Patent Application
20250196037
The application relates generally to air-oil separators for separating air from oil of an air-oil mixture.
Aircraft engines, such as gas turbine engines, typically have air-oil separators for removing air from oil. Various types and configurations of air-oil separators are known in the art. While these known systems have various benefits, there is still room in the art for improvement.
In one aspect, there is provided a gearbox de-oiler for an aircraft engine, comprising: a shaft mounted for rotation about an axis; a housing mounted to the shaft for rotation therewith about the axis, the housing defining a chamber containing a porous separator matrix, the chamber having an air-oil mixture inlet, an oil outlet, and an air outlet; a separation plate separating the porous separator matrix into a primary flow path segment and a secondary flow path segment, the primary flow path segment extending axially from and fluidly connecting the air-oil mixture inlet to a radial passage, the secondary flow path segment extending axially from and fluidly connecting the radial passage to the air outlet, the secondary flow path segment axially overlapping the primary flow path segment and disposed radially inwardly with respect thereto; and oil collector tubes projecting radially outwardly from the separation plate across at least a portion of the primary flow path segment, the oil collector tubes fluidly connecting the secondary flow path segment to the oil outlet.
In another aspect, there is provided an air-oil separator for an aircraft engine, comprising: a housing rotatable about a central axis, the housing having an outer and an inner circumferential wall extending axially from a first end wall to a second end wall, the outer and inner circumferential walls and the first and second end walls defining an annular chamber around the central axis, the annular chamber having an inlet defined in the first end wall for receiving an air-oil mixture, and an oil outlet defined in the outer circumferential wall; an annular separation plate projecting axially from the first end wall towards the second end wall inside the annular chamber radially inwardly from the inlet relative to the central axis, the annular separation plate dividing the annular chamber into a radially outer flow path segment and a radially inner flow path segment, the radially inner flow path segment serially connected in flow communication to the radially outer flow path segment and having an air outlet for discharging air extracted from the air-oil mixture received from the radially outer flow path segment; a porous separator matrix disposed in both the radially outer flow path segment and the radially inner flow path segment; and oil collector tubes projecting radially outwardly from the annular separation plate into the radially outer flow path segment towards the oil outlet in the outer circumferential wall of the housing, the oil collector tubes having respective oil inlets defined at a radially inner surface of the annular separation plate.
In a further aspect, there is provided a gearbox de-oiler for an aircraft engine, comprising: a shaft mounted for rotation about an axis; a housing mounted to the shaft for rotation therewith, the housing having an outer circumferential wall, an inner circumferential wall, a first end wall and a second end wall axially opposite to the first end wall, the outer circumferential wall, the inner circumferential wall, the first end wall and the second end wall defining a chamber therebetween, the chamber having an air-oil mixture inlet defined in the first end wall, a series of oil outlet holes defined in the outer circumferential wall, and an air outlet defined in the inner circumferential wall adjacent to the first end wall; a porous separator matrix disposed in the chamber; an annular separation plate extending axially from the first end wall through the porous separator matrix, the annular separation plate disposed radially inwardly from the air-oil mixture inlet, the annular separation plate and the outer circumferential wall defining therebetween a primary flow path segment extending axially from the air-oil mixture inlet towards the second end wall, the annular separation plate and the inner circumferential wall defining therebetween a secondary flow path segment, the secondary flow path segment extending axially from the second end wall to the first end wall and leading to the air outlet; and oil collector tubes extending radially outwardly from the annular separation plate towards the oil outlet holes in the outer circumferential wall, the oil collector tubes configured to collect oil centrifuged against the annular separation plate in the secondary flow path segment and to direct the oil to the oil outlet holes in the outer circumferential wall.
Reference is now made to the accompanying figures in which:
As known in the art, pressurized air, for instance compressor bleed air, may be used to seal the bearing and gearbox cavities. As the air flows through the seals (not shown) of the bearing and gearbox cavities, a certain amount of oil naturally becomes entrained with the air and it is desirable that this oil be separated from the air before the air is vented to the environment.
The exemplified air-oil separator 100 is particularly suited for use as a gearbox de-oiler. For instance, the air-oil separator 100 can be integrated to the AGB 20 shown in
Referring now more specifically to
As best shown in
The separator matrix 114 may be formed into an annular cylindrical body configured to entirely fill the annular chamber 102e around the hollow rotating shaft 104. The separator matrix 114 rotates jointly with the housing 102 and the shaft 104 inside the chamber C of the AGB 20. By flowing through the separator matrix 114, the oil in the air-oil mixture coalesce against the material of the separator matrix 114. Via the centrifugal force, the coalesced oil droplets merge radially away from the rotation axis, toward the outer circumferential wall 102a of the housing 102 where the oil droplets are discharged back into the chamber C of the AGB 20 via the oil exit holes 108a. Simultaneously, the air continues to flow toward a lower pressure zone downstream of the AGB 20 through the air exit holes 110a and the aperture(s) 112 located on the hollow rotating shaft 104. The air, with any residual oil, is thus vented through the air outlet 110 and the center of the hollow rotating shaft 104.
It can be appreciated that the oil content of the air-oil mixture decreases along its passage through the separator matrix 114. The efficiency (i.e., the ability to remove oil from the air-oil mixture) of the air-oil separator 100 is influenced by: 1) the rotational speed of the separator; 2) the metal foam sponge density and 3) the effective flow length. The effective flow length may be defined as the mean distance from the air-oil mixture inlet 106 to the air outlet 110. That is the distance travelled by the air-oil mixture through the separator matrix 114 between inlet 106 an outlet 110.
Accordingly, for a same metal foam sponge density and a same rotational speed, the efficiency of the air-oil separator 100 may be improved by increasing the effective flow length. Indeed, the longer the flow path is, the more efficient the separator can be. However, because of space constrains, there is often a need to minimize the overall axial and radial envelope of the air-oil separator. As will be seen hereinafter, according to at least some embodiments, the effective flow length of the air-oil separator 100 may be increased by creating serially interconnected flow paths within the separator matrix 114 and that without increasing the overall size of the separator. In this way, compact air-oil separators may be provided with greater effective flow length.
For instance, as best shown in
It is understood that the axial length of the gap G and, thus, the axial length L1 of the separation plate 120 relative to the axial length L2 of the chamber 102e may vary from engine to engine, notably depending upon the pressure differential between the air-oil mixture inlet 106 and the air outlet 110. According to some embodiments, the separation plate 120 could also extend fully across the chamber 102e to the second end wall 102d (i.e., L1=L2) and radial holes could be defined in the separation plate 120 at an axial location adjacent or next to the second end wall 102d of the housing 102 to provide a fluid passage between the primary and secondary flow paths F1, F2.
As can be appreciated from
According to the embodiment illustrated in
In addition to creating the secondary flow path segment F2, the separation plate 120 also acts as an oil collector. Indeed, the radially inner surface of the separation plate 120 provides a surface to collect the oil droplets that are coalesced in the secondary flow path segment F2 and flow radially outwards under the centrifugal effect. The plate 120 may be configured to promote oil flow towards the first end wall 102c to collect the oil through a set of oil collector tubes 140. As shown in
Still referring to
The purpose of the oil collector tubes 140 is to collect coagulated oil from the secondary flow path segment F2 and to direct it to the oil exit holes 108a in the outer circumferential wall 102a of the housing 102. If only exit holes were incorporated in the plate 120, there is a risk of some recirculation of the oil along the primary and secondary flow path segments F1, F2. The oil collector tubes 1140 reduces the risk of oil recirculation and further maximizes the efficiency of the air-oil separator 100. Referring to
Each oil collector tubes 140 has an inlet 140a defined in the radially inner surface of the separation plate 120 for collecting coagulated oil centrifuged against the radially inner surface of the separation plate 120 and an outlet 140b for directing the collected oil to the oil exit holes 108a in the primary flow path segment F1. According to the illustrated embodiment, the oil collector tubes 140 are embedded in the separator matrix 114 and have a radial height R2 which is less than the radial height R3 of the primary flow path segment F1 at the axial location of the oil collector tubes 140. That is the tubes 140 do not extend all the way to the oil exit holes 108a, but are rather spaced by a predetermined distance from the inner surface of the outer circumferential wall 102a). The oil collected from the secondary flow path F2 is thus discharged from the tubes 140 into the separator matrix 114, but close (i.e., in the radially outer half of the primary flow path segment F1) to the radial oil exit holes 108a to minimize the risk of recirculation. However, it is understood that the collector tubes 140 could extend all the way to the oil exit holes 108a such that collected oil from the secondary path segment F2 is not returned to the separator matrix 114, thereby eliminating any potential recirculation of oil through both the primary and secondary flow paths F1, F2.
The collector tubes 140 may be clocked or aligned with the oil exit holes 108a defined in the outer circumferential wall 102a of the housing 102 of the separator 100. This may provide more direct passage of the oil from the collector tubes 140 to the oil exit holes 108a. From the foregoing, it can be appreciated that numerous parameters of the tubes, such as the number of tubes, the inner diameter of the tubes, the length of the tubes, the position and distribution of the tubes, can be varied to optimize efficiency.
It is understood that more than one set of separation plate and associated oil collector tubes could be provided in the chamber 102e to extend the effective flow length of the air-oil separator 100. The plates and their respective sets of tubes could be axially staggered to define a serpentine passage through the separator matrix 114. For instance, a second plate could extend axially from the second end wall 102d at a radial location spaced radially inwardly from the first plate to create a third flow path segment leading to the air outlet 110. Various configurations are contemplated. Also, the separator plate and the associated oil collector tubes could be retrofitted to an existing air-oil separator.
In operation, the air-oil mixture flowing into the air-oil separator 100 via the inlet 106 is pressed into the porous separator matrix 114. As the mixture axially flows along the primary flow path segment F1, a first portion of the oil contained in the mixture is captured by the framework of the matrix 114 and discharged through the oil exits holes 108a by the centrifugal force. The air and residual oil flow through the secondary flow path segment F2, where a further portion of the oil is coagulated in the separator matrix 114 and centrifuged against the radially inner surface of the separation plate 120. The coagulated oil flows axially along the radially inner surface of the plate 120 towards the oil collector tubes 140. From the tubes 140, the additional oil collected from the secondary flow path segment F2 is discharged into the separator matrix 114 at a radial location close to the oil exit holes 10. The centrifugal force causes the oil discharged from the tubes 140 to flow from the separator matrix 114 to the oil exit holes 108a before being discharged from the separator 100. The de-oiled air flows to the downstream end of the secondary flow path F2 where it is vented via the air outlet 110 and the center of the shaft 104.
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. For example, while the air-oil separator has been described as part of an AGB, it is understood that it could be integrated to another gearbox or oil chamber of an engine. Also, while the engine has been shown as a turbofan engine, it is understood that the air-oil separator could be used on different types of engines, including a turboshaft engine, a turboprop engine, and an auxiliary power engine to name a few. 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.
