Rotor shaft with cooling bore inlets

Abstract

The invention relates to a rotor shaft adapted to rotate about a rotor axis thereof. The rotor shaft includes a rotor cavity configured concentrically or quasi-concentrically to the rotor axis inside the rotor shaft, and a plurality of cooling bores extending radially or quasi-radially outward from the inside to an outside of the rotor shaft. Each cooling bore having a bore inlet location and a distal bore outlet portion, the respective bore inlet location being adapted to abut on the rotor cavity. At least one side or part-side of the cooling bore inlet location is provided with an asymmetric edge fillet in order to maximize the wall thickness between two adjacent cooling bores.

Claims

1. A rotor shaft adapted to rotate about a rotor axis of the rotor shaft, the rotor shaft comprising: a rotor cavity configured concentrically or quasi-concentrically to the rotor axis inside the rotor shaft, a plurality of cooling bores extending outward from the inside to an outside of the rotor shaft and towards a direction of rotation of the rotor shaft, each of the plurality of cooling bores having a bore inlet and a bore outlet, wherein the each of the plurality of cooling bores comprises a constant cooling bore diameter extending from the bore inlet to the bore outlet, the respective bore inlet being adapted to abut on the rotor cavity, and wherein at least one side or part-side of the circumferential area of the bore inlet is provided with an edge fillet in order to maximize a wall thickness downstream of the edge fillet between two adjacent cooling bores, and wherein the edge fillet of each of the plurality of cooling bores has a radius of 0.3 to 0.7 of the cooling bore diameter and an opposite side of the bore inlet is without an edge fillet, and wherein the edge fillet of each of the plurality of plurality of cooling bores is arranged on a front of the bore in the direction of rotation of the rotor shaft.

2. The rotor shaft according to claim 1, wherein the edge fillet of the cooling bore is a milled edge fillet.

3. The rotor shaft according to claim 1, wherein the rotor shaft is a member of a gas or steam turbine or a turbo-machinery.

4. The rotor shaft according to claim 1, wherein the edge fillet has a depth and a width, and wherein the depth and the width of the edge fillet is 0.3 to 0.7 of the diameter of the cooling bore.

5. The rotor shaft according to claim 1, wherein the wall thickness abutting the rotor cavity between the rounded edge fillet of each of the plurality of cooling bores and the cooling bore inlet that is without the edge fillet is less than the constant cooling bore diameter.

6. A rotor shaft adapted to rotate about a rotor axis of the rotor shaft, the rotor shaft comprising: a rotor cavity configured concentrically or quasi-concentrically to the rotor axis inside the rotor shaft; and a plurality of cooling bores extending outward from the inside to an outside of the rotor shaft and towards a direction of rotation of the rotor, each of the plurality of cooling bores having a cooling bore extending from a bore inlet to a bore outlet, the respective bore inlet being adapted to abut the rotor cavity, and wherein at least one side or part-side of the circumferential area of the bore inlet is provided with a rounded edge fillet having a radius of 0.3 to 0.7 of a diameter of the cooling bore and an opposite side of the bore inlet is without an edge fillet, and wherein the edge fillet of the each of the plurality of plurality of cooling bores is arranged on a front of the bore in the direction of rotation of the rotor.

7. The rotor shaft according to claim 6, wherein the rounded edge fillet of the cooling bore is a milled round edge fillet.

8. The rotor shaft according to claim 6, wherein the rotor shaft is a member of a gas or steam turbine or a turbo-machinery.

9. The rotor shaft according to claim 6, wherein the rounded edge fillet has a depth and a width, and wherein the depth and the width of the rounded edge fillet is 0.3 to 0.7 of the diameter of the cooling bore.

10. The rotor shaft according to claim 6, wherein the wall thickness abutting the rotor cavity between the rounded edge fillet of each of the plurality of cooling bores and the cooling bore inlet that is without the edge fillet is less than the cooling bore diameter.

11. A rotor shaft adapted to rotate about a rotor axis of the rotor shaft, the rotor shaft comprising: a rotor cavity configured concentrically or quasi-concentrically to the rotor axis inside the rotor shaft; and a plurality of cooling bores extending outward from the inside to an outside of the rotor shaft and towards a direction of rotation of the rotor shaft, each of the plurality of cooling bores extending from a bore inlet to a bore outlet, the respective bore inlet being adapted to abut the rotor cavity, and wherein at least one side or part-side of the circumferential area of the bore inlet is provided with a rounded edge fillet having a radius of 0.3 to 0.7 of a diameter of the cooling bore and an opposite side of the bore inlet is without an edge fillet, and the edge fillet of the each of the plurality of cooling bores being arranged on a front of the bore in a direction of rotation of the rotor, and wherein a wall thickness abutting the rotor cavity between the rounded edge fillet of each of the plurality of cooling bores and the cooling bore inlet that is without the edge fillet is less than the cooling bore diameter.

12. The rotor shaft according to claim 11, wherein the rounded edge fillet of the cooling bore is a milled round edge fillet.

13. The rotor shaft according to claim 11, wherein the rotor shaft is a member of a gas or steam turbine or a turbo-machinery.

14. The rotor shaft according to claim 11, wherein the rounded edge fillet has a depth and a width, and wherein the depth and the width of the rounded edge fillet is 0.3 to 0.7 of the diameter of the cooling bore.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The advantages and features of the present disclosure will be better understood with reference to the following detailed description and claims taken in conjunction with the accompanying drawing, wherein like elements are identified with like symbols, and in which:

(2) FIG. 1 shows a perspective side view of a rotor shaft of a gas turbine;

(3) FIG. 2 shows a longitudinal section through the rotor shaft in accordance with FIG. 1, and illustrates an example referring to a rotor cavity having a number of cooling bores;

(4) FIG. 3 shows a partial view of the rotor cavity, depicting an embodiment of the invention with an asymmetric configuration of the cooling bores over a conventional rotor cavity in accordance with section view of FIG. 2;

(5) FIG. 4 shows an asymmetric configuration of the cooling bores in accordance with a partial section view IV-IV of FIG. 2.

DETAILED DESCRIPTION

(6) FIG. 1 reproduces a perspective side view of the rotor shaft 100, without blading, of a gas turbine and will be described in conjunction to FIG. 2. The rotor shaft 100, rotationally symmetric with respect to a rotor axis 110, is subdivided into a compressor part 101 and a turbine part 102. Between the two parts 101 and 102, inside the gas turbine dome, a combustion chamber may be arranged, into which air compressed in the compressor part 101 is introduced and out of which the hot gas flows through the turbine part 102. The turbine part 102, arranged one behind the other in the axial direction, has a plurality of rotor disks 103, in which axially oriented reception slots for the reception of corresponding moving blades are formed so as to be distributed over the circumference. Blade roots of the blades are held in the reception slots in the customary way by positive connection by means of a fir tree-like cross-sectional contour. The rotor cavity (see FIG. 2) may be connected to a central cooling air supply 104 running in an axial direction within the rotor shaft 100 to supply cool air therefrom to the rotor cavity, and there to the plurality of cooling bores (see FIG. 2).

(7) Basically, according to FIG. 2, the rotor shaft comprising a rotor cavity configured concentrically to the rotor axis inside the rotor shaft and a plurality of cooling bores extending radially outward from the inside to an outside of the rotor shaft. Each cooling bore having a bore inlet portion and a distal bore outlet portion, and the respective bore inlet portion is adapted to abut on the rotor cavity. Furthermore, the rotor cavity comprises a cross-sectional profile adapted to be circumferentially straight at a location whereas the each respective bore inlet portion abuts on the rotor cavity, enabling reduction in at least thermal and mechanical stresses across the major cross-sectional profile of the rotor cavity.

(8) In connection with FIG. 2 the rotor cavity 120 is configured concentrically to the rotor axis 110 inside the rotor shaft 100, according to FIGS. 1 and 2. Further, the plurality of cooling bores 130 is configured in a manner that extend radially outward from the inside to an outside of the rotor shaft 100. Each cooling bore 130 includes a bore inlet portion 132 and distal bore outlet portion 134. The respective bore inlet portion 132 being adapted to abut on the rotor cavity 120. The term abut is defined to mean that the bore inlet portion 132 and the rotor cavity 120 whereat the bore inlet portion 132 meets share a same plane. On the one part, the rotor cavity 120 may be connected to a central cooling air supply 104 running in an axial direction within the rotor shaft 100 to supply cool air therefrom to the rotor cavity 120, and there to the plurality of cooling bores 130. On the other part, the air could be delivered to the cavity differently. The cool air from the plurality of cooling bores 130 reaches the outside of the rotor shaft 100 between the blades and blade roots 103 for cooling thereto.

(9) FIG. 3 shows a most preferred embodiment of the present invention in accordance with section view of FIG. 2. The present embodiment introduces an asymmetric edge filet 150 at an inlet location of a cooling bore 130 in the rotor cavity 120. The cooling air flows through a different placed bore into a rotor cavity and enters the cooling air bores which guide it towards rotor blades (see FIG. 2).

(10) The rotational velocity of the cooling air is only very small in the rotor cavity. In the transition from the cavity to the cooling bores, the rotational velocity of the cooling air increases significantly which leads to pressure losses and recirculation areas at the bore inlet location 160.

(11) The introduction of the asymmetric edge fillet 150 allows for a smoother transition from the rotor cavity 120 to the cooling bores 130 and thus improves the flow conditions at the bore inlet location.

(12) The recirculation areas are reduced and, thus, the effective flow cross section in the cooling bore inlet location 160 is increased. This limits the Mach-number to smaller values and reduces the pressure losses significantly.

(13) For that reason, the cooling bore diameter D (see also FIG. 4) can be reduced while the cooling air velocity and pressure losses stay the same or increase only slightly.

(14) Due to the high number of cooling bores 130, the remaining wall thickness L (see also FIG. 4) between neighboring bores is only low which limits the rotor lifetime in this location. In order to keep the minimum wall thickness as big as possible, the edge fillet 150 is only applied on one side of the bores and is thus asymmetric while the other side remains basically without edge fillet, in order to keep the minimum wall thickness as big as possible, i.e. at least one side or part-side of the circumferential area of the cooling bore inlet 160 are provided with an asymmetric edge fillet 150 in order to maximize the wall thickness downstream of the edge fillet between two adjacent cooling bores.

(15) Referring to the asymmetry the side comprising the edge fillet 150 is applied at the front of the cooling bore 130 in direction of rotation of the rotor.

(16) The edge fillet 150 referring to the asymmetric side of the bore 130 is ideally milled, wherein each other manufacturing is also possible, as a round fillet with a radius R (item 170) between factors 0.3 to 0.7 of the cooling bore diameter a The cooling bore 130 comprising a constant cooling bore diameter D in the region between the first end of said bore inlet location 160 which is located in the direction to the bore outlet portion 134 and said bore outlet portion 134. As described above the opposite second end of the bore inlet location 160 abuts on the rotor cavity 120.

(17) Due to manufacturing limitations, the round fillet can be approximated by 3 or more milled chamfers with uniform angular steps in between. In case the fillet is approximated by chamfers, the overall width w (see FIG. 4) and the overall depth d of the edge fillet are also between factor 0.3 and 0.7 of the cooling bore diameter D.

(18) Accordingly, the final aim of the present invention consists in introduction of an asymmetric edge fillet at the inlet of a rotating cooling bore in a rotor disc in order to improve the flow conditions at the inlet and, thus, to reduce the inlet pressure losses, allowing for a smaller bore diameter for a given mass flow. Accordingly, the remaining wall thickness between neighboring bores is improved which is beneficial for the rotor lifetime.

(19) FIG. 4 shows the embodiment of the present invention in accordance with section view IV-IV of FIG. 2, in order to keep the minimum wall thickness as big as possible with respect to the high number of cooling bores 130, the edge fillet 150 is only applied on one side or part-side of the bores and is thus asymmetric while the other side remains basically without edge fillet, in order to keep the minimum wall thickness as big as possible.

(20) The edge fillet (see also description under FIG. 3) referring to the asymmetric side of the bore 130 is ideally milled as a round fillet with a radius between factors 0.3 to 0.7 of the cooling bore diameters D. Due to manufacturing limitations, the round fillet can be approximated by 3 or more milled chamfers with uniform angular steps in between. In case the fillet is approximated by chamfers, the overall width w and the overall depth d (see FIG. 4) of the edge fillet are also between factor 0.3 and 0.7 of the cooling bore diameter D.

(21) The improved rotor shaft of the present invention, especially with respect to the both described embodiments, is advantageous in various scopes. The rotor shaft may be adaptable in terms of reducing effect of thermal and mechanical stresses arise thereon while a machine or turbines in which relation it is being used is in running condition. Further, independent of factor whether the rotor shaft of the present disclosure being made of single piece or of multiple piece, the rotor shaft of the present disclosure is advantageous in withstanding or reducing effects of temperature and centrifugal or axial forces. The improved rotor shaft with such a cross-sectional profile is capable of exhibiting the total life cycle to be increased by 2 to 5 times of the conventional rotor in the discussed location. The rotor shaft of present disclosure is also advantageous in reducing the acting stresses in the area of the bore inlet by 10 to 40%. The acting stresses are a mixture of mechanical and thermal stresses. Further, the rotor shaft is convenient to use in an effective and economical way. Various other advantages and features of the present disclosure are apparent from the above detailed description and appendage claims.

(22) While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, preferred or advantageously in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as a, an, at least one and at least a portion are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language at least a portion and/or a portion is used the item may include a portion and/or the entire item unless specifically stated to the contrary.