WATER TURBINE, ESPECIALLY FRANCIS TYPE WATER TURBINE The present invention pertains to the field of hydraulic machines, especially Francis type water turbines. Such turbines include as their main parts a impeller, which has numerous blades. The vanes are generally interspersed in a fixed or mobile manner between guide vanes. The impeller generally has a vertical axis connected to a generator with a motor connection. The impeller is surrounded by a spiral body that supplies water on the impeller - possibly on the guide vanes. A suction tube is connected to the impeller. This tube has a vertical section followed by an elbow and finally a horizontal section. What is known as the spiral body as well as the suction tube are made of steel. They can be made from a single sheet or they can also be manufactured by casting. US 5 108 671 describes a process for the manufacture of a suction tube of a water turbine. Many slabs are manufactured, each of which includes a steel frame with concrete casting. US 992,782, US 3 729 165, US 4 997 602 and US 5 032 197 relate to the manufacture of metal molds for the construction of hollow spaces within constructions of
concrete. The object of the present invention is to provide a method and a device through which water conducting channels can be manufactured through a molding or casting process. In this way the manufacturing costs are limited and the dimensional stability of the channels is high. The conductive surfaces of water must be smooth and without steps. This object is achieved through the features of the independent claims. In accordance with the process of the present invention, a casting core is first obtained. The coating surface of the casting core corresponds to the water conducting surfaces of the flow channels to be manufactured, thus, for example, to the spiral body of a Francis-type turbine. The casting core is then placed in the position in which the water conducting channel will be found. The casting core is divided into two or more longitudinal sections. The longitudinal sections are joined before casting. They may be blocked between them, for example to the extent that the front sides of two neighboring sections have nails and against nails that are hooked between them of a type of bayonet closure. Blocking is achieved through the rotation of the two neighboring sections in relation to each other, and unlocking is achieved
also through rotation, however in the opposite direction. The casting core is then cast into concrete or other casting material hardenable with the passage of time. After hardening of the casting material, the longitudinal sections of the casting core are collected one after the other from the formed channel. The longitudinal sections of the casting core may have hollow spaces which are connected to each other in the form of a duct after the union of the longitudinal sections between them. The longitudinal sections can, at least in the area of their coating surface, be made of a material that can be expanded under an overpressure condition or shrink under a reduced pressure condition. As a material we can contemplate, for example, the rubber or an elastic material of this type, however other materials such as steel, concrete, plastic can be used. Prior to the hardening of the casting material, an overpressure can be applied in the hollow space of the longitudinal sections. In this way a densification of the water conducting surfaces of the channel is achieved and the roughness is reduced. When the casting material has hardened, a depression can be applied in the hollow spaces in such a way that they are reduced. After unlocking two
neighboring longitudinal sections can thus be collected the individual core sections of the manufactured water conducting channel. An important advantage lies in the fact that the casting cores can be reused in such a way that numerous equal or similar water conducting channels can be manufactured, for example, spiral bodies or suction pipes with the same casting core. It is also possible, in the case of a corresponding modular construction, to manufacture cast cores from longitudinal sections which can be used for several water conducting channels. The casting core according to the present invention as presented above is manufactured from the joining of several longitudinal sections. The individual longitudinal sections may in turn consist of two or more parts. In general, the casting core has a circular or almost circular cross section. However, other shapes can also be seen in cross section, for example an oval shape. Seen in transverse form, the individual longitudinal section may consist of the union of circular segments or ring segments. According to one embodiment of the present invention, a casting core is constructed from a skeleton whose intermediate space is filled by a filling material. The skeleton includes for example longitudinal ribs that are
In addition, it may have circumferential ribs that lie in inclined planes against the longitudinal axis of the casting core. The skeleton can be a light construction and possibly a flexible construction, for example of plastic or artificial resin reinforced with glass fibers. The neighboring rib-shaped fields can be filled with a filler such as a polymer, a cement or a mixture of the mentioned materials or other materials. The invention as well as the state of the art can be better understood based on the drawings. The individual drawings are presented below: Figure 1 shows a hydroelectric power station according to the present invention in axial section. Figure 2 shows a Francis-type turbine according to the state of the art in axial section. Figure 3 shows two sections of casting core according to the present invention joined and locked together. Figure 4 shows a blocking device. Figure 5 shows a casting core according to a first embodiment of the present invention in cross section.
Figure 6 shows a perspective representation of a casting core according to a second embodiment (skeleton construction) in the stage of its formation. Figure 7 shows a part of the casting core according to claim 6, in perspective representation. Figure 8 shows the object of Figure 6 in section, and specifically in a section perpendicular to its axis. Figure 9 shows the emptying core according to Figure 6 in the finished state. The hydroelectric power station illustrated in Figure 1 includes a generator part 1 as well as a turbine part 2. Both parts have the same vertical axis 5. The turbine part 2 includes a Francis-type turbine with an impeller, a spiral body 6 and a suction pipe 7. A concrete base 3 is recognized which completely surrounds the turbine part 2. The water conducting surfaces of the spiral body 6 as well as the suction pipe 7 are made of concrete. In contrast to this, the conventional Francis-type turbine according to FIG. 2 has a spiral body 6 and a suction pipe 7 made of steel. Figure 3 shows two longitudinal sections 8.2 and 8.2 of the casting core. These sections serve for the manufacture of the upper part of the suction pipe 7
shown in Figure 1. The longitudinal section 8.1 has the shape of a truncated cone, and the longitudinal section 8.2 is cylindrical. The two longitudinal sections 8.1 and 8.2 of the casting core can be locked between them by means of a blocking device 9. From FIG. 4, two locking clamps 9.1 and 9.2 can be seen. Each of these claws is placed in one of the longitudinal sections of casting core 8.1 and 8.2, respectively, and fixed therein. Blocking or unlocking is achieved through a relative rotation of the two longitudinal sections of casting core 8.1, 8.2. The water conducting channel to be manufactured - a spiral body, for example, or a suction pipe - can have any desired cross section over its length. For example, the longitudinal section of the casting core 8.1 in the form of a truncated cone can have a circular cross-section, the longitudinal section of the cylindrical casting core 8.2, however, can have a slightly elliptical shape. In a case of this type, special measures must be taken in order to be able to use the blocking principles described above with the two locking jaws 9.1 and 9.2. For this purpose, at least one of the two longitudinal sections is constructed, for example section 8.2 from two concentric bodies between them,
specifically an internal body 8.2.1 and an external body in the form of a ring 8.2.2. The limit surface 8.2.3 between these two bodies is a circular cylinder. The blocking claw 9.2 of the longitudinal section of the casting core 8.2 is in this case fixed to an internal body 8.2.1 of the longitudinal section of the casting core 8.2. The internal body 8.2.1 can rotate freely about its longitudinal axis which means that the external surface of the external body 8.2.2 can have a different cross-section of a circular cross-section. Incidentally, these two bodies 8.2.1 and 8.2.2 are fixed between them in the axial direction in such a way that a displacement in the axial direction of both bodies causes a joint displacement movement. The representation according to Figure 5 shows a casting core 8 constructed from an internal support beam 8.3 and an external covering 8.4. The support beam 8.3 can be a massive cylinder or a complete cylinder. It can consist of any material, for example steel, wood, concrete, plastic. It must present a certain rigidity. In the case in question, the cast core support beam consists, however, of a tube. It can be made of steel or plastic or other material. Conveniently, a material of reduced specific weight is manufactured. The specific weight may correspond, for example, to 1/5 or 1/10 or
even less than the specific weight of the steel. The outer casting layer 8.4 can be set tightly and tautly on the casting core support beam 8.3. However, it can also move freely in such a way that a ring gap remains between the inner surface of the lining and the outer surface of the support beam. The ring space may be minimal such that the surfaces facing each other of the support beam and the liner are practically in contact. The ring space in the presented case is connected to a medium, see medium duct 8.4 and connection 8.5. The medium can be air or a liquid. It can be connected to a source of overpressure or to a source of low pressure - not illustrated. Depending on the case, the coating of the casting core 8.4 can from time to time have very different wall thicknesses. For example, it can receive half the diameter of the entire casting core 8. It can also be comparatively thin, such as for example representing 1/10 or 1/20 or even less than the diameter of the entire casting core. If the support beam of the casting core 8.3 has the shape of a tube, as illustrated here, then the mechanical connection between two neighboring casting sections is very simple. The tube 8.3 of two sections of casting core 1.1 and 1.2 adjacent to each other can for example
connect telescopically A mutual lock, if necessary, can also be effected, for example, by means of a bayonet lock. The important thing is that the casting core 8 consists of individual longitudinal sections which can be joined and locked between them. The modality according to Figure 5 is especially interesting. The diameter of the core core coating 8.4 can specifically be a little smaller in the initial state than the internal width of the channel to be manufactured. The fabrication of the channel is carried out in the following manner: the casting core is completely constructed insofar as its individual longitudinal sections are joined and blocked between them. The casting core is accurately taken to the position that the channel to be manufactured will take. Then the casting core is integrated into the casting material, for example concrete. After a certain period of time, ie at the start of the hardening of the casting material, the longitudinal sections of the individual casting core 8.1, 8.2, etc., are subjected to a certain internal pressure. In this way the channel is slightly extended in the incipient state. This has the consequence that the water conducting surfaces of the channel are densified and smoothed at the same time, which will subsequently beneficially reduce the flow resistance.
Then the overpressure is removed again, whereby the casting core liner 8.4 contracts correspondingly and has a smaller size than the internal width of the channel. Then the longitudinal sections of the individual casting core 8.1, 8.2 etc. can easily be removed from the formed channel, after having previously removed the mutual locking between neighboring longitudinal sections, for example through the rotation of a section about its longitudinal axis. In certain cases, the core support beam of 8.3 can also be suppressed. In this case, it is also possible to work with a medium that is in an overpressure state in order to expand the casting core coating 8.4. The examples of modalities described so far can be described as a "first solution principle". This is characterized by its great simplicity. A second solution principle will be described below with reference to Figures 6 to 9. In accordance with the second solution principle, the casting core is constructed from a skeleton including longitudinal ribs which extend in the longitudinal direction of the longitudinal section of the casting core in question, as well as circumferential ribs extending in the circumferential direction of the section
longitudinal of the casting core. Figure 9 shows a complete casting core 8. This core is formed by a series of casting longitudinal sections 8.1, 8.2, 8.3. The complete casting core 8, as described above, is integrated in concrete, so that it is completely surrounded by concrete 99, as can be seen in Figure 8. After hardening, the longitudinal sections of casting core 8.1 etc. they are removed and removed individually from the manufactured channel. Each longitudinal section of casting core 8.1, 8.2, 8.3 includes a skeleton 12 - see Figure 6 - as well as a plate or slab 13 - see Figures 7 and 8. The skeleton or its ribs consist of a relatively light, strong, flexible material , for example artificial resin reinforced with glass fiber, epoxy material, plastic or the like. On the contrary, in the case in question, the individual plates 13 are made of a polymer, of concrete, or of a mixture of the above or of other filling materials. The skeleton 12 has an inner wall in the form of a tube 21 - see for example Figure 6, and further has two or more annular flanges 22 which can be characterized as circumferential ribs of the skeleton and several longitudinal flanges 23 which can be characterized as ribs
longitudinal The combination of the aforementioned parts has a grid configuration with a convex floor and upright side walls. The annular flanges 22 and the longitudinal flanges 23 cover areas of internal flanges 24 and outer flange regions 25 - see Figure 8. The outer flange area 25 extends from the inner tube-shaped wall 21 outwards and forms lateral surfaces of the flange. skeleton 12. The internal flange zones 24 extend from the internal tube-shaped wall 21 inwards into a working bore 17 of the casting core 10 formed from the numerous longitudinal sections of the casting core. The internal flange area 24 contains means for closing the longitudinal sections of the casting core 8.1, 8.2 etc. between them. In this case it is a mechanical fastening device for screws and nuts. The screws are inserted into perforations 27 in the areas of internal flanges 24. In the case of a preferred embodiment, at least one hole 27 is formed as a longitudinal hole to allow a mutual adjustment of the longitudinal sections of the casting core. The skeleton 12 comprises a plate 13 made of a polymer-concrete aggregate and is firmly bonded with this plate. The external surface of the plate 13 is connected to the circumferential edges 26 of the annular flanges 22 and of the longitudinal flanges 23. As concrete material of the plate 13 it is a
material of lower density and lower pressure resistance as well as greater flexibility and greater elasticity, compared to the usual concrete. The aggregate of polymer - concrete or cement to be used is formed of light polymer or foam polymers or similar particles with a low weight and a lower density. A certain amount of material can have, for example, the following constituent parts: 300 kg of cement, 150 kg of sand, 150 kg of water and 7 kg of a binder. In this way a product having a density equivalent of about 50% of the water density or about 500 g / 1 is obtained as well as a pressure resistance of about 20% compared to a customary concrete. Hardened concrete is significantly lighter than usual concrete. The material presents a specific weight as wood, has a certain flexibility and elasticity based on the presence of polystyrene in the structure of the particles. A wiring 15 can also be integrated into the slab, obviously also another reinforcing means such as, for example, a fabric or a wire mesh. The overall dimensions of the longitudinal sections of the individual casting core 8.1, 8.2 etc. they depend on the size and shape of the channel to be manufactured. However, the maximum dimensions of a longitudinal core section should be limited
that the weight should not exceed 40 kg in such a way that two men can easily handle it, especially in the case of joining and mounting in a single casting core 8. The circumferential edges 28 of the annular flanges 22 and of the longitudinal flanges 23 thus as the circumferential edges 33 of the spacing elements 32 between neighboring flanges 22 and 23 define the desired curvature of the outer surface 14 of the casting core 8. The more curved is the outer surface 14, the closer the flanges 22 and 23 will be between they. The spacer 32 - see Figure 8 - preferably consists of a material similar to the material forming the skeleton 12. The spacers 32 are inserted between neighboring pairs of annular flanges 22 and neighboring pairs of longitudinal flanges 23. In this way the circumferential edges 33 of the spacers 32 extend over the circumferential edges 26 of the flanges 22 and 23. In this construction the circumferential edges 23 of the spacers 32 serve as guides for the formation of the outer surface or coating surface 14 of the polymer plates - concrete 13 individual. If the longitudinal sections of casting core 8.1, 8.2 etc. they are joined in circumferential direction and also in the longitudinal direction and locked between them, the longitudinal section shown in Figure 6 is obtained.
The construction of this longitudinal section can be carried out at the site of the installation or it can be carried out elsewhere. On the external surface of a slab 13 a smooth layer 16 is preferably applied in order to provide a corresponding smooth water conducting surface in the channel being constructed. A smooth layer of this type preferably consists of a mixture of acrylic resin, cement and fine sand. Other materials such as polyurethane, epoxies can also be used as a smooth layer 16. The individual longitudinal sections joined together 8.1, 8.2 etc. they form the complete casting core 8 in this way. The casting core 8 is formed in such a way that after its assembly it can be subjected to pressure and in a certain way inflated. In this way the still wet concrete is subjected to a certain pressure in order to densify and smooth the mold surfaces. As shown in Figure 9, the work hole 17 is sealed through a pneumatic seal 41. A source of pressure medium 42 carries a pressure medium in the inner space of the casting core 8. The following will be described below. procedure for the construction of the casting core, the assembly and the manufacture of a hollow space or a channel. In order to form the skeleton 12 a matrix is manufactured
of sheet essentially conical, curved, allowing to vary the curvature. The tube-shaped inner wall 21 as well as the flanges 22 and 23 are made on the matrix of plastic material reinforced with glass fiber or with another similar material, and specifically in a thickness of approximately 1 to 2 centimeters. In the areas of internal flanges 24, perforations 27 are formed. As soon as all the parts of the skeleton (longitudinal sections of the casting core) 8.1, 8.2, etc. are formed. they are manufactured, a workshop assembly is carried out in order to determine the tolerances and to make an adjustment of the separators 32, which in turn form the mold surfaces 14. After a revision of the dimensions, all the elements of the mold are carefully marked. skeleton 12 in order to ensure a correct subsequent assembly at the site of the work. The parts of the skeleton 12 are reassembled at the site of the work, adjusted and measured in order to ensure correct positioning of the circumferential edges of spacing 33. Reinforcement elements 15 are fixed on the parts of the skeleton 12. A polymer-concrete mixture is then prepared by pouring it into the skeleton 12, for example by spraying. The polymer-concrete material is relatively viscous to facilitate the formation of the plates 13. The wet polymer-concrete material is applied manually, so shape rules are used
suitable in order to achieve the desired configuration of the mold surface 14. For this purpose the circumferential edges 33 of a skeleton 12 of this type serve as a guide. Since each skeleton 12 has its own group of circumferential edges 3 and is spaced apart from the longitudinal section of the neighboring casting core through the flanges 22 and 23, the plates 13 can be manufactured individually. In this way it is ensured that the external surfaces of each of the plates 13 have dimensional accuracy. After sufficient hardening of the material of the plates 13, usually a whole day, a smooth layer 16 is applied, for example by brush application. After hardening of the smooth layer 16 - in general several days - additional work is optionally carried out on the mold surface 14. Before the casting of concrete for the manufacture of the concrete structure 99, an agent can be applied to the smooth layer 16. of demolding in order to facilitate the removal of the casting core after the casting operation has been carried out. The assembled complete casting core is then subjected to pressure and the mold surface 14 is measured in order to ensure that it has the correct dimensions. Reinforcement rods are eventually placed for the concrete construction 99. Then the concrete is emptied
liquid in order to wrap the casting core 8. Eventually a lighter pressure is applied in order to obtain an expansion of the casting core 8. In this way an expansion of a few millimeters in radial direction can be achieved, for example 2 , 3, 4, 5, 6, 7, 8 mm. In the case of a typical installation, the concrete construction 99 can have four meters. It is cast longitudinally. As soon as the concrete has sufficiently hardened, the pressure of the casting core 8 is removed, the longitudinal sections of the casting core are unblocked between them and removed. Based on the pressure removal and based on the slight flexibility of the individual longitudinal sections, said individual longitudinal sections can be extracted through the work perforation 17. The longitudinal sections can then be cleaned, checked and eventually repaired. They can be reused for similar casting processes. The individual parts of the casting core, for example longitudinal sections of the neighboring casting core, can also be temporarily joined by means other than mechanically for the purpose of carrying out the casting process. For example, magnets placed on the front side ends of neighboring longitudinal core sections can be contemplated. The present invention allows to achieve the following advantages:
it allows the production of channels with water-conducting surfaces which have a particularly small roughness - the water-conducting surfaces can present a completely regular course, ie without edges or angles or steps - the invention can be used in the case of the conduction of water. pressure and suction side water in the case of water turbines, pumps and pump turbines - the cross-sectional shape and / or cross-sectional size of the flow channel can be modified along the flow path, example of a round cross section to an elliptical cross section, from an elliptical cross section to a round cross section - the cross sectional shape can be modified in the course of the flow path from a horizontal ellipsoidal shape to a vertical ellipsoidal shape
- the cross-sectional shape and / or cross-sectional size can be modified in order to optimize efficiency, for example in the case of a suction tube to avoid the formation of secondary currents - apart from the construction of channels that They carry streams of concrete or other molding material and hardenable with the passage of time, you can also manufacture steel parts or other materials and these parts can be integrated into the
material such as steel spurs.