Patent Application
20140286758
This application claims priority under 35 U.S.C. §119 to European Patent Application No. 13159879.9 filed in Europe on Mar. 19, 2013, the entire content of which is hereby incorporated by reference in its entirety.
This disclosure relates to exhaust gas turbines of turbochargers for combustion engines, and for example, to a nozzle ring for guiding the exhaust gas flow in such a gas turbine.
A known exhaust gas turbines of turbochargers for combustion engines with fixed turbine geometry includes a turbine nozzle for channeling the exhaust gases to a plurality of rotor blades. The turbine nozzle includes a plurality of circumferentially spaced stator vanes fixedly joined at their roots and tips to annular, radially inner and outer supporting rings. In case of a radial or mixed flow turbine, the stator vanes of the nozzle ring are fixed at their roots and tips to annular supporting rings being arranged next to each other on each opposing side of the flow channel.
As shown in
The total throat area can be obtained by providing substantially uniform individual throat areas between the adjacent vanes. Variations in throat area between adjacent vanes can provide undesirable aero-mechanical excitation pressure forces which may lead to undesirable vibration of the rotor blades disposed downstream from the nozzle.
U.S. Pat. No. 5,182,855 discloses a method of manufacturing a turbine nozzle for obtaining a predetermined value of throat area between adjacent vanes.
Nozzle rings for axial, radial, and mixed-flow turbocharger turbines can be commonly divided into two or more different segments including different number of nozzle vanes per angle. Compared to non-segmented nozzle rings with vanes that are uniformly distributed in a circumferential direction, the aerodynamic excitation of the rotor can be reduced and the mechanical integrity margin regarding high cycle fatigue can be improved.
An issue of the mentioned segmented nozzle ring design is that the nozzle throat area can differ from one segment to the other. Therefore, the exit flow angle of the nozzle can also differ from one segment to the other. Due to the non-uniformity of the flow, the rotor is excited in the first mode shapes and the thermodynamic efficiency of the turbine stage can be reduced compared to a stage with a nozzle ring having uniformly distributed vanes. Due to the non-uniformity of the flow, the nozzle ring is desirably arranged in a fixed position relative to the gas inlet casing.
A nozzle ring is disclosed for a turbine of an exhaust gas turbocharger, comprising: two supporting rings; and a plurality of circumferentially spaced vanes, each vane including: a root fixedly joined to one of the supporting rings; a tip fixedly joined to the other one of the supporting rings; a leading edge; a trailing edge; suction and pressure sides extending from the leading edge to the trailing edge and between the root and the tip; and a throat line extending from the root to the tip on the pressure side for defining a throat area with a trailing edge of an adjacent one of the vanes, the vanes being arranged in at least two segments, the segments having different vane per angle distribution, each segment including different numbers of vanes per angle, wherein the vanes are uniformly distributed in a circumferential direction within each segment and the throat area between neighboring vanes is the same for each pair of neighboring vanes in all segments.
An exhaust gas turbine is disclosed having a nozzle ring, which comprises: two supporting rings; and a plurality of circumferentially spaced vanes, each vane including: a root fixedly joined to one of the supporting rings; a tip fixedly joined to the other one of the supporting rings; a leading edge; a trailing edge; suction and pressure sides extending from the leading edge to the trailing edge and between the root and the tip; and a throat line extending from the root to the tip on the pressure side for defining a throat area with a trailing edge of an adjacent one of the vanes, the vanes being arranged in at least two segments, the segments having different vane per angle distribution, each segment including different numbers of vanes per angle, wherein the vanes are uniformly distributed in a circumferential direction within each segment and the throat area between neighboring vanes is the same for each pair of neighboring vanes in all segments.
A turbo charger is disclosed having a nozzle ring which comprises: two supporting rings; and a plurality of circumferentially spaced vanes, each vane including: a root fixedly joined to one of the supporting rings; a tip fixedly joined to the other one of the supporting rings; a leading edge; a trailing edge; suction and pressure sides extending from the leading edge to the trailing edge and between the root and the tip; and a throat line extending from the root to the tip on the pressure side for defining a throat area with a trailing edge of an adjacent one of the vanes, the vanes being arranged in at least two segments, the segments having different vane per angle distribution, each segment including different number of vanes per angle, wherein the vanes are uniformly distributed in a circumferential direction within each segment and the throat area between neighboring vanes is the same for each pair of neighboring vanes in all segments.
The accompanying drawings illustrate exemplary embodiments of the present disclosure. In such drawings:
Exemplary embodiments of the present disclosure provide a segmented nozzle ring including different numbers of nozzle vanes per segment which have uniform individual throat areas between the adjacent vanes.
For the segmented nozzle ring according to an exemplary embodiment of the disclosure, the throat area between neighboring vanes can be the same for each segment which is achieved by rotation (i.e., opening or closing of the throat area) of the individual vane compounds belonging to the different segments. The resulting uniform throat area can lead to a uniform exit flow angle of the nozzle and a uniform inlet flow angle of the rotor.
Based on that, high-cycle fatigue excitations of the rotor caused by the non-uniform flow can be eliminated, the thermodynamic efficiency of the turbine stage can be improved, and the nozzle ring need not be arranged in a fixed position relative to the gas inlet casing.
The thermodynamic efficiency of the turbine stage as well as the mechanical integrity margin of the rotor regarding high cycle fatigue can be improved. Higher rotor vanes can be realized providing an increased specific flow capacity. Aerodynamically improved rotor vanes can be used providing a higher thermodynamic efficiency. More compact products can be realized enabling reducing product costs. Higher thermodynamic efficiency allows to save engine fuel costs for the end customer. Because the nozzle ring should not be arranged in a fixed position relative to the gas inlet casing, a simpler and cheaper design can be realized which is easier and faster to mount, hence further enabling reducing product and service costs.
These and other advantages and features of the present disclosure will become apparent from the following description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, principles of the disclosure.
Each vane of the nozzle ring includes a root fixedly joined to the inner supporting ring, a tip fixedly joined to the outer supporting ring, a leading edge facing in an upstream direction, a trailing edge facing in a downstream direction, and oppositely facing suction, or convex, and pressure, or concave, sides, extending from the leading edge to the trailing edge and between the root and the tip.
Adjacent ones of the vanes define there between a converging channel for channeling the combustion gases between the vane and through the throats and downstream therefrom to a conventional turbine rotor stage.
As stated above and shown in
The nozzle ring includes two or more different segments. The segments include different number of vanes per angle. Within each individual segment, the vanes are uniformly distributed in circumferential direction. In contrast to known nozzle ring designs of that kind, the throat area between neighboring vanes is the same for each segment which is achieved by rotation (i.e., opening or closing) of the individual vane compounds belonging to the different segments.
The resulting uniform throat area can lead to a uniform exit flow angle of the nozzle and a uniform inlet flow angle of the rotor. Based on that, high-cycle fatigue excitations of the rotor caused by the non-uniform flow can be eliminated, the thermodynamic efficiency of the turbine stage can be improved, and the nozzle ring must not be arranged in a fixed position relative to the gas inlet casing.
In
In segment 1, the angle between the vanes is α1, in segment 2, the angle between the vanes is α2, where α1≠α2 applies. To achieve equal throat areas between neighboring vanes for each segment, individual vane compounds belonging to the different segments are positioned at specific profile rotation angles by being rotated around an axis perpendicular to the profile and extending from the root to the tip of each vane in one or the other direction (i.e., closing or opening), as illustrated in
The same concept can also be applied to a nozzle ring of a radial or mixed-flow turbocharger turbine stage, as shown in
Alternatively, the concept can be realized with arbitrary numbers of vanes and more than two segments, for example:
s≧2, n1≧1, n2≧1, . . . , ns≧1, ni≠nj, αi≠αj ∀i,j=1 . . . s,
In an exemplary embodiment of the disclosure, equal throat areas between neighboring vanes for segments including different number of vanes per angle can be achieved by using different airfoil profiles for the vanes of the different segments.
Alternatively to the arrangement shown in
While the disclosure has been described with reference to at least one exemplary embodiment, it is to be clearly understood by those skilled in the art that the disclosure is not limited thereto. Rather, the scope of the disclosure is to be interpreted only in conjunction with the appended claims.
Thus, it will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.
1 leading edge of vane
2, 2′ trailing edge of vane
3 tip of vane
4 root of vane
5 throat line
7, 7′ pressure side of vane
8, 8′ suction side of vane
A a minimum throat area
ns number of vanes per segment
α1, αj angle between two neighboring vanes of a segment
γ1, γ2 vane profile rotation angle
| Number | Date | Country | Kind |
|---|---|---|---|
| 13159879.9 | Mar 2013 | EP | regional |
