ELECTRODYNAMIC MACHINE COMPRISING A COOLING DUCT

Abstract

A turbine generator of the reverse-flow type having a rotor winding and a stator winding and a cooling duct, wherein the cooling duct is designed as a diffuser. The diffuser is designed such that a device is arranged on an internal cooling duct wall, which device prevents the flow of the cooling medium from stalling, leading to an improved, more uniform flow to a cooling apparatus.

Claims

1. An electrodynamic machine comprising a rotor winding and a stator winding and a cooling duct which is designed for the passage of a coolant and is limited by duct walls, wherein the duct walls have means for increasing turbulence in the flow of the coolant, wherein the cooling duct is designed as a diffuser, wherein the diffuser has a diffuser end and a cooler is arranged at the diffuser end, wherein the means for increasing turbulence are arranged on the surface of the duct wall in such a way that the turbulence slows down separation of the flow such that the flow onto the cooler arranged at the end of the diffuser is optimal.

2. The electrodynamic machine as claimed in claim 1, wherein the diffuser has an inner cooling duct wall with a first radius of curvature and an outer cooling duct wall with a second radius of curvature, wherein the first radius of curvature is smaller than the second radius of curvature, wherein the means for increasing turbulence is arranged on the inner cooling duct wall.

3. The electrodynamic machine as claimed in claim 1, wherein the means for increasing turbulence is designed as a trip wire.

4. The electrodynamic machine as claimed in claim 1, wherein the means for increasing turbulence is a depression.

5. The electrodynamic machine as claimed in claim 1, wherein the means for increasing turbulence has multiple raised portions.

6. The electrodynamic machine as claimed in claim 1, wherein the cooler and the diffuser are arranged at the front.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Identical components or components with the same function are here designated with the same reference numerals.

[0023] In the drawings,

[0024] FIG. 1 shows a schematic view in cross-section of a turbine generator;

[0025] FIG. 2 shows a schematic view in cross-section of part of the diffuser;

[0026] FIG. 3 shows a schematic view in cross-section of part of the diffuser in an embodiment according to the invention.

DETAILED DESCRIPTION OF INVENTION

[0027] As a result of the embodiment according to the invention, with the means for increasing turbulence, the mechanical load on the cooler is reduced and also entails better exploitability of the cooler. FIG. 1 shows a turbine generator 1 as an embodiment of an electrodynamic machine. The turbine generator 1 essentially comprises a rotor 2 with a rotor winding (not shown in detail). The rotor 2 is mounted so that it can rotate about an axis of rotation 3. A stator 4 with a stator winding (not shown in detail) is arranged around the rotor 2. Lastly, a turbine generator housing 5, which seals off the turbine generator inner housing 6 from the external environment 7, is arranged around the stator 4. A coolant, such as for example air or a gas such as hydrogen, situated in the inside 6 of the turbine generator is thus unable to pass to the outside 7. During operation, a relatively high current flows through both the rotor winding and the stator winding. Both the rotor winding and the stator winding thus need to be cooled appropriately. This is effected by the rotor 2 or cooling bores arranged in the stator 4 and through which a suitable coolant flows. Air, gas such as hydrogen, or water are known as coolants.

[0028] The rotor 2 rotates with a frequency of, for example, 50 Hz. Other frequencies are also known.

[0029] A fan 9, which sucks coolant situated in the inside 6 of the turbine generator, is arranged at the front 8. This is shown by the arrows 10 which point toward the fan 9, from the right to the left within the plane of the drawing. For reasons of clarity, only two arrows have been labeled with the reference numeral 10. The design of the turbine generator 1 is a so-called reverse-flow type. This means that the direction of flow of the coolant is from the inside to the outside. This means that the coolant is moved to the front of the turbine generator 1 via the fan 9. Other structures are known in which the coolant is moved to the front in the inside 6 of the turbine generator via a fan or a ventilator.

[0030] The turbine generator 1 has a cooling duct 11 which is designed for the passage of coolant and is limited by duct walls 12. The coolant first flows parallel to the axis of rotation 3 toward the fan 9 and is then diverted in the cooling duct 11 to a cooler 13. The heated coolant is cooled again in the cooler 13 and flows into the inside 6 of the turbine generator under the action of the fan, as shown by the flow arrows 14 in FIG. 1. For space reasons, the cooler 13 is arranged at essentially 90 degrees to the main direction of flow 15 of the coolant, wherein the main direction of flow 15 is oriented essentially parallel to the axis of rotation 3. The duct wall 12 has means 26 for increasing turbulence in the flow of the coolant. The cooling duct 11 is essentially designed as a diffuser 16.

[0031] FIGS. 2 and 3 show a portion of the diffuser 16, wherein FIG. 2 shows the diffuser 16 without the means 26 according to the invention, and FIG. 3 with the means according to the invention. The diffuser 16 is designed like a trumpet and is rotationally symmetrical about the axis of rotation 3 and has an inner cooling duct wall 17. This inner cooling duct wall 17 is characterized by a first radius of curvature 18. This means that the flow which is shown in FIGS. 2 and 3 by lines of flow 19 describes a curve which, viewed in the direction of flow, describes a curve to the right. Flow separation can occur at a separation point 20 as a result of a first radius of curvature 18 that is too small. The diffuser 16 moreover has an outer cooling duct wall 21 which is characterized by a second radius of curvature 22. As can be clearly seen in FIG. 2, the diffuser is characterized in that the first radius of curvature 18 is smaller than the second radius of curvature 22. The diffuser has a first flow cross-section 23 which is arranged at the inlet to the diffuser 16. The second flow cross-section 24 is at the outlet 25 of the diffuser 16, wherein the second flow cross-section 24 is greater than the first flow cross-section 23, as must be the case for a diffuser 16. The cooler 13 is arranged directly at the outlet 25 of the diffuser 16. As can be seen in FIG. 2, the flow at the outlet 25 of the diffuser 16 is concentrated on the outer cooling duct wall 21. According to the invention, this needs to be prevented, as shown in FIG. 3. For the sake of clarity, the reference numerals of the geometric features of the diffuser 16 have not been repeated in FIG. 3. The diffuser 16 in FIG. 3 is identical to that in FIG. 2 in its external geometrical features. The difference from FIG. 2 is that the inner cooling duct wall 17 has a means 26 for increasing turbulence in the flow of the coolant. In the example selected in FIG. 3, the means 26 takes the form of a trip wire. This means that the means 26 displays a slightly raised portion relative to the first cooling duct wall 17, which entails an influence on the flow of the coolant. The lines of flow 19, which owing to the introduction of the means 26 have a different characteristic than in FIG. 2, are shown in FIG. 3. It can be clearly seen that the lines of flow 19 at the outlet 25 display a more uniform orientation. This means that the flow onto the cooler 13, which is arranged at the outlet 25, is more uniform. As a result, a mechanical load on the cooler 13 is reduced. This results in better exploitation of the cooler 13. The trip wire is arranged around the whole cooling duct wall 17 such that essentially a ring, which cannot be shown in FIG. 3, is formed. The ring is arranged so that it is rotationally symmetrical about the axis of rotation 3.

[0032] In alternative embodiments, depressions can be arranged at the location of the means 26 designed as a trip wire. This is not shown in FIG. 3. These depressions can be designed like the surface of a golf ball. This means that the depressions are arranged regularly spaced apart on the inner cooling duct wall 17. The size and distribution of the depressions can be adapted accordingly to the flow conditions. In each case, the means 26 causes turbulence at the inner cooling duct wall 17.

[0033] In a further alternative embodiment, the means 26 can be designed with multiple raised portions. This means that a so-called sharkskin is formed at the location of the means 26. Such a sharkskin is characterized by pointed ridges, wherein the ridges are arranged longitudinally in the direction of flow. A detailed description of the sharkskin is not given here. The sharkskin is characterized by multiple ridges arranged parallel to one another.

[0034] Although the invention has not been illustrated and described in detail by the preferred exemplary embodiment, the invention is not limited by the examples disclosed and other variants can be derived by a person skilled in the art without going beyond the scope of the invention.