Mixed flow hydraulic machinery

Abstract

A mixed-flow hydraulic machine includes an impeller (1) and a guide vane (2), wherein a bladeless space (3) extends between the impeller and the guide vane, and wherein the hydraulic machine includes at least three resonators (4) for suppressing pressure fluctuations that may occur during operation of the hydraulic machine, and wherein each resonator (4) includes a cavity (5) and a pipe joint (6), wherein the pipe joint is connected to the cavity to which it belongs, and wherein the ends of the pipe joints facing away from the cavity open into the bladeless space, and wherein the resonators are designed such that they can suppress pressure fluctuations that occur during operation of the hydraulic machine, and wherein the resonators are arranged around the impeller in a circumferential direction at a uniform spacing, and wherein all resonators are tuned to one and the same resonant frequency.

Description

Technical Field

[0001] This invention relates to a mixed-flow hydraulic machine with an impeller. The invention also relates to avoiding pressure fluctuations that may occur during the operation of such a hydraulic machine. The hydraulic machine can be a turbine, a pump, or a pump-turbine. Background Technology

[0002] Hydraulic machinery of this class includes impellers and guide vanes. Here, the impeller is associated with a rotating system, while the guide vane is associated with a stationary system. The impeller comprises multiple working blades. In the case of a turbine or pump turbine, the guide vane comprises two concentrically arranged annular crowns with guide vanes, wherein the inner annular crown has movable guide vanes, while the outer annular crown has immovable guide vanes. The immovable guide vanes are often also referred to as crossbars. In the case of a pure pump, the guide vane comprises only annular crowns with immovable guide vanes. When flow passes through the hydraulic machinery and the impeller rotates, pressure fluctuations may occur due to the interaction of the circulation between the stationary guide vanes and the rotating working blades (i.e., due to rotor-stator interaction). Pressure fluctuations typically occur only at a selected frequency determined by the rotational speed and blade combination. Pressure fluctuations diffuse along the impeller and the helical casing (externally connected to the guide vane) and can be amplified by the hydroacoustic resonance effect (i.e., partial standing waves). The pressure fluctuations may cause unacceptably increased vibration and associated noise emissions, especially when the pressure fluctuations spread into the pressure pipes.

[0003] The following countermeasures are known in the prior art. For example, "Teck K.Tee: Noise reduction at Dinorwig power station, HYDRO 01, 2001" discloses a so-called "hydraulic silencer." Here, it is a cavity integrated into the wall of a spiral housing, which is connected to the interior of the spiral housing through numerous openings. An air bladder is arranged inside the cavity. "Robert Date: The sound of silence, International Water Power & Dam Construction, 1998" discloses a Helmholtz resonator arranged on a spiral housing. This resonator consists of a cavity connected to the spiral housing through a pipe joint ("nozzle pipe"). The frequency of the resonator can be changed by means of a movable sleeve ("sleeve"), by means of which the effective length of the pipe joint can be changed.

[0004] EP 0039459 A1 discloses an application of multiple resonators arranged side by side, wherein each resonator is tuned to a different frequency. For example, one resonator can be tuned to the fundamental frequency, and the other resonators can be tuned to harmonics of the fundamental frequency. Summary of the Invention

[0005] The objective of this invention is to describe an alternative arrangement that can effectively reduce the described pressure fluctuations in hydraulic machinery of the same category.

[0006] According to the invention, this task is solved by embodiments corresponding to the independent claim. Other advantageous embodiments of the invention are found in the dependent claims. Attached Figure Description

[0007] The invention is described below with reference to the accompanying drawings. Specifically:

[0008] Figure 1 Showing the type of mixed-flow hydraulic machinery;

[0009] Figure 2 Details of the hydraulic machinery according to the present invention are shown;

[0010] Figure 3 A hydraulic machine according to the invention, based on a first embodiment, is shown;

[0011] Figure 4 A hydraulic machine according to the invention, based on a second embodiment, is shown;

[0012] Figure 5 A hydraulic machine according to the invention, based on a third embodiment, is shown. Detailed Implementation

[0013] Figure 1 This mixed-flow hydraulic machine is illustrated in schematic. The hydraulic machine includes an impeller (identified by 1) and a guide vane (identified by 2). Figure 1 The line of sight coincides with the axis of rotation of the impeller. The impeller 1 includes multiple (one of which is designated 1.1) working blades. The guide vane 2 includes an annular crown of non-movable (one of which is designated 2.1) guide vanes. These non-movable guide vanes 2.1 are often also referred to as transverse embankments. The guide vane 2 also includes an annular crown of movable (one of which is designated 2.2) guide vanes. Figure 1 The configuration shown, with movable guide vanes 2.2, is typically used in turbines and pump turbines. If the hydraulic machinery is purely a pump, the annular crown including the movable guide vanes 2.2 is omitted and can therefore be considered optional. Figure 1 In the view shown, the guide vane 2 surrounds the impeller 1. The so-called bladeless space extends between the guide vane 2 and the impeller, which... Figure 1The image is shown in shaded areas and marked with the number 3. If the guide vane 2 includes movable guide vanes 2.2, the outer boundary of the bladeless space 3 is formed by a cylindrical surface that contacts but does not intersect with the movable guide vanes 2.2 when they are at their maximum proximity to the impeller 1. This is the so-called open position of the guide vane. If the guide vane 2 does not include movable guide vanes 2.2, the outer boundary of the bladeless space 3 is formed by a cylindrical surface that contacts but does not intersect with the immovable guide vanes 2.1. The inner boundary of the bladeless space 3 is formed by a cylindrical surface that contacts but does not intersect with the impeller 1. Therefore, the bladeless space 3 is generally tubular, with the impeller 1 located inside the tubular structure and the guide vane 2 extending outside the tubular structure.

[0014] Figure 2 A detailed diagram of the hydraulic machinery according to the present invention is shown in schematic form. Figure 2 The cross-sectional plane is arranged parallel to the rotation axis of impeller 1. Reference numerals correspond to... Figure 1 The accompanying reference numerals. According to... Figure 2 As shown, the axial boundary of the bladeless space 3 is defined by the boundary of the waterway through which water can flow during the operation of the hydraulic machinery. Here, during turbine operation, water flows from the guide vane 2 to the impeller 1, and flows in the opposite direction during pump operation. The hydraulic machinery according to the invention includes a resonator for suppressing pressure fluctuations (one of which is in...) Figure 2 (Identified by 4). Here, each resonator 4 includes a cavity identified by 5 and a connector identified by 6. The connector 6 is connected to the cavity 5 and arranged such that, in the bladeless space 3, the end of the connector 6 facing away from the cavity 4 opens into a water channel. This ensures that, during operation of the hydraulic machinery, the cavity 5 of the resonator 4 is filled with water and connected to the water channel via the connector 6. That is, the connector 6 is also filled with water.

[0015] The resonators 4 can be designed to suppress unwanted pressure fluctuations. For this purpose, the internal dimensions of the cavity 5 and the connector 6 can be selected such that the underwater acoustic resonant frequency of the resonator 4 is close to the frequency at which unwanted pressure fluctuations occur. Since pressure fluctuations are caused by the interaction between the rotor and stator, this can be the first, second, or third harmonic of the frequency through which the working blades pass, depending on the application and the blade combination (i.e., the number of working blades and guide blades). Because it is often impossible to accurately predict the resonator characteristics and temperature fluctuations can also have a significant impact, it is advantageous that the resonator 4 has adjustment mechanisms that allow for both initial tuning and readjustment of the resonant frequency during operation. For this purpose, an adjustable plunger is arranged in the cavity 5, its positioning of which can be precisely adjusted, for example, by means of a screw or other device. Figure 2One of the plungers is identified by the number 7. Adjusting plunger 7 allows for the setting of the effective cavity volume and, consequently, the resonant frequency of the resonator 4. The wall thickness of the steel resonator 4 is selected as follows, depending on the application, so that the resonator can reliably absorb sometimes very high static and dynamic pressure fluctuations.

[0016] Resonator 4 can be arranged on both sides of the waterway. Figure 2 In this configuration, one resonator 4 is positioned on the upper side, and the other resonator 4 is positioned on the lower side. Alternatively, all resonators 4 can be positioned on the upper side, or all resonators can be positioned on the lower side. Figure 2 A hydraulic machine with a vertical axis of rotation is shown. In a hydraulic machine with a horizontal axis of rotation, Figure 2 The arrangement shown is rotated 90°. In the hydraulic mechanism of the guide vane 2.2, one side of the waterway is obviously occupied by the adjustment mechanism of the guide vane 2.2, so it is generally advantageous that all the resonators 4 are arranged on the opposite side of the waterway.

[0017] Figure 3 A first embodiment of a hydraulic machine according to the invention, having a resonator 4, is shown. This hydraulic machine includes four resonators 4 arranged in a bladeless space such that they prevent vibrations from propagating in all directions around the impeller. For this purpose, the resonators 4 are arranged at a uniform spacing in the circumferential direction around the impeller. Figure 4 The illustrated hydraulic machine includes 20 movable guide vanes. The resonators 4 are distributed such that one resonator 4 is arranged at every five guide vanes. Here, these resonators 4 are arranged approximately centrally, that is, centrally with respect to the outline of the guide vane to which they belong. Similarly, they can also be further arranged towards the end of the guide vane to which they belong, closer to the impeller. Likewise, they can also be further arranged towards the end of the guide vane to which they belong, further away from the impeller. When a total of five resonators 4 are applied, a further uniform distribution of the resonators 4 is obtained in the example of the illustrated hydraulic machine, where one resonator 4 is arranged at every four guide vanes. When a total of ten resonators 4 are applied, a further uniform distribution of the resonators 4 is obtained in the example of the illustrated hydraulic machine, where one resonator 4 is arranged at every two guide vanes. When a total of twenty resonators 4 are applied, a further uniform distribution of the resonators 4 is obtained in the example of the illustrated hydraulic machine, where one resonator 4 is arranged at each guide vane. This arrangement scheme in… Figure 4 As shown in the figure. When a total of forty resonators 4 are applied, a further uniform distribution of the resonators 4 is obtained in the example of the hydraulic machinery shown, wherein two resonators 4 are arranged at each guide vane. This arrangement scheme is in Figure 5 As shown in the image.

[0018] Those skilled in the art can readily derive a suitable uniform distribution of the resonator 4 from the foregoing paragraphs of the described embodiments for any hydraulic machinery (i.e., for any number of guide vanes 2.1 or 2.2). As already mentioned, the orientation of the resonator 4 with respect to the absolute azimuth angle of the adjacent guide vane arrangement can be arbitrarily chosen.

[0019] Another possible derivation of the resonator 4 uniformly distributed around the impeller is as follows, starting from the number of working blades 1.1. Figures 3 to 5 The hydraulic mechanism shown includes nine working blades 1.1. Then, for example, three, nine, or eighteen resonators can be evenly arranged around the impeller. The azimuth orientation is also not important here.

[0020] However, the application of resonators 4 evenly distributed around the impeller is not limited to the number of guide vanes or working vanes. For example, systems including seven, eight, eleven, or thirteen resonators 4 can be selected. The azimuth orientation is also not important in this case.

[0021] According to the present invention, all resonators 4 are tuned to one and the same resonant frequency.

[0022] The inventors' research shows that a greater number of resonators 4 can achieve better vibration suppression. Furthermore, in this respect, a particularly advantageous arrangement is to guide the derivation of the number of guide vanes when determining the number of resonators 4. From an economic perspective, those skilled in the art strive to use as few resonators 4 as possible to dampen vibrations sufficiently. Those skilled in the art, within the scope of the technical teachings of this application, determine the required number and arrangement of resonators 4 for this purpose by means of underwater acoustic simulation calculations.

[0023] Finally, it should be mentioned that the technical teachings of this application are also suitable for modifying existing hydraulic machinery using the resonators 4 arranged accordingly, in order to improve the vibration behavior of these machines.

[0024] List of reference numerals

[0025] 1 Impeller

[0026] 1.1 Working blades

[0027] 2. Flow deflector

[0028] 2.1 Non-moving guide vanes (crosswalls)

[0029] 2.2 Movable guide vanes

[0030] 3. Bladeless space

[0031] 4 resonators

[0032] 5 chambers

[0033] 6 Pipe fittings

[0034] 7. Plunger

[0035] 8 Spiral Shell

[0036] 9. Pressure piping

Claims

1. A mixed-flow hydraulic machine, the mixed-flow hydraulic machine comprising an impeller (1) and a guide vane (2), wherein, The impeller (1) includes a plurality of working blades (1.1) and the guide vane (2) includes at least one annular crown of guide vanes (2.1, 2.2), and wherein a bladeless space (3) extends between the impeller (1) and the guide vane (2), wherein the hydraulic machinery includes at least three resonators (4) for suppressing pressure fluctuations that may occur during operation of the hydraulic machinery, and wherein each resonator (4) includes a cavity (5) and a pipe joint (6), wherein the pipe joint (6) is connected to the cavity (5) to which it belongs, and wherein the end of the pipe joint (6) facing away from the cavity (5) opens into the bladeless space (3), and wherein the resonator (4) is designed such that it can suppress pressure fluctuations that occur during operation of the hydraulic machinery, characterized in that the resonators (4) are arranged around the impeller (1) in a circumferential direction at a uniform spacing, and wherein all resonators (4) are tuned to one and the same resonant frequency.

2. The mixed-flow hydraulic machinery according to claim 1, wherein, Adjustable plungers (7) are arranged in the cavity (5) respectively. The plungers are configured such that the effective volume of the cavity (5) can be changed by changing the position of the plungers (7) in order to adjust the resonant frequency of the resonator (4).

3. The mixed-flow hydraulic machinery according to claim 1 or 2, wherein, The number of resonators (4) is determined such that the number of resonators (4) multiplied by a certain natural number yields the number of guide vanes (2.1, 2.2).

4. The mixed-flow hydraulic machinery according to claim 1 or 2, wherein, The number of resonators (4) is determined such that the number of guide vanes (2.1, 2.2) is multiplied by a certain natural number to obtain the number of resonators (4).

5. The mixed-flow hydraulic machinery according to any one of the preceding claims, wherein, The flow guide (2) includes an annular crown of a non-movable flow guide blade (2.1).

6. The mixed-flow hydraulic machinery according to any one of the preceding claims, wherein, The flow guide (2) includes an annular crown of movable flow guide blades (2.2).

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