Patent Application
20090160135
1. Field of the Invention
Embodiments of the subject matter disclosed relate generally to seals for rotary machines, such as steam turbines, gas turbines, aircraft engines, and compressors, and more particular to a labyrinth seal with reduced leakage flow by grooves and teeth synergistic action.
2. Description of the Related Art
Rotary machines such as steam and gas turbines used for power generation and mechanical drive applications, aircraft engines used for propulsion, and compressors used for pressurization, are generally large machines consisting of multiple turbine and compressor stages. In such machines, pressurized fluid flowing through the turbine and/or compressor stages passes through a series of stationary and rotary components. For example, in a typical steam turbine, the stationary components may include the machine casing and packing head, and the rotary component is the rotor. Annular seals mounted on the stationary components are used to control leakage of fluid along the path between the stationary and rotary components.
It would therefore be desirable to develop a labyrinth seal with improved performance so as to increase efficiency of steam turbines, gas turbines, aircraft engines, and compressors by limiting gas recycling inside the machine, thus raising effective process gas flow.
One or more of the above-summarized needs or others known in the art are addressed by labyrinth seals that include a stator, a plurality of teeth extending from the stator, a rotor disposed next to end portions of the plurality of teeth, the rotor including a plurality of grooves on the outside surface thereof, each groove being disposed between adjacent teeth of the stator, and a cavity on an external surface of the rotor formed between adjacent teeth, each groove being configured to induce a vortex motion to a leakage flow from a high-pressure side to a low-pressure side of the seal so as to reduce a flow rate of the leakage flow.
Labyrinth seals according to embodiments of the disclosed inventions also include a stator, a plurality of teeth extending from the stator, and a rotor disposed next to the end portions of the plurality of teeth of the stator, the rotor further including means for reducing a flow rate of a leakage flow from the high-pressure side to the low-pressure side of the seal.
Methods of reducing a leakage flow in a labyrinth seal are also within the scope of the subject matter disclosed. These methods include the rotating the leakage flow into a vortex in a cavity formed by a groove on an external surface of a rotor and two adjacent teeth of a stator.
The above brief description sets forth features of the various embodiments of the present invention in order that the detailed description that follows may be better understood, and in order that the present contributions to the art may be better appreciated. There are, of course, other features of the invention that will be described hereinafter and which will be for the subject matter of the appended claims.
In this respect, before explaining several embodiments of the invention in detail, it is understood that the various embodiments of the invention are not limited in their application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which the disclosure is based, may readily be utilized as a basis for designing other structures, methods, and/or systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the foregoing Abstract is to enable a patent examiner and/or the public generally, and especially scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. Accordingly, the Abstract is neither intended to define the invention or the application, which only is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
Embodiments of the subject matter disclosed relate generally to seals for rotary machines, such as steam turbines, gas turbines, aircraft engines, and compressors, and more particular to a labyrinth seal with reduced leakage flow by grooves and teeth synergistic action. As it will become more apparent from the detailed description of the subject matter disclosed herein, by causing a recirculation of the leakage flow between each tooth of a labyrinth seal, a substantial decrease in leakage flow results, thus creating a labyrinth seal with improved performance so as to increase efficiency of steam turbines, gas turbines, aircraft engines, and compressors by limiting gas recycling inside the machine, thus raising effective process gas flow. Those of ordinary skill will appreciate that the various embodiments disclosed herein for minimizing and/or eliminating seal leakage are not dependent on each other, i.e., each may be implemented without the other and various combinations are within the scope of the subject matter disclosed, as it will become apparent. Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, several embodiments of the improved labyrinth seal systems will be described.
Thus, one of the advantageous features of the disclosed labyrinth seal is the creation of a synergistic action between the static seal labyrinth and the rotating sleeve with special grooves. Modifying the cylindrical sleeve shape by making appropriate grooves generates a barrier effect to the leakage flow, thus reducing its flow rate by an effective vortex blockage action to the natural flow path for the leakage.
The embodiment of
As appreciated by those of ordinary skill in the applicable arts, once this new labyrinth seal design is standardized, it could be applied to critical centrifugal compressors where conventional seals do not meet desired standard performance. Computational Fluid Dynamics simulations of the disclosed seal performance indicate a reduction in leakage of 44%, cutting the leakage flow from 1.956 kg/s obtained for the simulation of a standard seal down to 1.089 kg/s for a seal having the structural features disclosed herein. In such simulations, the inlet stagnation pressure used as boundary condition was 371 bar at HP side of the seal for a gas with an inlet temperature of 45° C. and an outlet static pressure of 227 bar at the LP side of the seal. The rotor rotational speed used for the simulations was 10650 RPM and other fluid properties included: dynamic viscosity of 2.84×10-5 N s/m2, thermal conductivity of 0.0852 W/m K, ideal gas constant of 352.64 J/kg K, ratio of specific heats of 1.3, molecular weight of 20.55, specific heat at constant pressure of 1528.11 J/kg K, and modified molecular weight of 23.576.
Methods for controlling the temperature of a battery are also within the scope of the subject matter disclosed herein. Such methods include: the transferring range includes flowing a liquid through a plurality of liquid-circulating cooling plates within the battery.
Methods of reducing a leakage flow from a high-pressure side to a low-pressure side of a labyrinth seal comprising a stator, a plurality of teeth extending from the stator, and a rotor having an outside surface disposed next to end portions of the plurality of teeth of the stator. These methods include the rotating the leakage flow into a vortex in a cavity formed by a groove on an external surface of the rotor and two adjacent teeth of the stator. The rotating may further include the rotating of the leakage flow in a cavity formed by the groove and two adjacent sloping teeth of the stator, the cavity having either a circular or elliptical shape and the rotor having a flat portion on the external surface thereof next to end portions of the plurality of teeth.
While the disclosed embodiments of the subject matter described herein have been shown in the drawings and fully described above with particularity and detail in connection with several exemplary embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without materially departing from the novel teachings, the principles and concepts set forth herein, and advantages of the subject matter recited in the appended claims. Hence, the proper scope of the disclosed innovations should be determined only by the broadest interpretation of the appended claims so as to encompass all such modifications, changes, and omissions. In addition, the order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Finally, in the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.
