Showing papers on "Tip-speed ratio published in 1996"
TL;DR: In this article, the behavior of a wind power system equipped with a continuously variable transmission (c.v.t) was examined in turbulent wind conditions using a dynamic model, and the simulation results showed that, when the actual wind speed fluctuations are taken into account, incorporating a V-belt transmission between the turbine and the electric generator yields greater advantages in terms of energy output than it does when the system is assessed in the steady-state.
41 citations
01 Jan 1996
TL;DR: In this article, a simple numerical approach is taken to model the flow around a meteorology mast, which gives an almost two-dimensional flow round a cross-section at a certain height above the ground.
Abstract: In order to measure the efficiency of a wind turbine the non-dimensional power coefficient C{sub p} is measured as a function of the tip speed ratio. The power is non-dimensionalized with respect to the density, the swept area by the rotor and the third power of the wind speed. Since C{sub p} depends on the third power of the wind speed it is very important to measure the wind speed accurately. The wind speed is usually measured by a cup anemometer mounted on a rod which is mounted on a meteorology mast. The mast will often be a lattice construction consisting of three main beams shored up by smaller beams. The mast is a long slender construction, which gives an almost two-dimensional flow round a cross-section at a certain height above the ground. The cylindrical beams will give a local distortion of the wind speed in the vicinity of the mast. If the rod, on which the cup anemometer is mounted, is to short one will measure a wrong wind speed and thus a wrong power coefficient C{sub p}. To the authors knowledge only Cermak and Horn (1968) and Gill et al. (1967) approached the problem experimentally by wind tunnelmore » measurements on scale models. In this paper a simple numerical approach is taken to model the flow around the mast.« less
21 citations
TL;DR: In this article, a double fed induction generator with two pair of poles (DFTPPIG) was combined with a windmill such that it works only at one power characteristic with the optimum value of tip speed ratio (TSR).
5 citations
TL;DR: In this paper, a two-bladed WTGS with a horizontal axis rotor was evaluated to have rather poor performance in terms of annual output due to the deficiencies in aerodynamic design of blade and its high noise emission level which restricts the time range of operation.
4 citations
Patent•
15 Oct 1996
TL;DR: In this paper, the prohibited overspeed limit of a helicopter through the application of at least pressure altitude, outside air temperature, a rotor speed, total take-off weight, a fuel flow rate, transmission torque or the like was computed.
Abstract: PURPOSE: To reduce a pilot's burden and provide a highly reliable value by computing the prohibited overspeed limit of a helicopter through the application of at least pressure altitude, outside air temperature, a rotor speed, total take-off weight, a fuel flow rate, transmission torque or the like. CONSTITUTION: A computing section 15 calculates a coefficient of thrust (CT/σ) on the basis of a rotor tip speed Vt, a body weight W and air density ρ. In addition, a reference table part 16 similarly outputs the limit value μ ne of a tip speed ratio ρ. Also, a multiplication section 17 multiplied the value of μne by the rotor tip speed Vt for outputting a limit speed V2. Also, another computing section 18 calculates an acoustic velocity Vs, based on outside temperature TP, and multiplied the velocity Vs by the Mach number M, using a multiplier of 19. On the other hand, respective values of torque T1 and T2 are compared with threshold values of L1 and L2 in each comparison section 20. Binary signals B and B2 are, then, outputted and entered in a judgement section 22. Thereafter, a total judgement section 23 outputs the minimum values of limit speeds V2, V3 and V3 as the prohibited overspeed VNE of a helicopter.
2 citations