Patent Publication Number: US-2018030834-A1

Title: Axial flow turbine

Description:
TECHNICAL FIELD 
     The present invention relates to an axial flow turbine, and more particularly to an axial flow turbine having improved blade angle of a rotor thereof. 
     BACKGROUND ART 
     As general examples of a gas turbine or a steam turbine used in power generation plants and the like, there are an axial flow turbine, in a rotation shaft direction of which a fluid flows due to a direction of the flow of a working fluid, an oblique flow turbine, wherein a fluid flows diagonal to a rotation shaft, a radial turbine, in a radial direction of which a fluid flows, and the like. Thereamong, an axial flow turbine is suitable for medium or large-capacity power generation plants, and thus, is broadly used as a steam turbine and the like in large thermal power plants. 
     From the viewpoint of economic efficiency increase and environmental load reduction, increase in power generation efficiency of a power generation plant is required, and high performance of an axial flow turbine is an important issue. As factors determining the performance of a turbine, there are short-circuit loss, exhaust loss, mechanical loss, and the like. In particular, it is recognized that reduction of short-circuit loss is effective in improving performance. Although there are various types of short-circuit loss, short-circuit loss types may be broadly classified into airfoil loss caused by blade shape per se, secondary flow loss caused by flow crossing a flow channel between blades, leakage loss due to leakage of a working fluid out of a flow channel between blades, and the like. Thereamong, leakage loss includes bypass loss wherein the energy of steam is not effectively utilized due to a leakage flow flowing along a path other than a main stream path; mixing loss occurring when a leakage flow out of a main stream is introduced into the main stream again; interference loss occurring due to interference of reintroduced leakage flow with a downstream cascade; and the like. Accordingly, in reducing leakage loss, it is important to reintroduce a leakage flow into a main stream, without loss of the leakage flow, while reducing a leakage flow amount. 
     In view of this, Japanese Patent Application Publication No. 2011-106474 proposes a technology for installation of a guide plate for guiding a leakage flow at leakage flow path parts of the same end portions of blades. By the guide plate, a leakage direction of a leakage flow coincides with the direction of a main stream discharged from the same blades, thereby reducing mixing loss when a leakage flow joins a main stream. 
     However, such a conventional axial flow turbine have difficulties in minimizing loss out of a main stream, leakage loss, and short-circuit loss occurring due to collision of a fluid against blades. 
     Korean Patent Application Publication No. 10-0550366 discloses a multistage axial flow turbine. 
     DISCLOSURE 
     Technical Problem 
     Therefore, the present invention has been made in view of the above problems, and it is one object of the present invention to provide an axial flow turbine that may reduce main stream loss, leakage loss, and mixing loss, as energy loss due to flow of a fluid, and exhibit relatively high turbine efficiency. 
     Technical Solution 
     In accordance with one aspect of the present invention, provided is an axial flow turbine including a rotor mounting part; 
     a housing including a fluid supply part that surrounds the rotor mounting part; 
     a rotor installed at a rotation shaft at the housing, located at a rotor mounting part, and including a plurality of blades mounted thereon in a circumferential direction; and 
     a plurality of injection nozzles installed at a fluid supply part surrounding the rotor mounting part and provided to spray a high-pressure fluid to fluid collision surfaces of the blades, 
     wherein fluid collision surfaces of the blades mounted on the rotor are formed to be inclined in a rotation direction of the rotor with respect to a normal direction axis of a rotation center axis, and the injection nozzles formed at the fluid supply part are installed at an angle parallel to a normal direction of fluid collision surfaces of the blades. 
     In the present invention, fixing blades installed between the blades, which are installed at the rotor, and the rotation shaft and guiding a fluid are installed at a supporter extending, in a rotation shaft direction, from the fluid supply part of the housing. 
     The fluid collision surfaces of the blades installed at the rotor are formed to be inclined at a predetermined angle with respect to a rotation center axis of the rotor. 
     In accordance with another aspect of the present invention, there is provided an axial flow turbine including a housing including at least one fluid inlet formed in an upper part thereof and a rotor mounting part formed therein; a rotation shaft rotatably installed at the housing and passing through the rotor mounting part; a rotor installed at the rotation shaft and including a plurality of a rotor rotation force generators formed at edge portions thereof, 
     wherein each of the rotor rotation force generators formed at the rotor includes a fluid induction part formed from an upper surface in a rotation direction; a blade formation part formed from the fluid induction part in a radial direction, formed to be inclined in a rotation direction with respect to a normal direction axis perpendicular to a rotation center axis of the rotor, and colliding with a fluid; and an induction discharge part protruding from the blade formation part to an outer circumferential surface of the rotor. 
     In the present invention, the induction discharge part is formed in a direction opposite to a rotation direction from the blade formation part, and fluid induction resistance protrusions are formed on an inner circumferential surface of the housing corresponding to the induction discharge part. 
     Advantageous Effects 
     As apparent from the fore-going, the present invention advantageously provides an axial flow turbine that reduces short-circuit loss and leakage loss occurring when a fluid sprayed from injection nozzles collides with each blade while smoothing the flow of a fluid by adjusting the angles of fluid action blades and the angles of fluid collision surfaces of blades which cause rotational action due to collision with a fluid, and thus provides an increased turbine rotation rate. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a partially-cut sectional view of an embodiment of an axial flow turbine according to the present invention. 
         FIG. 2  illustrates a partially-cut perspective view of an axial flow turbine according to the present invention. 
         FIG. 3  illustrates a cross-sectional view of the axial flow turbine illustrated in  FIG. 1 . 
         FIG. 4  illustrates a partially-cut perspective view of a rotor of the present invention. 
         FIG. 5  illustrates a sectional view of another embodiment of an axial flow turbine according to the present invention. 
         FIG. 6  illustrates a partially-cut perspective view of the rotor illustrated in  FIG. 5 . 
         FIG. 7  illustrates a graph representing a relationship between stream velocity and a revolution speed of each of an axial flow turbine according to the present invention and a conventional axial flow turbine. 
     
    
    
     BEST MODE 
     An embodiment of an axial flow turbine according to the present invention is illustrated in  FIGS. 1 to 4 . 
     Referring the figures, an axial flow turbine  10  according to the present invention includes a rotor mounting part  21  included therein; a housing  20  in which the rotor mounting part  21  and a fluid supply part  22  partitioned by a sectional partition wall  23  are formed; a rotor  40  which is installed at the rotor mounting part  21  installed at a rotation shaft  30  that is installed at the housing  20  and on which a plurality of blades  41  is mounted in a circumferential direction; and a plurality of injection nozzles  50  which is installed at the sectional partition wall  23  and is provided to rotate the rotor  40  by spraying a fluid supplied to the fluid supply part  22  onto fluid collision surfaces  42  of the blades  41 . 
     A plurality of rotor mounting parts  21  may be installed to be stacked inside the housing  20  in a vertical direction of the rotation shaft  30 , and the rotor  40  is installed at each of the rotor mounting parts  21 . In addition, a fluid is supplied to the fluid supply part  22 , which is partitioned, in a circumferential direction, by the sectional partition wall  23  at an outer circumferential surface of the rotor mounting part  21  located at the uppermost side, through at least one fluid supply pipe  24  installed at an upper surface or side surface of the fluid supply part  22 . 
     In addition, a fluid supply part  22 ′ located at a lower part in a shaft direction communicates with the rotor mounting part  21  at an upper part in the shaft direction such that a fluid of the rotor mounting part  21  is introduced to the fluid supply part  22 ′. 
     As illustrated in  FIGS. 3 and 4 , the fluid collision surfaces  42  of the blades  41  mounted on the rotor  40  are formed to be inclined in a rotation direction of the rotor  40  with respect to a normal direction axis B of a rotation center axis C. An inclination angle a is preferably 5 to degrees. When the inclination angle a is set to 5 degrees or less, short-circuit loss interrupting collision of a fluid against the fluid collision surfaces of the blades  41  relatively increases. On the other hand, when the inclination angle a is 45 degrees or more, collision loss due to a main stream, i.e., the force component in a main stream direction, increases. 
     In addition, the injection nozzles  50  for spraying a fluid supplied from the fluid supply part  22  to the fluid collision surfaces  42  of the blades  41  are installed at an angle parallel to a normal direction of the fluid collision surfaces  42  of the blades  41 . An injection hole of each of the injection nozzles  50  is preferably installed to correspond to the center of the fluid collision surfaces  42 . In addition, preferably, an inner diameter of each of the injection nozzles  50  gradually increases from the injection hole of each of the injection nozzles  50  to the fluid supply part  22  so as to reduce loss in a tube, although not illustrated in the figures. 
     Meanwhile, the fluid collision surfaces  42  of the blades  41  installed at the rotor  40  are formed to be inclined at a predetermined angle with respect to the rotation center axis C of the rotor  40 . The fluid collision surfaces  42  are formed to be inclined irrespective of the shapes of blades or installation angles thereof. Preferably, an inclination angle d of each of the fluid collision surfaces  42  is 0 to 65 degrees. When an inclination angle b of each of the fluid collision surfaces  42  with respect to the rotation center axis C is 65 degrees or more, the force component in the main stream direction increases, whereby an occurrence frequency of leakage loss relatively increases. 
     In addition, a supporter  25  extending, by a predetermined length, from a fluid supply part side in a rotation shaft direction is formed at a lower part of the sectional partition wall  23  of the housing  20 . A through hole  26  is formed at the supporter  25  such that a fluid colliding with the fluid collision surfaces  42  of the blades  41  smoothly flows to the fluid supply part  22  at the lower part. 
     In addition, fixing blades  45  for guiding a fluid in the vicinity of inner end sides of the blades  41  are installed at a predetermined interval at an end side of the supporter  25  such that rotating blades  41  do not interfere with a fluid which has collided with the blades  41 . The fixing blades are preferably formed to be inclined in a rotation direction of the rotor  40 . 
       FIGS. 5 and 6  illustrate another embodiment of an axial flow turbine according to the present invention. In the embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals. 
     Referring to the figures, at least one fluid supply pipe  24  is formed at an upper part of the axial flow turbine  70  according to the present invention. In addition, the axial flow turbine  70  includes a housing  20  inside which a single rotor mounting part  21  is formed; a rotation shaft  30  which is rotatably installed at the housing  20  and passes through the rotor mounting part  21 ; and a plurality of rotors  90  including a plurality of rotor rotation force generators  80  that are formed at edge portions of the rotation shaft  30 . 
     The rotors  90  are formed in a disk shape. The rotor rotation force generators  80 , which are formed along edge portions of the rotors  90  and provide rotational force to the rotors  90  due to collision of a fluid, include a fluid induction part  81  formed from an upper surface of each of the rotors  90  in a rotation direction; a blade formation part  82  which is formed from the fluid induction part  81  in a radial direction to be inclined in a rotation direction with respect to a normal direction axis B perpendicular to a rotation center axis C of the rotors  90 , so that a fluid introduced through the fluid induction part  81  collides with the blade formation part  82 ; and an induction discharge part  83  protruding from the blade formation part  82  to an outer circumferential surface of each of the rotors  90 . The induction discharge part  83  is formed to be inclined in a direction opposite to a rotation direction from the blade formation part  82 , and fluid induction resistance protrusions  27  are formed on an inner circumferential surface of the housing corresponding to the induction discharge part  83 . 
     As illustrated in  FIG. 6 , an inclination angle a of the blade formation part  82  of each of the rotor rotation force generators  80  is preferably 5 to 45 degrees with respect to the normal direction axis B of the rotation center axis C. In addition, a fluid collision surface  85  of the blade formation part  82  installed at each of the rotors  90  is formed to be inclined at a predetermined angle with respect to the rotation center axis C of the rotors  90 . The inclination angle of the fluid collision surface  85  is preferably 0 to 65 degrees. 
     The fluid induction resistance protrusions  27 , which is formed on an inner circumferential surface of the housing  20  opposite to outer circumferential surfaces of the rotors  90 , downwardly induce flow of a fluid discharged from the fluid induction discharge part  83 , and includes at least one surface (not shown) corresponding to the fluid induction discharge part  83  of each of the rotors  90  such that reaction force due to collision of a fluid can act on the rotors  90 . 
     Operation effects of the axial flow turbine according to the present invention having the aforementioned configuration are described below. 
     First, the present invention may maximize a rate of rotation of a turbine while providing smooth fluid flow by optimizing the angles of fluid action blade surfaces. Referring to  FIGS. 1 to 4 , a high-pressure fluid is introduced to the fluid supply part  22  via the fluid supply pipe  24  of the housing  20  of the axial flow turbine  10 . 
     In addition, a high-temperature and high-pressure fluid introduced to the fluid supply part  22  is sprayed at high pressure through the injection nozzles  50  and collides with the fluid collision surfaces  42  of the blades  41  corresponding to the injection nozzles  50 , thereby rotating the rotor  40  at high speed. 
     By such a process, the fixing blades  45  induce a fluid travel direction toward the through hole  26  through which the rotation shaft  30  passes such that interference of the blades  41  of the rotor  40  does not occur. Accordingly, re-mixing with a fluid colliding with the fluid collision surfaces  42  of the blades  41  may be prevented, thereby minimizing mixing loss of a fluid. 
     In particular, since the fluid collision surfaces  42  of the blades  41  of the rotor  40  according to the present invention are formed to be inclined in a rotation direction of the rotor  40  with respect to the normal direction axis B of the rotation center axis C, collision surfaces of a fluid sprayed from the injection nozzles may be more widely secured and interference resistance of the blades introduced to the injection nozzles  50  in succession during rotation of the blades  41  may be reduced. Accordingly, the effect that a fluid continuously collides with the blades  41  of the rotor  40  may be obtained, whereby short-circuit loss of a fluid sprayed from the injection nozzles  50  may be relatively reduced. 
     As illustrated in  FIG. 7 , the present inventors confirmed that the axial flow turbine according to the present invention provides a high revolution speed in the case of a low-speed fluid, i.e., at a relatively low stream velocity. More particularly, the axial flow turbine of the present invention provides the same revolution speed as that of a conventional axial flow turbine at a lower fluid injection rate. Accordingly, it can be confirmed that the efficiency of the axial flow turbine according to the present invention is relatively high. 
     Meanwhile, referring to  FIGS. 5 and 6 , in the case of the axial flow turbine  70  according to the present invention, action and reaction simultaneously act on the rotors  90  when the rotors  90  are driven by a high-temperature and high-pressure fluid. That is, a fluid introduced to the fluid induction part  81  of each of the rotor rotation force generators  80  primarily acts as rotational force of the rotors  90  while colliding with the blade formation part  82 , and secondarily acts while being discharged through the fluid induction discharge part  83  formed in a direction opposite to the rotation direction. In particular, a fluid discharged through the fluid induction discharge part  83  causes a reaction while colliding with the fluid induction resistance protrusions  27 , thereby increasing rotational force of the rotors  90 . 
     In particular, since the blade formation part  82  is formed to be inclined in a rotation direction of the rotor with respect to the normal direction axis B of the rotation center axis C, collision surfaces of a fluid sprayed from the injection nozzles  50  may be relatively widely secured, thereby reducing fluid resistance. 
     The constituents of the present invention may be variously modified and may have various shapes. 
     While the present invention has been particularly shown and described with reference to the preferred embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be appreciated by those skilled in the art that numerous changes and modifications of the invention are possible without departing from the spirit and scope of the appended claims. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. In addition, the blades and the blade surfaces of the present invention may have various shapes and forms depending upon a field situation or a fluid type within a range within which angle ranges of the blades and blade surfaces of the present invention are not affected. 
     INDUSTRIAL APPLICABILITY 
     The technical idea of an axial flow turbine of the present invention may be repeatedly practiced providing the same result. Particularly, the axial flow turbine of the present invention may be used in various power generating facilities and as industrial power source.