Advanced blade testing methods for wind turbines puneet malhotra university of massachusetts amherst follow this and additional works at: part of themechanical engineering commons this thesis is brought to you for free and open access by [email protected] amherst. Abstract 1 introduction flutter speed predictions for mw-sized wind turbine blades don w lobitz sandia national laboratories albuquerque, new mexico 87185. Turbines operating at high pressure in high velocity flow are susceptible to flutter as reduced frequencies become sufficiently low, negative aerodynamic damping will be found in some modes ensuring that the total system damping is positive over the entire turbine operating envelope for all modes is of utmost importance in any design since flutter in a turbine often causes blade failures. Propulsion, the potential for blade flutter must be eliminated from the turbomachinery stages from both experimental and theoretical studies [5-6], it is found that flutter is caused primarily by the interaction of the turbomachinery blade motion with incoming flow fields. Blades that were translated in an oscillatory manner to model the vibration of turbine blades undergoing ﬂutter the aeroelasticity was modeled in the experiment by rotating the blade about a span-wise pivot, toward the hub of the apparatus the amplitude of the vibration was kept constant, as was the frequency of oscillation.
The thesis named ´fluttering analysis in wind turbine blade´ is worked mainly for the purpose of analyzing the fluttering behavior on blades of wind turbine by analyzing, structural analysis, modal analysis, aeroelastic stability analysis, fsi. The goal of this thesis is to evaluate if ﬂutter is a challenge to a 10 mw wind turbine flutter is an aeroelastic instability which occurs due to the interaction betweentheaerodynamicforcesandtheelasticityoftheblade torsionalmotions of the blade lead to variations in the aerodynamic forces due to changes in the angleofattackoftheairfoil. Blade flutter is the self-excited vibration of blades due to the interaction of structural-dynamic and aerodynamic forces it is a significant problem for the manufacturers of large-scale turbomachinery such as gas turbines, steam turbines and aircraft engines.
Flutter is controlled by the blade’s structure and the relative wind speed (rotational speed and oncoming wind speed) to the best of my knowledge, there have not been any flutter related failures of commercial wind turbines to date.
This is mainly because the conditions that would cause flutter in a turbine are far beyond that of the normal operating conditions, lying somewhere in the range of 2–5 times the normal operating speed of the turbine depending on its size. This paper describes a portion of a research effort to eliminate occurrences of flutter of low pressure turbine blades in aircraft engines fundamental unsteady aerodynamic experiments in an annular cascade plus correlating analyses are conducted to improve the understanding of the flutter mechanism in these blades and to identify the key flutter parameters.
This thesis investigates the feasibility of using friction dampers to control flutter in gas turbine engine rotor stages first, the stabilizing effects of blade-to-ground dampers were studied on the basis of a single degree of freedom model of an isolated blade to simulate aerodynamic instability. The rotor blades of big wind turbines are long and slender, with large forces on theblades thesebladesbendsandtwistduetotheelasticityoftheblades the blade bending aﬀects the aerodynamic forces on the blades by changing the an-gle of attack as a result an aeroelastic instability known as ﬂutter may occur.
Flutter does not exists on the smaller wind turbines due to blade stiffness whereas for large wind turbines critical flutter should be calculated to be minimum couple of times of the operating speed of the wind turbine [3. Flutter analysis blade flutter is the self-excited vibration of blades due to the interaction of structural-dynamic and aerodynamic forces it is a significant problem for the manufacturers of large-scale turbomachinery such as gas turbines, steam turbines and aircraft engines it can lead to dramatic blade loss in the short-term and high-cycle fatigue (hcf) in the long-term. Fluid structure interaction on wind turbine blades master’s thesis in solid and structural mechanics and fluid dynamics characteristics of the turbine blade has been speci ed the output is a nite element method, wind turbines, flutter, aeroelasticity i ii contents abstracti contentsiii.
Szechenyi, e, 1985, “fan blade flutter—single blade instability or blade to blade coupling” asme paper 85-gt-216. Advanced blade testing methods for wind turbines a thesis presented by puneet malhotra submitted to the graduate school of the university of massachusetts amherst in.