Topic
Rotational speed
About: Rotational speed is a research topic. Over the lifetime, 23327 publications have been published within this topic receiving 151696 citations. The topic is also known as: speed of revolution & revolution rate.
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Patent•
07 Jul 2009TL;DR: In this paper, a method for controlling the tip speed of a wind turbine blade was proposed, which includes determining the wind speed proximate the wind turbine, maintaining a first substantially constant rotational speed of the tip of the blade during variable wind speeds above a first predetermined nominal wind speed and below the second predetermined nominal speed.
Abstract: A method for controlling a tip speed of a blade of a wind turbine. The method includes determining the wind speed proximate the wind turbine; maintaining a first substantially constant rotational speed of the tip of the blade during variable wind speeds above a first predetermined nominal wind speed and below the second predetermined nominal wind speed; maintaining a second substantially constant rotational speed of the tip of the blade during variable wind speeds above a second predetermined nominal wind speed. The noise generated by wind at the second predetermined nominal wind speed is greater than noise generated by the blade at the second constant rotational speed of the tip of the blade.
38 citations
TL;DR: In this paper, the authors studied the effect of different blade rotational speeds on the formation and evolution of flow patterns in a vertical cylindrical mixer with two opposed flat blades with a 45° rake angle.
38 citations
TL;DR: In this paper, a thin-walled rotating pipe reinforced with functionally graded carbon nanotubes is modeled based on thinwalled Timoshenko beam theory and reinforced by singlewalled carbon nanotsubes with uniform distribution as well as three types of functionally graded distribution patterns.
Abstract: In this study, vibration and dynamic stability of fluid-conveying thin-walled rotating pipes reinforced with functionally graded carbon nanotubes are studied. The pipe is modeled based on thin-walled Timoshenko beam theory and reinforced by single-walled carbon nanotubes with uniform distribution as well as three types of functionally graded distribution patterns. The governing equations of motion and the associated boundary conditions are derived via Hamilton’s principle. The governing equations of motion are discretized via the Galerkin method, and the eigenfrequency and the stability region of the pipe are found using the eigenvalue analysis. Some numerical examples are presented to study the effects of length–radius ratio, carbon nanotubes distribution, volume fraction of carbon nanotubes, rotational speed and mass ratio on the non-dimensional eigenfrequency and critical flutter velocity of the thin-walled rotating pipe conveying fluid. The results show that the carbon nanotubes distribution has a significant effect on the non-dimensional eigenfrequency and critical flutter velocity. Also, it is found that the rotational speed has a stabilizing effect on the dynamic behavior of the system.
38 citations
Patent•
05 Jan 2012
TL;DR: In this article, an appliance for drying laundry (100) including a drying-air moisture-condensing system comprising a heat pump system (215,220,225) with a variable-output compressor (210), and at least one drying air variable-speed fan (250) for promoting the recirculation of the drying air, the appliance being adapted to perform at least a laundry drying cycle in: at least first drying mode wherein the compressor is driven to a first compressor mode having a compressor power consumption course and/or a compressor rotational speed course and or a frequency course of
Abstract: An appliance for drying laundry (100) including a drying-air moisture-condensing system comprising a heat pump system (215,220,225) with a variable-output compressor (210), and at least one drying air variable-speed fan (250) for promoting the recirculation of the drying air, the appliance being adapted to perform at least one laundry drying cycle in: at least a first drying mode wherein the compressor is driven to a first compressor mode having a compressor power consumption course and/or a compressor rotational speed course and/or a frequency course of the supply current/voltage of the compressor motor and the fan is driven to a first fan mode having a speed course, and at least a second drying mode wherein the compressor is driven to a second compressor mode comprising a compressor power consumption course and/or a compressor rotational speed course and/or a frequency course of the supply current/voltage of the compressor motor and the fan is driven to a second fan mode having a speed course, wherein for at least a portion of the drying cycle, a compressor power consumption and/or a compressor rotational speed and/or a frequency of the supply current/voltage of the compressor of the second compressor mode is/are higher than the one/s of the first compressor mode and the speed of the second fan mode is higher than the speed of the first fan mode.
38 citations
15 Jun 2004
TL;DR: Adapt optimal fuzzy system for rotational speed control is proposed by using the algorithm of the nearest-neighbour clustering learning to synthesize both mechanical and electrical dynamics of wind energy conversion system.
Abstract: Automatic control is crucial to the efficiency and reliability of wind power generation systems. Variable speed fixed pitch wind turbines have strong nonlinear and unstable characteristics with many uncertain factors and disturbances at large wind speed ranges. Based on the motion equation of the generator and wind turbine, adaptive optimal fuzzy system for rotational speed control is proposed by using the algorithm of the nearest-neighbour clustering learning. This algorithm synthesizes both mechanical and electrical dynamics of wind energy conversion system. System identification is a part of the controller. The rotational speed reference is determined by estimated aerodynamic torque using Kalman filter. The method avoids the inaccuracy of measuring the wind speed. Simulation results verify the effectiveness of the proposed control methods.
38 citations