Showing papers on "Turbine blade published in 1983"

Wind powered system for generating electricity

Abstract: A fixed pitch wind turbine rotor (18) is teeter mounted (76, 78, 80) onto a low speed input shaft (44) which is connected to the input (58) of a step-up transmission (46). The output (48) of the transmission (46) is connected to a rotary pole amplitude modulated induction machine (42) which is operable as a generator at a plurality of discreet speeds of rotation and is also operable as a startup motor for the rotor. A switch (45) responsive to the rotational speed of the wind turbine rotor switches the generator from one speed of operation to the other. The rotor hub (72) and the inner body portions (71) of two blades (68, 70), which extend radially outwardly in opposite directions from the hub (72), are constructed from steel. The outer end portions (73) of the blade (68, 70) are constructed from a lighter material, such as wood, and are both thinner and narrower than the remainder of the rotor. The outer end section (73) of each blade (68, 70) includes a main body portion and a trailing edge portion (104) which is hinge-connected to the main body portion. Each blade (68, 70) includes a centrifugal force operated positioning means (98, 100) which normally holds the drag brake section (104) in a retracted position, but operates in response to a predetermined magnitude of centrifugal force to move the drag brake (104) section into its deployed position. Each blade has an airfoil cross section and each blade (68, 70) has a plus twist inner portion adjacent the hub (72) changing to first a zero twist and then a minus twist as it extends radially outwardly from the hub (72).

Double multiple streamtube model with recent improvements

Abstract: The objective of the present paper is to show the new capabilities of the double multiple streamtube (DMS) model for predicting the aerodynamic loads and performance of the Darrieus vertical-axis turbine. The original DMS model has been improved (DMSV model) by considering the variation in the upwind and downwind induced velocities as a function of the azimuthal angle for each streamtube. A comparison is made of the rotor performance for several blade geometries (parabola, catenary, troposkien, and Sandia shape). A new formulation is given for an approximate troposkien shape by considering the effect of the gravitational field. The effects of three NACA symmetrical profiles, 0012, 0015 and 0018, on the aerodynamic performance of the turbine are shown. Finally, a semiempirical dynamic-stall model has been incorporated and a better approximation obtained for modeling the local aerodynamic forces and performance for a Darrieus rotor.

Evaluation of a Method for Heat Transfer Measurements and Thermal Visualization Using a Composite of a Heater Element and Liquid Crystals

Abstract: Commercially available elements of a composite consisting of a plastic sheet coated with liquid crystal, another sheet with a thin layer of a conducting material (gold or carbon), and copper bus bar strips were evaluated and found to provide a simple, convenient, accurate, and low-cost measuring device for use in heat transfer research. The particular feature of the composite is its ability to obtain local heat transfer coefficients and isotherm patterns that provide visual evaluation of the thermal performances of turbine blade cooling configurations. Examples of the use of the composite are presented.

The use of coloured smoke to visualize secondary flows in a turbine-blade cascade

Abstract: A coloured-smoke-visualization technique has been developed for the investigation of complex three-dimensional fluid flows. In particular, a coloured-smoke wire technique is used for the study of secondary flows in straight turbine cascades. Based on a large number of photographs and direct flow observation, the evolution of horseshoe and passage vortices through a high-turning turbine-blade passage is described.

Friction damping of flutter in gas turbine engine airfoils

Abstract: This paper investigates the feasibility of using blade-to-ground friction dampers to stabilize flutter in blades. The response of an equivalent one mode model in which the aerodynamic force is represented as negative viscous damping is examined to investigate the following issues: the range of amplitudes over which friction damping can stabilize the response, the maximum negative aerodynamic damping that can be stabilized in such a manner, the effect of simultaneous resonant excitation on these stability limits, and the determination of those damper parameters which will be the best for flutter control.

Seal means for a blade attachment slot of a rotor assembly

Abstract: A seal means 66 for a blade attachment slot of a rotor assembly 12 is disclosed. Various construction details which adapt the rotor assembly to block the leakage of cooling air from the blade attachment slot 40 as the cooling air is flowed to a rotor blade 22 are developed. In one embodiment, the seal means has a seal plate 68 and baffles 70,72 integral with the seal plate which define a cooling air chamber for receiving cooling air from a passage way 38 in a rotor disk 20. The seal plate extends axially and laterally to block the leakage of cooling air in the radial direction. Baffles extend radially from the plate for blocking the leakage of cooling air in the axial direction.

End seal for turbine blade bases

Abstract: An end seal for cooling air manifolds below the bases of a stage of air cooled turbine blades on a turbine wheel, the end seal including a seal ring having an annular planar portion abutting an end face of the turbine wheel inboard of the air manifolds and a right cylindrical flange perpendicular to the planar portion and underlying a corresponding cylindrical shoulder on the wheel and on the blade bases outboard of the air manifolds, and a plurality of end plates on the wheel having lugs underlying the cylindrical flange. The planar portion is axially clamped to the wheel to define a 360° inboard seal while centrifugal forces developed by the end plates during rotation of the wheel cause the lugs to radially clamp the cylindrical flange against the cylindrical shoulder on the wheel and blade bases to define a 360° outboard seal.

Wind turbine generator interaction with diesel generators on an isolated power system

Abstract: The Block Island Power Company (BIPCO), on Block Island, Rhode Island, operates an isolated electric power system consisting of diesel generation and an experimental wind turbine. The 150-kW wind turbine, designated MOD-OA by the U. S. Department of Energy is typically operated in parallel with two diesel generators to serve an average winter load of 350 kW. As part of an experimental program to evaluate wind turbine generator performance on the isolated diesel power system, the recordings from an extensive data measurement effort were reviewed and analyzed to define the nature of the dynamic interaction effects. The data were collected over a three-month period on the system to which the DOE/NASA experimental wind turbine was connected. During this time, the diesel units were lightly loaded resulting in up to 60 percent of the total load demand being supplied by the MOD-OA in periods of severely gusting winds. In three of the modes of normal MOD-OA operation. startup???synchronization, shutdown/cutout, and continuous fixed pitch running???power, frequency and voltage transients were comparable with those produced by typical load changes on the diesel system alone. In the fourth mode, variable pitch (constant power) control, a significant reduction in system damping sometimes occurred which gave rise to increased frequency and voltage perturbations under gusty wind conditions. Based on a linear model of the system it is shown that changes in control system settings could be made to improve damping.

Cooled turbine blade tip closure

Abstract: An improved high pressure turbine rotor blade and tip cap structure therefor is provided, which comprises, a plurality of metallic layers bonded to the tip end of the blade, each layer having a peipheral shape conforming to the camber of the blade, the layers defining a plurality of radially outwardly opening, serpentine-shaped passageways for passage of coolant fluid through the periphery of the tip end of the blade.

Gas turbine engine blade

Abstract: The invention comprises a blade for a gas turbine engine including an airfoil portion having a non-linear stacking axis intersecting a reference radial axis that is effective for generating a compressive component of bending stress due to centrifugal force acting on the blade. The compressive component of bending stress is provided in a life-limiting section of the blade, which, for example, includes trailing and leading edges of the blade. Inasmuch as the stacking axis, which represents the locus of centers of gravity of transverse sections of an airfoil portion of the blade, is non-linear, an increased amount of a compressive, component of bending stress can be generated at a life-limiting section between a root and tip of the blade without substantially increasing bending stress at the root of the blade due to the non-linear stacking.

Wind turbine rotor

Abstract: A fixed pitch wind turbine rotor (18) is teeter mounted (76, 78, 80) onto a low speed input shaft (44) which is connected to the input (58) of a step-up transmission (46). The output (48) of the transmission (46) is connected to a rotary pole amplitude modulated induction machine (42) which is operable as a generator at a plurality of discreet speeds of rotation and is also operable as a startup motor for the rotor. A switch (45) responsive to the rotational speed of the wind turbine rotor switches the generator from one speed of operation to the other. The rotor hub (72) and the inner body portions (71) of two blades (68, 70), which extend radially outwardly in opposite directions from the hub (72), are constructed from steel. The outer end portions (73) of the blade (68, 70) are constructed from a lighter material, such as wood, and are both thinner and narrower than the remainder of the rotor. The outer end section (73) of each blade (68, 70) includes a main body portion and a trailing edge portion (104) which is hinge-connected to the main body portion. Each blade (68, 70) includes a centrifugal force operated positioning means (98, 100) which normally holds the drag brake section (104) in a retracted position, but operates in response to a predetermined magnitude of centrifugal force to move the drag brake (104) section into its deployed position. Each blade has an airfoil cross section and each blade (68, 70) has a plus twist inner portion adjacent the hub (72) changing to first a zero twist and then a minus twist as it extends radially outwardly from the hub (72).

Wind-driven generator apparatus

Abstract: Disclosed is a wind-driven generator apparatus with variable pitch blades. The apparatus includes a yaw damping arrangement for resisting weathervaning rotation of a head assembly of the apparatus about a vertical axis and the apparatus further includes a pitch control mechanism for the blades which maintains the pitch substantially constant during normal operating r.p.m. of the blades but allows the blades to pitch up in an overspeed condition, and a brake mechanism for the generator shaft which includes an adjusting mechanism that compensates for wear in the brake.

Dry Friction Damping Mechanisms in Engine Blades

Abstract: In the context of jet engines, significant vibration damping due to dry friction can occur at (a) shroud interfaces of fans and (b) the platform of turbine blades fitted with “platform dampers.” Analytical and experimental studies in regard to this important source of nonaerodynamic damping of blade vibration are presented in this paper. Comparisons between results from analytical models and laboratory test data are made and discussed.Copyright © 1982 by ASME

Method and apparatus for masking a surface of a blade member

Abstract: A method and apparatus for masking from treatment selected surfaces of a turbine blade. The blade is positioned in an apparatus which includes a holder enclosing the airfoil section of the blade and a distinct spaced apart mask member elastically secured to the holder and having a deformable surface covering a surface of the blade spaced from the airfoil.

Cooling flow control device for turbine blades

Abstract: A flow control body in the aft end of a hollow core of a turbine vane provides localized increased velocity cooling air flow in a wide portion which is otherwise difficult to cool. The flow control body includes lands and grooves with the cooling air being constrained to flow through the grooves and provide localized cooling while conductive heat transfer through the lands to the flow control body provides substantial temperature uniformity along the length of the vane. Turbulence chambers may be formed in the flow control body to further control cooling and the shape or other parameters of the flow control body may be modified to accommodate uneven end-to-end heating of the vane.

Mathematical Model for the Analysis of Wind-Turbine Wakes

Abstract: The concept of wind farms with clustered wind turbines at a given site seems to offer an attractive means for extracting wind power on a large scale. Techniques for minimizing the effect of upstream wind-turbine wakes on downstream wind turbines are needed to optimize overall performance of the wind-turbine array. A numerical model for prediction of the interaction of the wind turbine with the prevailing wind flow is described. The model is based on a numerical solution of the three-dimensional Navier-Stokes equations for the planetary boundary layer with the hydrostatic approximation. Three different hypothetical wind-turbine configurations are analyzed to demonstrate the utility of this model. Model predictions from the present study compare favorably with the basic characteristics of measured wind-turbine wakes. Nomenclature a = axial interference factor D = turbine blade diameter / = Coriolis parameter k = von Karman constant KM = turbulent diffusion coefficient KM - dKM/dz, gradient of turbulent diffusion coefficient L = Monin-Obukov length P = atmospheric pressure t =time U = characteristic wind speed u = velocity component in x direction ur = velocity at reference height zr u* = friction velocity v = velocity component in y direction w = velocity component in z direction x,y,z = orthogonal Cartesian coordinates Z0 = aerodynamic surface roughness Z = height of the inversion base A = incremental change p = atmospheric density 6,\I/ = dimensionless functions Subscripts

Cooling device for movable turbine blade collars

Abstract: From an external turbine chamber (17), cooling air passages are formed through coils mounted in ball-and-socket fashion (26) in a cavity portion (21) above the stationary turbine nozzle vanes (16) from which it escapes downstream through holes (29) in the platform (15) of the stationary vanes (16) in the form of jets of air parallel to the flow of the main gas flow to create a cooling film on the leading edge (30) of the shroud (9) of the movable blades (10) of the turbine rotor in order to cool these blade shroud (9). An airtight connection between this supply chamber (17) and the main flow is ensured by a flexible seal (32) formed of elastic blades (33) in sections attached to one end of the downstream flange (14) of the turbine nozzle housing (11) and supported at the other end by the turbine ring (5).

A Comparative Study of the Influence of Different Means of Turbine Cooling on Gas Turbine Performance

Abstract: A comparative study of the influence of different means of turbine cooling on the thermodynamic efficiency and specific work of gas turbines is presented. A common general model of a simple open cycle gas turbine is used to compare the performance of turbines using different types of cooling; internal convection and impingement by air, film cooling by air, internal convection and impingement by steam, film cooling by steam and closed loop cooling by water. The results are also compared to the previously published results of the analysis of open loop water cooled gas turbines. The model evaluates the efficiency and specific work of simple cycle gas turbines as it is influenced by mixing losses of coolant with combustion gases, pumping work of coolant and heat transfer from the expanding gas. The study is performed in terms of dimensionless variables in order to achieve generality and to provide useful design guidelines and insights. Blades internally cooled by convection and impingement are treated as heat exchangers operating at constant metal temperature and the coolant exit temperature is simply expressed as a function of a heat exchanger effectiveness, an independent parameter which is normally a function of the intricacy of the layout of the cooling passages. The coolant requirements and heat transfer with film cooling are determined using a dimensionless correlation derived experimentally at M.I.T. Sample calculations give the optimum turbine inlet temperature of thermodynamic efficiency and specific work for different pressure ratios and typical dimensionless numbers. The data on specific work are significant because they can be readily used in evaluations of a given type of gas turbine in a combined cycle. The sensitivity of the efficiency and specific work to each key input parameter is reported.The use of superheated steam as a coolant can provide some performance advantages since the steam raised in a waste heat boiler expands with the combustion gases, increases the turbine mass flow and also provides a certain amount of heat regeneration. Performance results are also reported for this steam cooled gas turbine operating with mixed working fluid.Copyright © 1983 by ASME

Oxidation resistant protective coating system for gas turbine components, and process for preparation of coated components

Abstract: A coating for protecting the surfaces of gas turbine components such as single crystal turbine blades and vanes, wherein the coating has a composition (in weight percent) consisting essentially of chromium, 15-35; aluminum, 8-20; tantalum, 0-10; tantalum plus niobium, 0-10; silicon, 0.1-1.5; hafnium, 0.1-1.5; yttrium, 0-1; cobalt, 0-10; and nickel, balance totalling 100 percent. A preferred coating, which is particularly desirable for use with single-crystal turbine blades and vanes, has a composition consisting essentially of chromium, 17-23; aluminum, 10-13; tantalum plus niobium, 3-8; silicon, 0.1-1.5; hafnium, 0.1-1.5; yttrium, 0-0.8; cobalt, 0-trace; and nickel, balance totalling 100 percent. A process for preparing the coated component is also described.

Bowed turbine blade

Abstract: The invention comprises a blade for a gas turbine engine including an airfoil portion having a non-linear stacking axis which is effective for generating a compressive component of bending stress due to centrifugal force acting on the blade. The compressive component of bending stress is provided in a life-limiting section of the blade, which, for example, includes trailing and leading edges of the blade. Inasmuch as the stacking axis, which represents the locus of centers of gravity of transverse sections of an airfoil portion of the blade, is non-linear, an increased amount of a compressive component of bending stress can be generated at a life-limiting section between root and tip sections of the blade without substantially increasing bending stress at the root of the blade.

Aerodynamic performance of a Wells air turbine

Abstract: Experiments were performed in a unidirectional flow rig to assess the performance of the Wells self-rectifying air turbine. Results indicated that the efficiency of the turbine was very sensitive to the Reynolds number based on blade chord. Increase in Reynolds number by a factor of three resulted in an increase in peak efficiency from 37 to 60%. Increases in the solidity of the blade produced increases in pressure drop and power output but decreases in efficiency. The hub-to-tip ratio had only a weak influence on the turbine performance but is critical for starting conditions. It is concluded that a hub-to-tip ratio of 0.6 and a solidity of 0.6 are are the most favorable values, taking into consideration both the starting and running performances.

Apparatus for cooling turbine blades

Abstract: An apparatus for cooling turbine blades, especially of fluid outflow machines and including at least two cavities separated by a partition extending obliquely in the median, radial plane of the blade, the cavities with their partition walls being connected by acceleration link members for thermal exchange and the outflow and driving edges including fluid discharge openings formed therein. Each blade includes a fluid discharge opening located under the platform of the blade on the outflow edge side, through which most of the cooling air is discharged in the area of selected counter-pressure.

Techniques for Obtaining Detailed Heat Transfer Coefficient Measurements Within Gas Turbine Blade and Vane Cooling Passages

Abstract: This paper reviews the techniques developed jointly by Rolls-Royce Bristol and Oxford University for determining detailed heat transfer coefficient distributions inside turbine blade and vane cooling passages.These techniques make use of a low temperature phase change paint to map the heat flux distributions within models of the cooling passages. The paints change from an opaque coating to a clear liquid at a well defined melting point.Thus, the surface temperature history of a model subjected to transient convective heating is recorded. From this history the heat transfer coefficient distribution is deduced using a transient conduction analysis within the model. The general method may be applied to a range of model thicknesses and geometries. The Rolls-Royce data are usually obtained from the inner surface of thick walled models whereas the Oxford measurements are performed on the outside of thin walls.Results are presented for the detailed heat transfer coefficient distributions within a variety of cooling passages. Firstly, smooth ducts of circular cross section are considered and serve the purpose of validating the experimental techniques. Secondly, results for complex passages with varying cross-sectional area are presented, and the effect of introducing discrete roughness elements and film cooling exhausts into these ducts assessed. Finally, data obtained from a comprehensive examination of a typical engine multi-pass cooling geometry are presented.Copyright © 1983 by ASME

Air turbine drive for electrostatic spray gun

Abstract: An electrostatic spray gun having a rotatable voltage generator for providing electrical energy at low voltage for conversion within the spray gun into electrostatic high voltage energy, wherein a rotating voltage generator is driven by an air turbine under the influence of a pressurized input air supply, the pressurized air passing through conduits in the handle of the spray gun, an air valve actuated by a trigger, an air flow regulator, and into impinging contact against rotatable turbine blades. The air supply is exhausted from the spray gun through internal passages which provide cooling air to the electrical components within the spray gun, and through further passages opening from the bottom of the spray gun handle which minimize the audible noise caused by such air flow.

Method of containing fractured turbine blade fragments

Abstract: Method of containing fractured turbine engine components, for example rotor and blade fragments within turbine engine casings, comprising diffusing and impeding motion of the fractured blade fragment by encircling the turbine engine with an honeycomb structure; shielding the honeycomb with an outer shell which has a high bending stiffness and which encloses a series of subdivided compartments in juxtaposition with the honeycomb; and absorbing energy of the fractured blade fragments by supporting a series of ceramic blocks within the confined compartments adjacent said honeycomb. A suggested ceramic for use in the blocks is a hot-pressed silicon carbide. The method is distinguished from the prior art in its ability to sustain the subsonic velocities.

Jet spoiler arrangement for wind turbine

Abstract: An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the ends thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby inducing stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Comparison of NACA 6-series and 4-digit airfoils for Darrieus wind turbines

Abstract: The aerodynamic efficiency of Darrieus wind turbines as effected by blade airfoil geometry was investigated. Analysis was limited to curved-bladed machines having rotor solidities of 7 to 21% and operating at a Reynolds number of 3 X 10/sup 6/, Ten different airfoils, having thickness-to-chord ratios of 12, 15, and 18%, were studied. Performance estimates were made using a blade element/momentum theory approach. Results indicated that NACA 6-series airfoils yeild peak power coefficients as great as NACA 4-digit airfoils and have broader and flatter power coefficient-tip speed ratio curves. Sample calculations for an NACA 63/sub 2/-015 airfoil showed an annual energy output increase of 17-27%, depending on rotor solidity, compared to an NACA 0015 airfoil.

High pressure turbine rotor two-piece blade retainer

Abstract: A blade retainer for holding a turbine blade on a turbine rotor disc and sealing a cooling cavity formed between the disc and blade has a two-piece construction. The first piece performs the blade loading function, while the second piece performs the cavity sealing function. The two pieces are attached to the disc by a common set of fasteners, such as bolts.