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Blade pitch

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


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01 Jun 1961
TL;DR: In this article, an adaptation of the vortex lattice method developed for wings of arbitrary shape was developed to determine pitch and camber corrections for marine propellers with arbitrary blade outline and radial load distribution.
Abstract: : Methods are developed to determine pitch and camber corrections for marine propellers with arbitrary blade outline and radial load distribution. The pitch and camber is determined by the requirement that the desired load distribution be obtained with the sections operating at their ideal angle of attack. The method may be used both for homogeneous-flow and wake-adapted propellers. The method is an adaptation of the vortex lattice method developed for wings of arbitrary shape. By replacing the continuous vortex distribution by a lattice of discrete vortex elements, the singular integral equation occurring in lifting surface theory is replaced by a set of linear algebraic equations. From the form of these equations, it is shown that a propeller with symmetrical blades and with mean lines which are symmetrical about the mid-chord has no pitch correction due to lifting surface effect.

24 citations

01 Jan 1986
TL;DR: In this article, a higher harmonic control (HHC) system superimposes fourth harmonic inputs upon the stationary swashplate, which results in modified blade loads and reduced fuselage vibrations.
Abstract: The design, implementation, and flight test results of higher harmonic blade feathering for vibration reduction on the OH-6A helicopter are described. The higher harmonic control (HHC) system superimposes fourth harmonic inputs upon the stationary swashplate. These inputs are transformed into 3P, 4P and 5P blade feathering angles. This results in modified blade loads and reduced fuselage vibrations. The primary elements of this adaptive vibration suppression system are: (1) acceleration transducers sensing the vibratory response of the fuselage; (2) a higher harmonic blade pitch actuator system; (3) a flightworthy microcomputer, incorporating the algorithm for reducing vibrations, and (4) a signal conditioning system, interfacing between the sensors, the microcomputer and the HHC actuators. The program consisted of three distinct phases. First, the HHC system was designed and implemented on the MDHC OH-6A helicopter. Then, the open loop, or manual controlled, flight tests were performed, and finally, the closed loop adaptive control system was tested. In 1983, one portion of the closed loop testing was performed, and in 1984, additional closed loop tests were conducted with improved software. With the HHC system engaged, the 4P pilot seat vibration levels were significantly lower than the baseline ON-6A levels. Moreover, the system did not adversely affect blade loads or helicopter performance. In conclusion, this successful proof of concept project demonstrated HHC to be a viable vibration suppression mechanism.

23 citations

Journal ArticleDOI
TL;DR: In this article, the adaptive neuro fuzzy inference system (ANFIS) was used for variable selection in order to detect the predominant variables affecting the converted wind energy and then it was used to determine how four parameters, blade pitch angle, rotor speed, wind speed and rotor radius, affect the wind turbine power coefficient.

23 citations

Journal ArticleDOI
TL;DR: In this paper, a folding actuation mechanism with servo motor and worm-gear reducer was designed for wind turbine rotor control and a servo system with double feedback loops for blade fold angle control was proposed.

23 citations

Patent
Donald K Ferris1
04 Oct 1954

23 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202377
2022163
202184
2020110
2019105
2018109