Showing papers on "Wells turbine published in 1986"

Dynamic Stall: The Case of the Vertical Axis Wind Turbine

Abstract: This paper presents the results of an experimental investigation on a driven Darrieus turbine rotating at different tip speed ratios. For a Reynolds number of 3.8 x 10/sup 4/, the results indicate the presence of dynamic stall at tip speed ratio less than 4, and that helicopter blade aerodynamics can be used in order to explain some aspects of the phenomenon. It was observed that in deep stall conditions, a vortex is formed at the leading edge; this vortex moves over the airfoil surface with 1/3 of the airfoil speed and then is shed at the trailing edge. After its shedding, the vortex can interact with the airfoil surface as the blade passes downstream.

Film cooled vanes and turbines

Abstract: Film Cooled Vanes and Turbines The film of cooling air adjacent the outer surface of the airfoil of a turbine of a gas turbine engine issuing from internally of the turbine subsequent to cooling is controlled by regulating the pressure ratio of the internal to external pressures by forming an internal chamber extending longitudi-nally in the turbine and having fixed orifices admitting cooling air therein bearing a predetermined relationship to the exit orifices forming the film of cooling air. By regulating this pressure ratio the diameter of the exit holes can be longer than heretofore designs for a given application so that they can be precast rather than drilled and can be arranged to give fuller coverage of films of cooling air on the outer surface of the airfoil.

Studies on Wells Turbine for Wave Power Generator : 4th Report, Starting and Running Characteristics in Periodically Oscillating Flow

Abstract: In order to clarify the starting and running characteristics of a Wells turbine in an oscillating flow, an experimental investigation has been performed. The results have been compared with the analytical results. In the analysis, both starting and running characteristics were calculated on the basis of the experimental results obtained under steady unidirectional flow conditions. Comparison between experiment and analysis has shown that the effect of hysteresis and Reynolds number on torque coefficient should be considered in the analysis. Furthermore, running characteristics have been investigated from a view point of the method of load control.

Swirl nozzle for a cooling system in gas turbine engines

Abstract: Cooling air from turbine nozzle vanes of a hot gas turbine engine is collected from the vanes by an air connector. A conduit connects to the connector and terminates adjacent a turbine wheel so that air flows through the vanes and through the conduit to be emitted from the end thereof in a jet stream directed against the turbine wheel. A vaned swirl nozzle is inserted in the conduit and adjacent a turbine wheel to impart a turning impetus to the air flow stream being emitted from the nipple. The emitted air stream is then directed tangentially against or adjacent the turbine wheel in the direction of rotation thereof.

Gas turbine jet engine of multi-shaft double-flow construction

Abstract: A gas turbine jet propulsion unit of multi-shaft-double-flow construction in which a front compressor or fan supplies compressed air into a secondary channel arranged coaxially to the propulsion unit axis and formed between outer and inner wall structures, from which a secondary air component is taken and blown out against the turbine housing structures for purposes of turbine component cooling; the secondary air channel extends essentially over the entire propulsion unit length or at least up to the area near the turbine housing structure while the secondary air component is taken off from the secondary flow by way of openings in the inner wall structure which are arranged in direct proximity of the respective turbine housing structure.

Hydraulic turbine aeration apparatus

Abstract: An apparatus for aerating water discharging from a hydraulic turbine comprises an air distribution apparatus secured to the trailing edges of a turbine runner. The air distribution apparatus comprises a manifold which contains a bounded air channel extending the length of the runner blade trailing edge. A plurality of holes are formed along the mainfold extending between the channel and the turbine interior. The channel is in air flow communication with a source of oxygen.

A pneumatic hydro-electric power conversion system

Abstract: The invention provides for the generation of electrical power from low head water, such as the flowing water of rivers or the like, the electrical power is generated by passing the water in sequence over flexible bags (22, 24) or membranes to displace air under the flexible bags or membranes. The displacement of the air is utilised for the driving of a power generator such as an air turbine, and smooth power flow is achieved by diverting air displaced from the underside of one membrane into the cavity under the other membrane. The water flows over the membranes in sequence so that a self oscillating system is set up with the air being displaced back and forth from the cavities, and the displacement air being used to drive the air turbine. Preferably a bi-directional air turbine such as a Wells turbine is used.

Apparatus including distance sensors mounted on rotating shaft for measuring distances inside a turbine

Abstract: Apparatus for measuring precise distances between the turbine shaft and the interior surfaces of the inner and outer cylinders of a turbine is disclosed. A mandrel carrying proximity transducers is placed inside the inner and outer cylinders and rotated to preselected points. A proximeter generates a radio frequency electromagnetic field which is radiated in the immediate area of the proximity transducers. Energy losses caused by eddy currents generated in the interior surface of inner and outer cylinders are converted into linear output by a computer. Distances between the interior surface of the turbine and the transducers are calculated from the linear output. Comparison of measurements made with the top halves of the turbine removed with measurements made with the turbine halves installed permit determination of the "sag" in the turbine spindle introduced when the turbine is assembled.

Turbine rotor cooling

Abstract: Increased turbine inlet temperatures and/or extended life of turbine rotors in gas turbine engines is achieved by locating a plurality of passages (50) that extend axially in the disc (46) and turbine blades (32) of a so-called monorotor. The passages (50) have inlets (54) between compressor blades (18) on the rotor (20) and exit openings (52) in the free edges (38) of the turbine blades (32). Thus, air compressed by the compressor blades (18) is flowed through the passages (50) to cool the rotor (20).

Method and apparatus for improved polishing of turbine blades

Abstract: An improved method and apparatus for polishing turbine blades is disclosed wherein the path of a sanding shoe with respect to the turbine blade is controlled as the turbine blade is rotated on a spindle. The method involves plotting the profiles of the turbine blade in a number of planes, defining the profiles as a series of circle segments each having a center and an angular length, choosing an arbitrary center of rotation of the turbine blade, measuring the distances from the center of rotation to each of the circle segment centers, plotting the hypothetical path of the center of rotation about each circle segment center by each corresponding angular length, and using the derived path of the center of rotation to control the movement of the shoe in a vertical direction and the turbine blade in a horizontal direction as the turbine blade rotates. The apparatus includes spindle means for rotating the turbine blade about a center of rotation, and means for rotating the shoe axis about vertical and horizontal axes.

Supercharger intake air muffler or sound absorber, and method of muffling inrush air

Abstract: To reduce the speed of air being sucked towards a compressor turbine wheel, typically an exhaust gas supercharger turbine for an internal combustion engine, guide vanes (18) are located in the path of air being supplied to an inlet (3) of the compressor (1) which are positioned to impart a rotating component of motion to the air stream of air column being supplied to the compressor, the guide vanes extending essentially perpendicularly to the plane of radially positioned damping elements (14), while being inclined with respect to a radial line (19) passing through the axis of rotation of the compressor and, typically, of the housing (8) which has an air-pervious circumferential wall (8). The speed of air being supplied to the turbine thus can be reduced below Mach 1, thereby increasing the efficiency of operation of the turbine while substantially reducing its noise level.

Tidal power generating device using daryavaus type turbine

Abstract: PURPOSE:To generate electric power efficiently, by mounting a Daryavaus type turbine on a float and mounting a rudder perpendicular to a rotating shaft of the TTT turbine on a side surface of the float. CONSTITUTION:A Daryavaus type turbine 11 is mounted under a float 8 and a rudder 14 is mounted on a side of the float in a direction perpendicular to a rotating shaft 11a of the Daryavaus type turbine 11. With the arrangement, since the float 8 is directed to a prescribed direction at all times with respect to a tidal current, the DAryavaus type turbine 11 can be rotated in an optimum condition at all times regardless of a direction of the tidal current, whereby power generating efficiency can be improved.

Inertial speed control coupling for a gas turbine engine

Abstract: An inertial coupling is provided for substantially preventing rotational speed variations of a free power turbine in a multiple shaft gas turbine engine in response to a transient load condition. The inertial coupling comprises a gear assembly having first and second rotatable components driven respectively by the free power turbine and by the gas generator section of the gas turbine engine to cooperatively drive a free-wheeling inertial mass. The inertial mass is rotated at a constant speed during steady-state engine operation and provides sufficient rotational inertia during a transient load condition to couple the free power turbine temporarily to the gas generator section to maintain free power turbine speed substantially constant during adjustment of an engine fuel control to accommodate the changed engine load.

Channel for feeding water to a vertical-axis kaplan water turbine

Abstract: This invention relates to a channel for supplying water to a vertical-axis Kaplan water turbine, wherein the vertical side walls thereof are oriented in convergent manner in order that, at turbine level, they join an end face of rounded form, of which the radius of curvature is slightly greater than the radius of the guide blades located above the turbine and the sleeve of the turbine shaft and/or an inclined fixed wall downstream of the turbine are provided, for preventing the development of suction eddies downstream of the sleeve of the turbine shaft.

A Low Head Hydro Scheme Suitable for Small Tidal and River Applications

Abstract: The need to provide small communities with electrical power is well recognised. In many cases these communities are close to rivers or small estuaries which have energy capacities in the 10 kW to 100 kW range, and with an available head of 1 m to 2 m which is considered low in conventional hydro terms. The paper describes the operation of a modular device consisting of a chamber which acts as a water to air gearbox as water enters and leaves so expelling and inhaling air into and out of the chamber via a Wells turbine. Model tests of device performance are reported, and are used as input to the simulation of a full scale turbogenerator. Outline full scale design and costings are also discussed.

Improvements relating to hydro-electric power conversion systems

Abstract: The invention provides for the generation of electrical power from low head water, such as the flowing water of rivers or the like, the electrical power is generated by passing the water in sequence over flexible bags or membranes to displace air under the flexible bags or membranes. The displacement of the air is utilised for the driving of a power generator such as an air turbine, and smooth power flow is achieved by diverting air displaced from the underside of one membrane into the cavity under the other membrane. The water flows over the membranes in sequence so that a self oscillating system is set up with the air being displaced back and forth from the cavities, and the displacement air being used to drive the air turbine. Preferably a bi-directional air turbine such as a Wells turbine is used.

潮汐発電用クロスフロー水車に関する研究 : 第1報, 同一方向に回転する往復流水車

Abstract: In this paper, we propose the use of a cross-flow turbine for e tidal or wave power plant. This turbine can rotate in the same direction, even in reciprocating water or air flows produced by an oscillating water flow. This turbine has two symmetrical nozzle shapes around its axis. In order to investigate the feasibility of this kind of turbine the expriments were carried out in steady water flow. It is presented that the symmetrically shaped turbine can rotate in the same direction in reciprocating flows. A vortex is formed inside the runner similar to a cross-flow fan and asymmetry flow is produced. Its efficiency is about 54%. Improvement is expected by use of the experimental data for the condition inside the turbine.

Dual turbine drive

Abstract: A pair of cold air driven tubines are mounted in-line with each turbine driving one of two coaxial drive shafts. Each drive shaft is independently supported and separate drive air is supplied to each turbine such that the direction and speed of rotation of each drive shaft is independently controlled. Exhaust air from the forward turbine vents through an exhaust cavity that surrounds the aft turbine. Inlet drive air to the aft turbine is supplied via air ducts formed through the center of struts which extend radially from the inlet of the aft turbine, through the exhaust cavity and to an inlet port external to the turbine housing.

Craft with wind drive

Abstract: Wheels or marine screw propeller of a landcraft or watercraft are driven by a wind turbine via long shafts, hydraulic or mechanical transmission elements. In this case, the wind turbine is arranged such that a component of the lift produced at the turbine compensates the weight of the turbine including drive elements. Again, the point of application of the air forces acting on the turbine is located at the centre of gravity, at the lateral centre of gravity or in the vicinity of corresponding points in such a way that no, or insignificant heeling forces act on the craft, particularly in the case of watercraft. The support spar holding the turbine is connected to the chassis of the craft cardanically in order that the turbine can align itself automatically with the wind direction. During stoppage, the weight is compensated by a spring or a counterweight.

Aerodynamic characteristics of an oscillating airfoil

Abstract: This note presents aerodynamic data on an NACA 0018 airfoil oscillating in pitch in the NAE 2m x 3m Low Speed wind tunnel. The purpose of the test was to simulate the dynamic stall behavior of a Vertical Axis Wind Turbine blade section at the equatorial plane, under the unsteady conditions which may occur at low ratios of turbine tip speed to wind speed. Measurements were made of wing surface pressure time histories at various chordwise locations, during a complete cycle of oscillation. The dynamic effects on nose suction pressures were seen to increase their magnitude and to delay flow breakdown to a higher angle of attack. Corresponding increases in both normal and chord force were observed, and stemmed from the same cause.