Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Plural distributing means immediately upstream of runner
Reexamination Certificate
1999-10-01
2001-04-10
Ryznic, John E. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Plural distributing means immediately upstream of runner
C415S220000, C415S914000, C416S23600R
Reexamination Certificate
active
06213711
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates, in general, to a steam turbine, and in particular, to a steam turbine with a flow duct with blading configured within it and to a blade or vane for a steam turbine.
A turbine blade or vane for use in the wet steam region of the penultimate and final stages of turbines is described in German published, non-prosecuted Patent Application DE 195 46 008 A1. Such a turbine blade or vane is subject to erosive wear due to impinging water droplets. This erosive wear is reduced by the airfoil of the turbine blade or vane having surface roughness in the region of its leading edge and the region of the suction surface of the blade or vane or in at least a partial region thereof, which surface roughness is markedly increased relative to the surface roughness of the pressure surface of the airfoil. A film of water is held on the surface of the turbine blade or vane by this surface roughness. This film of water reduces the erosive effect of impinging water droplets.
German Patent DE 36 095 41 C2 deals with the reduction of the aerodynamic drag of a body in turbulent flow. The reduction in drag is achieved by reducing the turbulent wall shear stress. For this purpose, the surface of the body is provided with ribs in a plurality of rib formations. The ribs are arranged offset to one another laterally to a flow direction and have short extensions in the flow direction. In particular, DE 36 095 41 C2 reveals such a surface structure for reducing the drag of an aircraft wing.
German published, non-prosecuted Patent Application DE 43 19 628 A1 deals with the structuring of turbo-machine surfaces in contact with fluid. The flow losses are minimized by a applying a grooved structure. The special relationships of fluid pumps are taken into account in this publication.
German Utility Model G 90 13 099 relates to a rotor for extracting energy from a flowing medium or for releasing energy to a flowing medium consisting of a hub and at least one rotor blade. An increase in the efficiency of the rotor is achieved by a rotor blade of the rotor having a corrugated shape. In addition to the absolutely necessary corrugated shape, such a rotor blade can also be completely covered with grooving.
An impeller for a centrifugal compressor, in particular for a gas turbine, is described in U.S. Pat. No. 3,481,531. The impeller has vanes which extend radially outward and between which is located an impeller wall. The impeller wall is provided with grooves which extend radially outward so that a boundary layer of gas adhering to the wall is broken up and energy losses are therefore minimized.
U.S. Pat. No. 4,023,350 shows an appliance which reduces a pressure loss in a gas turbine. The appliance consists of a chain of protrusions which extends between two adjacent blades or vanes of a blading ring of the gas turbine. This chain of protrusions acts to generate a vortex so that a boundary layer thickness, and therefore losses due to transverse flows, are reduced.
In the VDI reports No. 1109 of 1994, Jetter and Rie&bgr; describe on page 241 of the article “Aerodynamic Properties of Turbine Blading Profiles of Different Manufacturing Qualities”, the influence of surface roughness on the efficiency of turbine blading profiles. The article states that surface roughnesses, such as milling grooves, have an influence on the profile loss but, because of the importance of other parameters, this influence cannot yet be accurately quantified.
A steam turbine is considered in the book “Turbo-machines” by Klaus Menny, B. G. Teubner Stuttgart, 1995. It is stated therein that water turbines, steam and gas turbines, windmills, centrifugal pumps and centrifugal compressors and propellers are combined under the collective designation of “turbo-machines”. A common feature of all these machines is that they are used for the purpose of withdrawing energy from an active fluid in order to drive another machine or to supply energy to an active fluid in order to increase the pressure of the latter. Using a simple turbine as an example, the mode of operation of a turbo-machine is explained. The active fluid enters the machine and flows first through a blading ring of stationary guide vanes. This increases the velocity and therefore the kinetic energy of the active fluid. Its pressure and therefore its potential energy are reduced. At the same time, the shape of the guide vanes produces a velocity component in the peripheral direction of a rotor blade ring downstream of the guide vane ring. By means of the rotor blade ring, the active fluid gives up its kinetic energy to the rotor, to which the rotor blade ring is connected, because the direction and frequently also the magnitude of the velocity of the active fluid is changed when flowing over the rotor blades. The rotor blade ring is made to rotate. The active fluid emerges from the machine with reduced energy content. The ratio between the mechanical energy gained from the turbine and the energy withdrawn from the active fluid characterizes the efficiency of the turbine.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a steam turbine with a high efficiency. A further object of the invention is to provide a steam turbine blade or vane that enables a higher efficiency of the steam turbine to be obtained.
With the foregoing and other objects in view there is provided, in accordance with the invention, a steam turbine that includes a duct wall with at least one region having a grooved structure with spaced apart groove cusps. The duct wall defines a flow duct extending along an axis, and blading is configured in the flow duct.
In such a steam turbine, a flow through the flow duct by an active fluid along a main flow direction, which differs locally, can be influenced in specified manner by means of the grooved structure applied to the duct wall. The duct wall does not then have to be a continuous surface. The duct wall is preferably composed of an inner wall and an outer wall of an annular flow duct. The influence on the flow through the duct relates particularly to transverse flows directed transversely to the main flow direction of the active fluid, i.e. to vortices which are damped by an increased flow resistance caused by the grooved structure. Since such transverse flows can cause a reduction in the efficiency, the damping of such transverse flows can contribute to increasing the efficiency of the steam turbine.
In accordance with an added feature of the invention, each blade or vane is preferably arranged in a blading ring. A spacing surface is located between two blades or vanes in adjacent blading rings, and this spacing surface is part of the duct wall. The grooved structure with the groove cusps extends on the spacing surface. The active fluid flows between two adjacent blades or vanes along the main flow direction fixed by the blades or vanes. The spacing surface can extend in the main flow direction beyond a connecting line between the end points of adjacent blades or vanes. The expression “located between” is used to define the position of the spacing surface rather than as a strict definition of its extent along the main flow direction. The spacing surfaces of a blading ring offer a particularly effective possibility of damping possibly occurring transverse flows by means of a grooved structure applied to these surfaces. The term blading ring is to be understood, for example, as a configuration in which the blades or vanes are arranged between an inner and an outer boundary, ring-shaped in each case, or in which the blades or vanes are only fastened at one end, for example on a rotor of a turbine.
In accordance with an additional feature of the invention, each blade or vane has an airfoil with an airfoil profile ending at the spacing surface, each groove cusp extending on the spacing surface being associated with an adjacent airfoil profile. The groove cusp is directed approximately in alignment with this airfoil profile. In consequence, the grooved structure is directed approxi
Bell Ralf
Müller Karl-Heinrich
Simon Volker
Ulm Wilfried
Greenberg Laurence A.
Lerner Herbert L.
Ryznic John E.
Siemens Aktiengesellschaft
Stemer Werner H.
LandOfFree
Steam turbine and blade or vane for a steam turbine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Steam turbine and blade or vane for a steam turbine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Steam turbine and blade or vane for a steam turbine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2491899