Turbine blade

About: Turbine blade is a research topic. Over the lifetime, 26920 publications have been published within this topic receiving 292855 citations.

Aerodynamic characteristics of seven symmetrical airfoil sections through 180-degree angle of attack for use in aerodynamic analysis of vertical axis wind turbines

Abstract: When work began on the Darrieus vertical axis wind turbine (VAWT) program at Sandia National Laboratories, it was recognized that there was a paucity of symmetrical airfoil data needed to describe the aerodynamics of turbine blades. Curved-bladed Darrieus turbines operate at local Reynolds numbers (Re) and angles of attack (..cap alpha..) seldom encountered in aeronautical applications. This report describes (1) a wind tunnel test series conducted at moderate values of Re in which 0 less than or equal to ..cap alpha.. less than or equal to 180/sup 0/ force and moment data were obtained for four symmetrical blade-candidate airfoil sections (NACA-0009, -0012, -0012H, and -0015), and (2) how an airfoil property synthesizer code can be used to extend the measured properties to arbitrary values of Re (10/sup 4/ less than or equal to Re less than or equal to 10/sup 7/) and to certain other section profiles (NACA-0018, -0021, -0025).

The Natural Excitation Technique (NExT) for modal parameter extraction from operating wind turbines

Abstract: The Natural Excitation Technique (NExT) is a method of modal testing that allows structures to be tested in their ambient environments This report is a compilation of developments and results since 1990, and contains a new theoretical derivation of NExT, as well as a verification using analytically generated data In addition, we compare results from NExT with conventional modal testing for a parked, vertical-axis wind turbine, and, for a rotating turbine, NExT is used to calculate the model parameters as functions of the rotation speed, since substantial damping is derived from the aeroelastic interactions during operation Finally, we compare experimental results calculated using NExT with analytical predictions of damping using aeroelastic theory

Progress in coatings for gas turbine airfoils

Abstract: The development of ever more efficient gas turbines has always been paced by the results of research and development in the concurrent fields of design and materials technology. Improved structural design and airfoil cooling technology applied to higher strength-at-temperature alloys cast by increasingly complex methods, and coated with steadily improved coating systems, have led to remarkably efficient turbine engines for aircraft propulsion and power generation. For first stage turbine blades, nickel-based superalloys in various wrought and cast forms, and augmented by coatings since the 1960s, have been singularly successful materials systems for the past 50 years—and still no real world substitutes are on the horizon. This paper traces the history of protective coatings for superalloy airfoils beginning with the simple aluminides, followed by modifications with silicon, chromium and platinum, then MCrAlY overlay coatings, and finally the elegant electron beam vapor deposited ceramic thermal barrier coatings recently introduced to service. The publicly available results of several decades of research supporting these advances are highlighted. These include generic research on oxidation and hot corrosion mechanisms of superalloys and coatings, the intricacies of protective oxide adherence, mechanisms of low temperature (Type II) hot corrosion, and of aluminide coating formation and mechanical properties of alloy–coating systems. With no promising turbine materials beyond coated nickel-base superalloys apparent in the foreseeable future, continued progress will likely be made by further refinement of control of thermally grown oxide adherence, and by more cost effective manufacturing processes for contemporary types of protective coatings.

Gas Turbine Film Cooling

Abstract: The durability of gas turbine engines is strongly dependent on the component temperatures. For the combustor and turbine airfoils and endwalls, film cooling is used extensively to reduce component temperatures. Film cooling is a cooling method used in virtually all of today's aircraft turbine engines and in many power-generation turbine engines and yet has very difficult phenomena to predict. The interaction of jets-in-crossflow, which is representative of film cooling, results in a shear layer that leads to mixing and a decay in the cooling performance along a surface. This interaction is highly dependent on the jet-to-crossflow mass and momentum flux ratios. Film-cooling performance is difficult to predict because of the inherent complex flowfields along the airfoil component surfaces in turbine engines. Film cooling is applied to nearly all of the external surfaces associated with the airfoils that are exposed to the hot combustion gasses such as the leading edges, main bodies, blade tips, and endwalls. In a review of the literature, it was found that there are strong effects of freestream turbulence, surface curvature, and hole shape on the performance of film cooling. Film cooling is reviewed through a discussion of the analyses methodologies, a physical description, and the various influences on film-cooling performance.

Pitch-controlled variable-speed wind turbine generation

Abstract: Wind energy is a viable option to complement other types of pollution-free generation. In the early development of wind energy, the majority of wind turbines were operated at constant speed. Recently, the number of variable-speed wind turbines installed in wind farms has increased and more wind turbine manufacturers are making variable-speed wind turbines. This paper covers the operation of variable-speed wind turbines with pitch control. The system the authors considered is controlled to generate maximum energy while minimizing loads. The maximization of energy was only carried out on a static basis and only drive train loads were considered as a constraint. In medium wind speeds, the generator and power converter control the wind turbine to capture maximum energy from the wind. In the high wind speed region, the wind turbine is controlled to maintain the aerodynamic power produced by the wind turbine. Two methods to adjust the aerodynamic power were investigated: pitch control and generator load control, both of which are employed to control the operation of the wind turbine. The authors analysis and simulation shows that the wind turbine can be operated at its optimum energy capture while minimizing the load on the wind turbine for a wide range of wind speeds.