Patent Application
20250237154
The disclosure relates generally to aircraft engines, and, more particularly, to a containment system for containing impeller fragments.
Aircraft engines and auxiliary power units are known to include turbines and compressors which rotate at high rotational speeds. Aviation regulations typically require engine manufacturers to demonstrate fragments containment following a specified burst event. While known containment structures may be suitable for their intended purposes, aviation safety is paramount and therefore improvements are always desirable.
In one aspect, there is provided an aircraft engine, comprising: an air inlet; a compressor section for receiving air from the air inlet, the compressor section having a centrifugal impeller mounted for rotation about an axis and an outer shroud, the centrifugal impeller including an impeller hub, the outer shroud extending radially outwardly of the impeller hub to define an annular flow path radially between the impeller hub and the outer shroud, the outer shroud at least in part surrounding the impeller hub, and blades extending radially outwardly from the impeller hub and operable to rotate within the annular flow path; and an air inlet case having a radially outer wall extending from the air inlet to the outer shroud and a radially inner wall extending from the air inlet to the impeller hub, an annular passage defined radially between the radially outer wall and the radially inner wall fluidly coupling the air inlet to the centrifugal impeller, the radially outer wall including a frangible element adjacent a junction between the radially outer wall and the outer shroud, the frangible element extending about an outer circumference of the radially outer wall and frangibly connecting the radially outer wall to the outer shroud.
In another aspect, there is provided an impeller containment system, comprising: an impeller having an impeller hub and a set of blades extending radially outwardly from the impeller hub; an outer shroud extending radially outwardly of the impeller to define an annular flow path radially between the impeller hub and the outer shroud; and an air inlet case having a radially outer wall operatively coupled to the outer shroud and a radially inner wall operatively coupled to the impeller hub, an annular passage defined radially between the radially outer wall and the radially inner wall to fluidly couple the centrifugal impeller to an upstream air inlet, the radially outer wall including a frangible element adjacent a junction between the radially outer wall and the outer shroud, the frangible element operable to detach at an occurrence of an impeller burst event to interrupt a load path between the impeller and the air inlet case.
In a further aspect, there is provided a method of limiting load transmission to an air inlet case of an aircraft engine upon bursting of a centrifugal compressor impeller of the aircraft engine, the method comprising: at least partially surrounding the centrifugal compressor impeller with a radially outer shroud; and frangibly attaching the radially outer shroud to the air inlet case, such that the radially outer shroud is detached from the air inlet case under a load impact of the centrifugal impeller bursting during operation of the aircraft engine.
Reference is now made to the accompanying figures in which:
The engine 10 in this example can be seen to include a high pressure spool including an impeller assembly 20 and a high-pressure turbine 16a, and a low pressure spool including a low-pressure turbine 16b. The low spool leads to a power shaft via a gear arrangement. The high pressure spool can be refer to herein as a compressor spool and the low spool can be referred to herein as the power spool.
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The impeller assembly 20 includes an outer shroud 38 extending radially outwardly of the impeller assembly 20. The outer shroud 38 surrounds, at least partially, the impeller assembly 20. A space between the impeller hub 24 and the outer shroud 38 defines part of an annular flow path 40 of the engine 10, with the impeller blades 26 extending across that flow path 40. Illustratively, the outer shroud 38 is operatively coupled to the first wall 32 at the upstream end of the flow path 40, while the second wall 34 is operably interfaced to the impeller hub 24, thereby fluidly coupling the annular flow path 40 to the annular passage 42 defined between the radially outer wall 32 and the radially inner wall 34, the annual passage 42 thereby fluidly coupling the air inlet 28 to the impeller assembly 20.
In the occurrence of an impeller burst event, for instance an impeller tri-hub burst event, various aviation requirements may require the one or more released fragments to be contained. For instance, if an impeller were to burst into multiple pieces (e.g., three pieces in the context of a tri-hub burst event), lobes should be contained within the surrounding structure, and energy should be absorbed to preserve the structural integrity of the surrounding parts. As the impeller burst energy is typically absorbed by the surrounding structural parts, it may impose high dynamic loads on these parts. In the shown case, in the context of a burst event within the impeller assembly 20, radial expansion emanating from the burst hub 24 and/or blades 26 may push the impeller shroud 38 in a radially outward direction. The shroud 38 may be prevented from expanding radially outwardly due to the presence of surrounding engine components (e.g., a diffuser downstream of the impeller assembly 20). As such, the load may propagate axially, for instance in an axially upstream direction relative to air flowing along the annular passage 42 along a load path extending from the shroud 38 to the air inlet 28 by way of the radially outer wall 32.
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According to the present disclosure, there is taught a method of limiting load transmission to an air inlet case of an aircraft engine upon bursting of a centrifugal compressor impeller of the aircraft engine. The centrifugal compressor impeller is at least partially surrounded with a radially outer shroud. The radially outer shroud is frangibly attached to the air inlet case, such that the shroud is detached from the air inlet case under a load impact of the centrifugal impeller bursting during operation of the engine.
In some embodiments, the frangibly attaching of the radially outer shroud to the air inlet case includes selectively removing material from the air inlet case adjacent an interface between the outer shroud and the air inlet case.
In some embodiments, the frangibly attaching includes forming a groove about a radially outer surface of the air inlet case, for instance by way of 3D printing.
It is noted that various connections are set forth between elements in the preceding description and in the drawings. It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. The term “connected” or “coupled to” may therefore include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements).
It is further noted that various method or process steps for embodiments of the present disclosure are described in the following description and drawings. The description may present the method and/or process steps as a particular sequence. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth in the description should not be construed as a limitation.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While various aspects of the present disclosure have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the present disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these particular features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the present disclosure. References to “various embodiments,” “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. The use of the indefinite article “a” as used herein with reference to a particular element is intended to encompass “one or more” such elements, and similarly the use of the definite article “the” in reference to a particular element is not intended to exclude the possibility that multiple of such elements may be present.
The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. Yet further modifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology.
