* for which the maximum Cp occurs. This paper considers the effects of adaptive blade pitch angle control on a turbine’s aerodynamic efficiency. Computer simulations and tests on a field turbine are used to verify the adaptive pitch control scheme. Simulation and field test results demonstrate that the adaptive pitch controller causes the pitch angle to approach its optimal value. Adaptive pitch control can be used to seek the optimal pitch angle for energy capture in Region 2 operation. Additional field operation is required before a statistically significant improvement in energy capture can be demonstrated.

Dynamics of high-bypass-engine thrust reversal using a variable-pitch fan

Abstract: The test program demonstrated that successful and rapid forward-to reverse-thrust transients can be performed without any significant engine operational limitations for fan blade pitch changes through either feather pitch or flat pitch. For through-feather-pitch operation with a flight inlet, fan stall problems were encountered, and a fan blade overshoot technique was used to establish reverse thrust.

Tonal and Broadband Noise Calculations for Aeroacoustic Optimization of a Pusher Propeller

Abstract: A multidisciplinary analysis and optimization is carried out for a propeller in a real pusher aircraft configuration with the goal of reducing the radiated noise power levels, while preserving the aerodynamic efficiency. The optimization process involves the shape of the blade and the position of the engine exhaust ducts. A coupling of the unsteady aerodynamic and structural-dynamic blade models provides the aeroelastic propeller model that drives a tonal and broadband aeroacoustic prediction. The tonal noise results from the periodic flow unsteadiness due to the nonaxial flight and to the impingement of the engine exhausts on the propeller disk. The broadband noise is mainly due to the interaction between the blade leading edge and the exhaust turbulence. It is shown that the tonal noise overwhelmsthebroadbandnoiseandthattheoptimizationaffectstheshapeofthebladeatthetipandinthespanwise segment hit by the exhausts. An overall sound pressure level reduction of 3.5 dB is achieved at the takeoff condition, while preserving the design propeller thrust and resulting in a small penalty on the propeller efficiency in cruise.

Aircraft propeller speed control

Abstract: The invention concerns a control for an aircraft propeller. During operation in reverse pitch, as occurs upon thrust reversal during a landing maneuver, the speed of the propeller is controlled by adjusting pitch of the propeller, in order to prevent overspeeding. Further, during the transition period while the propeller is converting from forward pitch to reverse pitch, the propeller presents a light load to the engine. At this time, fuel flow to the engine is limited in order to restrict delivery of energy to the propeller, again, for the purpose of preventing overspeeding.