METHOD FOR DESIGNING A TURBINE
First Claim
1. A method for designing a turbine having a plurality of stages disposed axially one behind the other in the direction of flow through the turbine, each stage being formed of a stationary row of a plurality of stator vanes and a rotating row of a plurality of rotor blades, the row of rotor blades of at least one of the stages having a plurality of rotor blade clusters each formed of at least two of the rotor blades having different airfoil profiles or different distances from adjacent rotor blades following in the direction of rotation, the stage having a vane-to-blade-cluster ratio (V/(B/P)) parameter indicating the ratio of the number of stator vanes (V) to the quotient (B/P) of the number of rotor blades (B) of the stage divided by the number of rotor blades per rotor blade cluster (P), the method comprising:
- designing the stage in such a way that, under a predetermined operating condition of the turbine, the vane-to-blade-cluster ratio parameter is above an upper cut-off limit or below a lower cut-off limit for the modes k==1, k=−
2 or k=−
3, in particular above an upper cut-off limit for the mode k=−
1 or between a lower cut-off limit for the mode k=−
1 and an upper cut-off limit for the mode k=−
2, of a frequency defined by a ratio of the blade-passing frequency to the number of rotor blades per rotor blade cluster or an integral multiple of this ratio.
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Accused Products
Abstract
A method for designing a turbine having a plurality of stages disposed axially one behind the other in the direction of flow through the turbine, each stage being formed of a stationary row of a plurality of stator vanes and a rotating row of a plurality of rotor blades. The row of rotor blades of at least one of these stages has a plurality of rotor blade clusters each formed of at least two rotor blades (A1, B1; A2, B2) having different airfoil profiles and/or different distances (φA, φB) from adjacent rotor blades following in the direction of rotation. A vane-to-blade-cluster ratio (V/(B/P)) parameter indicates the ratio of the number of stator vanes (V) to the quotient (B/P) of the number of rotor blades (B) of the stage divided by the number of rotor blades per rotor blade cluster (P). Under a predetermined operating condition of the turbine, this vane-to-blade-cluster ratio parameter is above an upper cut-off limit or below a lower cut-off limit for the modes k=−1, k=−2 and/or k=−3, in particular above an upper cut-off limit for the mode k=−1 or between a lower cut-off limit for the mode k=−1 and an upper cut-off limit for the mode k=−2, of a frequency defined by a ratio of the blade-passing frequency to the number of rotor blades per rotor blade cluster or an integral multiple of this ratio.
5 Citations
18 Claims
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1. A method for designing a turbine having a plurality of stages disposed axially one behind the other in the direction of flow through the turbine, each stage being formed of a stationary row of a plurality of stator vanes and a rotating row of a plurality of rotor blades, the row of rotor blades of at least one of the stages having a plurality of rotor blade clusters each formed of at least two of the rotor blades having different airfoil profiles or different distances from adjacent rotor blades following in the direction of rotation, the stage having a vane-to-blade-cluster ratio (V/(B/P)) parameter indicating the ratio of the number of stator vanes (V) to the quotient (B/P) of the number of rotor blades (B) of the stage divided by the number of rotor blades per rotor blade cluster (P), the method comprising:
designing the stage in such a way that, under a predetermined operating condition of the turbine, the vane-to-blade-cluster ratio parameter is above an upper cut-off limit or below a lower cut-off limit for the modes k==1, k=−
2 or k=−
3, in particular above an upper cut-off limit for the mode k=−
1 or between a lower cut-off limit for the mode k=−
1 and an upper cut-off limit for the mode k=−
2, of a frequency defined by a ratio of the blade-passing frequency to the number of rotor blades per rotor blade cluster or an integral multiple of this ratio.- View Dependent Claims (2, 3, 4, 5)
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6. A turbine of a gas turbine engine comprising:
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a plurality of stages disposed axially one behind the other in the direction of flow through the turbine, each stage being formed of a stationary row of a plurality of stator vanes and a rotating row of a plurality of rotor blades, the row of rotor blades of at least one of these stages having a plurality of rotor blade clusters which are each formed of at least two rotor blades having different airfoil profiles or different distances from adjacent rotor blades following in the direction of rotation; the at least one stage having a vane-to-blade-cluster ratio (V/(B/P)) parameter indicating the ratio of the number of stator vanes (V) to the quotient (B/P) of the number of rotor blades (B) of the stage divided by the number of rotor blades per rotor blade cluster (P); and
the stage having, under a predetermined operating condition of the turbine, the vane-to-blade-cluster ratio parameter above an upper cut-off limit or below a lower cut-off limit for the modes k=−
1, k='"'"'2 or k=−
3 or between a lower cut-off limit for the mode k=−
1 and an upper cut-off limit for the mode k=−
2, of a frequency defined by a ratio of the blade-passing frequency to the number of rotor blades per rotor blade cluster or an integral multiple of this ratio. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification