BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention.
FIG. 1 is a cross-sectional view of a turbine engine having aspects of this invention.
FIG. 2 is a partial cross-sectional view of the turbine engine shown in FIG. 1 taken along line 2-2.
FIG. 3 is a detailed partial cross-sectional view of a turbine blade gap control system shown in FIG. 2 taken along line 3-3.
FIG. 4 is a detailed view of the turbine blade assembly shown in FIG. 1 along line 4-4 before vane carrier shift.
FIG. 5 is a detailed view of the turbine blade assembly shown in FIG. 2 along line 5-5 with the vane carrier shifted axially relative to the turbine blade assembly.
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIGS. 1-5, this invention is directed to a turbine blade gap control system 10 for reducing a gap 12 formed between turbine blades 14 and ring segments 16 in turbine engines 18. Reducing the gap 12 increases the efficiency of the turbine engine 18 by reducing the amount of combustion gases flowing around the turbine blades 14 rather than through the blades 14. The turbine blade gap control system 10 may be configured to enable the turbine engine 18 to go through start up conditions, through a pinch point in the start up process before steady state operation where the tips 20 of the turbine blades 14 are closest to the ring segments 16 and into a steady state condition. The turbine blade gap control system 10 may be configured to reduce the size of the gap 12 at steady state operating conditions by moving a vane carrier 22 to which the ring segments 16 are attached axially. Such axial movement may reduce the gap 12 between the tips 20 of turbine blades 14 and ring segments 16 in turbine engines 18 in which the tips 20 of the turbine blades 14 are positioned at an acute angle 24 relative to a rotational axis 26 and the ring segments 16 are positioned in a similar manner.
As shown in FIG. 1, the turbine engine 18 may include a turbine blade assembly 28 formed from a plurality rows 30 of turbine blades 14 extending radially outward from a rotor 32. The rotor 32 may be any conventional rotor configured to rotate about the rotational axis 26. Each row 30 may be formed from a plurality of turbine blades 14 extending radially outward from the rotor 32. The turbine blades 14 of a row may all extend substantially equal distances from the rotor 32 such that the tips 20 are positioned within close proximity of the ring segments 16, yet offset to form the gap 12. During operation, the rotor 32 rotates as combustion gases pass by the turbine blades 14.
The turbine blades 14 may have tips 20 positioned at an acute angle 24 relative to a rotational axis 26 of the turbine blade assembly 28. In at least one embodiment, as shown in FIGS. 1, 4 and 5, the tips 20 of the turbine blades 14 may be positioned at an acute angle 24 of about 20 degrees. The ring segments 16 may include inner surfaces 34 that are positioned at substantially at the acute angle 24 relative to the rotational axis 26. The ring segments 16 may be positioned between the vane carrier 22 and the tips 20 of the turbine blades 14 in each row, wherein an inner surface 34 of each of the ring segments 16 is offset radially outward from the tips 20 of the turbine blades 14. The ring segments 16 may be attached to the vane carrier 22. The vane carrier 22 may be concentric with the rotor 32 and positioned radially outward from the turbine blades 14. In such a position, axial movement of the vane carrier 22 causes a reduction in the size of the gap 12. In at least one embodiment, the vane carrier 22 may be move axially between about 4 millimeters and about 5 millimeters, which results in a reduction of the gap 12 of about 1 millimeter.
The turbine blade gap control system 10 may be configured to move the vane carrier 22 and attached ring segments 16 axially relative to the turbine blade assembly 28 to reduce the size of the gaps 12 between the tips 20 of the turbine blades 14 and the ring segments 16. The turbine blade gap control system 10 may be formed from any device capable of moving the vane carrier 22 relative to the turbine blade assembly 28, and in particular, relative to the tips 20 of the turbine blades 14. In at least one embodiment, as shown in FIGS. 2 and 3, the turbine blade gap control system 10 may comprise at least one hydraulic arm 36 attached to the vane carrier 22 for moving the vane carrier 22 axially relative to the turbine blade assembly 28. The hydraulic arm 36 may be attached to an outer cylinder 38 or other support structure positioned radially outward from the vane carrier 22. As shown in FIG. 3, the hydraulic arm 36 may include four hydraulic arms 36 positioned around the outer cylinder 38. The hydraulic arms 36 may be positioned generally 90 degrees from each other around the outer cylinder 38. In other embodiments, the turbine blade gap control system 10 may include other numbers of hydraulic arms 36, and the hydraulic arms may be positioned in other configurations.
During use, the turbine engine 18 may be started and brought up to a steady state operating condition. At start up, the turbine blade gap control system 10 may have the carrier vane 22 and attached ring segments 16 positioned axially away from the tips 20 of the turbine blades 14. In this position, the turbine engine 18 may go from start up through a pinch point at which the turbine blade tips 20 are closest to the ring segments 16 without contact occurring. The turbine blades 14 and other turbine engine components may heat up to a steady state operating temperature at which the turbine blades 14 have ceased thermal expansion. Once the steady state operating conditions are reached, the turbine blade gap control system 10 may be used to reduce the size of the gap 12 by moving the vane carrier 22 axially along the rotational axis 26 relative to the turbine blade assembly 28. The hydraulic arms 36 may be used to move the vane carrier 22 axially relative to the turbine blade assembly 28.
The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention.
Patent Application
20080063513
