Showing papers on "Turbine blade published in 1976"

Dynamics of Wind Generators on Electric Utility Networks

Abstract: Dynamic interaction of wind-turbine-driven generators on electric utility networks was studied by computer simulation. Nonlinear representations of wind-turbine and various drive train elements and Park equation representations of synchronous and induction generators were implemented. An infinite capacity network was assumed. Time history responses for various system configurations were computed using as the input function severe wind gust data added to cyclical torque variations occurring at turbine blade frequency. Results indicated that severe transient mechanical and electrical stresses can be induced for certain system configurations. Best results were obtained by interposing rate or damped compliant couplings between the wind turbine and a synchronous generator. The induction generator did not appear to require such means. Blade pitch control (or equivalent) was required to limit output above rated wind velocities for wind turbines configured to produce maximum mum specific power. The blade pitch control loop must exhibit high performance to limit transient overshoots. An aerodynamically limited turbine driving an induction generator exhibited good response without the need for blade pitch control, but at the cost of increased turbine rotor diameter. Further work is indicated, taking into account wind-turbine aeroelastic effects, finite capacity networks, and other factors.

Aerodynamic performance of wind turbines. Final report

Abstract: The state-of-the-art of performance prediction methods for both horizontal and vertical axis wind turbines is presented. Strip theory methods for horizontal axis wind turbines are evaluated for various tip loss models. A comparison of these tip models is developed for the ERDA-NASA MOD-O rotor. The occurrence of multiple solutions in strip theory analysis is discussed and illustrated. The performance of high-solidity turbines such as the Chalk design is also presented. Corrections to the strip analysis techniques are developed and incorporated into the analysis used for conventional horizontal axis wind turbines. The predicted performance of the Chalk Turbines is presented. The configuration and performance of optimum horizontal axis wind turbines are discussed. Optimization schemes are developed and discussed and comparisons with the MOD-O rotor are made. Performance at off-design conditions is also examined. The performance model for the Darrieus Rotor is developed. Both linear and non-linear theories are developed. Multiple solutions are found to occur for Darrieus Rotors in the same manner as occurs for horizontal axis rotors. This flow model is compared to existing experimental data and shown to yield excellent agreement. An analytical model of the flow in a Savonius Rotor is presented.

Durability of zirconia thermal-barrier ceramic coatings on air-cooled turbine blades in cyclic jet engine operation

Abstract: Thermal barrier ceramic coatings of stabilized zirconia over a bond coat of Ni Cr Al Y were tested for durability on air cooled turbine rotor blades in a research turbojet engine. Zirconia stabilized with either yttria, magnesia, or calcia was investigated. On the basis of durability and processing cost, the yttria stabilized zirconia was considered the best of the three coatings investigated.

Cooled turbine blade

Abstract: A turbine blade includes a longitudinally extending cavity into which air for cooling the interior wall of the blade is admitted. The air passes from the cavity through each of a group of inserts each of which is constituted by a plurality of stepped overlapping walls with spaced air passages therethrough, these walls establishing therebetween corresponding cooling spaces interconnected by the passages and which are bounded at one side by the blade wall. The cooling air passes in succession through the cooling spaces of each insert and is discharged from the insert and thence from the blade through an outlet port formed in the blade wall and which is connected to the last cooling space of each insert through which the air is passed. The passages through the overlapping walls also provide impingement cooling of the blade wall. The outlet ports for the cooling air are formed in the suction side of the blade as well as in its trailing edge.

Overspeed spoilers for vertical axis wind turbine

Abstract: An overspeed spoiler for vertical axis wind turbines of the type having straight or curved airfoil blades attached to a vertical shaft formed by a relatively thin flat blade shaped spoiler element hinge mounted on the trailing edge, leading edge, or at a central position of a portion of the airfoil section with the element having two portions one of which is held flush or against a surface by spring means with a surface of the blade towards the turbine rotor axis and the other lies substantially parallel to the chordline of the airfoil, the weight and configuration of the element being such that a predetermined turbine rotor speed the element rotates against the spring force because of centrifugal action and takes up a position generally transverse to the air flow direction such as to cause much increased drag and control overspeeding of the rotor.

Wind turbine with automatic pitch and yaw control

Abstract: A wind turbine having a flexible central beam member supporting aerodynamic blades at opposite ends thereof and fabricated of uni-directional high tensile strength material bonded together into beam form so that the beam is lightweight, and has high tensile strength to carry the blade centrifugal loads, low shear modulus to permit torsional twisting thereof for turbine speed control purposes, and adequate bending stiffness to permit out-of-plane deflection thereof for turbine yard control purposes. A selectively off-set weighted pendulum member is pivotally connected to the turbine and connected to the beam or blade so as to cause torsional twisting thereof in response to centrifugal loading of the pendulum member for turbine speed control purposes.

Gas turbine engines with toroidal combustors

Abstract: A gas turbine engine is described in which a compressor, combustor and turbine are arranged in series flow relationship. The compressor discharge is outwardly angled. This pressurized air is then introduced into a toroidal combustion chamber of the combustor to create an annular vortex within which the combustion process is maintained. The hot gas stream generated is discharged from the combustion chamber to a centripital turbine which drives the compressor rotor. A portion of the pressurized air is introduced into the combustion chamber adjacent the hot gas stream discharge exit and in general flow opposition thereto, to dilute the hot gas stream and confine the combustion process within the combustion chamber, thereby minimizing the possibility of overtemperaturing the turbine. The combustor housing also defines the outer bounds of the hot gas stream flowing through the turbine. A power turbine converts a major portion of the energy of the hot gas stream to a motive shaft power output.

Method of refurbishing turbine blade air seal flanges

Abstract: A method of refurbishing the air seal flanges of turbine blades which have become worn, comprising the steps of adding a bead of welding material to the opposite side portions and the edge portions of the flange so as to build up those areas which have been worn away, and thereafter removing controlled amounts of the built up areas so as to restore the piece to its original geometry. In the latter step, the blade is clamped in a first machine having a pair of abrasive belts and a pair of pivotally mounted pressure shoes engageable with the backs of the belts respectively, such that their abrasive surfaces can be brought into engagement with the opposite sides of the air seal flanges. Controlled quantities of the built-up flange can be removed, depending on the degree of advancement of the shoes. In another machine, the blade is placed on a slide which approaches an abrasive belt backed by a special curved contour shoe, whereby as the edge of the seal engages the abrasive surface of the belt, the latter yields an extent, conforming to the particular contour of the shoe. This has the effect of imparting a predetermined, desired profile to the flange. Following the welding and refinishing operations, the geometry and physical characteristics of the refurbished blade closely resemble those of a new blade. By the above method, considerably less expense is entailed over that involved with discarding the old blades and fabricating new ones.

Centrifugal compressor with a splitter shroud in flow path

Abstract: A quick response gasifier spool for an automotive gas turbine engine has a shaft with a turbine wheel connected on one end thereof with a row of turbine blades driven by motive fluid from an engine combustor and further has a low inertia centrifugal compressor impeller with a low mass hub secured to the opposite end of the shaft. The impeller has a plurality of separate, free formed blades each having a root segment integrally formed with the hub; the blades including spaced apart radial tip portions joined by a continuous ring of span splitter elements located on the radial extent of each of the blades to prevent flutter between adjacent free blade radial tips and wherein each element of the continuous ring includes a leading edge and a trailing edge joined by a curved segment located along a flow streamline path between each of the individual blades. The ring and individual free formed blades define an open end back configuration on the centrifugal impeller to reduce fluid shear between the back face of the impeller and its rear closure plate.

Turbine rotor with pin mounted ceramic turbine blades

Abstract: An improved rotor for a gas turbine engine wherein the rotor has a plurality of ceramic turbine blades coupled by attachment pieces of high-temperature metal to a rotor disk. Each attachment piece has a root received in a corresponding groove in the outer periphery of the rotor disk. Also, each attachment piece is made to couple a pair of turbine blades to the rotor disk, the attachment piece having a pair of axially spaced, radially extending walls, each wall having a hole therethrough and the holes of the walls being aligned with each other. The roots of the two blades for each attachment piece are positioned between its spaced wall and the roots have cooperating projecting parts which engage each other and form a recess through which a pin extends when the ends of the pin are in the holes of the end walls. The roots of the blades of adjacent attachment pieces abut each other to keep the blades from moving laterally relative to respective attachment pieces.

Multiple-piece ceramic turbine blade

Abstract: A turbine blade comprised of at least a pair of abutting blade parts with each part having a root coupled to an attachment piece, the latter adapted to be coupled to a turbine rotor. The blade parts can be curved and each blade part may have a hollow space in the region where it abuts the other blade part to reduce the weight of the blade. The blade parts may be spigoted or mated with tongue and groove structure to reduce fluid leakage through the junction between the blade parts.

Gas turbine cooling system

Abstract: A cooling system for a gas turbine engine having a gasifier turbine and a power turbine each interconnected by a turbine casing utilizes compressed cooling air communicated to axial cavities in the ends of the respective turbine shafts. This compressed air is directed outwardly between a flange integrally formed with the turbine shaft and the turbine wheel for communication to the turbine blades. In the gasifier turbine the cooling air passes through longitudinal passages formed in each blade, while in the power turbine the cooling air is discharged adjacent the blade root. Wheel flanges affixed on either side of the turbine wheel serve to retain the blades axially on the wheel. Compressed cooling air is also communicated to the nozzle vanes of the gasifier turbine wherein internal passages communicate the air into the main gas stream. Certain nozzle vanes are equipped with passage means to communicate air to an annular chamber surrounding the gasifier turbine.

Stagnation region gas film cooling for turbine blade leading edge applications

Abstract: An experimental investigation was conducted to model the film-cooling performance for a turbine-vane leading edge using the stagnation region of a cylinder in cross flow. Experiments were conducted with a single row of spanwise-angled coolant holes for a range of the coolant blowing ratio with a freestream-to-wall temperature ratio of about 2.1 and a Reynolds number of 170,000, characteristic of the gas-turbine environment. Data from local heat-flux measurements are presented for coolant-hole injection angles of 25, 35, and 45 deg with the row of holes located at three positions relative to the stagnation line on the cylinder. Results show the spanwise (hole-to-hole) variation of heat-flux reduction due to film cooling and indicate conditions for the optimum film-cooling performance.

Semi-spar wound blade

Abstract: A wind turbine blade in the form of a semi-spar in which the outer portion of the finished blade shape is the filament wound spar itself and the remainder of the blade incorporates a trailing edge portion, increasing in dimension toward the blade base, this part of the blade being filament wound around the spar.

Rotor blade system for a gas turbine engine

Abstract: A rotor blade system which is adapted for long term reliable operation in a gas turbine engine is disclosed. Techniques for altering the natural frequency of the blade system to reduce the detrimental combined effects of external excitation and self-excitation are developed. One structure shown utilizes a shroud for the control of self-excitation in combination with a pin root to lower the fundamental first natural bending frequency of the blade system below the level of the 2E frequency at idle.

Blade attachment structure for gas turbine rotor

Abstract: Improved attachment structure for connecting ceramic blades to the rotor disk of a gas turbine rotor. The structure includes a plurality of metallic attachment pieces having roots inserted into respective grooves in the outer periphery of the rotor disk. Each attachment piece has an outer peripheral groove for receiving the root of a corresponding turbine blade formed of ceramic material. Specific embodiments of an attachment piece and a blade are disclosed, the blade having a base which engages the outer peripheral face of the corresponding attachment piece. The blade base and the corresponding attachment piece have aligned, spaced grooves at the opposed ends thereof for receiving ceramic plates which cover the adjacent parts of the attachment piece. Certain ends of the ceramic plates define recesses for receiving metallic plates which extend radially of the rotor disk and transmit torque from the blade to the attachment piece and thereby to the rotor disk.

Potential use of ceramic coating as a thermal insulation on cooled turbine hardware

Abstract: An analysis was made to determine the potential benefits of using a ceramic thermal insulation coating of calcia-stabilized zirconia on cooled engine parts. The analysis was applied to turbine vanes of a high temperature and high pressure core engine and a moderate temperature and low pressure research engine. Measurements made during engine operation showed that the coating substantially reduced vane metal wall temperatures. Evaluation of the durability of the coating on turbine vanes and blades in a furnace and engine were encouraging.

Gas turbine with superimposed blade rings - has additional compressor stages on either side of superimposed rings

Abstract: The air flows successively through a compressor, a combustion chamber and a power turbine coaxial with the compressor, the direction of flow through the turbine being opposite to that through the compressor. The compressor and turbine blades are mounted radially one on the other and separated by a ring which also separates the two passages from each other, so that compressor and turbine blades together form a double blade ring. On each side of this ring (17) the compressor has additional stages (27, 37, 47) whose number is determined by the fact that the pressure ratio across the ring separating compressor and turbine blades and on the same side of the blade ring is greater than unity and less than a predetermined figure.

Gas turbine jet propulsion engine

Abstract: A gas turbine engine has three turbines, the intermediate and high pressure turbines running at substantially constant corrected speed. The low pressure turbine has variable nozzle guide vanes and the low pressure compressor has variable stators so as to enable its speed to be varied, while its mass flow is arranged to be large at low speeds.

Sliding vane machine

Abstract: In a sliding vane machine a work can be accomplished by a pressure fluid rotating a rotor provided with a plurality of sliding vanes, which function as turbine blades, whereby the work is taken out as a rotational motion at the rotor shaft. If the machine is designed as a pump the shaft is rotated and the vanes act as impeller blades. In both cases it is desirous if the machine can adapt its work in response to varying loads. In accordance with the invention this is achieved by providing the machine with pressure plates controlling the effective working area of said vanes, the pressure plates thereby being adjusted by a fluid pressure which by means of a pressure actuated valve can be varied the pressure-actuated valve itself being controlled by the fluid pressure in a conduit supplying the pressure fluid to the machine.

Free vibrations of the ERDA-NASA 100 kW wind turbine

Abstract: The ERDA-NASA wind turbine (windmill), which consists of a 93-foot truss tower, a bed plate that supports mechanical and electrical equipment, and two 62.5-foot long blades, was analyzed to determine its free vibrations using NASTRAN. The finite element representation of the system consisted of beam and plate elements. The free vibrations of the tower alone, the blades alone, and the complete system were determined experimentally in the field. These results were obtained by instrumenting the tower or blades with an accelerometer and impacting the components with an instrumented mass. The predicted results for natural frequencies and mode shapes were in excellent agreement with measured data.

Torque converter having adjustably movable stator vane sections

Abstract: A torque converter comprises a stationary housing within which a rotatable impeller is mounted for driving a rotatable trubine. The bladed impeller is mounted on an engine driven input shaft, and the bladed turbine is mounted on an output shaft on the same axis as the input shaft. The impeller blades and turbine blades move through an annular oil-filled passage. A plurality of stator blades are disposed in the passage in spaced-apart radial arrangement around the axis of the shafts. Each stator blade is divided into two sections, namely, a fixed forward section and an adjustably movable or pivotable rear section. Means are provided to pivot the rear sections of all of the stator blades simultaneously so as to vary the width of the flow channel between each pair of adjacent stator blades between fully opened and fully closed positions and any position therebetween to thereby control the amount of oil available for use by the impeller and turbine and thereby enable regulation of the power output of the torque converter. The movable rear section of each stator blade is provided with a stem which extends through a sealed opening in the stationary housing and enables pivotal adjustment of the rear section of the stator blade about the axis of the stem. The stem axes are parallel to the shaft axes. Each stem is provided on the end thereof exteriorly of the housing with a rigidly attached small gear which meshes with a large ring gear exteriorly of the housing. Actuator means are provided exteriorly of the housing to adjustably rotate the ring gear in opposite directions to effect simultaneous adjusting movement of the rear section of all stator blades. The actuator means comprise a manually operable power assisted actuator and a power assist assembly.

Torque converter having adjustably movable stator vane sections and actuator means therefor

Abstract: A torque converter comprises a stationary housing within which a rotatable impeller is mounted for driving a rotatable turbine The bladed impeller is mounted on an engine driven input shaft, and the bladed turbine is mounted on an output shaft on the same axis as the input shaft The impeller blades and turbine blades move through an annular oil-filled passage A plurality of stator blades are disposed in the passage in spaced-apart radial arrangement around the axis of the shafts Eah stator blade is divided into two sections, namely, a fixed forward section and an adjustably movable or pivotable rear section Means are provided to pivot the rear sections of all of the stator blades simultaneously so as to vary the width of the flow channel between each pair of adjacent stator blades between fully opened and fully closed positions and any position therebetween to thereby control the amount of oil available for use by the impeller and turbine and thereby enable regulation of the power output of the torque converter The movable rear section of each stator blade is provided with a stem which extends through a sealed opening in the stationary housing and enables pivotal adjustment of the rear section of the stator blade about the axis of the stem The stem axes are parallel to the shaft axes Each stem is provided on the end thereof exteriorly of the housing with a rigidly attached small gear which meshes with a large ring gear exteriorly of the housing Actuator means are provided exteriorly of the housing to adjustably rotate the ring gear in opposite directions to effect simultaneous adjusting movement of the rear section of all stator blades The actuator means comprise a manually operable power assisted actuator and a power assist assembly

Combined turbine propellor propulsion for aircraft - combustion chambers and turbine are contained in compressor outer casing

Abstract: The propulsion unit consists of an outer casing (6) containing the combustion chambers (46) turbine stator blades (54) and the rotating turbine blades (56) which are fixed to the tips of propellor blades (100) fitted to the compressor (20) drive shaft (62). The output from the final compressor stage (22) is led through hollow outer casing support struts (8) to the combustion area. The combustion gas exhaust cross section is adjustable by means of a cone (72) actuated by a hydraulic unit (88). The propellor blades are adjustable for pitch and work in conjunction with the cone adjuster so that the secondary air flow from the propellors is mixed with the exhaust jet from the turbine.

Losses in Radial Inflow Turbines

Abstract: A study was conducted to determine experimentally and theoretically the losses in radial inflow turbine nozzles. Extensive experimental data was obtained to investigate the flow behavior in a full-scale radial turbine stator annulus. A theoretical model to predict the losses in both the vaned and vaneless regions of the nozzle was developed. In this analysis, the interaction effects between the stator and the rotor are not considered. It was found that the losses incurred due to the end wall boundary layers can be significant, especially if they are characterized by a strong crossflow. The losses estimated using the analytical study are compared with the experimentally determined values.

Turbine wheel with shear configured stress discontinuity

Abstract: An integrally cast turbine blade and wheel assembly has a plurality of circumferentially spaced radially outwardly directed blades on a peripheral rim that is connected by a wheel web to a central hub having a bore therethrough. The assembly includes a plurality of circumferentially spaced, pairs of grooves to define a plurality of weakened sections in the wheel rim and web that will selectively crack in shear to relieve stresses during either a tensile or compressive phase of wheel assembly operation produced during thermal cycling of an associated engine; and wherein resultant stress relief cracks define a labyrinth seal path to control gas bypass across the blade row.

Directional structures for advanced aircraft turbine blades

Abstract: In order to achieve the performance and durability requirements of advanced gas turbine engines, highpressure turbine blade materials with directional structures will be required. Directional structures can be obtained by liquid-solid (solidification) or solid-solid (recrystallization) reactions, or by composite fabrication techniques. Currently, directional solidification is used to produce columnar-grained superalloy turbine airfoils. This production process can be modified to provide single-crystal superalloys or directionally solidified eutectic turbine blades. Directional superalloy structures also can be obtained by a solid-state recrystallization process, referred to as directional recrystallization. In addition, directional composite structures are fabricated by reinforcing a superalloy matrix with high-strength refractory metal wires. These five directional turbine blade materials are compared for use in advanced gas turbine aircraft engines. The present status of each advanced material is reviewed, and the advantages and limitations of each is assessed.