Title of Invention

ROTOR WHEEL FOR A FRANCIS TURBINE

Abstract

Rotor wheel (1) of the Francis turbine comprising a plurality of moving blades (2), each moving blade having an entry edge (2.1) and an exit edge (2.2) which are bent in plan view and/or side view, the bonding of the moving blades having at least one turning point W1, W2, W3; a rotor wheel rim (1.2) and a rotor wheel base (1.1), the moving blades (2) being located between the rotor wheel rim and the rotor wheel base, characterized in that connecting point A of entry edge (2.1) with rotor wheel rim (1.2) lies either on the same vertical line or behind connecting point C of the entry edge (2.1) with rotor wheel base (1) when viewed in direction of rotation (3.1).

Full Text

The invention refers to the area of hydraulic machines in particular of the water turbines of the Francis type of design. To such turbines increasingly higher demands with regard to the efficiency and working area are placed. It is desirable to have a variable input with regard to the water flow volume from extremely partial load operation up to the over load operation. Also cavitation problems have continuously engaged the specialists. Therein the blade geometry plays an important role. Numerous efforts have been made through corresponding design of the flow path, in particular of the blades, to reduce the cavitation danger. Only as an example it is referred to WO 98/05863. The assignment therefore lies at the base of the invention to design a rotor wheel for Francis turbine of such type that a high efficiency is achieved in all possible load ranges and that the cavitation danger is reduced against known designs of rotor wheels. According to this invention, the individual blades are designed in fully definite way. The entry edges-seen in plan view -are bent. Therein it's course shows a turning point so that two bent sections follow one on top of the other. Besides the connection points of the entry edge at the rotor wheel rim and rotor wheel base-seen in side view-are assigned to each other in a wholly definite way. The connection point of the entry edge at the rotor wheel base is located namely-seen in direction of rotation-at the same position as the connection point of the entry edge at the rotor wheel rim. It can also lie in front of it. The invention is explained with the help of a drawing more closely. Therein following is represented in details. Figure 1 shows a Francis turbine in axial section Figure 2 shows a section from the rotor wheel of the turbine as per Figure 1 in magnified scale with line of vision perpendicular to the axis of rotation of the turbine (side view). Figure 3 illustrates again in side view, however perspectively represented, a second execution design of the invention. Figure 4 illustrates in a view analogous to that as per Figure 3 a third execution design of the invention. Figure 5 shows in perspective representation in a plan view a fourth execution design of a turbine blade as per invention. Figure 6 shows in a view analogous to that as per Figure 5 a fifth execution design of a turbine blade as per invention. Figure 7 shows a rotor wheel as per invention for a Francis turbine The Francis turbine shown in Figure 1 is constructed as followingly. A rotor wheel covers a multiple number of running blades. The rotor wheel is rotatable around an axis of rotation 3. Rotor wheel 1 is surrounded by a spiral casing 4.Besides a rim of guide blades 5 is preconnected to the rotor wheel 1. The turbine has a suction pipe 6. This covers an entry diffuser 6.1 with a pipe bend 6.2 connecting to it and a suction box 6.3 again connecting to it. Figure 2 is a view perpendicular to the axis of rotation 3 on a moving blade 2 and if fact on it's entry edge 2.1 -here represented thickened. The moving blade 2 is located between the rotor wheel base 1.1 and rotor wheel rim 1.2. It is connected in the area of the mentioned entry edge 2.1 to the rotor wheel base and to the rotor wheel rim that means mechanically firmly linked, either through welding or as single piece design. One considers the connection point A of the entry edge 2.1 to the rotor wheel rim 1.2 and the connection point C of the entry edge 2.1 to the rotor wheel base 1.1. Both the points A and C lie in direction 3.1 of the circulation of the rotor wheel 1 at the same position. In case one combines both the points A and C through a line with each other, then this line runs parallel to the axis of rotation 3. As per invention, connection point C could however also lie before con- nection point B, consequently in the circulation in direction 3.1 could in advance lead the connection point B. Besides one recognizes that the entry edge is bent. In the present case it shows two turning points. The second execution design shown in Figure 3 is exactly similar to that as per Figure 2. One recognizes again the rotor wheel base 1.1 the rotor wheel rim 1.2 as well as a blade 2 located in between. The entry edge 2.1 shows a turning point. The exit edge 2.2 runs in contrast in straight line. One recognizes again the connection point A at which the blade 2 in the area of it's entry edge 2.1 is connected to the rotor wheel rim 1.2 and the connection point C at which it is connected to the rotor wheel base 1.1. The line laid through both the points A and C - here represented in broken line - runs parallel or nearly parallel to the axis of rotation 3. The Figure 4 as per execution design, is equal to that as per Figure 3. However the mentioned link line runs between the connection points A and C inclined against axis of rotation 3. Both the execution designs are represented in the Figured 5 and 6 in the plan view. The blade profile 1.1.1 of rotor wheel base 1.1 as well as the blade profile 1.2.1 of the rotor wheel rim are likewise shown: In both cases the entry edge 2.1 describes a curve with a turning point. The curve is approximately S-shaped. In the Figures 3 to 6 also the connection points of the exit edge 2.2 at rotor wheel base and rotor wheel rim are represented. The blade 2 is connected in the area of the exit edge 2.2 to the rotor wheel base 1.1 at point D and to the rotor wheel rim at point B. The exit edge can have a straight line or bent course. It can be designed similar or equal, as the entry edge 2.1 Also the one connection point B can -seen in circulation direction- leads the other connection point D. However reverse is also possible that consequently connection point D leads the connection point B. Summary of reference numbers. 1. Rotor wheel 1.1 Rotor wheel base 1.1.1 Profile of rotor wheel base 1.2 Rotor wheel rim 1.2.1 Profile of rotor wheel rim 2. Moving blade 2.1 Entry edge 2.2 Exit edge 3. Axis of rotation 3.1 Direction of circulation 4. Spiral casing 5. Guide blades 6. Suction pipe 6.1 Entry diffuser 6.2 Bend 6.3 Suction box W1, W2, W3 Turning points A connection points of the blade in the entry edge area to the rotor wheel rim. B Connection point of the exit edge to the rotor wheel rim. C Connection point of the entry edge to the rotor wheel base. D Connection point of the exit edge to the rotor wheel base. -6- WE CLAIM: 1. Rotor wheel (1) of the Francis turbine comprising -a plurality of moving blades (2), each moving blade having an entry edge (2.1) and an exit edge (2.2) which are bent in plan view and/or side view, the bonding of the moving blades having at least one turning point W1,W2,W3; -a rotor wheel rim (1.2) and a rotor wheel base (1.1), the moving blades (2) being located between the rotor wheel rim and the rotor wheel base, characterized in that connecting point A of entry edge (2.1) with rotor wheel rim (1.2) lies either on the same vertical line or behind connecting point C of the entry edge (2.1) with rotor wheel base (1.1) when viewed in direction of rotation (3.1). 2. Rotor wheel as claimed in claim 1, wherein connection point B of the exit edge (2.2) with rotor wheel rim (1.2) lies on the same vertical line or in front of or behind connection point D of the exit edge (2.2) with rotor wheel base (1.1) when viewed in direction of rotation (3.1). Dated this 4th DAY OF JUNE, 2004. Rotor wheel (1) of the Francis turbine comprising a plurality of moving blades (2), each moving blade having an entry edge (2.1) and an exit edge (2.2) which are bent in plan view and/or side view, the bonding of the moving blades having at least one turning point W1, W2, W3; a rotor wheel rim (1.2) and a rotor wheel base (1.1), the moving blades (2) being located between the rotor wheel rim and the rotor wheel base, characterized in that connecting point A of entry edge (2.1) with rotor wheel rim (1.2) lies either on the same vertical line or behind connecting point C of the entry edge (2.1) with rotor wheel base (1) when viewed in direction of rotation (3.1).

Documents:

299-KOL-2004-FORM 27.pdf

299-kol-2004-granted-abstract.pdf

299-kol-2004-granted-claims.pdf

299-kol-2004-granted-correspondence.pdf

299-kol-2004-granted-description (complete).pdf

299-kol-2004-granted-drawings.pdf

299-kol-2004-granted-examination report.pdf

299-kol-2004-granted-form 1.pdf

299-kol-2004-granted-form 18.pdf

299-kol-2004-granted-form 2.pdf

299-kol-2004-granted-form 26.pdf

299-kol-2004-granted-form 3.pdf

299-kol-2004-granted-form 5.pdf

299-kol-2004-granted-priority document.pdf

299-kol-2004-granted-reply to examination report.pdf

299-kol-2004-granted-specification.pdf

299-kol-2004-granted-translated copy of priority document.pdf