Patent Application
20080087020
While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed that the present invention will be better understood from the following description in conjunction with the accompanying Drawing Figures, in which like reference numerals identify like elements, and wherein:
Referring to
The transition duct 10 may be formed by any known manufacturing process, and may comprise a body formed of an upper panel 28 and a lower panel 30 joined along longitudinally extending seams 32 (one illustrated) at longitudinal welds to form a panel assembly, as is known in the art. The upper and lower panels 28, 30 may also be provided with cooling holes in a manner known in the art. In addition, the upper and lower panels 28, 30 may be formed of a high temperature material such as a high temperature metal alloy including, without limitation, IN617 (Inconel 617) or H230 (Haynes 230). It should be noted that the transition duct 10 is not limited to any particular construction, and the invention encompasses any transition duct 10 that utilizes the profile described further below.
The interior surface of the body formed by the panels 28, 30 may preferably be provided with a coating to protect the interior of the transition duct 10 from deterioration, such as may be caused by prolonged exposure to the hot combustion gases traveling from the combustor 12. The coating may comprise a known coating material, such as is described in U.S. Pat. No. 6,644,032, incorporated herein by reference, or any other coating having similar protective properties. In addition, the coating is preferably a thin coating layer that will not substantially affect the beneficial profile characteristics provided by the present invention.
The profile of the transition duct 10 is described herein with reference to the uncoated surface profile of the interior surface of the body defined by the upper and lower panels 28, 30. Referring to
Coordinate values X, Y and Z are provided to identify points on the transition duct 10 for each discrete section 34 at specified angles θ substantially in accordance with the X, Y and Z coordinate values as set forth in Table 1 below. The values given in Table 1 are in millimeters. However, it should be understood that the present invention is not limited to particular dimensions, in that the X, Y and Z values given in Table 1 could be scaled up or down, i.e., may represent unitless scaled values, depending on the diameter of the particular combustion liner with which the transition duct 10 of the present invention is intended to be used.
Further, it should be noted that the coordinate values given in Table 1 correspond to coordinates on the transition duct 10 when at room temperature, and that the given coordinate values will not necessarily correspond to the location of particular points on the transition duct 10 when the transition duct 10 is at an elevated temperature during transfer of hot combustion gases.
The X and Y coordinate values are determined with reference to respective X and Y axes having a zero point or origin of a Cartesian coordinate system at the origin of the particular section 34 located substantially at the geometric center within each respective section 34 (see
It should be apparent that although the X, Y and Z coordinate values given in Table 1 provide discrete sections 34 comprising wireframe sections for defining the transition profile, the entire profile is defined by a best-fit curve to the given sections to define a smoothly continuous internal flow path formed by the interior surface of the transition duct 10. Further it may be noted that the data provided in Table 1 is computer generated and that limited deviations from this data may occur, within manufacturing tolerances, during production of the transition duct 10.
Referring to
The second section 34B of
The third section 34C of
The fourth section 34D of
As an alternative embodiment to the invention the internal profile may be provided within an envelope of the profile given by the coordinate values of Table 1. By way of example and without limitation, the internal profile described herein may be provided within an envelope of ±6.350 mm normal to any surface with the X, Y and Z coordinate values and the angles θ noted in Table 1.
The transition duct 10 described herein provides a preferred transition duct internal profile for transitioning from a generally circular inlet to a generally rectangular arc-like outlet while minimizing stress concentrations and providing frequency separation between the natural frequency of the transition duct 10 and the combustion resonant frequencies, resulting in a reduced likelihood of low cycle fatigue cracks.
The X, Y and Z coordinate values, determined by the above-described Cartesian coordinated system, identified at corresponding sweep angles θ are summarized in the following Table 1.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
