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Sample records for large nuclear turbines

  1. Large wind turbine generators

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Donovon, R. M.

    1978-01-01

    The development associated with large wind turbine systems is briefly described. The scope of this activity includes the development of several large wind turbines ranging in size from 100 kW to several megawatt levels. A description of the wind turbine systems, their programmatic status and a summary of their potential costs is included.

  2. Large, horizontal-axis wind turbines

    NASA Technical Reports Server (NTRS)

    Linscott, B. S.; Perkins, P.; Dennett, J. T.

    1984-01-01

    Development of the technology for safe, reliable, environmentally acceptable large wind turbines that have the potential to generate a significant amount of electricity at costs competitive with conventional electric generating systems are presented. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. There are several ongoing large wind system development projects and applied research efforts directed toward meeting the technology requirements for utility applications. Detailed information on these projects is provided. The Mod-O research facility and current applied research effort in aerodynamics, structural dynamics and aeroelasticity, composite and hybrid composite materials, and multiple system interaction are described. A chronology of component research and technology development for large, horizontal axis wind turbines is presented. Wind characteristics, wind turbine economics, and the impact of wind turbines on the environment are reported. The need for continued wind turbine research and technology development is explored. Over 40 references are sited and a bibliography is included.

  3. Design evolution of large wind turbine generators

    NASA Technical Reports Server (NTRS)

    Spera, D. A.

    1979-01-01

    During the past five years, the goals of economy and reliability have led to a significant evolution in the basic design--both external and internal--of large wind turbine systems. To show the scope and nature of recent changes in wind turbine designs, development of three types are described: (1) system configuration developments; (2) computer code developments; and (3) blade technology developments.

  4. Large horizontal axis wind turbine development

    NASA Technical Reports Server (NTRS)

    Robbins, W. H.; Thomas, R. L.

    1979-01-01

    The paper presents an overview of the NASA activities in large horizontal axis wind turbine development. First generation technology large wind turbines (Mod-0A, Mod-1) have been designed and are in operation at selected utility sites. Second generation machines (Mod-2) are scheduled to begin operations on a utility site in 1980. These machines are estimated to generate electricity at less than 4 cents/kWh when manufactured in modest production rates. Meanwhile, plans are being made to continue developing wind turbines which can meet the cost goals of 2 to 3 cents/kWh.

  5. Large-scale wind turbine structures

    NASA Technical Reports Server (NTRS)

    Spera, David A.

    1988-01-01

    The purpose of this presentation is to show how structural technology was applied in the design of modern wind turbines, which were recently brought to an advanced stage of development as sources of renewable power. Wind turbine structures present many difficult problems because they are relatively slender and flexible; subject to vibration and aeroelastic instabilities; acted upon by loads which are often nondeterministic; operated continuously with little maintenance in all weather; and dominated by life-cycle cost considerations. Progress in horizontal-axis wind turbines (HAWT) development was paced by progress in the understanding of structural loads, modeling of structural dynamic response, and designing of innovative structural response. During the past 15 years a series of large HAWTs was developed. This has culminated in the recent completion of the world's largest operating wind turbine, the 3.2 MW Mod-5B power plane installed on the island of Oahu, Hawaii. Some of the applications of structures technology to wind turbine will be illustrated by referring to the Mod-5B design. First, a video overview will be presented to provide familiarization with the Mod-5B project and the important components of the wind turbine system. Next, the structural requirements for large-scale wind turbines will be discussed, emphasizing the difficult fatigue-life requirements. Finally, the procedures used to design the structure will be presented, including the use of the fracture mechanics approach for determining allowable fatigue stresses.

  6. Large-scale wind turbine structures

    NASA Astrophysics Data System (ADS)

    Spera, David A.

    1988-05-01

    The purpose of this presentation is to show how structural technology was applied in the design of modern wind turbines, which were recently brought to an advanced stage of development as sources of renewable power. Wind turbine structures present many difficult problems because they are relatively slender and flexible; subject to vibration and aeroelastic instabilities; acted upon by loads which are often nondeterministic; operated continuously with little maintenance in all weather; and dominated by life-cycle cost considerations. Progress in horizontal-axis wind turbines (HAWT) development was paced by progress in the understanding of structural loads, modeling of structural dynamic response, and designing of innovative structural response. During the past 15 years a series of large HAWTs was developed. This has culminated in the recent completion of the world's largest operating wind turbine, the 3.2 MW Mod-5B power plane installed on the island of Oahu, Hawaii. Some of the applications of structures technology to wind turbine will be illustrated by referring to the Mod-5B design. First, a video overview will be presented to provide familiarization with the Mod-5B project and the important components of the wind turbine system. Next, the structural requirements for large-scale wind turbines will be discussed, emphasizing the difficult fatigue-life requirements. Finally, the procedures used to design the structure will be presented, including the use of the fracture mechanics approach for determining allowable fatigue stresses.

  7. Large Horizontal-Axis Wind Turbines

    NASA Technical Reports Server (NTRS)

    Thresher, R. W. (Editor)

    1982-01-01

    The proceedings of a workshop held in Cleveland, July 28-30, 1981 are described. The workshop emphasized recent experience in building and testing large propeller-type wind turbines, expanding upon the proceedings of three previous DOE/NASA workshops at which design and analysis topics were considered. A total of 41 papers were presented on the following subjects: current and advanced large wind turbine systems, rotor blade design and manufacture, electric utility activities, research and supporting technology, meteorological characteristics for design and operation, and wind resources assessments for siting.

  8. Upgrading of HP turbines for nuclear power stations

    SciTech Connect

    Marlow, B.A.; Brown, R.D.

    1998-12-31

    Many papers have been written on the upgrading of nuclear plant LP turbines but there are also strong reasons for the upgrading of the HP turbines. Two principal reasons are discussed in this paper. Fouling by deposition on the feedwater side of the stream generator tubes, frequently results in a reduction of pressure at the turbine stop valve and a consequent loss of power output. This loss of power can be largely offset by fitting increased capacity blading in part of the HP turbine which increases the swallowing capacity of the turbine. It is necessary to consider the increased capacity blading, bypassing of heaters and future fouling to arrive at an optimum solution. Since the design of the operating nuclear stations GEC ALSTHOM have made very significant advances in the design of steam turbine HP blading and it is now possible to upgrade the HP turbine with blades of modern design to give a substantial increase in power output. The pay back period for such a upgrade is short and the paper describes some of the Company`s successful nuclear HP upgrading in the UK. The two actions described above can be combined, or indeed, be carried out in conjunction with an LP upgrade.

  9. The NASA Lewis large wind turbine program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Baldwin, D. H.

    1981-01-01

    The program is directed toward development of the technology for safe, reliable, environmentally acceptable large wind turbines that have the potential to generate a significant amount of electricity at costs competitive with conventional electric generation systems. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. Advances are made by gaining a better understanding of the system design drivers, improvements in the analytical design tools, verification of design methods with operating field data, and the incorporation of new technology and innovative designs. An overview of the program activities is presented and includes results from the first and second generation field machines (Mod-OA, -1, and -2), the design phase of the third generation wind turbine (Mod-5) and the advanced technology projects. Also included is the status of the Department of Interior WTS-4 machine.

  10. Large horizontal axis wind turbine development

    NASA Technical Reports Server (NTRS)

    Robbins, W. H.; Thomas, R. L.

    1979-01-01

    An overview of the NASA activities concerning ongoing wind systems oriented toward utility application is presented. First-generation-technology large wind turbines were designed and are in operation at selected utility sites. In order to make a significant energy impact, costs of 2 to 3 cents per kilowatt hour must be achieved. The federal program continues to fund the development by industry of wind turbines which can meet the cost goals of 2 to 3 cents per kilowatt hour. Lower costs are achieved through the incorporation of new technology and innovative system design to reduce weight and increase energy capture.

  11. Meteorological aspects of siting large wind turbines

    SciTech Connect

    Hiester, T.R.; Pennell, W.T.

    1981-01-01

    This report, which focuses on the meteorological aspects of siting large wind turbines (turbines with a rated output exceeding 100 kW), has four main goals. The first is to outline the elements of a siting strategy that will identify the most favorable wind energy sites in a region and that will provide sufficient wind data to make responsible economic evaluations of the site wind resource possible. The second is to critique and summarize siting techniques that were studied in the Department of Energy (DOE) Wind Energy Program. The third goal is to educate utility technical personnel, engineering consultants, and meteorological consultants (who may have not yet undertaken wind energy consulting) on meteorological phenomena relevant to wind turbine siting in order to enhance dialogues between these groups. The fourth goal is to minimize the chances of failure of early siting programs due to insufficient understanding of wind behavior.

  12. Large steam turbine repair: A survey

    SciTech Connect

    Findlan, S.J.; Lube, B. )

    1991-07-01

    This report covers a survey taken to document the current state-of-the-art in repairs to large steam turbines. One objective was to provide information to assist utilities in making repair or replacement decisions. The survey revealed that a large number of repairs have been successfully repaired involving both mechanical and welding repair techniques. Repair techniques have been improving in recent years and are being used more frequently. No guidelines or codes exist for the repair of steam turbine components so each repair is primarily controlled by agreement between the utility, contractor and insurer. Types of repairs are reviewed in this report and in addition, the capabilities of various contractors who are currently active in providing repair service. 40 refs., 10 figs., 4 tabs.

  13. Large eddy simulation applications in gas turbines.

    PubMed

    Menzies, Kevin

    2009-07-28

    The gas turbine presents significant challenges to any computational fluid dynamics techniques. The combination of a wide range of flow phenomena with complex geometry is difficult to model in the context of Reynolds-averaged Navier-Stokes (RANS) solvers. We review the potential for large eddy simulation (LES) in modelling the flow in the different components of the gas turbine during a practical engineering design cycle. We show that while LES has demonstrated considerable promise for reliable prediction of many flows in the engine that are difficult for RANS it is not a panacea and considerable application challenges remain. However, for many flows, especially those dominated by shear layer mixing such as in combustion chambers and exhausts, LES has demonstrated a clear superiority over RANS for moderately complex geometries although at significantly higher cost which will remain an issue in making the calculations relevant within the design cycle. PMID:19531505

  14. Passive load control for large wind turbines.

    SciTech Connect

    Ashwill, Thomas D.

    2010-05-01

    Wind energy research activities at Sandia National Laboratories focus on developing large rotors that are lighter and more cost-effective than those designed with current technologies. Because gravity scales as the cube of the blade length, gravity loads become a constraining design factor for very large blades. Efforts to passively reduce turbulent loading has shown significant potential to reduce blade weight and capture more energy. Research in passive load reduction for wind turbines began at Sandia in the late 1990's and has moved from analytical studies to blade applications. This paper discusses the test results of two Sandia prototype research blades that incorporate load reduction techniques. The TX-100 is a 9-m long blade that induces bend-twist coupling with the use of off-axis carbon in the skin. The STAR blade is a 27-m long blade that induces bend-twist coupling by sweeping the blade in a geometric fashion.

  15. Control of large wind turbine generators connected to utility networks

    NASA Technical Reports Server (NTRS)

    Hinrichsen, E. N.

    1983-01-01

    This is an investigation of the control requirements for variable pitch wind turbine generators connected to electric power systems. The requirements include operation in very small as well as very large power systems. Control systems are developed for wind turbines with synchronous, induction, and doubly fed generators. Simulation results are presented. It is shown how wind turbines and power system controls can be integrated. A clear distinction is made between fast control of turbine torque, which is a peculiarity of wind turbines, and slow control of electric power, which is a traditional power system requirement.

  16. Fixed pitch rotor performance of large horizontal axis wind turbines

    NASA Technical Reports Server (NTRS)

    Viterna, L. A.; Corrigan, R. D.

    1982-01-01

    Experimental fixed pitch wind turbine performance data is presented for both the DOE/NASA Mod-0 and the Danish Gedser wind turbines. Furthermore, a method for calculating the output power from large fixed pitch wind turbines is presented. Modifications to classical blade element momentum theory are given that improve correlation with measured data. Improvement is particularly evident in high winds (low tip speed ratios) where aerodynamic stall occurs as the blade experiences high angles of attack.

  17. DOE/NASA Lewis large wind turbine program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.

    1982-01-01

    An overview of the large wind turbine activities managed by NASA is given. These activities include resuls from the first and second generation field machines (Mod-0A, -1, and -2), the status of the Department of Interior WTS-4 machine for which NASA is responsible for technical management, and the design phase of the third generation wind turbines (Mod-5).

  18. Large wind turbine development in Europe

    SciTech Connect

    Zervos, A.

    1996-12-31

    During the last few years we have witnessed in Europe the development of a new generation of wind turbines ranging from 1000-1500 kW size. They are presently being tested and they are scheduled to reach the market in late 1996 early 1997. The European Commission has played a key role by funding the research leading to the development of these turbines. The most visible initiative at present is the WEGA program - the development, together with Europe`s leading wind industry players of a new generation of turbines in the MW range. By the year 1997 different European manufacturers will have introduced almost a dozen new MW machine types to the international market, half of them rated at 1.5 MW. 3 refs., 3 tabs.

  19. Large, low cost composite wind turbine blades

    NASA Technical Reports Server (NTRS)

    Gewehr, H. W.

    1979-01-01

    A woven roving E-glass tape, having all of its structural fibers oriented across the tape width was used in the manufacture of the spar for a wind turbine blade. Tests of a 150 ft composite blade show that the transverse filament tape is capable of meeting structural design requirements for wind turbine blades. Composite blades can be designed for interchangeability with steel blades in the MOD-1 wind generator system. The design, analysis, fabrication, and testing of the 150 ft blade are discussed.

  20. Large Wind Turbine Design Characteristics and R and D Requirements

    NASA Technical Reports Server (NTRS)

    Lieblein, S. (Editor)

    1979-01-01

    Detailed technical presentations on large wind turbine research and development activities sponsored by public and private organizations are presented. Both horizontal and vertical axis machines are considered with emphasis on their structural design.

  1. Large wind turbine generators. [NASA program status and potential costs

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Donovon, R. M.

    1978-01-01

    The large wind turbine portion of the Federal Wind Energy Program consists of two major project efforts: (1) the Mod-0 test bed project for supporting research technology, and (2) the large experimental wind turbines for electric utility applications. The Mod-0 has met its primary objective of providing the entire wind energy program with early operations and performance data. The large experimental wind turbines to be tested in utility applications include three of the Mod-0A (200 kW) type, one Mod-1 (2000 kW), and possibly several of the Mod-2 (2500 kW) designs. This paper presents a description of these wind turbine systems, their programmatic status, and a summary of their potential costs.

  2. Advanced Seal Development for Large Industrial Gas Turbines

    NASA Technical Reports Server (NTRS)

    Chupp, Raymond E.

    2006-01-01

    Efforts are in progress to develop advanced sealing for large utility industrial gas turbine engines (combustion turbines). Such seals have been under developed for some time for aero gas turbines. It is desired to transition this technology to combustion turbines. Brush seals, film riding face and circumferential seals, and other dynamic and static sealing approaches are being incorporated into gas turbines for aero applications by several engine manufacturers. These seals replace labyrinth or other seals with significantly reduced leakage rates. For utility industrial gas turbines, leakage reduction with advanced sealing can be even greater with the enormous size of the components. Challenges to transitioning technology include: extremely long operating times between overhauls; infrequent but large radial and axial excursions; difficulty in coating larger components; and maintenance, installation, and durability requirements. Advanced sealing is part of the Advanced Turbine Systems (ATS) engine development being done under a cooperative agreement between Westinghouse and the US Department of Energy, Office of Fossil Energy. Seal development focuses on various types of seals in the 501ATS engine both at dynamic and static locations. Each development includes rig testing of candidate designs and subsequent engine validation testing of prototype seals. This presentation gives an update of the ongoing ATS sealing efforts with special emphasis on brush seals.

  3. Low frequency acoustic emissions from large horizontal axis wind turbines

    NASA Technical Reports Server (NTRS)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    1989-01-01

    Available test data and theoretical predictions of LF noise from large wind turbines of the type to be used for energy generation are briefly summarized. The main LF noise sources are identified as tower-wake/blade interactions and rotor-plane inflow gradients. Sound-pressure time histories, measured and calculated narrow-band and rotational noise spectra, and noise radiation patterns for the WTS-4 and WWG-0600 wind turbines are presented graphically.

  4. Superconductivity for Large Scale Wind Turbines

    SciTech Connect

    R. Fair; W. Stautner; M. Douglass; R. Rajput-Ghoshal; M. Moscinski; P. Riley; D. Wagner; J. Kim; S. Hou; F. Lopez; K. Haran; J. Bray; T. Laskaris; J. Rochford; R. Duckworth

    2012-10-12

    A conceptual design has been completed for a 10MW superconducting direct drive wind turbine generator employing low temperature superconductors for the field winding. Key technology building blocks from the GE Wind and GE Healthcare businesses have been transferred across to the design of this concept machine. Wherever possible, conventional technology and production techniques have been used in order to support the case for commercialization of such a machine. Appendices A and B provide further details of the layout of the machine and the complete specification table for the concept design. Phase 1 of the program has allowed us to understand the trade-offs between the various sub-systems of such a generator and its integration with a wind turbine. A Failure Modes and Effects Analysis (FMEA) and a Technology Readiness Level (TRL) analysis have been completed resulting in the identification of high risk components within the design. The design has been analyzed from a commercial and economic point of view and Cost of Energy (COE) calculations have been carried out with the potential to reduce COE by up to 18% when compared with a permanent magnet direct drive 5MW baseline machine, resulting in a potential COE of 0.075 $/kWh. Finally, a top-level commercialization plan has been proposed to enable this technology to be transitioned to full volume production. The main body of this report will present the design processes employed and the main findings and conclusions.

  5. Development of large, horizontal-axis wind turbines

    NASA Technical Reports Server (NTRS)

    Baldwin, D. H.; Kennard, J.

    1985-01-01

    A program to develop large, horizontal-axis wind turbines is discussed. The program is directed toward developing the technology for safe, reliable, environmentally acceptable large wind turbines that can generate a significant amount of electricity at costs competitive with those of conventional electricity-generating systems. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. Several ongoing projects in large-wind-turbine development are directed toward meeting the technology requirements for utility applications. The machines based on first-generation technology (Mod-OA and Mod-1) successfully completed their planned periods of experimental operation in June, 1982. The second-generation machines (Mod-2) are in operation at selected utility sites. A third-generation machine (Mod-5) is under contract. Erection and initial operation of the Mod-5 in Hawaii should take place in 1986. Each successive generation of technology increased reliability and energy capture while reducing the cost of electricity. These advances are being made by gaining a better understanding of the system-design drivers, improving the analytical design tools, verifying design methods with operating field data, and incorporating new technology and innovative designs. Information is given on the results from the first- and second-generation machines (Mod-OA, - 1, and -2), the status of the Department of Interior, and the status of the third-generation wind turbine (Mod-5).

  6. 14 CFR 135.379 - Large transport category airplanes: Turbine engine powered: Takeoff limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Large transport category airplanes: Turbine... category airplanes: Turbine engine powered: Takeoff limitations. (a) No person operating a turbine engine... existing at take- off. (b) No person operating a turbine engine powered large transport category...

  7. 14 CFR 135.379 - Large transport category airplanes: Turbine engine powered: Takeoff limitations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Large transport category airplanes: Turbine... category airplanes: Turbine engine powered: Takeoff limitations. (a) No person operating a turbine engine... existing at take- off. (b) No person operating a turbine engine powered large transport category...

  8. 14 CFR 135.379 - Large transport category airplanes: Turbine engine powered: Takeoff limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Large transport category airplanes: Turbine... category airplanes: Turbine engine powered: Takeoff limitations. (a) No person operating a turbine engine... existing at take- off. (b) No person operating a turbine engine powered large transport category...

  9. 14 CFR 135.379 - Large transport category airplanes: Turbine engine powered: Takeoff limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Large transport category airplanes: Turbine... category airplanes: Turbine engine powered: Takeoff limitations. (a) No person operating a turbine engine... existing at take- off. (b) No person operating a turbine engine powered large transport category...

  10. Summary of tower designs for large horizontal axis wind turbines

    NASA Technical Reports Server (NTRS)

    Frederick, G. R.; Savino, J. M.

    1986-01-01

    Towers for large horizontal axis wind turbines, machines with a rotor axis height above 30 meters and rated at more than 500 kW, have varied in configuration, materials of construction, type of construction, height, and stiffness. For example, the U.S. large HAWTs have utilized steel truss type towers and free-standing steel cylindrical towers. In Europe, the trend has been to use only free-standing and guyed cylindrical towers, but both steel and reinforced concrete have been used as materials of construction. These variations in materials of construction and type of construction reflect different engineering approaches to the design of cost effective towers for large HAWTs. Tower designs are the NASA/DOE Mod-5B presently being fabricated. Design goals and requirements that influence tower configuration, height and materials are discussed. In particular, experiences with United States large wind turbine towers are elucidated. Finally, current trends in tower designs for large HAWTs are highlighted.

  11. Energy potential and early operational experience for large wind turbines

    NASA Technical Reports Server (NTRS)

    Robbins, W. H.; Thomas, R. L.

    1980-01-01

    Projections for the total potential output of large wind turbines in the U.S. are reviewed. NASA has developed nine large windpowered generators, of 100 kW, 200 kW, 2 MW, and 2.5 MW capacities, with rotors 100-300 ft in diameter, and all with horizontal axes. Approximately 214,000 sq miles of the U.S. have been determined as having substantial wind regimes and terrain suitable for large wind turbine siting. This translates into 340,000 Mod 2 (2.5 MW) wind turbines producing 4.9 quads of electricity annually, equivalent to saving 2.5 billion barrels of oil/yr. The cost of electricity is seen as the critical factor in utility acceptance of large wind turbines, and the Mod 2 machines are noted to achieve the 2-4 cents/kWh (1977 dollars) COE which is necessary. Problems such as pollution, including visual, auditory, EM, and land use difficulties are considered, and solutions are indicated.

  12. Quiet airfoils for small and large wind turbines

    DOEpatents

    Tangler, James L.; Somers, Dan L.

    2012-06-12

    Thick airfoil families with desirable aerodynamic performance with minimal airfoil induced noise. The airfoil families are suitable for a variety of wind turbine designs and are particularly well-suited for use with horizontal axis wind turbines (HAWTs) with constant or variable speed using pitch and/or stall control. In exemplary embodiments, a first family of three thick airfoils is provided for use with small wind turbines and second family of three thick airfoils is provided for use with very large machines, e.g., an airfoil defined for each of three blade radial stations or blade portions defined along the length of a blade. Each of the families is designed to provide a high maximum lift coefficient or high lift, to exhibit docile stalls, to be relatively insensitive to roughness, and to achieve a low profile drag.

  13. Effects of Turbine Spacing in Very Large Wind Farms

    NASA Astrophysics Data System (ADS)

    Andersen, Søren Juhl; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming

    2015-11-01

    The Dynamic Wake Meandering model(DWM) by Larsen et al. (2007) is considered state of the art for modelling the wake behind a wind turbine. DWM assumes a quasi-steady wake deficit transported as a passive tracer by large atmospheric scales. The approach is also applied to wake interaction within wind farms, although certain aspects of the complex wake interaction are not captured, see Churchfield et al. (2014). Recent studies have shown how turbines introduce low frequencies in the wake, which could describe some of the shortcomings. Chamorro et al. (2015) identified three regions of different lengths scales. Iungo et al. (2013) related low frequencies to the hub vortex instability. Okulov et al. (2014) found Strouhal numbers in the far wake stemming from the rotating helical vortex core. Simulations by Andersen et al. (2013) found low frequencies to be inherent in the flow inside an infinite wind farm. LES simulations of large wind farms are performed with full aero-elastic Actuator Lines. The simulations investigate the inherent dynamics inside wind farms in the absence of atmospheric turbulence compared to cases with atmospheric turbulence. Resulting low frequency structures are inherent in wind farms for certain turbine spacings and affect both power production and loads. Funded by Danish Council for Strategic Research (grant 2104-09-067216/DSF), the Nordic Consortium on Optimization and Control of Wind Farms, and EuroTech wind project. The proprietary data for Vestas' NM80 turbine has been used.

  14. Airfoil family design for large offshore wind turbine blades

    NASA Astrophysics Data System (ADS)

    Méndez, B.; Munduate, X.; San Miguel, U.

    2014-06-01

    Wind turbine blades size has scaled-up during last years due to wind turbine platform increase especially for offshore applications. The EOLIA project 2007-2010 (Spanish Goverment funded project) was focused on the design of large offshore wind turbines for deep waters. The project was managed by ACCIONA Energia and the wind turbine technology was designed by ACCIONA Windpower. The project included the design of a wind turbine airfoil family especially conceived for large offshore wind turbine blades, in the order of 5MW machine. Large offshore wind turbines suffer high extreme loads due to their size, in addition the lack of noise restrictions allow higher tip speeds. Consequently, the airfoils presented in this work are designed for high Reynolds numbers with the main goal of reducing blade loads and mantainig power production. The new airfoil family was designed in collaboration with CENER (Spanish National Renewable Energy Centre). The airfoil family was designed using a evolutionary algorithm based optimization tool with different objectives, both aerodynamic and structural, coupled with an airfoil geometry generation tool. Force coefficients of the designed airfoil were obtained using the panel code XFOIL in which the boundary layer/inviscid flow coupling is ineracted via surface transpiration model. The desing methodology includes a novel technique to define the objective functions based on normalizing the functions using weight parameters created from data of airfoils used as reference. Four airfoils have been designed, here three of them will be presented, with relative thickness of 18%, 21%, 25%, which have been verified with the in-house CFD code, Wind Multi Block WMB, and later validated with wind tunnel experiments. Some of the objectives for the designed airfoils concern the aerodynamic behavior (high efficiency and lift, high tangential coefficient, insensitivity to rough conditions, etc.), others concern the geometry (good for structural design

  15. Large Eddy Simulation of Vertical Axis Wind Turbine Wakes

    NASA Astrophysics Data System (ADS)

    Shamsoddin, Sina; Porté-Agel, Fernando

    2014-05-01

    In this study, large-eddy simulation (LES) is combined with a turbine model to investigate the wake behind a vertical-axis wind turbine (VAWT) in a three dimensional turbulent flow. Two methods are used to model the subgrid-scale (SGS) stresses: (a) the Smagorinsky model, and (b) the modulated gradient model. To parameterize the effects of the VAWT on the flow, two VAWT models are developed: (a) the actuator surface model (ASM), in which the time-averaged turbine-induced forces are distributed on a surface swept by the turbine blades, i.e. the actuator surface, and (b) the actuator line model (ALM), in which the instantaneous blade forces are only spatially distributed on lines representing the blades, i.e. the actuator lines. This is the first time that LES is applied and validated for simulation of VAWT wakes by using either the ASM or the ALM techniques. In both models, blade-element theory is used to calculate the lift and drag forces on the blades. The results are compared with flow measurements in the wake of a model straight-bladed VAWT, carried out in the Institute de Méchanique et Statistique de la Turbulence (IMST) water channel. Different combinations of SGS models with VAWT models are studied and a fairly good overall agreement between simulation results and measurement data is observed. In general, the ALM is found to better capture the unsteady-periodic nature of the wake and shows a better agreement with the experimental data compared with the ASM. The modulated gradient model is also found to be a more reliable SGS stress modeling technique, compared with the Smagorinsky model, and it yields reasonable predictions of the mean flow and turbulence characteristics of a VAWT wake using its theoretically-determined model coefficient. Keywords: Vertical-axis wind turbines (VAWTs); VAWT wake; Large-eddy simulation; Actuator surface model; Actuator line model; Smagorinsky model; Modulated gradient model

  16. An overview of large wind turbine tests by electric utilities

    NASA Technical Reports Server (NTRS)

    Vachon, W. A.; Schiff, D.

    1982-01-01

    A summary of recent plants and experiences on current large wind turbine (WT) tests being conducted by electric utilities is provided. The test programs discussed do not include federal research and development (R&D) programs, many of which are also being conducted in conjunction with electric utilities. The information presented is being assembled in a project, funded by the Electric Power Research Institute (EPRI), the objective of which is to provide electric utilities with timely summaries of test performance on key large wind turbines. A summary of key tests, test instrumentation, and recent results and plans is given. During the past year, many of the utility test programs initiated have encountered test difficulties that required specific WT design changes. However, test results to date continue to indicate that long-term machine performance and cost-effectiveness are achievable.

  17. 14 CFR 91.1037 - Large transport category airplanes: Turbine engine powered; Limitations; Destination and...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Large transport category airplanes: Turbine....1037 Large transport category airplanes: Turbine engine powered; Limitations; Destination and alternate airports. (a) No program manager or any other person may permit a turbine engine powered large...

  18. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Large transport category airplanes: Turbine....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take...

  19. 14 CFR 91.1037 - Large transport category airplanes: Turbine engine powered; Limitations; Destination and...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Large transport category airplanes: Turbine....1037 Large transport category airplanes: Turbine engine powered; Limitations; Destination and alternate airports. (a) No program manager or any other person may permit a turbine engine powered large...

  20. 14 CFR 91.1037 - Large transport category airplanes: Turbine engine powered; Limitations; Destination and...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Large transport category airplanes: Turbine....1037 Large transport category airplanes: Turbine engine powered; Limitations; Destination and alternate airports. (a) No program manager or any other person may permit a turbine engine powered large...

  1. 14 CFR 91.1037 - Large transport category airplanes: Turbine engine powered; Limitations; Destination and...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Large transport category airplanes: Turbine....1037 Large transport category airplanes: Turbine engine powered; Limitations; Destination and alternate airports. (a) No program manager or any other person may permit a turbine engine powered large...

  2. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Large transport category airplanes: Turbine....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take...

  3. 14 CFR 91.1037 - Large transport category airplanes: Turbine engine powered; Limitations; Destination and...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Large transport category airplanes: Turbine....1037 Large transport category airplanes: Turbine engine powered; Limitations; Destination and alternate airports. (a) No program manager or any other person may permit a turbine engine powered large...

  4. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Large transport category airplanes: Turbine....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take...

  5. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Large transport category airplanes: Turbine....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take...

  6. 14 CFR 135.387 - Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate airports.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Large transport category airplanes: Turbine....387 Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate... alternate airport for a turbine engine powered large transport category airplane unless (based on...

  7. 14 CFR 135.387 - Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate airports.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Large transport category airplanes: Turbine....387 Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate... alternate airport for a turbine engine powered large transport category airplane unless (based on...

  8. 14 CFR 135.387 - Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate airports.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Large transport category airplanes: Turbine....387 Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate... alternate airport for a turbine engine powered large transport category airplane unless (based on...

  9. 14 CFR 135.387 - Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate airports.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Large transport category airplanes: Turbine....387 Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate... alternate airport for a turbine engine powered large transport category airplane unless (based on...

  10. Examination of turbine discs from nuclear power plants

    SciTech Connect

    Czajkowski, C.J.; Weeks, J.R.

    1982-01-01

    Investigations were performed on a cracked turbine disc from the Cooper Nuclear Power Station, and on two failed turbine discs (governor and generator ends) from the Yankee-Rowe Nuclear Power Station. Cooper is a boiling water reactor (BWR) which went into commercial operation in July 1974, and Yankee-Rowe is a pressurized water reactor (PWR) which went into commercial operation in June 1961. Cracks were identified in the bore of the Cooper disc after 41,913 hours of operation, and the disc removed for repair. At Yankee-Rowe two discs failed after 100,000 hours of operation. Samples of the Cooper disc and both Yankee-Rowe disc (one from the governor and one from the generator end of the LP turbine) were sent to Brookhaven National Laboratory (BNL) for failure analysis.

  11. Design of large Francis turbine using optimal methods

    NASA Astrophysics Data System (ADS)

    Flores, E.; Bornard, L.; Tomas, L.; Liu, J.; Couston, M.

    2012-11-01

    Among a high number of Francis turbine references all over the world, covering the whole market range of heads, Alstom has especially been involved in the development and equipment of the largest power plants in the world : Three Gorges (China -32×767 MW - 61 to 113 m), Itaipu (Brazil- 20x750 MW - 98.7m to 127m) and Xiangjiaba (China - 8x812 MW - 82.5m to 113.6m - in erection). Many new projects are under study to equip new power plants with Francis turbines in order to answer an increasing demand of renewable energy. In this context, Alstom Hydro is carrying out many developments to answer those needs, especially for jumbo units such the planned 1GW type units in China. The turbine design for such units requires specific care by using the state of the art in computation methods and the latest technologies in model testing as well as the maximum feedback from operation of Jumbo plants already in operation. We present in this paper how a large Francis turbine can be designed using specific design methods, including the global and local optimization methods. The design of the spiral case, the tandem cascade profiles, the runner and the draft tube are designed with optimization loops involving a blade design tool, an automatic meshing software and a Navier-Stokes solver, piloted by a genetic algorithm. These automated optimization methods, presented in different papers over the last decade, are nowadays widely used, thanks to the growing computation capacity of the HPC clusters: the intensive use of such optimization methods at the turbine design stage allows to reach very high level of performances, while the hydraulic flow characteristics are carefully studied over the whole water passage to avoid any unexpected hydraulic phenomena.

  12. Use of small turbine-type flowmeters to measure flow in large pipes

    NASA Technical Reports Server (NTRS)

    Minkin, H. L.; Hobart, H. F.

    1972-01-01

    Measurement of mass flow in large pipes using small turbine-type flowmeters is discussed. Experiments for determining accuracy of flowmeter and applicability to various types of flow measurement are reported. Illustration of turbine flowmeter and calibration curve are included.

  13. Weather response to a large wind turbine array

    NASA Astrophysics Data System (ADS)

    Barrie, D. B.; Kirk-Davidoff, D. B.

    2010-01-01

    Electrical generation by wind turbines is increasing rapidly, and has been projected to satisfy 15% of world electric demand by 2030. The extensive installation of wind farms would alter surface roughness and significantly impact the atmospheric circulation due to the additional surface roughness forcing. This forcing could be changed deliberately by adjusting the attitude of the turbine blades with respect to the wind, which would enable the "management" of a large array of wind turbines. Using a General Circulation Model (GCM), we represent a continent-scale wind farm as a distributed array of surface roughness elements. Here we show that initial disturbances caused by a step change in roughness grow within four and a half days such that the flow is altered at synoptic scales. The growth rate of the induced perturbations is largest in regions of high atmospheric instability. For a roughness change imposed over North America, the induced perturbations involve substantial changes in the track and development of cyclones over the North Atlantic, and the magnitude of the perturbations rises above the level of forecast uncertainty.

  14. Energy storage inherent in large tidal turbine farms.

    PubMed

    Vennell, Ross; Adcock, Thomas A A

    2014-06-01

    While wind farms have no inherent storage to supply power in calm conditions, this paper demonstrates that large tidal turbine farms in channels have short-term energy storage. This storage lies in the inertia of the oscillating flow and can be used to exceed the previously published upper limit for power production by currents in a tidal channel, while simultaneously maintaining stronger currents. Inertial storage exploits the ability of large farms to manipulate the phase of the oscillating currents by varying the farm's drag coefficient. This work shows that by optimizing how a large farm's drag coefficient varies during the tidal cycle it is possible to have some flexibility about when power is produced. This flexibility can be used in many ways, e.g. producing more power, or to better meet short predictable peaks in demand. This flexibility also allows trading total power production off against meeting peak demand, or mitigating the flow speed reduction owing to power extraction. The effectiveness of inertial storage is governed by the frictional time scale relative to either the duration of a half tidal cycle or the duration of a peak in power demand, thus has greater benefits in larger channels. PMID:24910516

  15. Energy storage inherent in large tidal turbine farms

    PubMed Central

    Vennell, Ross; Adcock, Thomas A. A.

    2014-01-01

    While wind farms have no inherent storage to supply power in calm conditions, this paper demonstrates that large tidal turbine farms in channels have short-term energy storage. This storage lies in the inertia of the oscillating flow and can be used to exceed the previously published upper limit for power production by currents in a tidal channel, while simultaneously maintaining stronger currents. Inertial storage exploits the ability of large farms to manipulate the phase of the oscillating currents by varying the farm's drag coefficient. This work shows that by optimizing how a large farm's drag coefficient varies during the tidal cycle it is possible to have some flexibility about when power is produced. This flexibility can be used in many ways, e.g. producing more power, or to better meet short predictable peaks in demand. This flexibility also allows trading total power production off against meeting peak demand, or mitigating the flow speed reduction owing to power extraction. The effectiveness of inertial storage is governed by the frictional time scale relative to either the duration of a half tidal cycle or the duration of a peak in power demand, thus has greater benefits in larger channels. PMID:24910516

  16. Large HAWT (Horizontal-Axis Wind Turbine) wake measurement and analysis

    NASA Astrophysics Data System (ADS)

    Miller, A. H.; Wegley, H. L.; Buck, J. W.

    1984-05-01

    From the theoretical fluid dynamics point of view, the wake region of a large horizontal-axis wind turbine was defined and described, and numerical models of wake behavior were developed. Wind tunnel studies of single turbine wakes and turbine array wakes were used to verify the theory and further refine the numerical models. The effects of scaling, rotor solidity, and topography on wake behavior are questions that remain unanswered. In the wind tunnel studies, turbines were represented by anything from scaled models to tea strainers or wire mesh disks whose solidity was equivalent to that of a typical wind turbine. The scale factor compensation for the difference in Reynolds number between the scale model and an actual turbine is complex, and not typically accounted for. Though it is wise to study the simpler case of wakes in flat topography, current indications are that wind turbine farm development is actually occurring in somewhat more complex terrain.

  17. 14 CFR 135.387 - Large transport category airplanes: Turbine engine powered: Landing limitations: Alternate airports.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Large transport category airplanes: Turbine... AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane Performance Operating Limitations § 135.387 Large transport category airplanes: Turbine engine powered: Landing limitations:...

  18. Towards Large Eddy Simulation of gas turbine compressors

    NASA Astrophysics Data System (ADS)

    McMullan, W. A.; Page, G. J.

    2012-07-01

    With increasing computing power, Large Eddy Simulation could be a useful simulation tool for gas turbine axial compressor design. This paper outlines a series of simulations performed on compressor geometries, ranging from a Controlled Diffusion Cascade stator blade to the periodic sector of a stage in a 3.5 stage axial compressor. The simulation results show that LES may offer advantages over traditional RANS methods when off-design conditions are considered - flow regimes where RANS models often fail to converge. The time-dependent nature of LES permits the resolution of transient flow structures, and can elucidate new mechanisms of vorticity generation on blade surfaces. It is shown that accurate LES is heavily reliant on both the near-wall mesh fidelity and the ability of the imposed inflow condition to recreate the conditions found in the reference experiment. For components embedded in a compressor this requires the generation of turbulence fluctuations at the inlet plane. A recycling method is developed that improves the quality of the flow in a single stage calculation of an axial compressor, and indicates that future developments in both the recycling technique and computing power will bring simulations of axial compressors within reach of industry in the coming years.

  19. Innovative design approaches for large wind turbine blades : final report.

    SciTech Connect

    Not Available

    2004-05-01

    The goal of the Blade System Design Study (BSDS) was investigation and evaluation of design and manufacturing issues for wind turbine blades in the one to ten megawatt size range. A series of analysis tasks were completed in support of the design effort. We began with a parametric scaling study to assess blade structure using current technology. This was followed by an economic study of the cost to manufacture, transport and install large blades. Subsequently we identified several innovative design approaches that showed potential for overcoming fundamental physical and manufacturing constraints. The final stage of the project was used to develop several preliminary 50m blade designs. The key design impacts identified in this study are: (1) blade cross-sections, (2) alternative materials, (3) IEC design class, and (4) root attachment. The results show that thick blade cross-sections can provide a large reduction in blade weight, while maintaining high aerodynamic performance. Increasing blade thickness for inboard sections is a key method for improving structural efficiency and reducing blade weight. Carbon/glass hybrid blades were found to provide good improvements in blade weight, stiffness, and deflection when used in the main structural elements of the blade. The addition of carbon resulted in modest cost increases and provided significant benefits, particularly with respect to deflection. The change in design loads between IEC classes is quite significant. Optimized blades should be designed for each IEC design class. A significant portion of blade weight is related to the root buildup and metal hardware for typical root attachment designs. The results show that increasing the number of blade fasteners has a positive effect on total weight, because it reduces the required root laminate thickness.

  20. Evaluation of blade-strike models for estimating the biological performance of large Kaplan hydro turbines

    SciTech Connect

    Deng, Z.; Carlson, T. J.; Ploskey, G. R.; Richmond, M. C.

    2005-11-01

    Bio-indexing of hydro turbines has been identified as an important means to optimize passage conditions for fish by identifying operations for existing and new design turbines that minimize the probability of injury. Cost-effective implementation of bio-indexing requires the use of tools such as numerical and physical turbine models to generate hypotheses for turbine operations that can be tested at prototype scales using live fish. Blade strike has been proposed as an index variable for the biological performance of turbines. Report reviews an evaluation of the use of numerical blade-strike models as a means with which to predict the probability of blade strike and injury of juvenile salmon smolt passing through large Kaplan turbines on the mainstem Columbia River.

  1. 14 CFR 135.381 - Large transport category airplanes: Turbine engine powered: En route limitations: One engine...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Large transport category airplanes: Turbine... Limitations § 135.381 Large transport category airplanes: Turbine engine powered: En route limitations: One engine inoperative. (a) No person operating a turbine engine powered large transport category...

  2. 14 CFR 135.381 - Large transport category airplanes: Turbine engine powered: En route limitations: One engine...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Large transport category airplanes: Turbine... Limitations § 135.381 Large transport category airplanes: Turbine engine powered: En route limitations: One engine inoperative. (a) No person operating a turbine engine powered large transport category...

  3. 14 CFR 135.381 - Large transport category airplanes: Turbine engine powered: En route limitations: One engine...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Large transport category airplanes: Turbine... Limitations § 135.381 Large transport category airplanes: Turbine engine powered: En route limitations: One engine inoperative. (a) No person operating a turbine engine powered large transport category...

  4. 14 CFR 135.381 - Large transport category airplanes: Turbine engine powered: En route limitations: One engine...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Large transport category airplanes: Turbine... Limitations § 135.381 Large transport category airplanes: Turbine engine powered: En route limitations: One engine inoperative. (a) No person operating a turbine engine powered large transport category...

  5. 14 CFR 135.383 - Large transport category airplanes: Turbine engine powered: En route limitations: Two engines...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Large transport category airplanes: Turbine... Limitations § 135.383 Large transport category airplanes: Turbine engine powered: En route limitations: Two...). No person may operate a turbine engine powered large transport category airplane along an...

  6. 14 CFR 135.383 - Large transport category airplanes: Turbine engine powered: En route limitations: Two engines...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Large transport category airplanes: Turbine... Limitations § 135.383 Large transport category airplanes: Turbine engine powered: En route limitations: Two...). No person may operate a turbine engine powered large transport category airplane along an...

  7. 14 CFR 135.383 - Large transport category airplanes: Turbine engine powered: En route limitations: Two engines...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Large transport category airplanes: Turbine... Limitations § 135.383 Large transport category airplanes: Turbine engine powered: En route limitations: Two...). No person may operate a turbine engine powered large transport category airplane along an...

  8. 14 CFR 135.383 - Large transport category airplanes: Turbine engine powered: En route limitations: Two engines...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Large transport category airplanes: Turbine... Limitations § 135.383 Large transport category airplanes: Turbine engine powered: En route limitations: Two...). No person may operate a turbine engine powered large transport category airplane along an...

  9. Variable-Speed Power-Turbine for the Large Civil Tilt Rotor

    NASA Technical Reports Server (NTRS)

    Suchezky, Mark; Cruzen, G. Scott

    2012-01-01

    Turbine design concepts were studied for application to a large civil tiltrotor transport aircraft. The concepts addressed the need for high turbine efficiency across the broad 2:1 turbine operating speed range representative of the notional mission for the aircraft. The study focused on tailoring basic turbine aerodynamic design design parameters to avoid the need for complex, heavy, and expensive variable geometry features. The results of the study showed that good turbine performance can be achieved across the design speed range if the design focuses on tailoring the aerodynamics for good tolerance to large swings in incidence, as opposed to optimizing for best performance at the long range cruise design point. A rig design configuration and program plan are suggested for a dedicated experiment to validate the proposed approach.

  10. The fault diagnosis of large-scale wind turbine based on expert system

    NASA Astrophysics Data System (ADS)

    Chen, Changzheng; Li, Yun

    2011-10-01

    The wind turbine is the critical equipment for wind power, due to the poor working environment and the long running, the wind turbine components will have a variety of failures. Planned maintenance which has long been used is unable to understand the operational status of equipment comprehensively and timely in a way, especially for large wind machine, the repair work took too long time and cause serious damage. Therefore, fault diagnosis and predictive maintenance becomes more imminent. In this paper, the fault symptoms and corresponding reason of the large-scale wind turbine parts are analyzed and summarized ,such as gear box, generator, yaw system, and so on . And on this basis, the large-scale wind turbine fault diagnosis expert system was constructed by using expert system tool CLIPS and Visual C + +.

  11. Pressure pulsations in combustion chambers of large gas turbines

    SciTech Connect

    Verhage, A.J.L.; Stevens, P.M.P.

    1998-07-01

    Flame instabilities and pressure pulsations have been measured in three different types of gas turbine combustors. These are the single and twin silo (such as the ABB GT13E and the Siemens V94.2), the annular combustion chamber (ABB GT 13E2, Siemens V84.3A, etc), and the multi-can combustors common on GEC-EGT gas turbines. Pressure pulsations are mostly resonant. They are interpreted with help of an acoustical model. Non-resonant modes at low frequencies (flame flicker) are ascribed to imperfect mixing especially in premix burners. At higher frequencies they are often due to vortices from the burners. Modifications of the burners, changes in the geometry of the liners and the addition of acoustical dampers are means to abate flame instabilities and the associated resonances. Judicious ways to run the gas turbine can help to avoid them. The efficiency of acoustical dampers of the Helmholtz type has been investigated experimentally and with model predictions.

  12. Methods of reducing wind power changes from large turbine arrays

    SciTech Connect

    Schlueter, R.; Dorsey, J.; Lotfalian, M.; Park, G.; Shayanfar, M.

    1983-06-01

    This paper discusses methods of reducing the WECS generation change through selection of the wind turbine model for each site, selection of an appropriate siting configuration, and wind array controls. An analysis of wind generation change from an echelon and a farm for passage of a thunderstorm is presented to establish the factors concerning the wind turbine model and siting configuration that contribute to these variations. Detailed simulation results indicate more precisely how these factors can be exploited to minimize the WECS generation changes observed. Reduction of the wind generation change over ten minutes is shown to reduce the increase in spinning reserve, unloadable generation and load following requirements on unit commitment when significant WECS generation is present and the farm penetration constraint is satisfied. Controls on the blade pitch angle of all wind turbines in an array or a battery control are shown to reduce both the wind generation change out of an array and the effective farm penetration in anticipation of a storm so that the farm penetration constraint may be satisfied.

  13. Potential benefits of a ceramic thermal barrier coating on large power generation gas turbine

    NASA Technical Reports Server (NTRS)

    Clark, J. S.; Nainiger, J. J.

    1977-01-01

    Thermal barrier coating design option offers benefit in terms of reduced electricity costs when used in utility gas turbines. Options considered include: increased firing temperature, increased component life, reduced cooling air requirements, and increased corrosion resistance (resulting in increased tolerance for dirty fuels). Performance and cost data were obtained. Simple, recuperated and combined cycle applications were considered, and distillate and residual fuels were assumed. The results indicate that thermal barrier coatings could produce large electricity cost savings if these coatings permit turbine operation with residual fuels at distillate-rated firing temperatures. The results also show that increased turbine inlet temperature can result in substantial savings in fuel and capital costs.

  14. Safety considerations in the design and operation of large wind turbines

    NASA Technical Reports Server (NTRS)

    Reilly, D. H.

    1979-01-01

    The engineering and safety techniques used to assure the reliable and safe operation of large wind turbine generators utilizing the Mod 2 Wind Turbine System Program as an example is described. The techniques involve a careful definition of the wind turbine's natural and operating environments, use of proven structural design criteria and analysis techniques, an evaluation of potential failure modes and hazards, and use of a fail safe and redundant component engineering philosophy. The role of an effective quality assurance program, tailored to specific hardware criticality, and the checkout and validation program developed to assure system integrity are described.

  15. Desirable airfoil characteristics for large variable-speed horizontal axis wind turbines

    SciTech Connect

    Giguere, P.; Selig, M.S.

    1997-08-01

    In an effort to define the desirable airfoil characteristics for large variable-speed wind turbines, a systematic study was performed using a series of airfoils designed to have similar aerodynamic properties, except for the amount of lift, which varied over a wide range. For several airfoil combinations, blade shapes were designed for a 750-kW wind turbine with a 48.8-m diameter rotor using the optimization code PROPGA together with PROPID, which is an inverse design method for horizontal-axis wind turbines. Roughness effects, including the consideration of dirty-blade performance in the blade-shape optimization process, were also considered and are discussed. The results and conclusions reveal practical design implications that should aid in the aerodynamic blade design of not only large but also other sizes of variable-speed wind turbines.

  16. Large wind turbines: A utility option for the generation of electricity

    NASA Technical Reports Server (NTRS)

    Robbins, W. H.; Thomas, R. L.; Baldwin, D. H.

    1980-01-01

    The wind resource is such that wind energy generation has the potential to save 6-7 quads of energy nationally. Thus, the Federal Government is sponsoring and encouraging the development of cost effective and reliable wind turbines. One element of the Federal Wind Energy Programs, Large Horizontal Axis Wind Turbine Development, is managed by the NASA Lewis Research Center for the Department of Energy. There are several ongoing wind system development projects oriented primarily toward utility application within this program element. In addition, a comprehensive technology program supporting the wind turbine development projects is being conducted. An overview is presented of the NASA activities with emphasis on application of large wind turbines for generation of electricity by utility systems.

  17. Multiple and variable speed electrical generator systems for large wind turbines

    NASA Technical Reports Server (NTRS)

    Andersen, T. S.; Hughes, P. S.; Kirschbaum, H. S.; Mutone, G. A.

    1982-01-01

    A cost effective method to achieve increased wind turbine generator energy conversion and other operational benefits through variable speed operation is presented. Earlier studies of multiple and variable speed generators in wind turbines were extended for evaluation in the context of a specific large sized conceptual design. System design and simulation have defined the costs and performance benefits which can be expected from both two speed and variable speed configurations.

  18. Weather response to management of a large wind turbine array

    NASA Astrophysics Data System (ADS)

    Barrie, D. B.; Kirk-Davidoff, D. B.

    2009-01-01

    Electrical generation by wind turbines is increasing rapidly, and has been projected to satisfy 15% of world electric demand by 2030. The extensive installation of wind farms would alter surface roughness and significantly impact the atmospheric circulation, due to the additional surface roughness forcing. This forcing could be changed deliberately by adjusting the attitude of the turbine blades with respect to the wind. Using a General Circulation Model (GCM), we represent a continent-scale wind farm as a distributed array of surface roughness elements. Here we show that initial disturbances caused by a step change in roughness grow within four and a half days such that the flow is altered at synoptic scales. The growth rate of the induced perturbations is largest in regions of high atmospheric instability. For a roughness change imposed over North America, the induced perturbations involve substantial changes in the track and development of cyclones over the North Atlantic, and the magnitude of the perturbations rises above the level of forecast uncertainty.

  19. Superconducting light generator for large offshore wind turbines

    NASA Astrophysics Data System (ADS)

    Sanz, S.; Arlaban, T.; Manzanas, R.; Tropeano, M.; Funke, R.; Kováč, P.; Yang, Y.; Neumann, H.; Mondesert, B.

    2014-05-01

    Offshore wind market demands higher power rate and reliable turbines in order to optimize capital and operational cost. These requests are difficult to overcome with conventional generator technologies due to a significant weight and cost increase with the scaling up. Thus superconducting materials appears as a prominent solution for wind generators, based on their capacity to held high current densities with very small losses, which permits to efficiently replace copper conductors mainly in the rotor field coils. However the state-of-the-art superconducting generator concepts still seem to be expensive and technically challenging for the marine environment. This paper describes a 10 MW class novel direct drive superconducting generator, based on MgB2 wires and a modular cryogen free cooling system, which has been specifically designed for the offshore wind industry needs.

  20. Structural fatigue test results for large wind turbine blade sections

    NASA Technical Reports Server (NTRS)

    Faddoul, J. R.; Sullivan, T. L.

    1982-01-01

    In order to provide quantitative information on the operating life capabilities of wind turbine rotor blade concepts for root-end load transfer, a series of cantilever beam fatigue tests was conducted. Fatigue tests were conducted on a laminated wood blade with bonded steel studs, a low cost steel spar (utility pole) with a welded flange, a utility pole with additional root-end thickness provided by a swaged collar, fiberglass spars with both bonded and nonbonded fittings, and, finally, an aluminum blade with a bolted steel fitting (Lockheed Mod-0 blade). Photographs, data, and conclusions for each of these tests are presented. In addition, the aluminum blade test results are compared to field failure information; these results provide evidence that the cantilever beam type of fatigue test is a satisfactory method for obtaining qualitative data on blade life expectancy and for identifying structurally underdesigned areas (hot spots).

  1. Innovative design approaches for large wind turbine blades

    NASA Astrophysics Data System (ADS)

    Jackson, K. J.; Zuteck, M. D.; van Dam, C. P.; Standish, K. J.; Berry, D.

    2005-04-01

    A preliminary design study of an advanced 50 m blade for utility wind turbines is presented and discussed. The effort was part of the Department of Energy WindPACT Blade System Design Study with the goal to investigate and evaluate design and manufacturing issues for wind turbine blades in the 1-10 MW size range. Two different blade designs are considered and compared in this article. The first is a fibreglass design, while the second design selectively incorporates carbon fibre in the main structural elements. The addition of carbon results in modest cost increases and provides significant benefits, particularly with respect to blade deflection. The structural efficiency of both designs was maximized by tailoring the thickness of the blade cross-sections to simplify the construction of the internal members. Inboard the blades incorporate thick blunt trailing edge aerofoils (flatback aerofoils), while outboard more conventional sharp trailing edge high-lift aerofoils are used. The outboard section chord lengths were adjusted to yield the least complex and costly internal blade structure. A significant portion of blade weight is related to the root buildup and metal hardware for typical root attachment designs. The results show that increasing the number of studs has a positive effect on total weight, because it reduces the required root laminate thickness. The aerodynamic performance of the blade aerofoils was predicted using computational techniques that properly simulate blunt trailing edge flows. The performance of the rotor was predicted assuming both clean and soiled blade surface conditions. The rotor is shown to provide excellent performance at a weight significantly lower than that of current rotors of this size. Copyright

  2. Large wind-turbine projects in the United States wind energy program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Robbins, W. H.

    1980-01-01

    The technological development of large, horizontal-axis wind turbines (100 kW-2500 kW) is surveyed with attention to prototype projects managed by NASA. Technical feasibility has been demonstrated in utility service for systems with a rated power of up to 200 kW and a rotor diameter of 125 ft (Mod-OA). Current designs of large wind turbines such as the 2500 kW Mod-2 are projected to be cost competitive for utility applications when produced in quantity, with capital costs of 600 to 700 dollars per kW (in 1977 dollars).

  3. Wind Turbine Wake Variability in a Large Wind Farm, Observed by Scanning Lidar

    NASA Astrophysics Data System (ADS)

    Lundquist, J. K.; Xiaoxia, G.; Aitken, M.; Quelet, P. T.; Rana, J.; Rhodes, M. E.; St Martin, C. M.; Tay, K.; Worsnop, R.; Irvin, S.; Rajewski, D. A.; Takle, E. S.

    2014-12-01

    Although wind turbine wake modeling is critical for accurate wind resource assessment, operational forecasting, and wind plant optimization, verification of such simulations is currently constrained by sparse datasets taken in limited atmospheric conditions, often of single turbines in isolation. To address this knowledge gap, our team deployed a WINDCUBE 200S scanning lidar in a 300-MW operating wind farm as part of the CWEX-13 field experiment. The lidar was deployed ~2000 m from a row of four turbines, such that wakes from multiple turbines could be sampled with horizontal scans. Twenty minutes of every hour were devoted to horizontal scans at ½ degree resolution at six different elevation angles. Twenty-five days of data were collected, with wind speeds at hub height ranging from quiescent to 14 m/s, and atmospheric stability varying from unstable to strongly stable. The example scan in Fig. 1a shows wakes from a row of four turbines propagating to the northwest. This extensive wake dataset is analyzed based on the quantitative approach of Aitken et al. (J. Atmos. Ocean. Technol. 2014), who developed an automated wake detection algorithm to characterize wind turbine wakes from scanning lidar data. We have extended the Aitken et al. (2014) method to consider multiple turbines in a single scan in order to classify the large numbers of wakes observed in the CWEX-13 dataset (Fig. 1b) during southerly flow conditions. The presentation will explore the variability of wake characteristics such as the velocity deficit and the wake width. These characteristics vary with atmospheric stability, atmospheric turbulence, and inflow wind speed. We find that the strongest and most persistent wakes occur at low to moderate wind speeds (region 2 of the turbine power curve) in stable conditions. We also present evidence that, in stable conditions with strong changes of wind direction with height, wakes propagate in different directions at different elevations above the surface

  4. Sound propagation studies for a large horizontal axis wind turbine

    NASA Technical Reports Server (NTRS)

    Shepherd, K. P.; Hubbard, H. H.

    1985-01-01

    Systematic noise measurements in three directions with respect to the wind vector, over a range of distances to 1050 m, over a range of frequencies from 8 Hz to 2000 Hz, and for a stable wind turbine noise source (WTS-4) in windy conditions (V = 9.4 to 13.0 m/s) are presented. At frequencies above 63 Hz in the downwind and crosswind directions the sound pressure levels decay with distance according to predictions based on atmospheric absorption and spherical spreading, assuming no excess attenuation due to ground effects. In the upwind direction there is excess attenuation due to an acoustic shadow zone. The assumption of a distributed noise source leads to better noise estimates in the upwind direction. For very low frequencies 8 to 16 Hz no excess attenuation was observed in the upwind direction at distances up to 1050 m and a sound pressure level decay rate of approximately 3 dB per doubling of distance was observed in the downwind direction.

  5. Theoretical and experimental power from large horizontal-axis wind turbines

    SciTech Connect

    Viterna, L A; Janetzke, D C

    1982-09-01

    A method for calculating the output power from large horizontal-axis wind turbines is presented. Modifications to the airfoil characteristics and the momentum portion of classical blade element-momentum theory are given that improve correlation with measured data. Improvement is particularly evident at low tip speed ratios where aerodynamic stall can occur as the blade experiences high angles of attack. Output power calculated using the modified theory is compared with measured data for several large wind turbines. These wind turbines range in size from the DOE/NASA 100 kW Mod-O (38 m rotor diameter) to the 2000 kW Mod-1 (61 m rotor diameter). The calculated results are in good agreement with measured data from these machines.

  6. Theoretical and experimental power from large horizontal-axis wind turbines

    NASA Technical Reports Server (NTRS)

    Viterna, L. A.; Janetzke, D. C.

    1982-01-01

    A method for calculating the output power from large horizontal-axis wind turbines is presented. Modifications to the airfoil characteristics and the momentum portion of classical blade element-momentum theory are given that improve correlation with measured data. Improvement is particularly evident at low tip-speed ratios where aerodynamic stall can occur as the blade experiences high angles of attack. Output power calculated using the modified theory is compared with measured data for several large wind turbines. These wind turbines range in size from the DOE/NASA 100 kW Mod-0 (38 m rotor diameter) to the 2000 kW Mod-1 (61 m rotor diameter). The calculated results are in good agreement with measured data from these machines.

  7. Free yaw performance of the Mod-0 large horizontal axis 100 kW wind turbine

    NASA Technical Reports Server (NTRS)

    Corrigan, R. D.; Viterna, L. A.

    1982-01-01

    The NASA Mod-0 Large Horizontal Axis 100 kW Wind Turbine was operated in free yaw with an unconed teetered, downwind rotor mounted on a nacelle having 8-1/2 deg tilt. Two series of tests were run, the first series with 19 meter twisted aluminum blades and the second series with 19 meter untwisted steel spar blades with tip control. Rotor speed were nominally 20, 26 and 31 rpm. It was found the nacelle stabilized in free yaw at a yaw angle of between -55 deg to -45 deg was relatively independent of wind speed and was well damped to short term variations in wind direction. Power output of the wind turbine in free yaw, aligned at a large yaw angle, was considerably less than that if the wind turbine were aligned with the wind. For the Mod-0 wind turbine at 26 rpm, the MOSTAB computer code calculations of the free yaw alignment angle and power output compare reasonably well with experimental data. MOSTAB calculations indicate that elimination of tilt and adding coning will improve wind turbine alignment with the wind and that wind shear has a slight detrimental effect on the free yaw alignment angle.

  8. Free yaw performance of the Mod-0 large horizontal axis 100 kW wind turbine

    NASA Astrophysics Data System (ADS)

    Corrigan, R. D.; Viterna, L. A.

    The NASA Mod-0 Large Horizontal Axis 100 kW Wind Turbine was operated in free yaw with an unconed teetered, downwind rotor mounted on a nacelle having 8-1/2 deg tilt. Two series of tests were run, the first series with 19 meter twisted aluminum blades and the second series with 19 meter untwisted steel spar blades with tip control. Rotor speed were nominally 20, 26 and 31 rpm. It was found the nacelle stabilized in free yaw at a yaw angle of between -55 deg to -45 deg was relatively independent of wind speed and was well damped to short term variations in wind direction. Power output of the wind turbine in free yaw, aligned at a large yaw angle, was considerably less than that if the wind turbine were aligned with the wind. For the Mod-0 wind turbine at 26 rpm, the MOSTAB computer code calculations of the free yaw alignment angle and power output compare reasonably well with experimental data. MOSTAB calculations indicate that elimination of tilt and adding coning will improve wind turbine alignment with the wind and that wind shear has a slight detrimental effect on the free yaw alignment angle.

  9. Large Scale Quantum Simulations of Nuclear Pasta

    NASA Astrophysics Data System (ADS)

    Fattoyev, Farrukh J.; Horowitz, Charles J.; Schuetrumpf, Bastian

    2016-03-01

    Complex and exotic nuclear geometries collectively referred to as ``nuclear pasta'' are expected to naturally exist in the crust of neutron stars and in supernovae matter. Using a set of self-consistent microscopic nuclear energy density functionals we present the first results of large scale quantum simulations of pasta phases at baryon densities 0 . 03 < ρ < 0 . 10 fm-3, proton fractions 0 . 05 nuclear symmetry energy on these pasta configurations. This work is supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  10. Large Eddy Simulation study of fully developed thermal wind-turbine array boundary layers

    NASA Astrophysics Data System (ADS)

    Meneveau, Charles; Calaf, Marc; Parlange, Marc B.

    2010-05-01

    It is well known that when wind turbines are deployed in large arrays, their efficiency decreases due to complex interactions among themselves and with the atmospheric boundary layer (ABL). For wind farms whose length exceeds the height of the ABL by over an order of magnitude, a "fully developed" flow regime can be established. In this asymptotic regime, changes in the stream-wise direction can be neglected and the relevant exchanges occur in the vertical direction. Such a fully developed wind-turbine array boundary layer (WTABL) has recently been studied using Large Eddy Simulations (LES) under neutral stability conditions (Calaf et al. Physics of Fluids 22, 2010). Related wind-tunnel experiments on the WTABL are reported in Cal et al., J. Renewable and Sustainable Energy 2, 2010). The simulations showed the existence of two log-laws, one above and one below the wind turbine region. These results confirm basic assumptions made in prior work by Frandsen (J. Wind Eng. Ind. Aerodyn. 39, 1992) and Frandsen et al. (Wind Energy 9, 2006), and have enabled the development of more accurate parameterizations of the effective roughness scale for a wind farm. Now, a suite of Large Eddy Simulations, in which wind turbines are also modeled using the classical "drag disk" concept are performed but for non-neutral conditions. The aim is to study the effects of different thermal ABL stratifications, and thus to better understand the efficiency and characteristics of large wind farms and the associated land-atmosphere interactions for realistic atmospheric flow regimes. Such studies help to unravel the physics involved in extensive aggregations of wind turbines, allowing us to design better wind farm arrangements. By considering various turbine loading factors, surface roughness values and different atmospheric stratifications, it is possible to analyze the influence of these on the induced surface roughness, and the sensible heat roughness length. These last two can be used to

  11. Synchronization of the DOE/NASA 100-kilowatt wind turbine generator with a large utility network

    NASA Technical Reports Server (NTRS)

    Gilbert, L. J.

    1977-01-01

    The DOE/NASA 100 kilowatt wind turbine generator system was synchronized with a large utility network. The system equipments and procedures associated with the synchronization process were described. Time history traces of typical synchronizations were presented indicating that power and current transients resulting from the synchronizing procedure are limited to acceptable magnitudes.

  12. 14 CFR 135.379 - Large transport category airplanes: Turbine engine powered: Takeoff limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Large transport category airplanes: Turbine engine powered: Takeoff limitations. 135.379 Section 135.379 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR CARRIERS AND OPERATORS FOR COMPENSATION OR HIRE: CERTIFICATION AND OPERATIONS...

  13. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. 135.385 Section 135.385 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR CARRIERS AND OPERATORS FOR COMPENSATION OR HIRE: CERTIFICATION...

  14. Influence of atmospheric stability on wind-turbine wakes: A large-eddy simulation study

    NASA Astrophysics Data System (ADS)

    Abkar, Mahdi; Porté-Agel, Fernando

    2014-05-01

    In this study, large-eddy simulation is combined with a turbine model to investigate the influence of atmospheric stability on wind-turbine wakes. In the simulations, subgrid-scale turbulent fluxes are parameterized using tuning-free Lagrangian scale-dependent dynamic models. These models optimize the local value of the model coefficients based on the dynamics of the resolved scales. The turbine-induced forces are parameterized with an actuator-disk model with rotation. In this technique, blade-element theory is used to calculate the lift and drag forces acting on the blades. Emphasis is placed on the structure and characteristics of wind-turbine wakes in the cases where the incident flows to the turbine have the same mean velocity at the hub height but different stability conditions. The simulation results show that atmospheric stability has a significant effect on the spatial distribution of the mean velocity deficit and turbulent fluxes in the wake region. In particular, the magnitude of the velocity deficit increases with increasing stability in the atmosphere. In addition, the locations of the maximum turbulence intensity and turbulent stresses are closer to the turbine in convective boundary layer compared with neutral and stable ones. Detailed analysis of the resolved turbulent kinetic energy (TKE) budget inside the wake reveals also that the thermal stratification of the incoming wind considerably affects the magnitude and spatial distribution of the turbulent production, transport term and dissipation rate (transfer of energy to the subgrid scales). It is also shown that the near-wake region can be extended to a farther distance downstream in stable condition compared with neutral and unstable counterparts. In order to isolate the effect of atmospheric stability, additional simulations of neutrally-stratified atmospheric boundary layers are performed with the same turbulence intensity at hub height as convective and stable ones. The results show that the

  15. Effects of Large Energetic Vortices on Axial-Flow Hydrokinetic Turbines

    SciTech Connect

    Gunawan, Budi; Neary, Vincent S; Hill, Craig; Chamorro, Leonardo

    2012-01-01

    Large scale coherent motions around marine and hydrokinetic (MHK) machines can significantly increase the structural loading and affect the overall performance of the machines. Characterization of the approach turbulence and their impact on the instantaneous response of MHK devices is essential for improving their design and performance. This preliminary study investigates the effect of turbulence and dominant energetic coherent structures induced by a vertical cylinder on the structural load and energy production in a model MHK turbine. Results show that the power generated by the turbine is significantly reduced by the presence of the cylinder. This reduction depends on the distance from the cylinder and the level of turbulence around the rotor area.

  16. Approximate method for calculating free vibrations of a large-wind-turbine tower structure

    NASA Technical Reports Server (NTRS)

    Das, S. C.; Linscott, B. S.

    1977-01-01

    A set of ordinary differential equations were derived for a simplified structural dynamic lumped-mass model of a typical large-wind-turbine tower structure. Dunkerley's equation was used to arrive at a solution for the fundamental natural frequencies of the tower in bending and torsion. The ERDA-NASA 100-kW wind turbine tower structure was modeled, and the fundamental frequencies were determined by the simplified method described. The approximate fundamental natural frequencies for the tower agree within 18 percent with test data and predictions analyzed.

  17. 14 CFR 135.383 - Large transport category airplanes: Turbine engine powered: En route limitations: Two engines...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Large transport category airplanes: Turbine... DEMAND OPERATIONS AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Airplane Performance Operating Limitations § 135.383 Large transport category airplanes: Turbine engine powered: En route limitations:...

  18. Stratificaiton Effects on wake of large wind turbines in wind farm

    NASA Astrophysics Data System (ADS)

    Bhaganagar, Kiran; Debnath, Mithu

    2013-11-01

    The focus of the present talk is to demonstrate the interplay of the complex interactions between the wind turbulence and the wake turbulence under different stratification conditions. Large eddy simulation (LES) has been used to simulate flow over multi mega-watt wind turbines. The results have revealed different empirical relations for the mean velocity deficit decay and turbulence kinetic energy decay rates in the wake region of the wind turbine. The simulation for wind farm has revealed the wake decay rates as a function of the radial and streamwise distance from the upstream wind turbine. Vertical mixing plays a major role in altering the flow dynamics in the wake region. Support from NSF CBET-1348480, NSF HRD-1242180 and TACC Supercomputing.

  19. Large-eddy simulations of a single vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Rahromostaqim, Mahsa; Posa, Antonio; Balaras, Elias; Leftwich, Megan

    2013-11-01

    Recently vertical axis wind turbines (VAWTs) have been receiving increased attention due to various potential advantages over the more common horizontal axis wind turbines. They can be placed for example in urban areas where space is limited, since they are moderately sized and virtually silent. In this study we will report large-eddy simulations (LES) of a Windspire VAWT. Computations will be conducted using an immersed boundary formulation, where the equations of motion are solved on a fixed Cartesian grid and the turbine blades rotate with a fixed tip speed ratio. The primary objective of this first series of LES is to understand the interaction between the wakes generated by the individual airfoils. To keep the computational cost low and increase the parametric regime we can examine, we will consider only part of the turbine hight and utilize periodic boundary conditions along the turbine axis. The computations will exactly mimic the conditions of closely coordinated experiments of a scaled down VAWT, which will enable us to access the impact of features that will not be captured, such as the tip vortices for example, on the results. Preliminary results reveal a complex interaction of the wakes created by the rotating airfoils and the boundary layer on the airfoils.

  20. Optimized Application of MSR and Steam Turbine Retrofits in Nuclear Power Plants

    SciTech Connect

    Crossland, Robert; McCoach, John; Gagelin, Jean-Philippe

    2004-07-01

    The benefit to a nuclear power plant from a steam turbine retrofit has often been clearly demonstrated in recent years but, for light water nuclear plants, the Moisture Separator Reheaters (MSRs) are also of prime importance. This paper describes how refurbishment of these crucial components can only provide full potential performance benefit when made in conjunction with a steam turbine retrofit (although in practice these activities are frequently separated). Examples are given to show how combined application is best handled within a single organization to ensure optimized integration into the thermal cycle. (authors)

  1. Size Reduction Techniques for Large Scale Permanent Magnet Generators in Wind Turbines

    NASA Astrophysics Data System (ADS)

    Khazdozian, Helena; Hadimani, Ravi; Jiles, David

    2015-03-01

    Increased wind penetration is necessary to reduce U.S. dependence on fossil fuels, combat climate change and increase national energy security. The U.S Department of Energy has recommended large scale and offshore wind turbines to achieve 20% wind electricity generation by 2030. Currently, geared doubly-fed induction generators (DFIGs) are typically employed in the drivetrain for conversion of mechanical to electrical energy. Yet, gearboxes account for the greatest downtime of wind turbines, decreasing reliability and contributing to loss of profit. Direct drive permanent magnet generators (PMGs) offer a reliable alternative to DFIGs by eliminating the gearbox. However, PMGs scale up in size and weight much more rapidly than DFIGs as rated power is increased, presenting significant challenges for large scale wind turbine application. Thus, size reduction techniques are needed for viability of PMGs in large scale wind turbines. Two size reduction techniques are presented. It is demonstrated that 25% size reduction of a 10MW PMG is possible with a high remanence theoretical permanent magnet. Additionally, the use of a Halbach cylinder in an outer rotor PMG is investigated to focus magnetic flux over the rotor surface in order to increase torque. This work was supported by the National Science Foundation under Grant No. 1069283 and a Barbara and James Palmer Endowment at Iowa State University.

  2. Comparison of measured and calculated sound pressure levels around a large horizontal axis wind turbine generator

    NASA Technical Reports Server (NTRS)

    Shepherd, Kevin P.; Willshire, William L., Jr.; Hubbard, Harvey H.

    1989-01-01

    Results are reported from a large number of simultaneous acoustic measurements around a large horizontal axis downwind configuration wind turbine generator. In addition, comparisons are made between measurements and calculations of both the discrete frequency rotational harmonics and the broad band noise components. Sound pressure time histories and noise radiation patterns as well as narrow band and broadband noise spectra are presented for a range of operating conditions. The data are useful for purposes of environmental impact assessment.

  3. Numerical simulation of pressure fluctuations in a large Francis turbine runner

    NASA Astrophysics Data System (ADS)

    Wang, Fujun; Liao, Cuilin; Tang, Xuelin

    2012-11-01

    The pressure fluctuation caused by unsteady flow in runner is one of the main reasons of vibration for a large Francis hydraulic turbine. It directly affects the steady operation of the hydraulic turbine unit. The existing research of the pressure fluctuation in hydraulic turbine mainly focuses on the unsteady flow in draft tube. Accurate distribution of pressure fluctuations inside a runner is not very clear. In this paper, the numerical method for predicting the pressure fluctuations in runner is investigated and the numerical simulation is performed for a large Francis hydraulic turbine. It is proved that the combination of shear-stress transport(SST) k- ω turbulence model and pressure-implicit with splitting of operators(PISO) algorithm could give more reliable prediction of pressure fluctuations in runner. The frequencies of pressure fluctuations in runner are affected by the flow in guide vane and the flow in draft tube. The first dominant frequency is significantly determined by the flow in draft tube, especially at part load condition. This frequency is approximately equal to one-third of the runner rotating frequency. The evident second dominant frequency is exactly equal to the guide vane passing frequency. The peak-to-peak amplitudes of pressure fluctuations in runner at small guide vane open angle are larger than that at large open angle at the same operating head. The amplitudes at points on blade pressure surface are generally greater than that on suction surface. The research results could be used to direct the hydraulic design and operation stability improvement of a large Francis hydraulic turbine.

  4. Large eddy simulations of vertical axis wind turbines to optimize farm design

    NASA Astrophysics Data System (ADS)

    Hezaveh, Seyed Hossein; Bou-Zeid, Elie

    2013-11-01

    Wind energy production, and research have expanded considerably in the past decade. These efforts aim to reduce dependence on fossil fuels and the greenhouse gas emissions associated with current modes of energy production. However, with expanding wind farms, the land areas occupied by such farms become a limitation. Recently, interest in vertical axis wind turbines (VAWTs) has increased due to key advantages of this technology: compared to horizontal axis turbines, VAWTs can be built with larger scales, their performance is not sensitive to wind direction, and the ability to place their generators at the bottom of the mast can make them more stable offshore. In this study, we focus on how the Aspheric Boundary Layer (ABL) will react to the presence of large VAWT farms. We present a state-of-art representation of VAWTs using an actuator line model in a Large Eddy Simulations code for the ABL. Validations are made against several experimental datasets, which include flow details and power coefficient curves, the wake of an individual turbine is visualized and analyzed, and the interaction of adjacent turbines is investigated in view of optimizing their interactions and the configuration of VAWT farms.

  5. Measurement and prediction of broadband noise from large horizontal axis wind turbine generators

    NASA Technical Reports Server (NTRS)

    Grosveld, F. W.; Shepherd, K. P.; Hubbard, H. H.

    1995-01-01

    A method is presented for predicting the broadband noise spectra of large wind turbine generators. It includes contributions from such noise sources as the inflow turbulence to the rotor, the interactions between the turbulent boundary layers on the blade surfaces with their trailing edges and the wake due to a blunt trailing edge. The method is partly empirical and is based on acoustic measurements of large wind turbines and airfoil models. Spectra are predicted for several large machines including the proposed MOD-5B. Measured data are presented for the MOD-2, the WTS-4, the MOD-OA, and the U.S. Windpower Inc. machines. Good agreement is shown between the predicted and measured far field noise spectra.

  6. Retrofit of LP rotors on nuclear turbines in Belgium

    SciTech Connect

    Aubry, P.; Billerey, B.; Goffin, J.P.

    1996-11-01

    Tractebel Energy Engineering (TEE) had several options available for eliminating the defects related to stress-corrosion in the LP shrunk-on disk rotors of 500 and 1,000 MW turbines. After conducting a technical and financial analysis, TEE decided to replace the existing rotors with welded rotors associated with a new steam path: the performance improvements proposed and guaranteed by Gec Alsthom (GA) have helped to economically justify the replacement solution. Moreover the new technology implemented will increase turbine reliability and availability. The heat rate tests carried out on Tihange 1 have revealed a gain greater than expected, thus confirming the better performance of the new steam path, designed by GA and the right choice made by TEE and its customers.

  7. Large-Eddy Simulations of Wind Turbine Wakes Subject to Different Atmospheric Stabilities

    NASA Astrophysics Data System (ADS)

    Churchfield, M.; Lundquist, J. K.; Lee, S.; Clifton, A.

    2014-12-01

    As a byproduct of energy extraction, wind turbines create a low-speed, turbulent wake that propagate downwind. When wind turbines are situated in a group, as in a wind plant, the interactions of these wakes with other turbines are important because wake effects decrease the efficiency of the wind plant, and they increase mechanical loads on individual turbines. Wakes propagate downstream differently depending on the inflow conditions, and these conditions are heavily dominated by atmospheric stability. For example, we know that wakes are more persistent in stable conditions than in unstable conditions. Also, stable conditions often have significant wind veer which skews wakes laterally. Different levels of turbulence intensity are associated with different atmospheric stability levels, and turbulence intensity acts to diffuse wakes and to cause wake meandering. Wake physics are complex, and to understand them better, a high-resolution representation of the flow is necessary. Measurements are difficult with current sensing equipment because of the sheer size of wakes and the unsteady atmospheric environment in which they are found. Numerical simulations complement measurements and provide a high-resolution representation of the entire three-dimensional, unsteady flow field. In this work, we use large-eddy simulation (LES), the highest fidelity type of computational fluid dynamics (CFD) feasible for high-Reynolds-number wake flow. LES directly resolves the larger, energy-containing turbulent scales and models the effects of the subgrid scales that the computational mesh cannot resolve. Our solver is based on the OpenFOAM open-source CFD toolbox. Turbines are modeled using rotating actuator lines. Here, we present our LES of the wake behind a modern 1.5 MW turbine subject to different inflow atmospheric stability. We will present results of wakes subject to stable (strongly and weakly stable), neutral, and unstable conditions. We are particularly interested in how

  8. Compressor and Turbine Models of Brayton Units for Space Nuclear Power Systems

    SciTech Connect

    Gallo, Bruno M.; El-Genk, Mohamed S.; Tournier, Jean-Michel

    2007-01-30

    Closed Brayton Cycles with centrifugal flow, single-shaft turbo-machines are being considered, with gas cooled nuclear reactors, to provide 10's to 100's of electrical power to support future space exploration missions and Lunar and Mars outposts. Such power system analysis is typically based on the cycle thermodynamics, for given operating pressures and temperatures and assumed polytropic efficiencies of the compressor and turbine of the Brayton energy conversion units. Thus the analysis results not suitable for modeling operation transients such as startup and changes in the electric load. To simulate these transients, accurate models of the turbine and compressor in the Brayton rotating unit, which calculate the changes in the compressor and turbine efficiencies with system operation are needed. This paper presents flow models that account for the design and dimensions of the compressor impeller and diffuser, and the turbine stator and rotor blades. These models calculate the various enthalpy losses and the polytropic efficiencies along with the pressure ratios of the turbine and compressor. The predictions of these models compare well with reported performance data of actual hardware. In addition, the results of a parametric analysis to map the operations of the compressor and turbine, as functions of the rotating shaft speed and inlet Mach number of the gas working fluid, are presented and discussed. The analysis used a binary mixture of He-Xe with a molecular weight of 40 g/mole as the working fluid.

  9. Compressor and Turbine Models of Brayton Units for Space Nuclear Power Systems

    NASA Astrophysics Data System (ADS)

    Gallo, Bruno M.; El-Genk, Mohamed S.; Tournier, Jean-Michel

    2007-01-01

    Closed Brayton Cycles with centrifugal flow, single-shaft turbo-machines are being considered, with gas cooled nuclear reactors, to provide 10's to 100's of electrical power to support future space exploration missions and Lunar and Mars outposts. Such power system analysis is typically based on the cycle thermodynamics, for given operating pressures and temperatures and assumed polytropic efficiencies of the compressor and turbine of the Brayton energy conversion units. Thus the analysis results not suitable for modeling operation transients such as startup and changes in the electric load. To simulate these transients, accurate models of the turbine and compressor in the Brayton rotating unit, which calculate the changes in the compressor and turbine efficiencies with system operation are needed. This paper presents flow models that account for the design and dimensions of the compressor impeller and diffuser, and the turbine stator and rotor blades. These models calculate the various enthalpy losses and the polytropic efficiencies along with the pressure ratios of the turbine and compressor. The predictions of these models compare well with reported performance data of actual hardware. In addition, the results of a parametric analysis to map the operations of the compressor and turbine, as functions of the rotating shaft speed and inlet Mach number of the gas working fluid, are presented and discussed. The analysis used a binary mixture of He-Xe with a molecular weight of 40 g/mole as the working fluid.

  10. Prediction of broadband noise from large horizontal axis wind turbine generators

    NASA Technical Reports Server (NTRS)

    Grosveld, F. W.

    1984-01-01

    A method is presented for predicting the broadband noise spectra of large horizontal axis wind turbine generators. It includes contributions from such noise sources as the inflow turbulence to the rotor, the interactions between the turbulent boundary layers on the blade surfaces with their trailing edges and the wake due to a blunt trailing edge. The method is partly empirical and is based on acoustic measurements of large wind turbines and airfoil models. The predicted frequency spectra are compared with measured data from several machines including the MOD-OA, the MOD-2, the WTS-4 and the U.S. Wind-power Inc. machine. Also included is a broadband noise prediction for the proposed MOD-5B. The significance of the effects of machine size, power output, trailing edge bluntness and distance to the receiver is illustrated. Good agreement is obtained between the predicted and measured far field noise spectra.

  11. A method to estimate weight and dimensions of large and small gas turbine engines

    NASA Technical Reports Server (NTRS)

    Onat, E.; Klees, G. W.

    1979-01-01

    A computerized method was developed to estimate weight and envelope dimensions of large and small gas turbine engines within + or - 5% to 10%. The method is based on correlations of component weight and design features of 29 data base engines. Rotating components were estimated by a preliminary design procedure which is sensitive to blade geometry, operating conditions, material properties, shaft speed, hub tip ratio, etc. The development and justification of the method selected, and the various methods of analysis are discussed.

  12. A simplified model for average kinetic energy flux within large wind turbine arrays

    NASA Astrophysics Data System (ADS)

    Markfort, Corey; Zhang, Wei; Porte-Agel, Fernando

    2015-11-01

    We investigate the kinetic energy distribution within an array of wind turbines using a 1-D model for the interactions between large-scale wind farms and the atmospheric boundary layer (ABL). Obstructed shear flow scaling is used to predict the development length of the wind farm flow as well as vertical momentum flux. Within the region of flow development, momentum and energy is advected into the wind farm and wake turbulence draws excess momentum in from between turbines. This is characterized by large dispersive fluxes. Once the flow within the farm is developed, the area - averaged velocity profile exhibits an inflection point, characteristic of obstructed shear flows. The inflected velocity profile is responsible for a characteristic turbulence eddy scale, which may be responsible for a significant amount of the vertical momentum and energy flux. Prediction of this scale is useful for determining the amount of available power for harvesting. The model result for kinetic energy flux is compared to wind tunnel measurements. The model is useful for optimizing wind turbine spacing and layout, and for assessing the impacts of wind farms on nearby wind resources and the environment.

  13. Flutter performance of bend-twist coupled large-scale wind turbine blades

    NASA Astrophysics Data System (ADS)

    Hayat, Khazar; de Lecea, Alvaro Gorostidi Martinez; Moriones, Carlos Donazar; Ha, Sung Kyu

    2016-05-01

    The bend-twist coupling (BTC) is proven to be effective in mitigating the fatigue loads for large-scale wind turbine blades, but at the same time it may cause the risk of flutter instability. The BTC is defined as a feature of twisting of the blade induced by the primary bending deformation. In the classical flutter, the BTC arises from the aerodynamic loads changing with the angle of attack. In this study, the effects of the structural BTC on the flutter are investigated by considering the layup unbalances (ply angle, material and thickness of the composite laminates) in the NREL 5-MW wind turbine rotor blade of glass fiber/epoxy [02/+45/-45]S laminates. It is numerically shown that the flutter speed may decrease by about 5 percent with unbalanced ply-angle only (one side angle, from 45° to 25°). It was then demonstrated that the flutter performance of the wind turbine blade can be increased by using lighter and stiffer carbon fibers which ensures the higher structural BTC at the same time.

  14. Usage of advanced thick airfoils for the outer part of very large offshore turbines

    NASA Astrophysics Data System (ADS)

    Grasso, F.; Ceyhan, O.

    2014-06-01

    Nowadays one of the big challenges in wind energy is connected to the development of very large wind turbines with 100 m blades and 8-10MW power production. The European project INNWIND.EU plays an important role in this challenge because it is focused on exploring and exploiting technical innovations to make these machines not only feasible but also cost effective. In this context, the present work investigates the benefits of adopting thick airfoils also at the outer part of the blade. In fact, if these airfoils are comparable to the existing thinner ones in terms of aerodynamics, the extra thickness would lead to a save in weight. Lightweight blades would visibly contribute to reduce the cost of energy of the turbines and make them cost effective. The reference turbine defined in INNWIND.EU project has been adjusted to use the new airfoils. The results show that the rotor performance is not sacrificed when the 24% airfoils are replaced by the ECN 30% thick airfoils, while 24% extra thickness can be obtained.

  15. A large-eddy simulation study of wake propagation and power production in an array of tidal-current turbines.

    PubMed

    Churchfield, Matthew J; Li, Ye; Moriarty, Patrick J

    2013-02-28

    This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally periodic precursor simulation is performed to create turbulent flow data. Then those data are used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modelled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. We found that staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement. For example, using a larger precursor domain would better capture elongated turbulent structures, and including salinity and temperature equations would account for density stratification and its effect on turbulence. Additionally, the wall shear stress modelling could be improved, and more array configurations could be examined. PMID:23319713

  16. Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines: Preprint

    SciTech Connect

    Churchfield, M. J.; Li, Y.; Moriarty, P. J.

    2012-07-01

    This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. Staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement, such as the use of a larger precursor domain to better capture elongated turbulent structures, the inclusion of salinity and temperature equations to account for density stratification and its effect on turbulence, improved wall shear stress modelling, and the examination of more array configurations.

  17. Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines: Preprint

    SciTech Connect

    Churchfield, M. J.; Li, Y.; Moriarty, P. J.

    2011-07-01

    This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used to determine the inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. Staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement, such as the use of a larger precursor domain to better capture elongated turbulent structures, the inclusion of salinity and temperature equations to account for density stratification and its effect on turbulence, improved wall shear stress modeling, and the examination of more array configurations.

  18. Large-eddy simulation of 3D turbulent flow past a complete marine hydrokinetic turbine

    NASA Astrophysics Data System (ADS)

    Kang, S.; Sotiropoulos, F.

    2011-12-01

    A high-resolution computational framework was recently developed by Kang et al (Adv. Water Resour., submitted) for simulating three-dimensional (3D), turbulent flow past real-life, complete marine hydrokinetic (MHK) turbine configurations. In this model the complex turbine geometry is resolved by employing the curvilinear immersed boundary (CURVIB) method, which solves the 3D unsteady incompressible Navier-Stokes equations in generalized curvilinear domains with embedded arbitrarily complex, moving and/or stationary immersed boundaries (Ge and Sotiropoulos, 2007). Turbulence is simulated using the large-eddy simulation (LES) approach adapted in the context of the CURVIB method, with a wall model based on solving the simplified boundary layer equations used to reconstruct boundary conditions near all solid surfaces (Kang et al., 2011). The model can resolve the flow patterns generated by the rotor and all stationary components of the turbine as well as the interactions of the flow structures with the channel bed. We apply this model to carry out LES of the flow past the model-size hydrokinetic turbine deployed in the St. Anthony Falls Laboratory main channel. The mean velocities and second-order turbulence statistics measured in the downstream wake using acoustic Doppler velocimetry (ADV) are compared with the LES results. The comparisons show that the computed mean velocities and turbulent stresses are in good agreement with the measurements. The high-resolution LES data are used to explore physically important downstream flow characteristics such as the time-averaged wake structure, recovery of cross-sectionally averaged power potential, near-bed scour potential, etc. This work is supported by Verdant Power.

  19. Computational Assessment of the Aerodynamic Performance of a Variable-Speed Power Turbine for Large Civil Tilt-Rotor Application

    NASA Technical Reports Server (NTRS)

    Welch, Gerard E.

    2011-01-01

    The main rotors of the NASA Large Civil Tilt-Rotor notional vehicle operate over a wide speed-range, from 100% at take-off to 54% at cruise. The variable-speed power turbine offers one approach by which to effect this speed variation. Key aero-challenges include high work factors at cruise and wide (40 to 60 deg.) incidence variations in blade and vane rows over the speed range. The turbine design approach must optimize cruise efficiency and minimize off-design penalties at take-off. The accuracy of the off-design incidence loss model is therefore critical to the turbine design. In this effort, 3-D computational analyses are used to assess the variation of turbine efficiency with speed change. The conceptual design of a 4-stage variable-speed power turbine for the Large Civil Tilt-Rotor application is first established at the meanline level. The design of 2-D airfoil sections and resulting 3-D blade and vane rows is documented. Three-dimensional Reynolds Averaged Navier-Stokes computations are used to assess the design and off-design performance of an embedded 1.5-stage portion-Rotor 1, Stator 2, and Rotor 2-of the turbine. The 3-D computational results yield the same efficiency versus speed trends predicted by meanline analyses, supporting the design choice to execute the turbine design at the cruise operating speed.

  20. Improving the turbine district heating installations of single-circuit nuclear power plants

    NASA Astrophysics Data System (ADS)

    Kondurov, E. P.; Kruglikov, P. A.; Smolkin, Yu. V.

    2015-10-01

    Ways for improving the turbine district heating installations of single-circuit nuclear power plants are considered as a possible approach to improving the nuclear power plant energy efficiency. The results of thermal tests carried out at one of single-circuit NPPs in Russia with a view to reveal the possibilities of improving the existing heat-transfer equipment of the turbine district heating installation without making significant investments in it were taken as a basis for the analysis. The tests have shown that there is certain energy saving potential in some individual units and elements in the turbine district heating installation's process circuit. A significant amount of thermal energy can be obtained only by decreasing the intermediate circuit temperature at the inlet to the heater of the first district-heating extraction. The taking of this measure will also lead to an additional amount of generated electricity because during operation with the partially loaded first heater, the necessary amount of heat has to be obtained from the peaking heater by reducing live steam. An additional amount of thermal energy can also be obtained by eliminating leaks through the bypass control valves. The possibility of achieving smaller consumption of electric energy for power plant auxiliaries by taking measures on reducing the available head in the intermediate circuit installation's pump unit is demonstrated. Partial cutting of pump impellers and dismantling of control valves are regarded to be the most efficient methods. The latter is attributed to qualitative control of the turbine district heating installation's thermal load. Adjustment of the noncondensable gas removal system will make it possible to improve the performance of the turbine district heating installation's heat-transfer equipment owing to bringing the heat-transfer coefficients in the heaters to the design level. The obtained results can be used for estimating the energy saving potential at other

  1. Aerodynamic Investigation of Incidence Angle Effects in a Large Scale Transonic Turbine Cascade

    NASA Technical Reports Server (NTRS)

    McVetta, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2013-01-01

    Aerodynamic measurements showing the effects of large incidence angle variations on an HPT turbine blade set are presented. Measurements were made in NASA's Transonic Turbine Blade Cascade Facility which has been used in previous studies to acquire detailed aerodynamic and heat transfer measurements for CFD code validation. The current study supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50 percent speed range from takeoff to altitude cruise. This results in 50deg or more variations in VSPT blade incidence angles. The cascade facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Using existing blade geometry with previously acquired aerodynamic data, the tunnel was re-baselined and the new incidence angle range was exercised. Midspan exit total pressure and flow angle measurements were obtained at seven inlet flow angles. For each inlet angle, data were obtained at five flow conditions with inlet Reynolds numbers varying from 6.83×10(exp 5) to 0.85×10(exp 5) and two isentropic exit Mach numbers of 0.74 and 0.34. The midspan flowfield measurements were acquired using a three-hole pneumatic probe located in a survey plane 8.6 percent axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.

  2. Aerodynamic Investigation of Incidence Angle Effects in a Large Scale Transonic Turbine Cascade. Revision 1

    NASA Technical Reports Server (NTRS)

    McVetta, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2014-01-01

    Aerodynamic measurements showing the effects of large incidence angle variations on an HPT turbine blade set are presented. Measurements were made in NASA's Transonic Turbine Blade Cascade Facility which has been used in previous studies to acquire detailed aerodynamic and heat transfer measurements for CFD code validation. The current study supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50 percent speed range from takeoff to altitude cruise. This results in 50 deg or more variations in VSPT blade incidence angles. The cascade facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Using existing blade geometry with previously acquired aerodynamic data, the tunnel was re-baselined and the new incidence angle range was exercised. Midspan exit total pressure and flow angle measurements were obtained at seven inlet flow angles. For each inlet angle, data were obtained at five flow conditions with inlet Reynolds numbers varying from 6.83×10 (exp 5) to 0.85×10(exp 5) and two isentropic exit Mach numbers of 0.74 and 0.34. The midspan flowfield measurements were acquired using a three-hole pneumatic probe located in a survey plane 8.6 percent axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.

  3. Aerodynamic Investigation of Incidence Angle Effects in a Large Scale Transonic Turbine Cascade

    NASA Technical Reports Server (NTRS)

    McVetta, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2012-01-01

    Aerodynamic measurements showing the effects of large incidence angle variations on an HPT turbine blade set are presented. Measurements were made in NASA's Transonic Turbine Blade Cascade Facility which has been used in previous studies to acquire detailed aerodynamic and heat transfer measurements for CFD code validation. The current study supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50% speed range from takeoff to altitude cruise. This results in 50 degrees or more variations in VSPT blade incidence angles. The cascade facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Using existing blade geometry with previously acquired aerodynamic data, the tunnel was re-baselined and the new incidence angle range was exercised. Midspan exit total pressure and flow angle measurements were obtained at seven inlet flow angles. For each inlet angle, data were obtained at five flow conditions with inlet Reynolds numbers varying from 6.83 × 10(exp 5) to 0.85 ×10(exp 5) and two isentropic exit Mach numbers of 0.74 and 0.34. The midspan flowfield measurements were acquired using a three-hole pneumatic probe located in a survey plane 8.6% axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition

  4. Aging of turbine drives for safety-related pumps in nuclear power plants

    SciTech Connect

    Cox, D.F.

    1995-06-01

    This study was performed to examine the relationship between time-dependent degradation and current industry practices in the areas of maintenance, surveillance, and operation of steam turbine drives for safety-related pumps. These pumps are located in the Auxiliary Feedwater (AFW) system for pressurized-water reactor plants and in the Reactor Core Isolation Cooling and High-Pressure Coolant Injection systems for boiling-water reactor plants. This research has been conducted by examination of failure data in the Nuclear Plant Reliability Data System, review of Licensee Event Reports, discussion of problems with operating plant personnel, and personal observation. The reported failure data were reviewed to determine the cause of the event and the method of discovery. Based on the research results, attempts have been made to determine the predictability of failures and possible preventive measures that may be implemented. Findings in a recent study of AFW systems indicate that the turbine drive is the single largest contributor to AFW system degradation. However, examination of the data shows that the turbine itself is a reliable piece of equipment with a good service record. Most of the problems documented are the result of problems with the turbine controls and the mechanical overspeed trip mechanism; these apparently stem from three major causes which are discussed in the text. Recent improvements in maintenance practices and procedures, combined with a stabilization of the design, have led to improved performance resulting in a reliable safety-related component. However, these improvements have not been universally implemented.

  5. Wind flow characteristics in the wakes of large wind turbines. Volume 1: Analytical model development

    NASA Technical Reports Server (NTRS)

    Eberle, W. R.

    1981-01-01

    A computer program to calculate the wake downwind of a wind turbine was developed. Turbine wake characteristics are useful for determining optimum arrays for wind turbine farms. The analytical model is based on the characteristics of a turbulent coflowing jet with modification for the effects of atmospheric turbulence. The program calculates overall wake characteristics, wind profiles, and power recovery for a wind turbine directly in the wake of another turbine, as functions of distance downwind of the turbine. The calculation procedure is described in detail, and sample results are presented to illustrate the general behavior of the wake and the effects of principal input parameters.

  6. A Wind-Tunnel Simulation of the Wake of a Large Wind Turbine in a Weakly Unstable Boundary Layer

    NASA Astrophysics Data System (ADS)

    Hancock, P. E.; Zhang, S.

    2015-09-01

    Measurements have been made in the wake of a model wind turbine in both a weakly unstable and a baseline neutral atmospheric boundary layer, in the EnFlo stratified-flow wind tunnel, between 0.5 and 10 rotor diameters from the turbine, as part of an investigation of wakes in offshore winds. In the unstable case the velocity deficit decreases more rapidly than in the neutral case, largely because the boundary-layer turbulence levels are higher with consequent increased mixing. The height and width increase more rapidly in the unstable case, though still in a linear manner. The vertical heat flux decreases rapidly through the turbine, recovering to the undisturbed level first in the lower part of the wake, and later in the upper part, through the growth of an internal layer. At 10 rotor diameters from the turbine, the wake has strong features associated with the surrounding atmospheric boundary layer. A distinction is drawn between direct effects of stratification, as necessarily arising from buoyant production, and indirect effects, which arise only because the mean shear and turbulence levels are altered. Some aspects of the wake follow a similarity-like behaviour. Sufficiently far downstream, the decay of the velocity deficit follows a power law in the unstable case as well as the neutral case, but does so after a shorter distance from the turbine. Tentatively, this distance is also shorter for a higher loading on the turbine, while the power law itself is unaffected by turbine loading.

  7. Large Parabolic Dish collectors with small gas-turbine, Stirling engine or photovoltaic power conversion systems

    SciTech Connect

    Gehlisch, K.; Heikal, H.; Mobarak, A.; Simon, M.

    1982-08-01

    A comparison for different solar thermal power plants is presented and demonstrates that the large parabolic dish in association with a gas turbine or a Sterling engine could be a competitive system design in the net power range of 50-1000KW. The important advantages of the Large Parabolic Dish concept compared to the Farm and Tower concept are discussed: concentration ratios up to 5000 and uniform heat flux distribution throughout the day which allow very high receiver temperatures and therefor high receiver efficiency to operate effectively Stirling motors or small gas turbines in the mentioned power range with an overall efficiency of 20 to 30%. The high focal plane concentration leads to the efficient use of ceramic materials for receivers of the next generation, applicable in temperature ranges up to 1,300 /sup 0/C for energy converters. Besides the production of electricity, the system can supply process heat in the temperature range of 100 to 400 /sup 0/C as waste heat from the gas turbo converter and heat at temperature levels from 500 to 900 /sup 0/C (1300 /sup 0/C) directly out of the receiver.

  8. Detection of very large ions in aircraft gas turbine engine combustor exhaust: charged small soot particles?

    NASA Astrophysics Data System (ADS)

    Wilhelm, S.; Haverkamp, H.; Sorokin, A.; Arnold, F.

    Small electrically charged soot particles (CSP) present in the exhaust of a jet aircraft engine combustor have been detected by a Large Ion Mass Spectrometer and quantitatively measured by an Ion Mobility Analyzer. The size and concentration measurements which took place at an aircraft gas-turbine engine combustor test-rig at the ground covered different combustor conditions (fuel flow=FF, fuel sulphur content=FSC). At the high-pressure turbine stage of the engine, CSP-diameters were mostly around 6 nm and CSP-concentrations reached up to 4.8×10 7 cm -3 (positive and negative) corresponding to a CSP-emission index ECSP=2.5×10 15 CSP kg -1 fuel burnt. The ECSP increased with FF but did not increase with FSC. The latter indicates that sulphur was not a major component of the large ions. Possible CSP-sources and CSP-sinks as well as CSP-roles are discussed.

  9. Large eddy simulation of a large wind-turbine array in a conventionally neutral atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Allaerts, Dries; Meyers, Johan

    2015-06-01

    Under conventionally neutral conditions, the boundary layer is frequently capped by an inversion layer, which counteracts vertical entrainment of kinetic energy. Very large wind farms are known to depend on vertical entrainment to transport energy from above the farm towards the turbines. In this study, large eddy simulations of an infinite wind-turbine array in a conventionally neutral atmospheric boundary layer are performed. By carefully selecting the initial potential-temperature profile, the influence of the height and the strength of a capping inversion on the power output of a wind farm is investigated. Results indicate that both the height and the strength have a significant effect on the boundary layer flow, and that the height of the neutral boundary layer is effectively controlled by the capping inversion. In addition, it is shown that the vertical entrainment rate decreases for increasing inversion strength or height. In our infinite wind-farm simulations, varying the inversion characteristics leads to differences in power extraction on the order of 13% ± 0.2% (for increasing the strength from 2.5 to 10 K), and 31% ± 0.4% (for increasing the height from 500 to 1500 m). A detailed analysis of the mean kinetic-energy equation is included, showing that the variation in power extraction originates from the work done by the driving pressure gradient related to the boundary layer height and the geostrophic angle, while entrainment of kinetic energy from the free atmosphere does not play a significant role. Also, the effect of inversion strength on power extraction is energetically not related to different amounts of energy entrained, but explained by a difference in boundary layer growth, leading to higher boundary layers for lower inversion strengths. We further present a simple analytical model that allows to obtain wind-farm power output and driving power for the fully developed regime as function of Rossby number and boundary layer height.

  10. Large Eddy Simulation of a Wind Turbine Airfoil at High Freestream-Flow Angle

    SciTech Connect

    2015-04-13

    A simulation of the airflow over a section of a wind turbine blade, run on the supercomputer Mira at the Argonne Leadership Computing Facility. Simulations like these help identify ways to make turbine blades more efficient.

  11. Stability of large horizontal-axis axisymmetric wind turbines. Ph.D. Thesis - Delaware Univ.

    NASA Technical Reports Server (NTRS)

    Hirschbein, M. S.; Young, M. I.

    1980-01-01

    The stability of large horizontal axis, axi-symmetric, power producing wind turbines was examined. The analytical model used included the dynamic coupling of the rotor, tower and power generating system. The aerodynamic loading was derived from blade element theory. Each rotor blade was permitted tow principal elastic bending degrees of freedom, one degree of freedom in torsion and controlled pitch as a rigid body. The rotor hub was mounted in a rigid nacelle which may yaw freely or in a controlled manner. The tower can bend in two principal directions and may twist. Also, the rotor speed can vary and may induce perturbation reactions within the power generating equipment. Stability was determined by the eigenvalues of a set of linearized constant coefficient differential equations. All results presented are based on a 3 bladed, 300 ft. diameter, 2.5 megawatt wind turbine. Some of the parameters varied were; wind speed, rotor speed structural stiffness and damping, the effective stiffness and damping of the power generating system and the principal bending directions of the rotor blades. Unstable or weakly stable behavior can be caused by aerodynamic forces due to motion of the rotor blades and tower in the plane of rotation or by mechanical coupling between the rotor system and the tower.

  12. Requirements for Large Eddy Simulation Computations of Variable-Speed Power Turbine Flows

    NASA Technical Reports Server (NTRS)

    Ameri, Ali A.

    2016-01-01

    Variable-speed power turbines (VSPTs) operate at low Reynolds numbers and with a wide range of incidence angles. Transition, separation, and the relevant physics leading to them are important to VSPT flow. Higher fidelity tools such as large eddy simulation (LES) may be needed to resolve the flow features necessary for accurate predictive capability and design of such turbines. A survey conducted for this report explores the requirements for such computations. The survey is limited to the simulation of two-dimensional flow cases and endwalls are not included. It suggests that a grid resolution necessary for this type of simulation to accurately represent the physics may be of the order of Delta(x)+=45, Delta(x)+ =2 and Delta(z)+=17. Various subgrid-scale (SGS) models have been used and except for the Smagorinsky model, all seem to perform well and in some instances the simulations worked well without SGS modeling. A method of specifying the inlet conditions such as synthetic eddy modeling (SEM) is necessary to correctly represent the inlet conditions.

  13. An experimental study of heat transfer in a large-scale turbine rotor passage

    SciTech Connect

    Blair, M.F. )

    1994-01-01

    An experimental study of the heat transfer distribution in a turbine rotor passage was conducted in a large-scale, ambient temperature, rotating turbine model. Heat transfer was measured for both the full-span suction and pressure surfaces of the airfoil and for the hub endwall surface. The objective of this program was to document the effects of flow three dimensionality on the heat transfer in a rotating blade row (versus a stationary cascade). Of particular interest were the effects of the hub and tip secondary flows, tip leakage, and the leading-edge horseshoe vortex system. The effect of surface roughness on the passage heat transfer was also investigated. Midspan results are compared with both smooth-wall and rough-wall finite-difference two-dimensional heat transfer predictions. Contour maps of Stanton number for both the rotor airfoil and endwall surfaces revealed numerous regions of high heat transfer produced by the three-dimensional flows within the rotor passage. Of particular importance are regions of local enhancement (as much as 100 percent over midspan values) produced on the airfoil suction surface by the secondary flows and tip-leakage vortices an on the hub endwall by the leading-edge horseshoe vortex system.

  14. Large eddy simulation for predicting turbulent heat transfer in gas turbines.

    PubMed

    Tafti, Danesh K; He, Long; Nagendra, K

    2014-08-13

    Blade cooling technology will play a critical role in the next generation of propulsion and power generation gas turbines. Accurate prediction of blade metal temperature can avoid the use of excessive compressed bypass air and allow higher turbine inlet temperature, increasing fuel efficiency and decreasing emissions. Large eddy simulation (LES) has been established to predict heat transfer coefficients with good accuracy under various non-canonical flows, but is still limited to relatively simple geometries and low Reynolds numbers. It is envisioned that the projected increase in computational power combined with a drop in price-to-performance ratio will make system-level simulations using LES in complex blade geometries at engine conditions accessible to the design process in the coming one to two decades. In making this possible, two key challenges are addressed in this paper: working with complex intricate blade geometries and simulating high-Reynolds-number (Re) flows. It is proposed to use the immersed boundary method (IBM) combined with LES wall functions. A ribbed duct at Re=20 000 is simulated using the IBM, and a two-pass ribbed duct is simulated at Re=100 000 with and without rotation (rotation number Ro=0.2) using LES with wall functions. The results validate that the IBM is a viable alternative to body-conforming grids and that LES with wall functions reproduces experimental results at a much lower computational cost. PMID:25024418

  15. Dynamic Response of Large Wind Power Plant Affected by Diverse Conditions at Individual Turbines

    SciTech Connect

    Elizondo, Marcelo A.; Lu, Shuai; Lin, Guang; Wang, Shaobu

    2014-07-31

    Diverse operating conditions at individual wind turbine generators (WTG) within wind power plants (WPPs) can affect the WPP dynamic response to system faults. For example, individual WTGs can experience diverse terminal voltage and power output caused by different wind direction and speed, affecting the response of protection and control limiters. In this paper, we present a study to investigate the dynamic response of a detailed WPP model under diverse power outputs of its individual WTGs. Wake effect is considered as the reason for diverse power outputs. The diverse WTG power output is evaluated in a test system where a large 168-machine test WPP is connected to the IEEE-39-bus system. The power output from each WTG is derived from a wake effect model that uses realistic statistical data for incoming wind speed and direction. The results show that diverse WTG output due to wake effect can affect the WPP dynamic response activating specialized control in some turbines. In addition, transient stability is affected by exhibiting uncertainty in critical clearing time calculation.

  16. Feasibility study of aileron and spoiler control systems for large horizontal axis wind turbines

    NASA Astrophysics Data System (ADS)

    Wentz, W. H., Jr.; Snyder, M. H.; Calhoun, J. T.

    1980-05-01

    The feasibility of using aileron or spoiler controls as alternates to pitch control for large horizontal axis wind turbines was studied. The NASA Mod-0 100 kw machine was used as the basis for the study. Specific performance studies were conducted for 20% chord ailerons over the outboard 30% span, and for 10% chord spoilers over the same portion of the span. Both control systems utilized control deflections up to 60 deg. Results of the study show that either ailerons or spoilers can provide the control necessary to limit turbine power in high wind conditions. The aileron system, as designed, provides overspeed protection at hurricane wind speeds, low wind speed starting torque of 778 N-m (574 ft. lb) at 3.6 m/sec, and a 1.3 to 1.5% increase in annual energy compared to a fixed pitch rotor. The aileron control system preliminary design study includes aileron loads analysis and the design of a failsafe flyweight actuator for overspeed protection in the event of a hydraulic system failure.

  17. Large eddy simulation for predicting turbulent heat transfer in gas turbines

    PubMed Central

    Tafti, Danesh K.; He, Long; Nagendra, K.

    2014-01-01

    Blade cooling technology will play a critical role in the next generation of propulsion and power generation gas turbines. Accurate prediction of blade metal temperature can avoid the use of excessive compressed bypass air and allow higher turbine inlet temperature, increasing fuel efficiency and decreasing emissions. Large eddy simulation (LES) has been established to predict heat transfer coefficients with good accuracy under various non-canonical flows, but is still limited to relatively simple geometries and low Reynolds numbers. It is envisioned that the projected increase in computational power combined with a drop in price-to-performance ratio will make system-level simulations using LES in complex blade geometries at engine conditions accessible to the design process in the coming one to two decades. In making this possible, two key challenges are addressed in this paper: working with complex intricate blade geometries and simulating high-Reynolds-number (Re) flows. It is proposed to use the immersed boundary method (IBM) combined with LES wall functions. A ribbed duct at Re=20 000 is simulated using the IBM, and a two-pass ribbed duct is simulated at Re=100 000 with and without rotation (rotation number Ro=0.2) using LES with wall functions. The results validate that the IBM is a viable alternative to body-conforming grids and that LES with wall functions reproduces experimental results at a much lower computational cost. PMID:25024418

  18. An experimental study of heat transfer in a large-scale turbine rotor passage

    NASA Technical Reports Server (NTRS)

    Blair, Michael F.

    1992-01-01

    An experimental study of the heat transfer distribution in a turbine rotor passage was conducted in a large-scale, ambient temperature, rotating turbine model. Heat transfer was measured for both the full-span suction and pressure surfaces of the airfoil as well as for the hub endwall surface. The objective of this program was to document the effects of flow three-dimensionality on the heat transfer in a rotating blade row (vs a stationary cascade). Of particular interest were the effects of the hub and tip secondary flows, tip leakage and the leading-edge horseshoe vortex system. The effect of surface roughness on the passage heat transfer was also investigated. Midspan results are compared with both smooth-wall and rough-wall finite-difference two-dimensional heat transfer predictions. Contour maps of Stanton number for both the rotor airfoil and endwall surfaces revealed numerous regions of high heat transfer produced by the three-dimensional flows within the rotor passage. Of particular importance are regions of local enhancement (as much as 100 percent over midspan values) produced on the airfoil suction surface by the secondary flows and tip-leakage vortices and on the hub endwall by the leading-edge horseshoe vortex system.

  19. Unsteady Aero Computation of a 1 1/2 Stage Large Scale Rotating Turbine

    NASA Technical Reports Server (NTRS)

    To, Wai-Ming

    2012-01-01

    This report is the documentation of the work performed for the Subsonic Rotary Wing Project under the NASA s Fundamental Aeronautics Program. It was funded through Task Number NNC10E420T under GESS-2 Contract NNC06BA07B in the period of 10/1/2010 to 8/31/2011. The objective of the task is to provide support for the development of variable speed power turbine technology through application of computational fluid dynamics analyses. This includes work elements in mesh generation, multistage URANS simulations, and post-processing of the simulation results for comparison with the experimental data. The unsteady CFD calculations were performed with the TURBO code running in multistage single passage (phase lag) mode. Meshes for the blade rows were generated with the NASA developed TCGRID code. The CFD performance is assessed and improvements are recommended for future research in this area. For that, the United Technologies Research Center's 1 1/2 stage Large Scale Rotating Turbine was selected to be the candidate engine configuration for this computational effort because of the completeness and availability of the data.

  20. Feasibility study of aileron and spoiler control systems for large horizontal axis wind turbines

    NASA Technical Reports Server (NTRS)

    Wentz, W. H., Jr.; Snyder, M. H.; Calhoun, J. T.

    1980-01-01

    The feasibility of using aileron or spoiler controls as alternates to pitch control for large horizontal axis wind turbines was studied. The NASA Mod-0 100 kw machine was used as the basis for the study. Specific performance studies were conducted for 20% chord ailerons over the outboard 30% span, and for 10% chord spoilers over the same portion of the span. Both control systems utilized control deflections up to 60 deg. Results of the study show that either ailerons or spoilers can provide the control necessary to limit turbine power in high wind conditions. The aileron system, as designed, provides overspeed protection at hurricane wind speeds, low wind speed starting torque of 778 N-m (574 ft. lb) at 3.6 m/sec, and a 1.3 to 1.5% increase in annual energy compared to a fixed pitch rotor. The aileron control system preliminary design study includes aileron loads analysis and the design of a failsafe flyweight actuator for overspeed protection in the event of a hydraulic system failure.

  1. Exploring Advanced Technology Gas Turbine Engine Design and Performance for the Large Civil Tiltrotor (LCTR)

    NASA Technical Reports Server (NTRS)

    Snyder, Christopher A.

    2014-01-01

    A Large Civil Tiltrotor (LCTR) conceptual design was developed as part of the NASA Heavy Lift Rotorcraft Systems Investigation in order to establish a consistent basis for evaluating the benefits of advanced technology for large tiltrotors. The concept has since evolved into the second-generation LCTR2, designed to carry 90 passengers for 1,000 nautical miles at 300 knots, with vertical takeoff and landing capability. This paper explores gas turbine component performance and cycle parameters to quantify performance gains possible for additional improvements in component and material performance beyond those identified in previous LCTR2 propulsion studies and to identify additional research areas. The vehicle-level characteristics from this advanced technology generation 2 propulsion architecture will help set performance levels as additional propulsion and power systems are conceived to meet ever-increasing requirements for mobility and comfort, while reducing energy use, cost, noise and emissions. The Large Civil Tiltrotor vehicle and mission will be discussed as a starting point for this effort. A few, relevant engine and component technology studies, including previous LCTR2 engine study results will be summarized to help orient the reader on gas turbine engine architecture, performance and limitations. Study assumptions and methodology used to explore engine design and performance, as well as assess vehicle sizing and mission performance will then be discussed. Individual performance for present and advanced engines, as well as engine performance effects on overall vehicle size and mission fuel usage, will be given. All results will be summarized to facilitate understanding the importance and interaction of various component and system performance on overall vehicle characteristics.

  2. Long term reliability and machine operation diagnosis with fiber optic sensors at large turbine generators

    NASA Astrophysics Data System (ADS)

    Bosselmann, T.; Strack, S.; Villnow, M.; Weidner, J. R.; Willsch, M.

    2013-05-01

    The increasing quantity of renewable energy in electric power generation leads to a higher flexibility in the operation of conventional power plants. The turbo generator has to face the influence of frequent start-stop-operation on thermal movement and vibration of the stator end windings. Large indirect cooled turbo generators have been equipped with FBG strain and temperature sensors to monitor the influence of peak load operation. Fiber optic accelerometers measure the vibration of the end windings at several turbine generators since many years of operation. The long term reliability of fiber optic vibration, temperature and strain sensors has been successfully proved during years of online operation. The analysis of these data in correlation to significant operation parameter lead to important diagnostic information.

  3. Analysis and numerical optimization of gas turbine space power systems with nuclear fission reactor heat sources

    NASA Astrophysics Data System (ADS)

    Juhasz, Albert J.

    2005-07-01

    A new three objective optimization technique is developed and applied to find the operating conditions for fission reactor heated Closed Cycle Gas Turbine (CCGT) space power systems at which maximum efficiency, minimum radiator area, and minimum total system mass is achieved. Such CCGT space power systems incorporate a nuclear reactor heat source with its radiation shield; the rotating turbo-alternator, consisting of the compressor, turbine and the electric generator (three phase AC alternator); and the heat rejection subsystem, principally the space radiator, which enables the hot gas working fluid, emanating from either the turbine or a regenerative heat exchanger, to be cooled to compressor inlet conditions. Numerical mass models for all major subsystems and components developed during the course of this work are included in this report. The power systems modeled are applicable to future interplanetary missions within the Solar System and planetary surface power plants at mission destinations, such as our Moon, Mars, the Galilean moons (Io, Europa, Ganymede, and Callisto), or Saturn's moon Titan. The detailed governing equations for the thermodynamic processes of the Brayton cycle have been derived and successfully programmed along with the heat transfer processes associated with cycle heat exchangers and the space radiator. System performance and mass results have been validated against a commercially available non-linear optimization code and also against data from existing ground based power plants.

  4. Turbines in the sky

    SciTech Connect

    Boyle, R.V.; Riple, J.C.

    1987-07-01

    Gas turbines are being investigated as power sources for the proposed Star Wars weapons flatforms. The gas turbine engine offers the best opportunity for exploiting the high-temperature potential of both nuclear and chemical combustion. The use of mature gas turbine technology and existing materials would result in highly reliable PCUs capable of meeting SDI's requirements. However, operation under the temperature limits imposed by existing materials would result in a prohibitively heavy system. Cooled blades would somewhat increase temperature capability; however the turbine's mass, though reduced, would still be unacceptably large. The greatest improvements would result from the ability to operate at temperatures of up to 2000 K, pressures up to 14 MPa, and stress up to 690 MPa.

  5. A Supercritical CO{sub 2} Gas Turbine Power Cycle for Next-Generation Nuclear Reactors

    SciTech Connect

    Dostal, Vaclav; Driscoll, Michael J.; Hejzlar, Pavel; Todreas, Neil E.

    2002-07-01

    Although proposed more than 35 years ago, the use of supercritical CO{sub 2} as the working fluid in a closed circuit Brayton cycle has so far not been implemented in practice. Industrial experience in several other relevant applications has improved prospects, and its good efficiency at modest temperatures (e.g., {approx}45% at 550 deg. C) make this cycle attractive for a variety of advanced nuclear reactor concepts. The version described here is for a gas-cooled, modular fast reactor. In the proposed gas-cooled fast breeder reactor design of present interest, CO{sub 2} is also especially attractive because it allows the use of metal fuel and core structures. The principal advantage of a supercritical CO{sub 2} Brayton cycle is its reduced compression work compared to an ideal gas such as helium: about 15% of gross power turbine output vs. 40% or so. This also permits the simplification of use of a single compressor stage without inter-cooling. The requisite high pressure ({approx}20 MPa) also has the benefit of more compact heat exchangers and turbines. Finally, CO{sub 2} requires significantly fewer turbine stages than He, its principal competitor for nuclear gas turbine service. One disadvantage of CO{sub 2} in a direct cycle application is the production of N-16, which will require turbine plant shielding (albeit much less than in a BWR). The cycle efficiency is also very sensitive to recuperator effectiveness and compressor inlet temperature. It was found necessary to split the recuperator into separate high-and low-temperature components, and to employ intermediate re-compression, to avoid having a pinch-point in the cold end of the recuperator. Over the past several decades developments have taken place that make the acceptance of supercritical CO{sub 2} systems more likely: supercritical CO{sub 2} pipelines are in use in the western US in oil-recovery operations; 14 advanced gas-cooled reactors (AGR) are employed in the UK at CO{sub 2} temperatures up to

  6. Modelling Turbine Loads during an Extreme Coherent Gust using Large Eddy Simulation

    NASA Astrophysics Data System (ADS)

    Storey, R. C.; Norris, S. E.; Cater, J. E.

    2014-06-01

    A group of wind turbines operating in extreme transient wind conditions has been simulated using LES and an actuator model. An extreme wind event is introduced into the simulation domain using transient boundary conditions. The event is based on the extreme coherent gust (ECG) structure from the International Wind Turbine Design Standard IEC61400-1:2005 which consists of a simultaneous gust and wind direction change. Details of the implementation are discussed with regard to adapting the analytical functions described in the standard. A recently developed actuator sector method is used to represent the wind turbines in the simulation. The actuator method is coupled to the aero-elastic wind turbine simulation code FAST to allow dynamic control of the wind turbines based on the ambient flow conditions. Standard baseline controllers are used to regulate generator torque, actuate blade pitch angle and control yaw direction. A span-wise periodic array of turbines operating in a steady atmospheric boundary layer is simulated before the introduction of the ECG structure. The convection of the wind event is analysed, along with the subsequent response of the wind turbines and loading during the wind event is quantified. The simulations demonstrate a methodology for modelling groups of turbines operating in transient wind conditions that can be used to study turbine loads or test new turbine control strategies.

  7. Rotordynamic Feasibility of a Conceptual Variable-Speed Power Turbine Propulsion System for Large Civil Tilt-Rotor Applications

    NASA Technical Reports Server (NTRS)

    Howard, Samuel

    2012-01-01

    A variable-speed power turbine concept is analyzed for rotordynamic feasibility in a Large Civil Tilt-Rotor (LCTR) class engine. Implementation of a variable-speed power turbine in a rotorcraft engine would enable high efficiency propulsion at the high forward velocities anticipated of large tilt-rotor vehicles. Therefore, rotordynamics is a critical issue for this engine concept. A preliminary feasibility study is presented herein to address this concern and identify if variable-speed is possible in a conceptual engine sized for the LCTR. The analysis considers critical speed placement in the operating speed envelope, stability analysis up to the maximum anticipated operating speed, and potential unbalance response amplitudes to determine that a variable-speed power turbine is likely to be challenging, but not impossible to achieve in a tilt-rotor propulsion engine.

  8. Evaluation of Blade-Strike Models for Estimating the Biological Performance of Large Kaplan Hydro Turbines

    SciTech Connect

    Deng, Zhiqun; Carlson, Thomas J.; Ploskey, Gene R.; Richmond, Marshall C.

    2005-11-30

    BioIndex testing of hydro-turbines is sought as an analog to the hydraulic index testing conducted on hydro-turbines to optimize their power production efficiency. In BioIndex testing the goal is to identify those operations within the range identified by Index testing where the survival of fish passing through the turbine is maximized. BioIndex testing includes the immediate tailrace region as well as the turbine environment between a turbine's intake trashracks and the exit of its draft tube. The US Army Corps of Engineers and the Department of Energy have been evaluating a variety of means, such as numerical and physical turbine models, to investigate the quality of flow through a hydro-turbine and other aspects of the turbine environment that determine its safety for fish. The goal is to use these tools to develop hypotheses identifying turbine operations and predictions of their biological performance that can be tested at prototype scales. Acceptance of hypotheses would be the means for validation of new operating rules for the turbine tested that would be in place when fish were passing through the turbines. The overall goal of this project is to evaluate the performance of numerical blade strike models as a tool to aid development of testable hypotheses for bioIndexing. Evaluation of the performance of numerical blade strike models is accomplished by comparing predictions of fish mortality resulting from strike by turbine runner blades with observations made using live test fish at mainstem Columbia River Dams and with other predictions of blade strike made using observations of beads passing through a 1:25 scale physical turbine model.

  9. Large-Scale Wind Turbine Testing in the NASA 24.4m (80) by 36.6m(120) Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Zell, Peter T.; Imprexia, Cliff (Technical Monitor)

    2000-01-01

    The 80- by 120-Foot Wind Tunnel at NASA Ames Research Center in California provides a unique capability to test large-scale wind turbines under controlled conditions. This special capability is now available for domestic and foreign entities wishing to test large-scale wind turbines. The presentation will focus on facility capabilities to perform wind turbine tests and typical research objectives for this type of testing.

  10. Implementation and assessment of turbine wake models in the Weather Research and Forecasting model for both mesoscale and large-eddy simulation

    SciTech Connect

    Singer, M; Mirocha, J; Lundquist, J; Cleve, J

    2010-03-03

    Flow dynamics in large wind projects are influenced by the turbines located within. The turbine wakes, regions characterized by lower wind speeds and higher levels of turbulence than the surrounding free stream flow, can extend several rotor diameters downstream, and may meander and widen with increasing distance from the turbine. Turbine wakes can also reduce the power generated by downstream turbines and accelerate fatigue and damage to turbine components. An improved understanding of wake formation and transport within wind parks is essential for maximizing power output and increasing turbine lifespan. Moreover, the influence of wakes from large wind projects on neighboring wind farms, agricultural activities, and local climate are all areas of concern that can likewise be addressed by wake modeling. This work describes the formulation and application of an actuator disk model for studying flow dynamics of both individual turbines and arrays of turbines within wind projects. The actuator disk model is implemented in the Weather Research and Forecasting (WRF) model, which is an open-source atmospheric simulation code applicable to a wide range of scales, from mesoscale to large-eddy simulation. Preliminary results demonstrate the applicability of the actuator disk model within WRF to a moderately high-resolution large-eddy simulation study of a small array of turbines.

  11. Detection of low frequency impulsive noise from large wind turbine generators

    NASA Technical Reports Server (NTRS)

    Shepherd, K. P.

    1985-01-01

    The thresholds of detection of low frequency, impulsive wind turbine sounds in the presence of background noise were examined. Seven wind turbine sounds, six of which were synthesized, were used in conjunction with three background noise conditions; quiet, 35, and 45 dB(A). The results indicate that thresholds of detection are predictable based on assumed characteristics of the auditory system. The synthesized wind turbine sounds were found to adequately represent a real recording.

  12. Results of a utility survey of the status of large wind turbine development

    NASA Technical Reports Server (NTRS)

    Watts, A.; Quraeshi, S.; Rowley, L. P.

    1979-01-01

    Wind energy conversion systems were surveyed from a utility viewpoint to establish the state of the art with regard to: (1) availability of the type of machines; (2) quality of power generation; (3) suitability for electrical grid; (4) reliability; and (5) economics. Of the 23 designs discussed, 7 have vertical axis wind turbines, 9 have upwind horizontal axis turbines, and 7 have downwind horizontal axis turbines.

  13. Preliminary results of the large experimental wind turbine phase of the national wind energy program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Sholes, T.; Sholes, J. E.

    1975-01-01

    The preliminary results of two projects in the development phase of reliable wind turbines designed to supply cost-competitive electrical energy were discussed. An experimental 100 kW wind turbine design and its status are first reviewed. The results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs are also discussed. These studies predict wind energy costs of 1.5 to 7 cents per kW-h for wind turbines produced in quantities of 100 to 1000 per year and located at sites having average winds of 12 to 18 mph.

  14. Large nuclear hikes may force user exodus

    SciTech Connect

    Barber, J.

    1984-06-18

    If continued construction on uncompleted nuclear plants causes Ohio and Michigan utility rates to jump anywhere from 44 to 97%, industry may flee the area and throw 54,000 people out of work, according to recent studies. At issue are the Midland 2 nuclear plant in Jackson, Michigan and the Zimmer Plant outside Cincinnati, which is scheduled to be converted to a coal-fired plant. Other factors would influence the job exodus, but higher power costs would have a major impact on area industries. Unemployment will also result when construction workers are no longer needed for the plants. Other areas of the country face similar power price increases. Both the Ohio and Michigan reports are based on power demand and cost projections.

  15. Effect of Derating and Shutting Down of Turbines on the Extracted Power of Large Wind Farms in Thermally-Stratified Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Adkins, K. A.

    2015-12-01

    Wind power is being increasingly employed to help meet an increasing energy demand in a more environmentally friendly manner and, consequently, large wind farms consisting of thousands of turbines have been constructed and deployed in various areas. Due to a multitude of factors, the layout of these multi-turbine arrays is not always optimized for maximum wind farm power extraction. Additionally, the shutting down or derating of certain wind turbines may impact the efficiency of large wind farms. In this study, a large eddy simulation (LES) of a fully developed wind turbine array boundary layer is performed in thermally stratified conditions. The impact on the overall plant performance, quantified by the collective extracted power of the turbines, is explored using a systematic shut down and derating of selected turbines.

  16. 14 CFR 135.381 - Large transport category airplanes: Turbine engine powered: En route limitations: One engine...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Large transport category airplanes: Turbine engine powered: En route limitations: One engine inoperative. 135.381 Section 135.381 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR CARRIERS AND OPERATORS FOR COMPENSATION OR HIRE:...

  17. Dynamic global Vreman model for large eddy simulation of inhomogeneous turbulent flow in a full passage of Francis turbine

    NASA Astrophysics Data System (ADS)

    Wang, W. Q.; Hao, D. W.; Zhang, L. X.; Guo, Y. K.

    2012-11-01

    In the present study, the subgrid-scale (SGS) eddy-viscosity model developed by Vreman [Phys. Fluids 16 (2004) 3670] and its dynamic version [Phys. Fluids 19 (2007) 065110] are tested in large-eddy simulations (LES) of the inhomogeneous turbulent flow in a full passage of Francis turbine. Distributions of pressure, velocity and vortices as well as some flow structure are gained, which is helpful to examine the performance of SGS model for complex turbulent flow and understand the flow characters in full passage of Francis turbine.

  18. Self-similarity and turbulence characteristics of wind turbine wakes via large-eddy simulation (Invited)

    NASA Astrophysics Data System (ADS)

    Xie, S.; Archer, C. L.

    2013-12-01

    In this study, a new large-eddy simulation code, the Wind Turbine and Turbulence Simulator (WiTTS), is developed to study the wake generated from a single wind turbine in the neutral ABL. The WiTTS formulation is based on a scale-dependent Lagrangian dynamical model of the sub-grid shear stress and uses actuator lines to simulate the effects of the rotating blades. WiTTS is first tested against wind tunnel experiments and then used to study the commonly-used assumptions of self-similarity and axis-symmetry of the wake under neutral conditions for a variety of wind speeds and turbine properties. The mean velocity deficit shows good self-similarity properties following a normal distribution in the horizontal plane at the hub-height level. Self-similarity is a less valid approximation in the vertical near the ground, due to strong wind shear and ground effects. The mean velocity deficit is strongly dependent on the thrust coefficient or induction factor. A new relationship is proposed to model the mean velocity deficit along the centerline at the hub-height level to fit the LES results piecewise throughout the wake. A logarithmic function is used in the near and intermediate wake regions whereas a power function is used in the far-wake. These two functions provide a better fit to both simulated and observed wind velocity deficits than other functions previously used in wake models such as WAsP. The wind shear and impact with the ground cause an anisotropy in the expansion of the wake such that the wake grows faster horizontally than vertically. The wake deforms upon impact with the ground and spreads laterally. WiTTS is also used to study the turbulence characteristics in the wake. Aligning with the mean wind direction, the streamwise component of turbulence intensity is the dominant among the three components and thus it is further studied. The highest turbulence intensity occurs near the top-tip level. The added turbulence intensity increases fast in the near

  19. Assessment of Aerodynamic Challenges of a Variable-Speed Power Turbine for Large Civil Tilt-Rotor Application

    NASA Technical Reports Server (NTRS)

    Welch, Gerand E.

    2010-01-01

    The main rotors of the NASA Large Civil Tilt-Rotor notional vehicle operate over a wide speed-range (100% at take-off to 54% at cruise). The variable-speed power turbine, when coupled to a fixed-gear-ratio transmission, offers one approach to accomplish this speed variation. The key aero-challenges of the variable-speed power turbine are related to high work factors at cruise, where the power turbine operates at 54% of take-off speed, wide incidence variations into the vane, blade, and exit-guide-vane rows associated with the power-turbine speed change, and the impact of low aft-stage Reynolds number (transitional flow) at 28 kft cruise. Meanline and 2-D Reynolds-Averaged Navier- Stokes analyses are used to characterize the variable-speed power-turbine aerodynamic challenges and to outline a conceptual design approach that accounts for multi-point operation. Identified technical challenges associated with the aerodynamics of high work factor, incidence-tolerant blading, and low Reynolds numbers pose research needs outlined in the paper

  20. Large Eddy Simulation of Wind Turbine Wake Dynamics in the Stable Boundary Layer Using the Weather Research and Forecasting Model

    NASA Astrophysics Data System (ADS)

    Aitken, M.; Kosovic, B.; Mirocha, J. D.; Lundquist, J. K.

    2014-12-01

    To thoroughly verify the actuator disk model recently implemented in WRF for large eddy simulation (LES) of wind turbine wakes, simulations of various types of turbines and atmospheric conditions must be compared to full-scale field measurements of the real atmosphere. Here, numerical simulations are compared to nacelle-based scanning lidar measurements taken in stable atmospheric conditions during a field campaign conducted at a wind farm in the western United States. Using several wake characteristics—such as the velocity deficit, centerline location, and wake width—as metrics for model verification, the simulations show good agreement with the observations. Notably, the average velocity deficit was seen to be quite high in both the experiment and simulation, resulting from a low average wind speed and therefore high average turbine thrust coefficient. Moreover, new features—namely rotor tilt and drag from the nacelle and tower—were added to the existing actuator disk model in WRF-LES. Compared to the rotor, the effect of the tower and nacelle on the flow is relatively small but nevertheless important for an accurate representation of the entire turbine. Adding rotor tilt to the model causes the vertical location of the wake center to shift upward. Continued advancement of the actuator disk model in WRF-LES will help lead to optimized turbine siting and controls at wind farms.

  1. Aeroelastic Stability Investigations for Large-scale Vertical Axis Wind Turbines

    NASA Astrophysics Data System (ADS)

    Owens, B. C.; Griffith, D. T.

    2014-06-01

    The availability of offshore wind resources in coastal regions, along with a high concentration of load centers in these areas, makes offshore wind energy an attractive opportunity for clean renewable electricity production. High infrastructure costs such as the offshore support structure and operation and maintenance costs for offshore wind technology, however, are significant obstacles that need to be overcome to make offshore wind a more cost-effective option. A vertical-axis wind turbine (VAWT) rotor configuration offers a potential transformative technology solution that significantly lowers cost of energy for offshore wind due to its inherent advantages for the offshore market. However, several potential challenges exist for VAWTs and this paper addresses one of them with an initial investigation of dynamic aeroelastic stability for large-scale, multi-megawatt VAWTs. The aeroelastic formulation and solution method from the BLade Aeroelastic STability Tool (BLAST) for HAWT blades was employed to extend the analysis capability of a newly developed structural dynamics design tool for VAWTs. This investigation considers the effect of configuration geometry, material system choice, and number of blades on the aeroelastic stability of a VAWT, and provides an initial scoping for potential aeroelastic instabilities in large-scale VAWT designs.

  2. A dynamic wall model for Large-Eddy simulations of wind turbine dedicated airfoils

    NASA Astrophysics Data System (ADS)

    J, Calafell; O, Lehmkuhl; A, Carmona; D, Pérez-Segarra C.; A, Oliva

    2014-06-01

    This work aims at modelling the flow behavior past a wind turbine dedicated airfoil at high Reynolds number and large angle of attack (AoA). The DU-93-W-210 airfoil has been selected. To do this, Large Eddy Simulations (LES) have been performed. Momentum equations have been solved with a parallel unstructured symmetry preserving formulation while the wall-adapting local-eddy viscosity model within a variational multi-scale framework (VMS- WALE) is used as the subgrid-scales model. Since LES calculations are still very expensive at high Reynolds Number, specially at the near-wall region, a dynamic wall model has been implemented in order to overcome this limitation. The model has been validated with a very unresolved Channel Flow case at Reτ = 2000. Afterwards, the model is also tested with the Ahmed Car case, that from the flow physics point of view is more similar to an stalled airfoil than the Channel Flow is, including flow features as boundary layer detachment and recirculations. This case has been selected because experimental results of mean velocity profiles are available. Finally, a flow around a DU-93-W-210 airfoil is computed at Re = 3 x 106 and with an AoA of 15°. Numerical results are presented in comparison with Direct Numerical Simulation (DNS) or experimental data for all cases.

  3. Characterizing large river sounds: Providing context for understanding the environmental effects of noise produced by hydrokinetic turbines

    DOE PAGESBeta

    Bevelhimer, Mark S.; Deng, Z. Daniel; Scherelis, Constantin C.

    2016-01-06

    Underwaternoise associated with the installation and operation of hydrokinetic turbines in rivers and tidal zones presents a potential environmental concern for fish and marine mammals. Comparing the spectral quality of sounds emitted by hydrokinetic turbines to natural and other anthropogenic sound sources is an initial step at understanding potential environmental impacts. Underwater recordings were obtained from passing vessels and natural underwater sound sources in static and flowing waters. Static water measurements were taken in a lake with minimal background noise. Flowing water measurements were taken at a previously proposed deployment site for hydrokinetic turbines on the Mississippi River, where soundsmore » created by flowing water are part of all measurements, both natural ambient and anthropogenic sources. Vessel sizes ranged from a small fishing boat with 60 hp outboard motor to an 18-unit barge train being pushed upstream by tugboat. As expected, large vessels with large engines created the highest sound levels, which were, on average, 40 dB greater than the sound created by an operating hydrokinetic turbine. As a result, a comparison of sound levels from the same sources at different distances using both spherical and cylindrical sound attenuation functions suggests that spherical model results more closely approximate observed sound attenuation.« less

  4. Characterizing large river sounds: Providing context for understanding the environmental effects of noise produced by hydrokinetic turbines.

    PubMed

    Bevelhimer, Mark S; Deng, Z Daniel; Scherelis, Constantin

    2016-01-01

    Underwater noise associated with the installation and operation of hydrokinetic turbines in rivers and tidal zones presents a potential environmental concern for fish and marine mammals. Comparing the spectral quality of sounds emitted by hydrokinetic turbines to natural and other anthropogenic sound sources is an initial step at understanding potential environmental impacts. Underwater recordings were obtained from passing vessels and natural underwater sound sources in static and flowing waters. Static water measurements were taken in a lake with minimal background noise. Flowing water measurements were taken at a previously proposed deployment site for hydrokinetic turbines on the Mississippi River, where sounds created by flowing water are part of all measurements, both natural ambient and anthropogenic sources. Vessel sizes ranged from a small fishing boat with 60 hp outboard motor to an 18-unit barge train being pushed upstream by tugboat. As expected, large vessels with large engines created the highest sound levels, which were, on average, 40 dB greater than the sound created by an operating hydrokinetic turbine. A comparison of sound levels from the same sources at different distances using both spherical and cylindrical sound attenuation functions suggests that spherical model results more closely approximate observed sound attenuation. PMID:26827007

  5. Stochastic aspects of nuclear large amplitude motion

    SciTech Connect

    Kolomietz, V.M.

    1995-08-01

    A consistent description of the macroscopic large amplitude dynamics and processes of internal excitation of a nucleus is suggested. The cranking model approach is used for the calculation of the response function of the nucleus in a moving frame. Using spectral statistics smearing, the collective mass, friction, and diffusion coefficients are derived. The relation of the response function in a moving frame to the correlation function in a classical chaotic system is established. The rate of dissipation due to the Landau-Zener transitions and through the Kubo mechanism is considered.

  6. Design and wind tunnel evaluation of a symmetric airfoil series for large wind turbine applications

    SciTech Connect

    Gregorek, G.M.

    1984-05-01

    Using the Eppler analytic design methodology, a family of symmetric airfoils with thickness to chord ratios of 0.21, 0.25, and 0.29 has been designed for applications to large wind turbines. The airfoil series, designed for Reynolds numbers above 4 x 10/sup 6/, has a contour that maintains its thickness to the 0.7 chord position, allowing use of a deep aft spar for structural integrity. Wind tunnel tests of the 21 percent thick airfoil conducted in The Ohio State University Airfoil Test Facilities at M = 0.25 and Re = 2, 4, and 8 x 10/sup 6/ showed good agreement with predicted surface pressures and lift and drag coefficients when the angle of attack was low and the Reynolds number was 8 x 10/sup 6/. At the lowest Reynolds number, both the measured lift curve slope and the maximum lift coefficient differ significantly from theory. In the post-stall region, agreement with theory and experiment is poor, at all Reynolds numbers, verifying the need for improved analytic methods in this important flow regime.

  7. Investigation into the flow-induced instability of high-pressure rotors or large steam turbines

    SciTech Connect

    Thomas, J.P.

    1988-01-01

    The flow-induced instability of high-pressure rotors of large steam turbine generators has been a world-wide problem, and the subject of some controversy regarding the primary phenomena and major influencing parameters. In this study a simple one-dimensional model for the flow in a labyrinth seal was developed and solved for the linear dynamic coefficients. Dimensional analysis was employed to identify the major influencing parameters. The theoretical values for the dynamic coefficients were compared with published test data and found to be in qualitative agreement. Parametric studies were performed on typical sealing geometries to provide insight into the influence of the major design parameters on the aerodynamic excitation forces affecting rotor-system instability. A computer program utilizing the finite-element method was developed for considering the effect of the flow-induced forces on the damped natural frequencies and linear stability of complex rotor systems. System damping was calculated for several high-pressure rotor designs and results compared with actual operating experience. The importance of the various system components (i.e. seals, blading, bearings, etc.) with regard to the overall system stability was evaluated by means of the relative energy per cycle.

  8. Aero-Thermal Prediction in High Pressure Turbine Cascade using Large Eddy Simulation

    NASA Astrophysics Data System (ADS)

    Bhaskaran, Rathakrishnan; Lele, Sanjiva

    2008-11-01

    The aero-thermal performance of an uncooled, smooth high pressure (HP) turbine cascade in the presence of free-stream turbulence is studied using a high-order overset mesh Large Eddy Simulation (LES) procedure. A HP vane cascade designed at the von Karman Institute (VKI) for fluid dynamics, Belgium, is used as the model geometry. Simulations matching experimental conditions, except for the Reynolds number which is about half of the experimental value, have been carried out. Significant enhancement in the blade heat-transfer is seen in the presence of inflow turbulence. Eddies from the free-stream turbulence get stretched around the blade, creating long streaky structures in the blade boundary layer. These structures quickly break down on the suction side, while they persist on the pressure side. The blade heat transfer signature from the simulations does not show transition of the boundary layer at the Reynolds number of the simulation. This is consistent with the trend seen in the experiments where transition is delayed by lowering the Reynolds number. New simulations matching the experimental Reynolds number are currently under way.

  9. Gas Turbine Characteristics for a Large Civil Tilt-Rotor (LCTR)

    NASA Technical Reports Server (NTRS)

    Snyder, Christopher A.; Thurman, Douglas R.

    2010-01-01

    In support of the Fundamental Aeronautics Program, Subsonic Rotary Wing Project; an engine system study has been undertaken to help define and understand some of the major gas turbine engine parameters required to meet performance and weight requirements as defined by earlier vehicle system studies. These previous vehicle studies will be reviewed to help define gas turbine performance goals. Assumptions and analysis methods used will be described. Performance and weight estimates for a few conceptual gas turbine engines meeting these requirements will be given and discussed. Estimated performance for these conceptual engines over a wide speed variation (down to 50 percent power turbine rpm at high torque) will be presented. Finally, areas needing further effort will be suggested and discussed.

  10. Large wind turbines: A utility option for the generation of electricity

    NASA Technical Reports Server (NTRS)

    Robbins, W. H.; Thomas, R. L.; Baldwin, D. H.

    1980-01-01

    The economic and technical potential of wind energy in the United States is discussed. Particular attention is given to the status of wind turbine operational experience as well as the environmental posture of the technology.

  11. Preliminary results of the large experimental wind turbine phase of the national wind energy program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Sholes, J. E.

    1975-01-01

    A major phase of the wind energy program is the development of reliable wind turbines for supplying cost-competitive electrical energy. This paper discusses the preliminary results of two projects in this phase of the program. First an experimental 100 kW wind turbine design and its status are reviewed. Also discussed are the results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs. These studies show wind energy costs of 7 to 1.5 c/kWH for wind turbines produced in quantities of 100 to 1000 a year and located at sites having average winds of 12 to 18 mph.

  12. Guide to the evaluation of human exposure to noise from large wind turbines

    NASA Technical Reports Server (NTRS)

    Stephens, D. G.; Shepherd, K. P.; Hubbard, H. H.; Grosveld, F.

    1982-01-01

    Guidance for evaluating human exposure to wind turbine noise is provided and includes consideration of the source characteristics, the propagation to the receiver location, and the exposure of the receiver to the noise. The criteria for evaluation of human exposure are based on comparisons of the noise at the receiver location with the human perception thresholds for wind turbine noise and noise-induced building vibrations in the presence of background noise.

  13. Active stall control for large offshore horizontal axis wind turbines; a conceptual study considering different actuation methods

    NASA Astrophysics Data System (ADS)

    Pereira, R.; van Bussel, G. J. W.; Timmer, W. A.

    2014-12-01

    The increasing size of Horizontal Axis Wind Turbines and the trend to install wind farms further offshore demand more robust design options. If the pitch system could be eliminated, the availability of Horizontal Axis Wind Turbines should increase. This research investigates the use of active stall control to regulate power production in replacement of the pitch system. A feasibility study is conducted using a blade element momentum code and taking the National Renewable Energy Laboratory 5 MW turbine as baseline case. Considering half of the blade span is equipped with actuators, the required change in the lift coefficient to regulate power was estimated in ΔCl = 0.7. Three actuation technologies are investigated, namely Boundary Layer Transpiration, Trailing Edge Jets and Dielectric Barrier Discharge actuators. Results indicate the authority of the actuators considered is not sufficient to regulate power, since the change in the lift coefficient is not large enough. Active stall control of Horizontal Axis Wind Turbines appears feasible only if the rotor is re-designed from the start to incorporate active-stall devices.

  14. Space and Terrestrial Power System Integration Optimization Code BRMAPS for Gas Turbine Space Power Plants With Nuclear Reactor Heat Sources

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.

    2007-01-01

    In view of the difficult times the US and global economies are experiencing today, funds for the development of advanced fission reactors nuclear power systems for space propulsion and planetary surface applications are currently not available. However, according to the Energy Policy Act of 2005 the U.S. needs to invest in developing fission reactor technology for ground based terrestrial power plants. Such plants would make a significant contribution toward drastic reduction of worldwide greenhouse gas emissions and associated global warming. To accomplish this goal the Next Generation Nuclear Plant Project (NGNP) has been established by DOE under the Generation IV Nuclear Systems Initiative. Idaho National Laboratory (INL) was designated as the lead in the development of VHTR (Very High Temperature Reactor) and HTGR (High Temperature Gas Reactor) technology to be integrated with MMW (multi-megawatt) helium gas turbine driven electric power AC generators. However, the advantages of transmitting power in high voltage DC form over large distances are also explored in the seminar lecture series. As an attractive alternate heat source the Liquid Fluoride Reactor (LFR), pioneered at ORNL (Oak Ridge National Laboratory) in the mid 1960's, would offer much higher energy yields than current nuclear plants by using an inherently safe energy conversion scheme based on the Thorium --> U233 fuel cycle and a fission process with a negative temperature coefficient of reactivity. The power plants are to be sized to meet electric power demand during peak periods and also for providing thermal energy for hydrogen (H2) production during "off peak" periods. This approach will both supply electric power by using environmentally clean nuclear heat which does not generate green house gases, and also provide a clean fuel H2 for the future, when, due to increased global demand and the decline in discovering new deposits, our supply of liquid fossil fuels will have been used up. This is

  15. Nucleon structure at large x: nuclear effects in deuterium

    SciTech Connect

    Wally Melnitchouk

    2010-07-01

    I review quark momentum distributions in the nucleon at large momentum fractions x. Particular attention is paid to the impact of nuclear effects in deuterium on the d/u quark distribution ratio as x -> 1. A new global study of parton distributions, using less restrictive kinematic cuts in Q^2 and W^2, finds strong suppression of the d quark distribution once nuclear corrections are accounted for.

  16. Large area nuclear particle detectors using ET materials

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The purpose of this SBIR Phase 1 feasibility effort was to demonstrate the usefulness of Quantex electron-trapping (ET) materials for spatial detection of nuclear particles over large areas. This demonstration entailed evaluating the prompt visible scintillation as nuclear particles impinged on films of ET materials, and subsequently detecting the nuclear particle impingement information pattern stored in the ET material, by means of the visible-wavelength luminescence produced by near-infrared interrogation. Readily useful levels of scintillation and luminescence outputs are demonstrated.

  17. Lewis Research Center studies of multiple large wind turbine generators on a utility network

    NASA Technical Reports Server (NTRS)

    Gilbert, L. J.; Triezenberg, D. M.

    1979-01-01

    A NASA-Lewis program to study the anticipated performance of a wind turbine generator farm on an electric utility network is surveyed. The paper describes the approach of the Lewis Wind Energy Project Office to developing analysis capabilities in the area of wind turbine generator-utility network computer simulations. Attention is given to areas such as, the Lewis Purdue hybrid simulation, an independent stability study, DOE multiunit plant study, and the WEST simulator. Also covered are the Lewis mod-2 simulation including analog simulation of a two wind turbine system and comparison with Boeing simulation results, and gust response of a two machine model. Finally future work to be done is noted and it is concluded that the study shows little interaction between the generators and between the generators and the bus.

  18. Vibration characteristics of a large wind turbine tower on non-rigid foundations

    NASA Technical Reports Server (NTRS)

    Yee, S. T.; Cang, T. Y. P.; Scavuzzo, R. J.; Timmerman, D. H.; Fenton, J. W.

    1977-01-01

    Vibration characteristics of the Mod-OA wind turbine supported by nonrigid foundations were investigated for a range of soil rigidities. The study shows that the influence of foundation rotation on the fundamental frequency of the wind turbine is quite significant for cohesive soils or loose sand. The reduction in natural frequency can be greater than 20 percent. However, for a foundation resting on well graded, dense granular materials or bedrock, such effect is small and the foundation can be treated as a fixed base.

  19. Inlet Turbulence and Length Scale Measurements in a Large Scale Transonic Turbine Cascade

    NASA Technical Reports Server (NTRS)

    Thurman, Douglas; Flegel, Ashlie; Giel, Paul

    2014-01-01

    Constant temperature hotwire anemometry data were acquired to determine the inlet turbulence conditions of a transonic turbine blade linear cascade. Flow conditions and angles were investigated that corresponded to the take-off and cruise conditions of the Variable Speed Power Turbine (VSPT) project and to an Energy Efficient Engine (EEE) scaled rotor blade tip section. Mean and turbulent flowfield measurements including intensity, length scale, turbulence decay, and power spectra were determined for high and low turbulence intensity flows at various Reynolds numbers and spanwise locations. The experimental data will be useful for establishing the inlet boundary conditions needed to validate turbulence models in CFD codes.

  20. The gas turbine-modular helium reactor (GT-MHR), high efficiency, cost competitive, nuclear energy for the next century

    SciTech Connect

    Zgliczynski, J.B.; Silady, F.A.; Neylan, A.J.

    1994-04-01

    The Gas Turbine-Modular Helium Reactor (GT-MHR) is the result of coupling the evolution of a small passively safe reactor with key technology developments in the US during the last decade: large industrial gas turbines, large active magnetic bearings, and compact, highly effective plate-fin heat exchangers. The GT-MHR is the only reactor concept which provides a step increase in economic performance combined with increased safety. This is accomplished through its unique utilization of the Brayton cycle to produce electricity directly with the high temperature helium primary coolant from the reactor directly driving the gas turbine electrical generator. This cannot be accomplished with another reactor concept. It retains the high levels of passive safety and the standardized modular design of the steam cycle MHTGR, while showing promise for a significant reduction in power generating costs by increasing plant net efficiency to a remarkable 47%.

  1. A Large-eddy Simulation Study of Vertical Axis Wind Turbine Wakes in the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Shamsoddin, Sina; Porté-Agel, Fernando

    2016-04-01

    Vertical axis wind turbines (VAWTs) offer some advantages over their horizontal axis counterparts, and are being considered as a viable alternative to conventional horizontal axis wind turbines (HAWTs). Nevertheless, a relative shortage of scientific, academic and technical investigations of VAWTs is observed in the wind energy community with respect to HAWTs. Having this in mind, in this work, we aim to study the wake of a single VAWT, placed in the atmospheric boundary layer, using large-eddy simulation (LES) coupled with actuator line model (ALM). It is noteworthy that this is the first time that such a study is being performed. To do this, for a typical 1 MW VAWT design, first, the variation of power coefficient with both the chord length of the blades and the tip-speed ratio is analyzed using LES-ALM, and an optimum combination of chord length and tip-speed ratio is obtained. Subsequently, the wake of a VAWT with these optimum specifications is thoroughly examined by showing different relevant mean and turbulent wake flow statistics. Keywords: vertical axis wind turbine (VAWT); VAWT wake; Atmospheric Boundary Layer (ABL); large eddy simulation (LES); actuator line model (ALM); turbulence.

  2. Modeling the effect of control on the wake of a utility-scale turbine via large-eddy simulation

    NASA Astrophysics Data System (ADS)

    Yang, Xiaolei; Annoni, Jennifer; Seiler, Pete; Sotiropoulos, Fotis

    2014-06-01

    A model of the University of Minnesota EOLOS research turbine (Clipper Liberty C96) is developed, integrating the C96 torque control law with a high fidelity actuator line large- eddy simulation (LES) model. Good agreement with the blade element momentum theory is obtained for the power coefficient curve under uniform inflow. Three different cases, fixed rotor rotational speed ω, fixed tip-speed ratio (TSR) and generator torque control, have been simulated for turbulent inflow. With approximately the same time-averaged ω, the time- averaged power is in good agreement with measurements for all three cases. Although the time-averaged aerodynamic torque is nearly the same for the three cases, the root-mean-square (rms) of the aerodynamic torque fluctuations is significantly larger for the case with fixed ω. No significant differences have been observed for the time-averaged flow fields behind the turbine for these three cases.

  3. Large eddy simulation of pressure fluctuations at off-design condition in a Francis turbine based on cavitation model

    NASA Astrophysics Data System (ADS)

    Su, W. T.; Li, X. B.; Li, F. C.; Han, W. F.; Wei, X. Z.; Guo, J.

    2013-12-01

    To study the instability of a Francis turbine at off-design operating condition, a hydraulic model was established and the flow characteristics at the off-design point were studied based on large eddy simulation (LES). The simulation was conducted for both single phase model and cavitation model. The results were compared with the experimental data. Results show that the simulation based on cavitation model can capture more channel vortex structures than single phase calculation. The result of vortex rope by cavitation model is similar to the experimental result. The dominant frequency can be obtained by these two methods, while the result based on cavitation model can capture the high frequency component at the inlet of draft tube. Great difference can be seen from the internal flow of the two simulation results. These conclusions can provide a basis for the study of instability of Francis turbine.

  4. Aging assessment of large electric motors in nuclear power plants

    SciTech Connect

    Villaran, M.; Subudhi, M.

    1996-03-01

    Large electric motors serve as the prime movers to drive high capacity pumps, fans, compressors, and generators in a variety of nuclear plant systems. This study examined the stressors that cause degradation and aging in large electric motors operating in various plant locations and environments. The operating history of these machines in nuclear plant service was studied by review and analysis of failure reports in the NPRDS and LER databases. This was supplemented by a review of motor designs, and their nuclear and balance of plant applications, in order to characterize the failure mechanisms that cause degradation, aging, and failure in large electric motors. A generic failure modes and effects analysis for large squirrel cage induction motors was performed to identify the degradation and aging mechanisms affecting various components of these large motors, the failure modes that result, and their effects upon the function of the motor. The effects of large motor failures upon the systems in which they are operating, and on the plant as a whole, were analyzed from failure reports in the databases. The effectiveness of the industry`s large motor maintenance programs was assessed based upon the failure reports in the databases and reviews of plant maintenance procedures and programs.

  5. Nuclear-pumped lasers for large-scale applications

    SciTech Connect

    Anderson, R.E.; Leonard, E.M.; Shea, R.F.; Berggren, R.R.

    1989-05-01

    Efficient initiation of large-volume chemical lasers may be achieved by neutron induced reactions which produce charged particles in the final state. When a burst mode nuclear reactor is used as the neutron source, both a sufficiently intense neutron flux and a sufficiently short initiation pulse may be possible. Proof-of-principle experiments are planned to demonstrate lasing in a direct nuclear-pumped large-volume system; to study the effects of various neutron absorbing materials on laser performance; to study the effects of long initiation pulse lengths; to demonstrate the performance of large-scale optics and the beam quality that may be obtained; and to assess the performance of alternative designs of burst systems that increase the neutron output and burst repetition rate. 21 refs., 8 figs., 5 tabs.

  6. Blade System Design Studies Volume I: Composite Technologies for Large Wind Turbine Blades

    NASA Astrophysics Data System (ADS)

    Griffin, D.

    2002-07-01

    As part of the U.S. Department of Energy's Wind Partnerships for Advanced Component Technologies (WindPACT) program, Global Energy Concepts LLC (GEC) is performing a study concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. The project team for this work includes experts in all areas of wind turbine blade design, analysis, manufacture, and testing. Constraints to cost-effective scaling-up of the current commercial blade designs and manufacturing methods are identified, including self-gravity loads, transportation, and environmental considerations. A trade-off study is performed to evaluate the incremental changes in blade cost, weight, and stiffness for a wide range of composite materials, fabric types, and manufacturing processes.

  7. Influence of bearing support structures on shaft vibration of large hydraulic pump/turbines

    SciTech Connect

    Pistner, C.A.; Greenplate, B.S.; Waddell, A.M.

    1995-12-31

    Start-up transient loads from pump/turbine impellers can cause excessive vibration problems in the shaft system. If the radial guide bearing supports are structurally soft or loose, or if the bearings are worn, the resulting radial shaft movement causes abnormal wear. The wear normally occurs at the impeller sealing surfaces, main shaft seals, motor/generator components, piping, brackets, foundation connections, etc. This paper explores the critical factors causing shaft system vibration problems at the Tennessee Valley Authority`s Raccoon Mountain Pumped Storage Plant, as well as the unique modifications which were implemented to strengthen and improve the units. The solution involved extensive three-dimensional finite element structural and thermal transient analyses of the original and re-designed turbine shoe bearing, bearing housings, and support structures. The conclusion compares the calculated and measured shaft system response to transient loads of the original and modified system.

  8. Clustering for unsupervised fault diagnosis in nuclear turbine shut-down transients

    NASA Astrophysics Data System (ADS)

    Baraldi, Piero; Di Maio, Francesco; Rigamonti, Marco; Zio, Enrico; Seraoui, Redouane

    2015-06-01

    Empirical methods for fault diagnosis usually entail a process of supervised training based on a set of examples of signal evolutions "labeled" with the corresponding, known classes of fault. However, in practice, the signals collected during plant operation may be, very often, "unlabeled", i.e., the information on the corresponding type of occurred fault is not available. To cope with this practical situation, in this paper we develop a methodology for the identification of transient signals showing similar characteristics, under the conjecture that operational/faulty transient conditions of the same type lead to similar behavior in the measured signals evolution. The methodology is founded on a feature extraction procedure, which feeds a spectral clustering technique, embedding the unsupervised fuzzy C-means (FCM) algorithm, which evaluates the functional similarity among the different operational/faulty transients. A procedure for validating the plausibility of the obtained clusters is also propounded based on physical considerations. The methodology is applied to a real industrial case, on the basis of 148 shut-down transients of a Nuclear Power Plant (NPP) steam turbine.

  9. Simulation studies of multiple large wind turbine generators on a utility network

    NASA Technical Reports Server (NTRS)

    Gilbert, L. J.; Triezenberg, D. M.

    1979-01-01

    The potential electrical problems that may be inherent in the inertia of clusters of wind turbine generators and an electric utility network were investigated. Preliminary and limited results of an analog simulation of two MOD-2 wind generators tied to an infinite bus indicate little interaction between the generators and between the generators and the bus. The system demonstrated transient stability for the conditions considered.

  10. Large wind turbine siting handbook: television interference assessment. Final subcontract report

    SciTech Connect

    Senior, T B.A.; Sengupta, D L

    1983-01-01

    The rotating blades of a horizontal axis wind turbine can distort the video portion of a television signal and thereby interfere with TV reception in the vicinity of the machine. The nature of this interference is described and methods are presented for calculating the zone within which the interference may be severs. Specific results are given for the MOD-OA, MOD-1 and MOD-2 machines as functions of the TV frequency.

  11. New high efficiency low capital coal fueled combined cycle using existing CFBs and large gas turbines

    SciTech Connect

    Rohrer, J.W.

    1999-07-01

    Advanced Coal Power Technologies (IGCC, PFBII, and HIPPS) despite over two decades of technical development, have seen a disappointing lack of commercial (unsubsidized) utilization. Pulverized coal (PC) steam cycles still dominate because of the intrinsic high capital cost of advanced coal technologies. Recent studies have shown that partial gasification combined cycles yield higher efficiencies than full gasification IGCC cycles. They also show that atmospheric CFB combustors suffer little or no efficiency penalty versus pressurized combustors (and have substantially lower capital costs) because turbine exhaust heat can be fully recovered as the combustion air supply for atmospheric combustors. One new atmospheric partial gasification combined cycle is particularly promising from both a capital cost and efficiency basis. It integrates existing coal atmospheric CFB boiler technology with conventional simple cycle high temperature gas turbines. The CFB boiler also supplies hot bed material to an inexpensive raw coal devolatilizer riser tube which produces a medium-high BTU turbine fuel gas without the need for an expensive power robbing oxygen plant.

  12. Orbital transfer of large space structures with nuclear electric rockets

    NASA Technical Reports Server (NTRS)

    Silva, T. H.; Byers, D. C.

    1980-01-01

    This paper discusses the potential application of electric propulsion for orbit transfer of a large spacecraft structure from low earth orbit to geosynchronous altitude in a deployed configuration. The electric power was provided by the spacecraft nuclear reactor space power system on a shared basis during transfer operations. Factors considered with respect to system effectiveness included nuclear power source sizing, electric propulsion thruster concept, spacecraft deployment constraints, and orbital operations and safety. It is shown that the favorable total impulse capability inherent in electric propulsion provides a potential economic advantage over chemical propulsion orbit transfer vehicles by reducing the number of Space Shuttle flights in ground-to-orbit transportation requirements.

  13. Large volume multiple-path nuclear pumped laser

    SciTech Connect

    Hohl, F.; Deyoung, R.J.

    1981-11-01

    Large volumes of gas are excited by using internal high reflectance mirrors that are arranged so that the optical path crosses back and forth through the excited gaseous medium. By adjusting the external dielectric mirrors of the laser, the number of paths through the laser cavity can be varied. Output powers were obtained that are substantially higher than the output powers of previous nuclear laser systems. Official Gazette of the U.S. Patent and Trademark Office

  14. Large Eddy Simulation of Flow in Turbine Cascades Using LESTool and UNCLE Codes

    NASA Technical Reports Server (NTRS)

    Huang, P. G.

    2004-01-01

    During the period December 23,1997 and December August 31,2004, we accomplished the development of 2 CFD codes for DNS/LES/RANS simulation of turbine cascade flows, namely LESTool and UNCLE. LESTool is a structured code making use of 5th order upwind differencing scheme and UNCLE is a second-order-accuracy unstructured code. LESTool has both Dynamic SGS and Spalart's DES models and UNCLE makes use of URANS and DES models. The current report provides a description of methodologies used in the codes.

  15. Large Eddy Simulation of Flow in Turbine Cascades Using LEST and UNCLE Codes

    NASA Technical Reports Server (NTRS)

    Ashpis, David (Technical Monitor); Huang, P. G.

    2004-01-01

    During the period December 23, 1997 and December August 31, 2004, we accomplished the development of 2 CFD codes for DNS/LES/RANS simulation of turbine cascade flows, namely LESTool and UNCLE. LESTool is a structured code making use of 5th order upwind differencing scheme and UNCLE is a second-order-accuracy unstructured code. LESTool has both Dynamic SGS and Sparlart's DES models and UNCLE makes use of URANS and DES models. The current report provides a description of methodologies used in the codes.

  16. A Transverse Flux High-Temperature Superconducting Generator Topology for Large Direct Drive Wind Turbines

    NASA Astrophysics Data System (ADS)

    Keysan, Ozan; Mueller, Markus A.

    The cost and mass of an offshore wind turbine power-train can be reduced by using high-temperature superconducting generators, but for a successful commercial design the superconducting generator should be as reliable as its alternatives. In this paper, we present a novel transverse flux superconducting generator topology which is suitable for low-speed, high-torque applications. The generator is designed with a stationary superconducting field winding and a variable reluctance claw pole motor for simplified mechanical structure and maximum reliability. 3D FEA simulation results of a 70 kW prototype is presented.

  17. Enhancing kinetic energy entrainment in LES of large wind farms by unconventional forcing at the turbine rotors

    NASA Astrophysics Data System (ADS)

    Verhulst, Claire; Meneveau, Charles

    2015-11-01

    Vertical entrainment of mean kinetic energy is believed to be a limiting factor for power generation in very large wind farms, which operate in the turbulent atmospheric boundary layer and experience detrimental wake effects. A new approach, meant to increase vertical entrainment and aid wake recovery, is proposed and evaluated with a preliminary ``proof of concept'' test using Large Eddy Simulation (LES) with periodic boundary conditions to obtain realistic fully developed flow. In addition to the traditional actuator thrust force, a synthetic vertical force is applied at the turbine rotors to force high-speed flow downward and low-speed flow upward. The ratio of the vertical force and the thrust force, held constant within each case, ranges from 0 to 1 across six cases and is applied independently at each turbine. The proposed approach is found to increase the power extraction and mean kinetic energy entrainment significantly, by up to 95% when the vertical force is similar in magnitude to the thrust force. The effect of the forcing scheme on the mean velocity field is considered in detail. In addition, a quadrant analysis is performed to determine how the synthetic forcing changes the statistical characteristics of the mean kinetic energy entrainment within the wind farm. This work was supported by NSF grant 1243482 (the WINDINSPIRE project).

  18. Performance Analysis of a Wind Turbine Driven Swash Plate Pump for Large Scale Offshore Applications

    NASA Astrophysics Data System (ADS)

    Buhagiar, D.; Sant, T.

    2014-12-01

    This paper deals with the performance modelling and analysis of offshore wind turbine-driven hydraulic pumps. The concept consists of an open loop hydraulic system with the rotor main shaft directly coupled to a swash plate pump to supply pressurised sea water. A mathematical model is derived to cater for the steady state behaviour of entire system. A simplified model for the pump is implemented together with different control scheme options for regulating the rotor shaft power. A new control scheme is investigated, based on the combined use of hydraulic pressure and pitch control. Using a steady-state analysis, the study shows how the adoption of alternative control schemes in a the wind turbine-hydraulic pump system may result in higher energy yields than those from a conventional system with an electrical generator and standard pitch control for power regulation. This is in particular the case with the new control scheme investigated in this study that is based on the combined use of pressure and rotor blade pitch control.

  19. Blade System Design Studies Volume I: Composite Technologies for Large Wind Turbine Blades

    SciTech Connect

    GRIFFIN, DAYTON A.; ASHWILL, THOMAS D.

    2002-07-01

    As part of the U.S. Department of Energy's Wind Partnerships for Advanced Component Technologies (WindPACT) program, Global Energy Concepts LLC (GEC) is performing a study concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. The project team for this work includes experts in all areas of wind turbine blade design, analysis, manufacture, and testing. Constraints to cost-effective scaling-up of the current commercial blade designs and manufacturing methods are identified, including self-gravity loads, transportation, and environmental considerations. A trade-off study is performed to evaluate the incremental changes in blade cost, weight, and stiffness for a wide range of composite materials, fabric types, and manufacturing processes. Fiberglass/carbon fiber hybrid blades are identified as having a promising combination of cost, weight, stiffness and fatigue resistance. Vacuum-assisted resin transfer molding, resin film infision, and pre-impregnated materials are identified as having benefits in reduced volatile emissions, higher fiber content, and improved laminate quality relative to the baseline wet lay-up process. Alternative structural designs are identified, including jointed configurations to facilitate transportation. Based on the results to date, recommendations are made for further evaluation and testing under this study to verify the predicted material and structural performance.

  20. Synchronization of the ERDA-NASA 100 LkW wind turbine generator with large utility networks

    NASA Technical Reports Server (NTRS)

    Hwang, H. H.; Gilbert, L. J.

    1977-01-01

    The synchronizing of a wind turbine generator against an infinite bus under random conditions is studied. With a digital computer, complete solutions for rotor speed, generator power angle, electromagnetic torque, wind turbine torque, wind turbine blade pitch angle, and armature current are obtained and presented by graphs.

  1. Implementation of a Biaxial Resonant Fatigue Test Method on a Large Wind Turbine Blade

    SciTech Connect

    Snowberg, D.; Dana, S.; Hughes, S.; Berling, P.

    2014-09-01

    A biaxial resonant test method was utilized to simultaneously fatigue test a wind turbine blade in the flap and edge (lead-lag) direction. Biaxial resonant blade fatigue testing is an accelerated life test method utilizing oscillating masses on the blade; each mass is independently oscillated at the respective flap and edge blade resonant frequency. The flap and edge resonant frequency were not controlled, nor were they constant for this demonstrated test method. This biaxial resonant test method presented surmountable challenges in test setup simulation, control and data processing. Biaxial resonant testing has the potential to complete test projects faster than single-axis testing. The load modulation during a biaxial resonant test may necessitate periodic load application above targets or higher applied test cycles.

  2. Evidence for a Large Natural Nuclear Reactor in Mars Past

    NASA Astrophysics Data System (ADS)

    Brandenburg, J. E.

    2006-05-01

    It has long been known that The isotopic ratios 129 Xe/132Xe and 40Ar/36Ar are very high in Mars atmosphere relative to Earth or meteoritic backgrounds. This fact has allowed the SNC meteorites to be identified as Martian based on their trapped gases (1). However, while the isotopic anomalies explained one mystery, the origin of the SNC meteorites, they created a new mystery: the rock samples from Mars show no evidence of the large amounts of Iodine or Potassium that would give naturally give rise to the Xenon and Argon isotopic anomalies (2). In fact, the Martian meteorites are depleted in Potassium relative to earth rocks. This is added to the fact that for other isotopic systems such as 80Kr, Mars rock samples must be irradiated by neutrons at fluences of 1015 /cm2 to explain observed abundances (1) . Compounding the mystery is the fact that Mars surface layer has elevated levels of Uranium and Thorium relative to Earth and even its own rocks, as determined from SNCs (3). These anomalies can be explained if some large nuclear energy release, such as by natural nuclear reactors known to have operated on Earth (4) in in some concentrated ore body, occurred with perhaps a large volcano like explosion that spread residues over the planets surface. Based on gamma ray observations from orbit (3), and the correlations of normally uncorrelated Th and K deposits , the approximate location of this event would appear to have been in the north of Mars in a region in Acidalia Planitia centered at 45N Latitude and 15W Longitude (5). The possibility of such a large radiological event in Mars past adds impetus to Mars exploration efforts and particularly to a human mission to Mars to learn more about this possible occurrence. (1) Swindle, T. D. , Caffee, M. W., and Hohenberg, C. M., (1986) "Xenon and other Noble Gases in Shergottites" Geochimica et Cosmochimica Acta, 50, pp 1001-1015. (2) Banin, A., Clark, B.C., and Wanke, H. "Surface Chemistry and Mineralogy" (1992) in "Mars

  3. Large Eddy Simulation of Wind Turbine Wakes in Prescribed Neutral and Non-Neutral Atmospheric Boundary Layers

    NASA Astrophysics Data System (ADS)

    Sarlak Chivaee, Hamid; Sørensen, Jens N.

    2014-12-01

    Large eddy simulation (LES) of an infinitely long wind farm in a fully developed flow is carried out based on solution of the incompressible Navier-Stokes equations. The wind turbines are modeled as equivalent rotating actuator disks by applying aerodynamic loads on the flow field using tabulated aerodynamic lift and drag coefficients to save computational time. As a substitute to standard wall modeling LES, a ''prescribed mean shear" profile (hereafter called PMS) approach has been implemented and analysed for generating the desired turbulent shear flow. It is applied on Neutral, Stable and Convective atmospheric boundary layers in presence of the -actuator disc represented- wind turbines and qualitatively meaningful results of mean and fluctuating velocity field is obtained. The effect of four different sub-grid scale (SGS) models on the flow structure is investigated and it is seen that subgrid scale modeling (in particular, the Mix-O and Smagorinsky models) improves the accuracy of the simulations. An optimal grid resolution is also proposed for this kind of simulation.

  4. Waste heat recovery options in a large gas-turbine combined power plant

    NASA Astrophysics Data System (ADS)

    Upathumchard, Ularee

    This study focuses on power plant heat loss and how to utilize the waste heat in energy recovery systems in order to increase the overall power plant efficiency. The case study of this research is a 700-MW natural gas combined cycle power plant, located in a suburban area of Thailand. An analysis of the heat loss of the combustion process, power generation process, lubrication system, and cooling system has been conducted to evaluate waste heat recovery options. The design of the waste heat recovery options depends to the amount of heat loss from each system and its temperature. Feasible waste heat sources are combustion turbine (CT) room ventilation air and lubrication oil return from the power plant. The following options are being considered in this research: absorption chillers for cooling with working fluids Ammonia-Water and Water-Lithium Bromide (in comparison) and Organic Rankine Cycle (ORC) with working fluids R134a and R245fa. The absorption cycles are modeled in three different stages; single-effect, double-effect and half-effect. ORC models used are simple ORC as a baseline, ORC with internal regenerator, ORC two-phase flash expansion ORC and ORC with multiple heat sources. Thermodynamic models are generated and each system is simulated using Engineering Equation Solver (EES) to define the most suitable waste heat recovery options for the power plant. The result will be synthesized and evaluated with respect to exergy utilization efficiency referred as the Second Law effectiveness and net output capacity. Results of the models give recommendation to install a baseline ORC of R134a and a double-effect water-lithium bromide absorption chiller, driven by ventilation air from combustion turbine compartment. The two technologies yield reasonable economic payback periods of 4.6 years and 0.7 years, respectively. The fact that this selected power plant is in its early stage of operation allows both models to economically and effectively perform waste heat

  5. Large Eddy Simulation of wind turbine wakes: detailed comparisons of two codes focusing on effects of numerics and subgrid modeling

    NASA Astrophysics Data System (ADS)

    Martínez-Tossas, Luis A.; Churchfield, Matthew J.; Meneveau, Charles

    2015-06-01

    In this work we report on results from a detailed comparative numerical study from two Large Eddy Simulation (LES) codes using the Actuator Line Model (ALM). The study focuses on prediction of wind turbine wakes and their breakdown when subject to uniform inflow. Previous studies have shown relative insensitivity to subgrid modeling in the context of a finite-volume code. The present study uses the low dissipation pseudo-spectral LES code from Johns Hopkins University (LESGO) and the second-order, finite-volume OpenFOAMcode (SOWFA) from the National Renewable Energy Laboratory. When subject to uniform inflow, the loads on the blades are found to be unaffected by subgrid models or numerics, as expected. The turbulence in the wake and the location of transition to a turbulent state are affected by the subgrid-scale model and the numerics.

  6. Large Eddy Simulation of Wind Turbine Wakes. Detailed Comparisons of Two Codes Focusing on Effects of Numerics and Subgrid Modeling

    SciTech Connect

    Martinez-Tossas, Luis A.; Churchfield, Matthew J.; Meneveau, Charles

    2015-06-18

    In this work we report on results from a detailed comparative numerical study from two Large Eddy Simulation (LES) codes using the Actuator Line Model (ALM). The study focuses on prediction of wind turbine wakes and their breakdown when subject to uniform inflow. Previous studies have shown relative insensitivity to subgrid modeling in the context of a finite-volume code. The present study uses the low dissipation pseudo-spectral LES code from Johns Hopkins University (LESGO) and the second-order, finite-volume OpenFOAMcode (SOWFA) from the National Renewable Energy Laboratory. When subject to uniform inflow, the loads on the blades are found to be unaffected by subgrid models or numerics, as expected. The turbulence in the wake and the location of transition to a turbulent state are affected by the subgrid-scale model and the numerics.

  7. Large Eddy Simulation of Wind Turbine Wakes. Detailed Comparisons of Two Codes Focusing on Effects of Numerics and Subgrid Modeling

    DOE PAGESBeta

    Martinez-Tossas, Luis A.; Churchfield, Matthew J.; Meneveau, Charles

    2015-06-18

    In this work we report on results from a detailed comparative numerical study from two Large Eddy Simulation (LES) codes using the Actuator Line Model (ALM). The study focuses on prediction of wind turbine wakes and their breakdown when subject to uniform inflow. Previous studies have shown relative insensitivity to subgrid modeling in the context of a finite-volume code. The present study uses the low dissipation pseudo-spectral LES code from Johns Hopkins University (LESGO) and the second-order, finite-volume OpenFOAMcode (SOWFA) from the National Renewable Energy Laboratory. When subject to uniform inflow, the loads on the blades are found to bemore » unaffected by subgrid models or numerics, as expected. The turbulence in the wake and the location of transition to a turbulent state are affected by the subgrid-scale model and the numerics.« less

  8. Nuclear EMP simulation for large-scale urban environments. FDTD for electrically large problems.

    SciTech Connect

    Smith, William S.; Bull, Jeffrey S.; Wilcox, Trevor; Bos, Randall J.; Shao, Xuan-Min; Goorley, John T.; Costigan, Keeley R.

    2012-08-13

    In case of a terrorist nuclear attack in a metropolitan area, EMP measurement could provide: (1) a prompt confirmation of the nature of the explosion (chemical or nuclear) for emergency response; and (2) and characterization parameters of the device (reaction history, yield) for technical forensics. However, urban environment could affect the fidelity of the prompt EMP measurement (as well as all other types of prompt measurement): (1) Nuclear EMP wavefront would no longer be coherent, due to incoherent production, attenuation, and propagation of gamma and electrons; and (2) EMP propagation from source region outward would undergo complicated transmission, reflection, and diffraction processes. EMP simulation for electrically-large urban environment: (1) Coupled MCNP/FDTD (Finite-difference time domain Maxwell solver) approach; and (2) FDTD tends to be limited to problems that are not 'too' large compared to the wavelengths of interest because of numerical dispersion and anisotropy. We use a higher-order low-dispersion, isotropic FDTD algorithm for EMP propagation.

  9. Gas Turbine Energy Conversion Systems for Nuclear Power Plants Applicable to LiFTR Liquid Fluoride Thorium Reactor Technology

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.

    2014-01-01

    This panel plans to cover thermal energy and electric power production issues facing our nation and the world over the next decades, with relevant technologies ranging from near term to mid-and far term.Although the main focus will be on ground based plants to provide baseload electric power, energy conversion systems (ECS) for space are also included, with solar- or nuclear energy sources for output power levels ranging tens of Watts to kilo-Watts for unmanned spacecraft, and eventual mega-Watts for lunar outposts and planetary surface colonies. Implications of these technologies on future terrestrial energy systems, combined with advanced fracking, are touched upon.Thorium based reactors, and nuclear fusion along with suitable gas turbine energy conversion systems (ECS) will also be considered by the panelists. The characteristics of the above mentioned ECS will be described, both in terms of their overall energy utilization effectiveness and also with regard to climactic effects due to exhaust emissions.

  10. Volcanic ash ingestion by a large gas turbine aeroengine: fan-particle interaction

    NASA Astrophysics Data System (ADS)

    Vogel, Andreas; Clarkson, Rory; Durant, Adam; Cassiani, Massimo; Stohl, Andreas

    2016-04-01

    Airborne particles from explosive volcanic eruptions are a major safety threat for aviation operations. The fine fraction of the emitted particles (<63 microns diameter) may remain in the atmosphere for days, or even weeks, and can affect commercial air traffic routes. Over the past century, there have been a considerable number of aircraft encounters with drifting volcanic ash clouds. Particles ingested into the engine cause erosion of upstream surfaces of compressor fan blades and rotor-path components, and can also cause contamination or blockage of electrical systems and the fuel system such as fuel nozzles and air bleed filters. Ash particles that enter the hot-section of the engine (combustor and turbine stages; temperature between 1400-1800°C) are rapidly heated above the glass transition temperature (about 650-1000°C) and become soft (or form a melt) and can stick as re-solidified deposits on nozzle guide vanes. The glass deposits change the internal aerodynamic airflow in the engine and can affect the cooling capability of the different components by clogging the cooling inlets/outlets, which can lead to a loss of power or flame-out. The nature of volcanic ash ingestion is primarily influenced by the fan at the front of the engine which produces the thrust that drives the aircraft. The ingested air is split between the core (compressor/combustor/turbine) and bypass (thrust) at a ratio of typically between, 1:5-10 on modern engines. Consequently, the ash particles are fractionated between the core and bypass by the geometry and dynamics of the fan blades. This study uses computational fluid dynamics (CFD) simulations of particle-laden airflows into a turbofan engine under different atmospheric and engine operation conditions. The main aim was to investigate the possible centrifugal effect of the fan blades as a function of particle size, and to relate this to the core intake concentration. We generated a generic 3D axial high-bypass turbofan engine using

  11. Large-Scale Uncertainty and Error Analysis for Time-dependent Fluid/Structure Interactions in Wind Turbine Applications

    SciTech Connect

    Alonso, Juan J.; Iaccarino, Gianluca

    2013-08-25

    The following is the final report covering the entire period of this aforementioned grant, June 1, 2011 - May 31, 2013 for the portion of the effort corresponding to Stanford University (SU). SU has partnered with Sandia National Laboratories (PI: Mike S. Eldred) and Purdue University (PI: Dongbin Xiu) to complete this research project and this final report includes those contributions made by the members of the team at Stanford. Dr. Eldred is continuing his contributions to this project under a no-cost extension and his contributions to the overall effort will be detailed at a later time (once his effort has concluded) on a separate project submitted by Sandia National Laboratories. At Stanford, the team is made up of Profs. Alonso, Iaccarino, and Duraisamy, post-doctoral researcher Vinod Lakshminarayan, and graduate student Santiago Padron. At Sandia National Laboratories, the team includes Michael Eldred, Matt Barone, John Jakeman, and Stefan Domino, and at Purdue University, we have Prof. Dongbin Xiu as our main collaborator. The overall objective of this project was to develop a novel, comprehensive methodology for uncertainty quantification by combining stochastic expansions (nonintrusive polynomial chaos and stochastic collocation), the adjoint approach, and fusion with experimental data to account for aleatory and epistemic uncertainties from random variable, random field, and model form sources. The expected outcomes of this activity were detailed in the proposal and are repeated here to set the stage for the results that we have generated during the time period of execution of this project: 1. The rigorous determination of an error budget comprising numerical errors in physical space and statistical errors in stochastic space and its use for optimal allocation of resources; 2. A considerable increase in efficiency when performing uncertainty quantification with a large number of uncertain variables in complex non-linear multi-physics problems; 3. A

  12. Optimizing liquid effluent monitoring at a large nuclear complex.

    PubMed

    Chou, Charissa J; Barnett, D Brent; Johnson, Vernon G; Olson, Phil M

    2003-12-01

    Effluent monitoring typically requires a large number of analytes and samples during the initial or startup phase of a facility. Once a baseline is established, the analyte list and sampling frequency may be reduced. Although there is a large body of literature relevant to the initial design, few, if any, published papers exist on updating established effluent monitoring programs. This paper statistically evaluates four years of baseline data to optimize the liquid effluent monitoring efficiency of a centralized waste treatment and disposal facility at a large defense nuclear complex. Specific objectives were to: (1) assess temporal variability in analyte concentrations, (2) determine operational factors contributing to waste stream variability, (3) assess the probability of exceeding permit limits, and (4) streamline the sampling and analysis regime. Results indicated that the probability of exceeding permit limits was one in a million under normal facility operating conditions, sampling frequency could be reduced, and several analytes could be eliminated. Furthermore, indicators such as gross alpha and gross beta measurements could be used in lieu of more expensive specific isotopic analyses (radium, cesium-137, and strontium-90) for routine monitoring. Study results were used by the state regulatory agency to modify monitoring requirements for a new discharge permit, resulting in an annual cost savings of US dollars 223,000. This case study demonstrates that statistical evaluation of effluent contaminant variability coupled with process knowledge can help plant managers and regulators streamline analyte lists and sampling frequencies based on detection history and environmental risk. PMID:15160897

  13. Synchronization of the ERDA-NASA 100 kW wind turbine generator with large utility networks

    NASA Technical Reports Server (NTRS)

    Hwang, H. H.; Gilbert, L. J.

    1977-01-01

    The synchronizing of a wind turbine generator against an infinite bus under random conditions is studied for the first time. With a digital computer, complete solutions for rotor speed, generator power angle, electromagnetic torque, wind turbine torque, wind turbine blade pitch angle, and armature current are obtained and presented by graphs. Experiments have been recently performed on the ERDA-NASA 100 kW wind turbine. Experimental results matched computer study results very closely and confirmed that the synchronization can be accomplished by means of the existing speed control system and an automatic synchronizer.

  14. Examples of the Influence of Turbine Wakes on Downwind Power Output, Surface Wind Speed, Turbulence and Flow Convergence in Large Wind Farms

    NASA Astrophysics Data System (ADS)

    Takle, E. S.; Rajewski, D. A.; Lundquist, J. K.; Doorenbos, R. K.

    2014-12-01

    We have analyzed turbine power and concurrent wind speed, direction and turbulence data from surface 10-m flux towers in a large wind farm for experiments during four summer periods as part of the Crop Wind Energy Experiment (CWEX). We use these data to analyze surface differences for a near-wake (within 2.5 D of the turbine line), far wake (17 D downwind of the turbine line), and double wake (impacted by two lines of turbines about 34 D downwind of the first turbine line) locations. Composites are categorized by10 degree directional intervals and three ambient stability categories as defined by Rajewski et al. (2013): neutral (|z/L|<0.05), stable (z/L>0.05) and unstable (z/L<-0.05), where z is the height of the measurement and L is the Monin-Obhukov length. The dominant influence of the turbines is under stably stratified conditions (i. e., mostly at night). A 25% to 40% increase in mean wind speed occurs when turbine wakes are moving over the downwind station at a distance of 2.8 D and 5.4 D (D = fan diameter). For the double wake condition (flux station leeward of two lines of turbines) we find a daytime (unstable conditions) speed reduction of 20% for southerly wind, but for nighttime (stable conditions) the surface speeds are enhancedby 40-60% for SSW-SW winds. The speedup is reduced as wind directions shift to the west. We interpret these speed variations as due to the rotation of the wake and interaction (or not) with higher speed air above the rotor layer in highly sheared nocturnal low-level jet conditions. From a cluster of flux stations and three profiling lidars deployed within and around a cluster of turbines in 2013 (CWEX-13) we found evidence of mesoscale influences. In particular, surface convergence (wind direction deflection of 10-20 degrees) was observed during periods of low nighttime winds (hub-height winds of 4-6 m/s) with power reduction of 50-75%. This is consistent with a similar range of deflection observed from a line of turbines in CWEX

  15. Safety aspects of ground testing for large nuclear rockets

    SciTech Connect

    Goldman, M.I.

    1988-02-01

    Present nuclear rocket reactors under test in Nevada are operated at nominal power levels of 1000 Mw. It does not seem unreasonable in the future to anticipate reactors with power levels in the range up to 5,000 Mw for space applications. It has been shown that the normal testing of large nuclear rocket engines at NRDS could impose some restrictions on the fuel performance which would not otherwise be required by space flight operation. The only apparent alternative would require a capability for decontaminating effluent gases prior to release to the atmosphere. In addition to the source restrictions, tests will almost certainly be controlled by wind and atmospheric stability conditions, and the requirements for monitoring and control of off-site exposures will be much more stringent than those presently in force. An analysis of maximum accidents indicates that projections of present credible occurrences cannot be tolerated in larger engine tests. The apparent alternatives to a significant (order of magnitude or better) reduction in credible accident consequences, are the establishment of an underground test facility, a facility in an area equivalent to the Pacific weapons proving ground, or in space.

  16. Calculation of flow distribution in large radius ratio stages of axial flow turbines and comparison of theory and experiment

    NASA Technical Reports Server (NTRS)

    Herzog, J.

    1974-01-01

    A method of calculating stage parameters and flow distribution of axial turbines is described. The governing equations apply to space between the blade rows and are based on the assumption of rotationally symmetrical, compressible, adiabatic flow conditions. Results are presented for stage design and flow analysis calculations. Theoretical results from the calculation system are compared with experimental data from low pressure steam turbine tests.

  17. Large Scale Computing and Storage Requirements for Nuclear Physics Research

    SciTech Connect

    Gerber, Richard A.; Wasserman, Harvey J.

    2012-03-02

    IThe National Energy Research Scientific Computing Center (NERSC) is the primary computing center for the DOE Office of Science, serving approximately 4,000 users and hosting some 550 projects that involve nearly 700 codes for a wide variety of scientific disciplines. In addition to large-scale computing resources NERSC provides critical staff support and expertise to help scientists make the most efficient use of these resources to advance the scientific mission of the Office of Science. In May 2011, NERSC, DOE’s Office of Advanced Scientific Computing Research (ASCR) and DOE’s Office of Nuclear Physics (NP) held a workshop to characterize HPC requirements for NP research over the next three to five years. The effort is part of NERSC’s continuing involvement in anticipating future user needs and deploying necessary resources to meet these demands. The workshop revealed several key requirements, in addition to achieving its goal of characterizing NP computing. The key requirements include: 1. Larger allocations of computational resources at NERSC; 2. Visualization and analytics support; and 3. Support at NERSC for the unique needs of experimental nuclear physicists. This report expands upon these key points and adds others. The results are based upon representative samples, called “case studies,” of the needs of science teams within NP. The case studies were prepared by NP workshop participants and contain a summary of science goals, methods of solution, current and future computing requirements, and special software and support needs. Participants were also asked to describe their strategy for computing in the highly parallel, “multi-core” environment that is expected to dominate HPC architectures over the next few years. The report also includes a section with NERSC responses to the workshop findings. NERSC has many initiatives already underway that address key workshop findings and all of the action items are aligned with NERSC strategic plans.

  18. A carbon-13 and proton nuclear magnetic resonance study of some experimental referee broadened-specification /ERBS/ turbine fuels

    NASA Technical Reports Server (NTRS)

    Dalling, D. K.; Pugmire, R. J.

    1982-01-01

    Preliminary results of a nuclear magnetic resonance (NMR) spectroscopy study of alternative jet fuels are presented. A referee broadened-specification (ERBS) aviation turbine fuel, a mixture of 65 percent traditional kerosene with 35 percent hydrotreated catalytic gas oil (HCGO) containing 12.8 percent hydrogen, and fuels of lower hydrogen content created by blending the latter with a mixture of HCGO and xylene bottoms were studied. The various samples were examined by carbon-13 and proton NMR at high field strength, and the resulting spectra are shown. In the proton spectrum of the 12.8 percent hydrogen fuel, no prominent single species is seen while for the blending stock, many individual lines are apparent. The ERBS fuels were fractionated by high-performance liquid chromatography and the resulting fractions analyzed by NMR. The species found are identified.

  19. Very high efficiency small nuclear gas turbine power plant concept (HTGR-GT/BC) for special applications

    SciTech Connect

    McDonald, C.F.; Cavallaro, L.; Kapich, D.; Medwid, W.A.

    1984-06-01

    To meet the energy needs of special terrestrial defense installations, where a premium is placed on high plant efficiency, conceptual studies have been performed on an advanced closed-cycle gas turbine system with a high-temperature gas-cooled reactor (HTGR) as the heat source. Emphasis has been placed on system compactness and plant simplicity. A goal of plant operation for extended periods with no environmental contact had a strong influence on the design features. To realize a high plant efficiency (over 50%) for this mode of operation, a combined cycle was investigated. A primary helium Brayton power conversion system coupled with a Freon bottoming cycle was selected. Details are presented of the reactor arrangement, power conversion system, major components, installation, and performance for a compact nuclear power plant currently in a very early stage of concept definition.

  20. Study of mean- and turbulent-velocity fields in a large-scale turbine-vane passage

    NASA Technical Reports Server (NTRS)

    Bailey, D. A.

    1979-01-01

    Laser-Doppler velocimetry, and to a lesser extent hot-wire anemometry, were employed to measure three components of the mean velocity and the six turbulent stresses at four planes within the turbine inlet-guide-vane passage. One variation in the turbulent inlet boundary layer thickness and one variation in the blade aspect ratio (span/axial chord) were studied. A longitudinal vortex (passage vortex) was clearly identified in the exit plane of the passage for the three test cases. The maximum turbulence intensities within the longitudinal vortex were found to be on the order of 2 to 4 percent, with large regions appearing nonturbulent. Because a turbulent wall boundary layer was the source of vorticity that produced the passage vortex, these low turbulence levels were not anticipated. For the three test cases studied, the lateral velocity field extended significantly beyond the region of the longitudinal velocity defect. Changing the inlet boundary layer thickness produced a difference in the location, the strength, and the extent of the passage vortex. Changing the aspect ratio of the blade passage had a measurable but less significant effect. The experiment was performed in a 210 mm pitch, 272 mm axial chord model in low speed wind tunnel at an inlet Mach number of 0.07.

  1. Cracked shaft detection on large vertical nuclear reactor coolant pump

    NASA Technical Reports Server (NTRS)

    Jenkins, L. S.

    1985-01-01

    Due to difficulty and radiation exposure associated with examination of the internals of large commercial nuclear reactor coolant pumps, it is necessary to be able to diagnose the cause of an excessive vibration problem quickly without resorting to extensive trial and error efforts. Consequently, it is necessary to make maximum use of all available data to develop a consistent theory which locates the problem area in the machine. This type of approach was taken at Three Mile Island, Unit #1, in February 1984 to identify and locate the cause of a continuously climbing vibration level of the pump shaft. The data gathered necessitated some in-depth knowledge of the pump internals to provide proper interpretation and avoid misleading conclusions. Therefore, the raw data included more than just the vibration characteristics. Pertinent details of the data gathered is shown and is necessary and sufficient to show that the cause of the observed vibration problem could logically only be a cracked pump shaft in the shaft overhang below the pump bearing.

  2. Response of a thermal barrier system to acoustic excitation in a gas turbine nuclear reactor

    SciTech Connect

    Betts, W.S. Jr.; Blevins, R.D.

    1980-11-01

    A gas turbine located within a High-Temperature Gas-Cooled Reactor (HTGR) induces high acoustic sound pressure levels into the primary coolant (helium). This acoustic loading induces high cycle fatigue stresses which may control the design of the thermal barrier system. This study examines the dynamic response of a thermal barrier configuration consisting of a fibrous insulation compressed against the reactor vessel by a coverplate which is held in position by a central attachment fixture. The results of dynamic vibration analyses indicate the effect of the plate size and curvature and the attachment size on the response of the thermal barrier.

  3. Large-Eddy Simulations of Plasma Flow Control on a GOE735 Wind Turbine Airfoil

    NASA Astrophysics Data System (ADS)

    Czulak, Alexander; Franck, Jennifer

    2015-11-01

    Active flow control using plasma actuation was studied for the GOE735 airfoil and compared to non-actuated baseline cases using numerical simulations. This investigation considers two-dimensional simulations at a Reynolds number of 1,000 using direct numerical simulation (DNS) as well as three-dimensional simulations at a Reynolds number of 50,000 and 100,000 using large-eddy simulation (LES). Plasma actuation is applied in terms of a source term within the boundary layer close to the airfoil surface. Angles of attack of 0°, 5° and 15° were considered, and control is shown to be effective at increasing the lift coefficient, decreasing the drag coefficient and reducing the root mean squared deviation of both lift and drag. An analysis of the flow physics reveals that the actuated cases delay the point of separation, reduce the wake width and diminish the size and strength of the shed vortices. For this particular airfoil, there are significant differences in Reynolds number in terms of the baseline flow, control effectiveness and performance factors such as lift and drag.

  4. Defining Gas Turbine Engine Performance Requirements for the Large Civil TiltRotor (LCTR2)

    NASA Technical Reports Server (NTRS)

    Snyder, Christopher A.

    2013-01-01

    Defining specific engine requirements is a critical part of identifying technologies and operational models for potential future rotary wing vehicles. NASA's Fundamental Aeronautics Program, Subsonic Rotary Wing Project has identified the Large Civil TiltRotor (LCTR) as the configuration to best meet technology goals. This notional vehicle concept has evolved with more clearly defined mission and operational requirements to the LCTR-iteration 2 (LCTR2). This paper reports on efforts to further review and refine the LCTR2 analyses to ascertain specific engine requirements and propulsion sizing criteria. The baseline mission and other design or operational requirements are reviewed. Analysis tools are described to help understand their interactions and underlying assumptions. Various design and operational conditions are presented and explained for their contribution to defining operational and engine requirements. These identified engine requirements are discussed to suggest which are most critical to the engine sizing and operation. The most-critical engine requirements are compared to in-house NASA engine simulations to try to ascertain which operational requirements define engine requirements versus points within the available engine operational capability. Finally, results are summarized with suggestions for future efforts to improve analysis capabilities, and better define and refine mission and operational requirements.

  5. Proceedings of the 1998 international joint power generation conference (FACT-Vol.22). Volume 1: Fuels and combustion technologies; Gas turbines; Environmental engineering; Nuclear engineering

    SciTech Connect

    Gupta, A.; Natole, R.; Sanyal, A.; Veilleux, J.

    1998-07-01

    Papers are arranged under the following topical sections: Fuels and combustion technologies; Low NOx burner applications; Low cost solutions to utility NOx compliance issues; Coal combustion--Retrofit experiences, low NOx, and efficiency; Highly preheated air combustion; Combustion control and optimization; Advanced technology for gas fuel combustion; Spray combustion and mixing; Efficient power generation using gas turbines; Safety issues in power industry; Efficient and environmentally benign conversion of wastes to energy; Artificial intelligence monitoring, control, and optimization of power plants; Combustion modeling and diagnostics; Advanced combustion technologies and combustion synthesis; Aero and industrial gas turbine presentations IGTI gas turbine division; NOx/SO{sub 2}; Plant cooling water system problems and solutions; Issues affecting plant operations and maintenance; and Costs associated with operating and not operating a nuclear power plant. Papers within scope have been processed separately for inclusion on the database.

  6. The effects of Reynolds number, rotor incidence angle and surface roughness on the heat transfer distribution in a large-scale turbine rotor passage

    NASA Technical Reports Server (NTRS)

    Blair, M. F.

    1991-01-01

    A combined experimental and computational program was conducted to examine the heat transfer distribution in a turbine rotor passage geometrically similar to the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump (HPFTP). Heat transfer was measured and computed for both the full span suction and pressure surfaces of the rotor airfoil as well as for the hub endwall surface. The objective of the program was to provide a benchmark-quality database for the assessment of rotor heat transfer computational techniques. The experimental portion of the study was conducted in a large scale, ambient temperature, rotating turbine model. The computational portion consisted of the application of a well-posed parabolized Navier-Stokes analysis of the calculation of the three-dimensional viscous flow through ducts simulating a gas turbine package. The results of this assessment indicate that the procedure has the potential to predict the aerodynamics and the heat transfer in a gas turbine passage and can be used to develop detailed three dimensional turbulence models for the prediction of skin friction and heat transfer in complex three dimensional flow passages.

  7. Wind Turbine Box - energy fluxes around a characteristic wind turbine

    NASA Astrophysics Data System (ADS)

    Calaf, Marc; Cortina, Gerard; Sharma, Varun

    2015-11-01

    This research project presents a new tool, so called ``Wind Turbine Box'', that allows for the direct comparison between the flow around a single wind turbine and the flow around a characteristic wind turbine immersed within a large wind farm. The Wind Turbine Box consists of a limited control volume defined around each wind turbine that is timely co-aligned with each corresponding turbine's yaw-angle. Hence it is possible to extract flow statistics around each wind turbine, regardless of whether the turbine is fully isolated or it is plunged within a large wind farm. The Wind Turbine Box tool has been used to compute the energy fluxes around a characteristic wind turbine of a large wind farm to better understand the wake replenishment processes throughout a complete diurnal cycle. The effective loading of the wind farm has been gradually increased, ranging from quasi-isolated wind turbines to a highly packed wind farm. For this purpose, several Large Eddy Simulations have been run, forced with a constant geostrophic wind and a time varying surface temperature extracted from a selected period of the CASES-99 field experiment. Results illustrate the differences in the flow dynamics as it evolves around a characteristic wind turbine within a large wind farm and its asymptotic transition to the fully developed wind turbine array boundary layer.

  8. Investigating wind turbine impacts on near-wake flow using profiling Lidar data and large-eddy simulations with an actuator disk model

    SciTech Connect

    Mirocha, Jeffrey D.; Rajewski, Daniel A.; Marjanovic, Nikola; Lundquist, Julie K.; Kosovic, Branko; Draxl, Caroline; Churchfield, Matthew J.

    2015-08-27

    In this study, wind turbine impacts on the atmospheric flow are investigated using data from the Crop Wind Energy Experiment (CWEX-11) and large-eddy simulations (LESs) utilizing a generalized actuator disk (GAD) wind turbine model. CWEX-11 employed velocity-azimuth display (VAD) data from two Doppler lidar systems to sample vertical profiles of flow parameters across the rotor depth both upstream and in the wake of an operating 1.5 MW wind turbine. Lidar and surface observations obtained during four days of July 2011 are analyzed to characterize the turbine impacts on wind speed and flow variability, and to examine the sensitivity of these changes to atmospheric stability. Significant velocity deficits (VD) are observed at the downstream location during both convective and stable portions of four diurnal cycles, with large, sustained deficits occurring during stable conditions. Variances of the streamwise velocity component, σu, likewise show large increases downstream during both stable and unstable conditions, with stable conditions supporting sustained small increases of σu , while convective conditions featured both larger magnitudes and increased variability, due to the large coherent structures in the background flow. Two representative case studies, one stable and one convective, are simulated using LES with a GAD model at 6 m resolution to evaluate the compatibility of the simulation framework with validation using vertically profiling lidar data in the near wake region. Virtual lidars were employed to sample the simulated flow field in a manner consistent with the VAD technique. Simulations reasonably reproduced aggregated wake VD characteristics, albeit with smaller magnitudes than observed, while σu values in the wake are more significantly underestimated. The results illuminate the limitations of using a GAD in combination with coarse model resolution in the simulation of near wake physics, and validation thereof using VAD data.

  9. Investigating wind turbine impacts on near-wake flow using profiling Lidar data and large-eddy simulations with an actuator disk model

    DOE PAGESBeta

    Mirocha, Jeffrey D.; Rajewski, Daniel A.; Marjanovic, Nikola; Lundquist, Julie K.; Kosovic, Branko; Draxl, Caroline; Churchfield, Matthew J.

    2015-08-27

    In this study, wind turbine impacts on the atmospheric flow are investigated using data from the Crop Wind Energy Experiment (CWEX-11) and large-eddy simulations (LESs) utilizing a generalized actuator disk (GAD) wind turbine model. CWEX-11 employed velocity-azimuth display (VAD) data from two Doppler lidar systems to sample vertical profiles of flow parameters across the rotor depth both upstream and in the wake of an operating 1.5 MW wind turbine. Lidar and surface observations obtained during four days of July 2011 are analyzed to characterize the turbine impacts on wind speed and flow variability, and to examine the sensitivity of thesemore » changes to atmospheric stability. Significant velocity deficits (VD) are observed at the downstream location during both convective and stable portions of four diurnal cycles, with large, sustained deficits occurring during stable conditions. Variances of the streamwise velocity component, σu, likewise show large increases downstream during both stable and unstable conditions, with stable conditions supporting sustained small increases of σu , while convective conditions featured both larger magnitudes and increased variability, due to the large coherent structures in the background flow. Two representative case studies, one stable and one convective, are simulated using LES with a GAD model at 6 m resolution to evaluate the compatibility of the simulation framework with validation using vertically profiling lidar data in the near wake region. Virtual lidars were employed to sample the simulated flow field in a manner consistent with the VAD technique. Simulations reasonably reproduced aggregated wake VD characteristics, albeit with smaller magnitudes than observed, while σu values in the wake are more significantly underestimated. The results illuminate the limitations of using a GAD in combination with coarse model resolution in the simulation of near wake physics, and validation thereof using VAD data.« less

  10. Nuclear States with Abnormally Large Radii (size Isomers)

    NASA Astrophysics Data System (ADS)

    Ogloblin, A. A.; Demyanova, A. S.; Danilov, A. N.; Belyaeva, T. L.; Goncharov, S. A.

    2015-06-01

    Application of the methods of measuring the radii of the short-lived excited states (Modified diffraction model MDM, Inelastic nuclear rainbow scattering method INRS, Asymptotic normalization coefficients method ANC) to the analysis of some nuclear reactions provide evidence of existing in 9Be, 11B, 12C, 13C the excited states whose radii exceed those of the corresponding ground states by ~ 30%. Two types of structure of these "size isomers" were identified: neutron halo an α-clusters.

  11. Implementation of a generalized actuator disk wind turbine model into the weather research and forecasting model for large-eddy simulation applications

    SciTech Connect

    Mirocha, J. D.; Kosovic, B.; Aitken, M. L.; Lundquist, J. K.

    2014-01-10

    A generalized actuator disk (GAD) wind turbine parameterization designed for large-eddy simulation (LES) applications was implemented into the Weather Research and Forecasting (WRF) model. WRF-LES with the GAD model enables numerical investigation of the effects of an operating wind turbine on and interactions with a broad range of atmospheric boundary layer phenomena. Numerical simulations using WRF-LES with the GAD model were compared with measurements obtained from the Turbine Wake and Inflow Characterization Study (TWICS-2011), the goal of which was to measure both the inflow to and wake from a 2.3-MW wind turbine. Data from a meteorological tower and two light-detection and ranging (lidar) systems, one vertically profiling and another operated over a variety of scanning modes, were utilized to obtain forcing for the simulations, and to evaluate characteristics of the simulated wakes. Simulations produced wakes with physically consistent rotation and velocity deficits. Two surface heat flux values of 20 W m–2 and 100 W m–2 were used to examine the sensitivity of the simulated wakes to convective instability. Simulations using the smaller heat flux values showed good agreement with wake deficits observed during TWICS-2011, whereas those using the larger value showed enhanced spreading and more-rapid attenuation. This study demonstrates the utility of actuator models implemented within atmospheric LES to address a range of atmospheric science and engineering applications. In conclusion, validated implementation of the GAD in a numerical weather prediction code such as WRF will enable a wide range of studies related to the interaction of wind turbines with the atmosphere and surface.

  12. Adaptive Disturbance Tracking Theory with State Estimation and State Feedback for Region II Control of Large Wind Turbines

    NASA Technical Reports Server (NTRS)

    Balas, Mark J.; Thapa Magar, Kaman S.; Frost, Susan A.

    2013-01-01

    A theory called Adaptive Disturbance Tracking Control (ADTC) is introduced and used to track the Tip Speed Ratio (TSR) of 5 MW Horizontal Axis Wind Turbine (HAWT). Since ADTC theory requires wind speed information, a wind disturbance generator model is combined with lower order plant model to estimate the wind speed as well as partial states of the wind turbine. In this paper, we present a proof of stability and convergence of ADTC theory with lower order estimator and show that the state feedback can be adaptive.

  13. Small turbines, big unknown

    SciTech Connect

    Gipe, P.

    1995-07-01

    While financial markets focus on the wheeling and dealing of the big wind companies, the small wind turbine industry quietly keeps churning out its smaller but effective machines. Some, the micro turbines, are so small they can be carried by hand. Though worldwide sales of small wind turbines fall far short of even one large windpower plant, figures reach $8 million to $10 million annually and could be as much as twice that if batteries and engineering services are included.

  14. Large volume multiple path nuclear lasing of /He-3/-Ar

    NASA Technical Reports Server (NTRS)

    De Young, R. J.; Hohl, F.

    1980-01-01

    Output power of 550 W has been achieved from a nuclear-pumped multiple path laser system containing (He-3)-Ar by using the (He-3)(n, p)3(H) nuclear reaction for power deposition. Lasing was achieved in Ar at 1790 nm. The complex beam profile was resolved by an InAs array detector. Laser output was directly proportional to thermal neutron flux, and also increased proportionally with increasing (He-3) pressure up to 292.6 kPa. The variation of the laser output power with the number of passes through the excited medium was found to peak at 5-7 passes.

  15. Turbinate surgery

    MedlinePlus

    Turbinectomy; Turbinoplasty; Turbinate reduction; Nasal airway surgery ... There are several types of turbinate surgery: Turbinectomy: All or part of the lower turbinate is taken out. This can be done in several different ways, but sometimes a ...

  16. Coalescing Wind Turbine Wakes

    NASA Astrophysics Data System (ADS)

    Lee, S.; Churchfield, M.; Sirnivas, S.; Moriarty, P.; Nielsen, F. G.; Skaare, B.; Byklum, E.

    2015-06-01

    A team of researchers from the National Renewable Energy Laboratory and Statoil used large-eddy simulations to numerically investigate the merging wakes from upstream offshore wind turbines. Merging wakes are typical phenomena in wind farm flows in which neighboring turbine wakes consolidate to form complex flow patterns that are as yet not well understood. In the present study, three 6-MW turbines in a row were subjected to a neutrally stable atmospheric boundary layer flow. As a result, the wake from the farthest upstream turbine conjoined the downstream wake, which significantly altered the subsequent velocity deficit structures, turbulence intensity, and the global meandering behavior. The complexity increased even more when the combined wakes from the two upstream turbines mixed with the wake generated by the last turbine, thereby forming a “triplet” structure. Although the influence of the wake generated by the first turbine decayed with downstream distance, the mutated wakes from the second turbine continued to influence the downstream wake. Two mirror-image angles of wind directions that yielded partial wakes impinging on the downstream turbines yielded asymmetric wake profiles that could be attributed to the changing flow directions in the rotor plane induced by the Coriolis force. The turbine wakes persisted for extended distances in the present study, which is a result of low aerodynamic surface roughness typically found in offshore conditions.

  17. Coalescing Wind Turbine Wakes

    DOE PAGESBeta

    Lee, S.; Churchfield, M.; Sirnivas, S.; Moriarty, P.; Nielsen, F. G.; Skaare, B.; Byklum, E.

    2015-06-18

    A team of researchers from the National Renewable Energy Laboratory and Statoil used large-eddy simulations to numerically investigate the merging wakes from upstream offshore wind turbines. Merging wakes are typical phenomena in wind farm flows in which neighboring turbine wakes consolidate to form complex flow patterns that are as yet not well understood. In the present study, three 6-MW turbines in a row were subjected to a neutrally stable atmospheric boundary layer flow. As a result, the wake from the farthest upstream turbine conjoined the downstream wake, which significantly altered the subsequent velocity deficit structures, turbulence intensity, and the globalmore » meandering behavior. The complexity increased even more when the combined wakes from the two upstream turbines mixed with the wake generated by the last turbine, thereby forming a "triplet" structure. Although the influence of the wake generated by the first turbine decayed with downstream distance, the mutated wakes from the second turbine continued to influence the downstream wake. Two mirror-image angles of wind directions that yielded partial wakes impinging on the downstream turbines yielded asymmetric wake profiles that could be attributed to the changing flow directions in the rotor plane induced by the Coriolis force. In conclusion, the turbine wakes persisted for extended distances in the present study, which is a result of low aerodynamic surface roughness typically found in offshore conditions« less

  18. Coalescing Wind Turbine Wakes

    SciTech Connect

    Lee, S.; Churchfield, M.; Sirnivas, S.; Moriarty, P.; Nielsen, F. G.; Skaare, B.; Byklum, E.

    2015-06-18

    A team of researchers from the National Renewable Energy Laboratory and Statoil used large-eddy simulations to numerically investigate the merging wakes from upstream offshore wind turbines. Merging wakes are typical phenomena in wind farm flows in which neighboring turbine wakes consolidate to form complex flow patterns that are as yet not well understood. In the present study, three 6-MW turbines in a row were subjected to a neutrally stable atmospheric boundary layer flow. As a result, the wake from the farthest upstream turbine conjoined the downstream wake, which significantly altered the subsequent velocity deficit structures, turbulence intensity, and the global meandering behavior. The complexity increased even more when the combined wakes from the two upstream turbines mixed with the wake generated by the last turbine, thereby forming a "triplet" structure. Although the influence of the wake generated by the first turbine decayed with downstream distance, the mutated wakes from the second turbine continued to influence the downstream wake. Two mirror-image angles of wind directions that yielded partial wakes impinging on the downstream turbines yielded asymmetric wake profiles that could be attributed to the changing flow directions in the rotor plane induced by the Coriolis force. In conclusion, the turbine wakes persisted for extended distances in the present study, which is a result of low aerodynamic surface roughness typically found in offshore conditions

  19. The effects of Reynolds number, rotor incidence angle, and surface roughness on the heat transfer distribution in a large-scale turbine rotor passage

    NASA Technical Reports Server (NTRS)

    Blair, Michael F.; Anderson, Olof L.

    1989-01-01

    A combined experimental and computational program was conducted to examine the heat transfer distribution in a turbine rotor passage geometrically similiar to the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump (HPFTP). Heat transfer was measured and computed for both the full-span suction and pressure surfaces of the rotor airfoil as well as for the hub endwall surface. The primary objective of the program was to provide a benchmark-quality data base for the assessment of rotor passage heat transfer computational procedures. The experimental portion of the study was conducted in a large-scale, ambient temperature, rotating turbine model. Heat transfer data were obtained using thermocouple and liquid-crystal techniques to measure temperature distributions on the thin, electrically-heated skin of the rotor passage model. Test data were obtained for various combinations of Reynolds number, rotor incidence angle and model surface roughness. The data are reported in the form of contour maps of Stanton number. These heat distribution maps revealed numerous local effects produced by the three-dimensional flows within the rotor passage. Of particular importance were regions of local enhancement produced on the airfoil suction surface by the main-passage and tip-leakage vortices and on the hub endwall by the leading-edge horseshoe vortex system. The computational portion consisted of the application of a well-posed parabolized Navier-Stokes analysis to the calculation of the three-dimensional viscous flow through ducts simulating the a gas turbine passage. These cases include a 90 deg turning duct, a gas turbine cascade simulating a stator passage, and a gas turbine rotor passage including Coriolis forces. The calculated results were evaluated using experimental data of the three-dimensional velocity fields, wall static pressures, and wall heat transfer on the suction surface of the turbine airfoil and on the end wall. Particular attention was paid to an

  20. Wind Turbine Structural Dynamics

    NASA Technical Reports Server (NTRS)

    Miller, D. R. (Editor)

    1978-01-01

    A workshop on wind turbine structural dynamics was held to review and document current United States work on the dynamic behavior of large wind turbines, primarily of the horizontal-axis type, and to identify and discuss other wind turbine configurations that may have lower cost and weight. Information was exchanged on the following topics: (1) Methods for calculating dynamic loads; (2) Aeroelasticity stability (3) Wind loads, both steady and transient; (4) Critical design conditions; (5) Drive train dynamics; and (6) Behavior of operating wind turbines.

  1. A new method for dual-axis fatigue testing of large wind turbine blades using resonance excitation and spectral loading

    NASA Astrophysics Data System (ADS)

    White, Darris L.

    The demand for cost effective renewable energy sources has resulted in the continual refinement of modern wind turbine designs. These refinements generally result in larger wind turbines and wind turbine blades. In order to reduce maintenance expenses, and improve quality and reliability, each new blade design must be subjected to a high cycle fatigue test. With blades expected to soon reach 70 meters in length, traditional fatigue test systems and methods are becoming less practical. Additionally, the relationship between the flap and lead-lag bending moments has not been well understood. This work explores the accuracy of current test methods compared to service loads, presents a new method for fatigue testing larger blades and experimentally validates the analysis. A dynamic model of a generic wind turbine blade and test system has been developed to evaluate the strain profiles during testing, evaluate control strategies and optimize the test accuracy. The relationship between the flap and lead-lag strains resulting from service bending moments has been analyzed. A load spectrum based on the relationship between the flap and lead-lag loads has been developed and compared to traditional test conditions. The effect of using the load spectrum on the test system stability has been analyzed and a new state-space controller has been designed. A 3-D finite element model of a generic wind turbine blade has been used to evaluate the damage accumulation for current test load conditions and the proposed load spectrum. A nonlinear damage accumulation model has been derived to evaluate the effects of load sequencing. Additionally, a new method for applying the fatigue loads to the blades has been developed and implemented. A system that applies a harmonic force at the resonance frequency of the blade in the flap direction has been designed. The new system will reduce the costs and time associated with performing a fatigue test on wind turbine blades. The new system is also

  2. Response measurements for two building structures excited by noise from a large horizontal axis wind turbine generator

    NASA Technical Reports Server (NTRS)

    Hubbard, H. H.; Shepherd, K. P.

    1984-01-01

    Window and wall acceleration measurements and interior noise measurements ere made for two different building structures during excitation by noise from the WTS-4 horizontal axis wind turbine generator operating in a normal power generation mode. With turbine noise input pulses resulted in acceleration pulses for the wall and window elements of the two tests buildings. Response spectra suggest that natural vibration modes of the structures are excited. Responses of a house trailer were substantially greater than those for a building of sturdier construction. Peak acceleration values correlate well with similar data for houses excited by flyover noise from commercial and military airplanes and helicopters, and sonic booms from supersonic aircraft. Interior noise spectra have peaks at frequencies corresponding to structural vibration modes and room standing waves; and the levels for particular frequencies and locations can be higher than the outside levels.

  3. Effect of wind turbine generator model and siting on wind power changes out of large WECS arrays

    NASA Technical Reports Server (NTRS)

    Schleuter, R. A.; Park, G. L.; Lotfalian, M.; Dorsey, J.; Shayanfar, H.

    1981-01-01

    Methods of reducing the WECS generation change through selection of the wind turbine model for each site, selection of an appropriate siting configuration, and wind array controls are discussed. An analysis of wind generation change from an echelon and a farm for passage of a thunderstorm is presented. Reduction of the wind generation change over ten minutes is shown to reduce the increase in spinning reserve, unloadable generation and load following requirements on unit commitment when significant WECS generation is present and the farm penetration constraint is satisfied. Controls on the blade pitch angle of all wind turbines in an array or a battery control are shown to reduce both the wind generation change out of an array and the effective farm penetration in anticipation of a storm so that the farm penetration constraint may be satisfied.

  4. Nuclear localization of Merkel cell polyomavirus large T antigen in Merkel cell carcinoma

    SciTech Connect

    Nakamura, Tomoyuki; Sato, Yuko; Watanabe, Daisuke; Ito, Hideki; Shimonohara, Nozomi; Tsuji, Takahiro; Nakajima, Noriko; Suzuki, Yoshio; Matsuo, Koma; Nakagawa, Hidemi; Sata, Tetsutaro; Katano, Harutaka

    2010-03-15

    To clarify whether mutations in the large T gene encoded by Merkel cell polyomavirus affect the expression and function of large T antigen in Merkel cell carcinoma cases, we investigated the expression of large T antigen in vitro and in vivo. Immunohistochemistry using a rabbit polyclonal antibody revealed that large T antigen was expressed in the nuclei of Merkel cell carcinoma cells with Merkel cell polyomavirus infection. Deletion mutant analyses identified an Arg-Lys-Arg-Lys sequence (amino acids 277-280) as a nuclear localization signal in large T antigen. Sequence analyses revealed that there were no mutations in the nuclear localization signal in any of the eleven Merkel cell polyomavirus strains examined. Furthermore, stop codons were not observed in the upstream of the nuclear localization signal in any of the Merkel cell carcinoma cases examined. These data suggest that the nuclear localization signal is highly conserved and functional in Merkel cell carcinoma cases.

  5. Large area nuclear particle detectors using ET materials, phase 2

    NASA Technical Reports Server (NTRS)

    Wrigley, Charles Y.; Storti, George M.; Walter, Lee; Mathews, Scott

    1990-01-01

    This report presents work done under a Phase 2 SBIR contract for demonstrating large area detector planes utilizing Quantex electron trapping materials as a film medium for storing high-energy nuclide impingement information. The detector planes utilize energy dissipated by passage of the high-energy nuclides to produce localized populations of electrons stored in traps. Readout of the localized trapped electron populations is effected by scanning the ET plane with near-infrared, which frees the trapped electrons and results in optical emission at visible wavelengths. The effort involved both optimizing fabrication technology for the detector planes and developing a readout system capable of high spatial resolution for displaying the recorded nuclide passage tracks.

  6. Formation of large target residues in intermediate energy nuclear collisions

    SciTech Connect

    Loveland, W.; Aleklett, K.; Sihver, L.; Xu, Z.; Seaborg, G.T.

    1987-04-01

    We have used radiochemical techniques to measure the yields, angular distributions and velocity spectra of the large (A/sub frag/ greater than or equal to 2/3 A/sub tgt/) target residues from the fragmentation of /sup 197/Au by intermediate energy /sup 12/C, /sup 20/Ne, /sup 32/S, /sup 40/Ar, /sup 84/Kr, and /sup 139/La projectiles. The fragment moving frame angular distributions are asymmetric for the lighter projectiles (C-Ar). The fragment velocity spectra are Maxwellian for the Kr induced reactions and non-Maxwellian for the reactions induced by the lighter ions. We interpret these results in terms of a change in the dominant fragment production mechanism(s) from one(s) involving a fast non-equilibrium process for the lighter ions to a slow, equilibrium process for Kr. Comparison of the measured yields and angular distributions with calculations made using a Boltzmann transport equation with appropriate modifications for Pauli blocking, etc., show excellent agreement between data and theory. 12 refs., 12 figs.

  7. Necessity and Requirements of a Collaborative Effort to Develop a Large Wind Turbine Blade Test Facility in North America

    SciTech Connect

    Cotrell, J.; Musial, W.; Hughes, S.

    2006-05-01

    The wind power industry in North America has an immediate need for larger blade test facilities to ensure the survival of the industry. Blade testing is necessary to meet certification and investor requirements and is critical to achieving the reliability and blade life needed for the wind turbine industry to succeed. The U.S. Department of Energy's (DOE's) Wind Program is exploring options for collaborating with government, private, or academic entities in a partnership to build larger blade test facilities in North America capable of testing blades up to at least 70 m in length. The National Renewable Energy Laboratory (NREL) prepared this report for DOE to describe the immediate need to pursue larger blade test facilities in North America, categorize the numerous prospective partners for a North American collaboration, and document the requirements for a North American test facility.

  8. Terry turbine controls guide

    SciTech Connect

    Golas, R.S. . Steam Turbine Motor and Generator Div.); Wheeler, K.A. )

    1990-09-01

    While utility experience with Terry turbines has been positive, controls and adjustments of controls have required frequent attention. This technical guide addresses the Terry turbine controls, such as trip system, throttle valve linkage and governors. This guide will familiarize personnel who have not had prior experience with the design, organization and setup of these control systems. This document provides instructions for a broad range of utility personnel on optimum methods for the repair, maintenance, adjustment, and troubleshooting of the Terry turbine controls. The guide includes an engineering description of the operation and prevalent failure mechanisms, preventive and predictive maintenance suggestions, repair and adjustment methods, and spare parts recommendations. This guide will be a standalone updated reference manual. It will include drawings and descriptions affecting all required maintenance on the control system, and does not cover site specific appurtenances. Included are both generic and specific recommendations for utility maintenance engineers and technicians. These recommendations will help implement an effective maintenance or upgrade program for Terry turbine controls. This guide is a valuable resource for operating history and common control related problems. The preparation of this manual included the review of the applicable INPO Standby Turbine-Driven Pump Operating Experience Compilation. Individual utilities can use this guide to review their specific maintenance practices and develop improved procedures where applicable. The guide can also be used by some utilities to upgrade their Terry turbine control system. The guide is applicable to the nuclear industry and any other industry utilizing the Terry turbine models included in the document.

  9. Cytomegalovirus Primary Envelopment Occurs at Large Infoldings of the Inner Nuclear Membrane▿

    PubMed Central

    Buser, Christopher; Walther, Paul; Mertens, Thomas; Michel, Detlef

    2007-01-01

    We have investigated the morphogenesis of human and murine cytomegalovirus by transmission electron microscopy after high-pressure freezing, freeze substitution, and plastic embedding. We observed large tubular infoldings of the inner nuclear membrane that were free of lamina and active in primary envelopment and subsequent transport of capsids to the nuclear periphery. Semiquantitative determinations of the enlarged inner nuclear membrane area and the location of the primary envelopment of nucleocapsids demonstrated that this structure represents a virus-induced specialized membrane domain at which the particles are preferentially enveloped. This is a previously undescribed structural element relevant in cytomegalovirus morphogenesis. PMID:17192309

  10. Defective nuclear import of Tpr in Progeria reflects the Ran sensitivity of large cargo transport.

    PubMed

    Snow, Chelsi J; Dar, Ashraf; Dutta, Anindya; Kehlenbach, Ralph H; Paschal, Bryce M

    2013-05-13

    The RanGTPase acts as a master regulator of nucleocytoplasmic transport by controlling assembly and disassembly of nuclear transport complexes. RanGTP is required in the nucleus to release nuclear localization signal (NLS)-containing cargo from import receptors, and, under steady-state conditions, Ran is highly concentrated in the nucleus. We previously showed the nuclear/cytoplasmic Ran distribution is disrupted in Hutchinson-Gilford Progeria syndrome (HGPS) fibroblasts that express the Progerin form of lamin A, causing a major defect in nuclear import of the protein, translocated promoter region (Tpr). In this paper, we show that Tpr import was mediated by the most abundant import receptor, KPNA2, which binds the bipartite NLS in Tpr with nanomolar affinity. Analyses including NLS swapping revealed Progerin did not cause global inhibition of nuclear import. Rather, Progerin inhibited Tpr import because transport of large protein cargoes was sensitive to changes in the Ran nuclear/cytoplasmic distribution that occurred in HGPS. We propose that defective import of large protein complexes with important roles in nuclear function may contribute to disease-associated phenotypes in Progeria. PMID:23649804