The invention relates to a gas turbine cooled shroud assembly segment.
A portion of the core air flow from the compressor section of a gas turbine engine is typically used for air cooling of various components that are exposed to hot combustion gases, such as the turbine blades and turbine shrouds.
Since a portion of the energy created by combustion is utilized to drive the compressor and create compressed air, use of compressed cooling air represents a necessary penalty and energy loss for the engine. Obviously, any minimization of the compressed air portion used for cooling would represent an increase in the efficiency of the engine. While cooled shroud segments are well known in the art, the potential efficiency savings that can be achieved by even small reductions in the amount of secondary cooling air required means that improvement to known devices are consistently sought and highly valued.
It is therefore an object of the present invention to provide a cooled shroud assembly in which spent cooling air from the turbine shroud is reused downstream.
Further objects of the invention will be apparent from review of the disclosure, drawings and description of the invention below.
The invention provides a cooled turbine shroud segment for a gas turbine engine, having an axially extending shroud ring segment with an inner surface, an outer surface, an upstream flange and a downstream flange. The flanges mount the shroud ring within an engine casing. A perforated cooling air impingement plate is disposed on the outer surface of the shroud ring between the upstream flange and the downstream flange, with an impingement plenum defined between the impingement plate and the outer surface. Axially extending cooling bores in the ring segment extend between the impingement plenum and an outlet. A trough adjacent the outlet directs cooling air from the outlet towards a downstream stator vane to cool the stator vane.
In order that the invention may be readily understood, an embodiment of the invention is illustrated by way of example in the accompanying drawings.
Further details of the invention and its advantages will be apparent from the detailed description included below.
As best shown in
As seen in
The radially outer surface 20 of the shroud ring 18 preferably includes an upstream circumferential trough 26 which is open to the impingement plenum 24 and is in communication with at least one of the longitudinal bores 25. The inclusion of troughs 26 aids in evacuating the spent impingement cooling air and conducting air through the bores 25 for further cooling of the thermal mass of the shroud ring 18. According to the present invention the outer surface 20 of the ring 18 also preferably includes a downstream circumferential trough 27, with at least one axially extending cooling bore 25 communicating between the plenum 24 and the downstream trough 27.
Therefore, in use cooling air passes through the impingement plate 23 and impingement cooling jets are directed at the outer surface 20 of the shroud ring 18 as shown in
As seen in
Referring to
Although the above description relates to a specific preferred embodiment as presently contemplated by the inventor, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein. For example, the redirecting trough 27 may be replaced by any device which suitably serves to redirect the secondary air flow. The shroud segment 12 may have any number of configurations other than the typical one described above. Cooling bores 25 need not be exactly as described and other means of ducting the secondary flow to redirecting trough 27 may be employed with satisfactory result. The impingement plate 23 may not be present, but rather P3 (or other) cooling air may be directly supplied to the outer face of the shroud.
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Number | Date | Country | |
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20040120803 A1 | Jun 2004 | US |