Turbine blade with particle separator

Abstract

A turbine blade (100) comprising an outer wall (101) defining a cavity (102), the cavity being configured to receive a coolant flow, and a separator (103) disposed in the cavity and configured to separate suspended particles from the coolant flow, the separator (103) comprising a plenum (104) configured to receive the coolant flow, and one or more separation members (105) configured to interact with the coolant flow to separate suspended particles therefrom. The separator (103) is configured to divide the coolant flow into a scavenge stream (S) comprising the particles separated from the coolant flow, and a main stream (M) which is substantially free of, or has a reduced concentration of, the particles which have been separated from the coolant flow by the separator.

Description

[0001] TURBINE BLADE

[0002] BACKGROUND

[0003] The present invention relates to a turbine blade, and in particular a turbine blade for a gas turbine engine such as a jet engine.

[0004] In a gas turbine engine, several stages of turbines are provided after a combustor. In general, in order to minimise the specific fuel consumption of the engine, the temperature of the gas entering the turbine (also known as the turbine entry temperature, TET) is set to be high as possible. In modem gas turbine engines, the TET may be as high as 1850K, which is higher than the limit at which the materials from which the turbine blades are typically made can operate (and indeed is typically higher than the melting point of the material from which the blades are made).

[0005] Thus, in order to allow the turbine to operate, a coolant is provided to the turbine blade. Typically, a system of internal passageways in the engine feeds coolant gas (i.e. air which enters the engine) from the compressor (where the temperature is significantly lower) to the interior of the turbine blades. This coolant gas is used in two ways. First, the coolant gas may remove heat from the blades by convection (from the surface of the blade to the coolant in the interior cavity of the blade), and may also be ejected from the interior of the blade so as to provide a shielding film around the external blade surfaces.

[0006] The trailing edge of a typical turbine blade is responsible for a significant portion of the aerodynamic loss associated with a turbine stage. In order to minimise these loses, the trailing edge is typically made as thin (or sharp) as possible, which may in turn reduce the form drag caused by the shape of the aerofoil.

[0007] However, making the trailing edge as thin as possible may also reduce the internal volume inside the blade available for convection of heat (as described above) from the blade to the coolant. Further, air which is supplied from the compressor of the engine to be used as a coolant may include fine particles (e.g. sand in the air ingested by the engine). Such particlesmay form a coating on the interior of the blade by accumulation, which may in turn further adversely affect cooling functionality by restricting and / or blocking coolant flow through passageways in the blade. In particular, larger particles may adhere to surfaces and / or block passageways at a higher rate than smaller particles. In turn, this may provide an upper limit on the size of other cooling features which can be provided inside the blade (because features with fine geometry are typically more easily blocked).

[0008] It is an aim of the present invention to at least partially address the problems noted above.

[0009] SUMMARY OF THE INVENTION

[0010] According to a first aspect, there is provided a turbine blade comprising an outer wall defining a cavity, the cavity being configured to receive a coolant flow, and a separator disposed in the cavity and configured to separate suspended particles from the coolant flow, the separator comprising a plenum configured to receive the coolant flow, and one or more separation members configured to interact with the coolant flow to separate suspended particles therefrom.

[0011] Optionally, the separator is configured to divide the coolant flow into a scavenge stream comprising the particles separated from the coolant flow, and a main stream having a lower concentration of suspended particles than the scavenge stream.

[0012] Optionally, the plenum further comprises an outlet configured to exhaust said scavenge stream.

[0013] Optionally, the outlet is in fluid communication with a radially outer surface of the outer wall.

[0014] Optionally, the outlet is configured to exhaust 5% or less of the total mass flow of the coolant through the plenum.

[0015] Optionally, the separator is configured to direct the scavenge stream parallel to the main stream.Optionally, the separator comprises a plurality of said separation members.

[0016] Optionally, the one or more separation members have a circular cross-section.

[0017] Optionally, the one or more separation members have a square cross-section.

[0018] Optionally, the one or more separation members have a rectangular cross-section.

[0019] Optionally, the one or more separation members have a z-shaped cross-section.

[0020] Optionally, the one or more separation members have an aerofoil cross-section.

[0021] Optionally, the separation members are arranged in an array along the plenum.

[0022] Optionally, the separation members are arranged in a straight line.

[0023] Optionally, the separation members are arranged along a curved line

[0024] Optionally, the separation members are disposed at a constant angle of incidence relative to a coolant flow direction through the plenum.

[0025] Optionally, the separation members are disposed at a varying angle of incidence relative to a coolant flow direction through the plenum.

[0026] Optionally, the separation members are disposed with varying spacing.

[0027] Optionally, the separator includes a single separation member comprising a protrusion configured to separate said scavenge stream from said main stream, and wherein the plenum comprises a curved portion upstream of the separation member configured to induce curvature in the coolant flow.Optionally, the plenum includes a coolant inlet.

[0028] Optionally, the coolant inlet is disposed radially inward of the outlet.

[0029] Optionally, the plenum is tapered such that the coolant flow area reduces along a flow path of the coolant through the plenum.

[0030] Optionally, the plenum includes a curved wall.

[0031] Optionally, the one or more separation members are configured to induce curvature in coolant flow through the cavity

[0032] Optionally, the separator is located in the trailing 50% of the blade.

[0033] Optionally, the turbine blade further comprises a plurality of heat transfer members disposed in the cavity, wherein the separation members are disposed between the plenum and the heat transfer members.

[0034] According to a second aspect, there is provided a gas turbine engine comprising the blade as described above.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will now be described, by way of non-limitative example only, with reference to the accompanying drawings, in which:

[0037] Figure 1 shows a partially cutaway perspective view of a turbine blade according to the present invention;

[0038] Figure 2 shows a further arrangement of a partially cutaway perspective view of a turbine blade according to the present invention;

[0039] Figure 3 shows a cross sectional view through the turbine blade of figure 1;Figure 4 shows a cross sectional view through a turbine blade according to the present invention;

[0040] Figure 5 shows a section view through a separator of a turbine blade according to the present invention;

[0041] Figure 6 shows a section view through a separator of a turbine blade according to the present invention;

[0042] Figure 7 shows a section view through a separator of a turbine blade according to the present invention;

[0043] Figure 8 shows a section view through a separator of a turbine blade according to the present invention;

[0044] Figure 9 shows a section view through a separator of a turbine blade according to the present invention;

[0045] Figure 10 shows a section view through a separator of a turbine blade according to the present invention;

[0046] Figure 11 shows a section view through a separator of a turbine blade according to the present invention;

[0047] Figure 12 shows a section view through a separator of a turbine blade according to the present invention;

[0048] Figure 13 shows the flow velocity through the separator of figure 12; and

[0049] Figure 14 shows a section view through a separator of a turbine blade according to the present invention.

[0050] DETAILED DECRIPTION

[0051] A first arrangement of a turbine blade according to the present invention is shown in figure 1. The turbine blade 100 comprises as outer wall 101 defining a cavity 102, and a separator 103 disposed in the cavity. The cavity 102 is configured to receive a coolant flow. The separator 103 is configured to separate suspended particles from the coolant flow. The coolant flow may be a gas, which may be air bled from the compressor or from elsewhere in the engine.

[0052] The cavity 102 is an internal space in the interior of the turbine blade. The cavity may be defined by the outer wall of the turbine blade. It will also be understood that there may beintermediate walls between the outer wall of the turbine blade and the cavity. The coolant may be supplied to the blade (and in particular to the interior of the cavity by any suitable means. For example, in the arrangement shown in figure 1, coolant is delivered to the blade through a passage in the root of the blade, which enters the blade at the radially inner end surface of the blade. The passage of coolant entering the blade in the arrangement of figure 1 is depicted by dotted arrow C in figure 1.

[0053] The separator 103 is disposed in the cavity 102. The function of the separator is to separate suspended particles (such as particles of dust or dirt) from the coolant flow. The separator 103 includes a plenum configured 104 configured to receive the coolant flow, and one or more separation members 105 configured to interact with the coolant flow to separate suspended particles therefrom. In the arrangement of figure 1, the separation members have a square cross-section (in a plane substantially parallel to the blade surface). The configuration and function of the separator is described in more detail below.

[0054] The separator 103 divides the coolant flow into a scavenge stream (represented by arrow S in figure 1) comprising the particles separated from the coolant flow, and a main stream which is substantially free of (or has a reduced concentration of) the particles which have been separated from the coolant flow by the separator. In other words, the main stream has a lower concentration of suspended particles than the incoming coolant flow to the separator. The main stream also has a lower concentration of suspended particles than the scavenge stream. This functionality is described in more detail below.

[0055] As shown in figure 1, the main stream may exit the blade through openings (which can be referred to as a main stream outlet) at or near the trailing edge of the blade, represented by arrow M in figure 1.

[0056] As also shown in figure 1, the scavenge stream may exit the blade through an outlet 106 (which may be referred to as a scavenge outlet). In other words, the outlet 106 is configured to exhaust the scavenge stream. The scavenge stream exits (i.e. is exhausted from) both the plenum of the separator and from the blade itself.The outlet 106 may be formed in (or otherwise in fluid communication with) the outer wall of the blade. In some arrangements, and as shown in figure 1, the outlet 106 may be in fluid communication with (and may also be formed in) a radially outer surface of the outer wall (and thus in a radially outer surface of the blade). The outlet 106 may be configured to exhaust a relatively small proportion of the coolant flow. For example, the outlet may be configured to exhaust 5% or less of the total mass flow of the coolant through the plenum. This ratio may be set by the area of the outlet 106. An outlet configured to exhaust this proportion of the total mass flow may provide effective removal of particulate matter, whilst also minimising impact on the overall cooling due to the removal of a portion of coolant.

[0057] Figure 2 shows a similar arrangement to that of figure 1. However, rather than the separation members having a square cross section, the separation members instead have a Z-shaped cross section. That is, each separation member has a first section, a second section and a third section, with the second section being interposed between the first section and the third section. The first section and third section extend parallel to each other, and the second section is angled (at an angle of less than 90 degrees) relative to the first and third sections. The first section is located at the leading edge of the separation members (i.e. at the upstream end of the coolant flow over the separation members), and the third section is located at the trailing edge of the third section (i.e. at the downstream end of the coolant flow over the separation members). The relative lengths of the sections and the angles therebetween may vary from those depicted in figure 2.

[0058] Figure 3 shows a partial sectional view through the separator 103 of the arrangement of figure 1. The section is taken substantially parallel to the suction surface of the blade, in the trailing half of the blade (i.e. the cutaway section of figure 1). For clarity, the rest of the turbine blade is not depicted in figure 3. The lines labelled P in figure 3 represent the tracks of suspended particles through the separator, and the dashed arrows labelled M represent the path of the main stream coolant.

[0059] Figure 4 shows a sectional view (similar to that of figure 3) of a further arrangement of separator 103. Again, the rest of the turbine blade is not depicted in figure 4. However, the separator of figure 4 is similar to those shown in figures 1-3, except that the cross section ofthe separation members is rectangular (i.e. the separation members are flat plates or vanes) rather than being square or z-shaped. It will be understood that the separator shown in figure 4 may be used with a blade arrangement similar to those shown in figures 1-3, and that any of the features described above in relation to figures 1-3 are equally applicable to the separator of figure 4. It will be understood that other arrangements are possible in which the separation members have different rectangular shapes to those shown in figure 4. In general, the aspect ratio of the rectangular separators may be such that the separators take the form of flat plates (i.e. are substantially longer in one direction than the other) or vanes. For example, the aspect ratio of the plates may be 2:1, 3:1, 5:1 or 10:1.

[0060] The below description of the separator 103 applies to the separators depicted in each of figures 1-4.

[0061] The separator 103 is disposed in the cavity 102. The function of the separator is to separate suspended particles (such as particles of dust or dirt) from the coolant flow. The separator 103 includes a plenum configured 104 configured to receive the coolant flow, and one or more separation members 105 configured to interact with the coolant flow to separate suspended particles therefrom. The separation members 105 may extend across the cavity in the thickness direction of the turbine blade (i.e. between the interior of the pressure surface and the interior of the suction surface).

[0062] The one or more separation members 105 may act to separate suspended particles from the coolant flow by inducing curvature in coolant flow through the cavity. This is illustrated by the streamlines in figure 4 in particular (although the same applies to figure 3). This phenomenon is known as inertial separation. This may in turn result in suspended particles being separated from the coolant flow. The separation may be particularly effective where the coolant flow velocity is high (compared to known arrangements with no separator) at the entrance to the separator. This coolant flow velocity may be provided by feeding the separator directly from a supply outside of the turbine blade (e.g. a compressor air bleed, as described above), and / or by the design of flow features upstream of the separator and inside the blade. In some examples, the separator inlet flow velocity may be of the order of four times the coolant flow velocity in arrangements with no separator.That is, the presence of the separation members 105 in the coolant flow (and consequent impact of some of the coolant flow with the separation members) may cause the streamlines of the coolant flow to become curved. This may in turn cause suspended particles to slip from the coolant flow. That is, the particles may no longer follow the streamlines of the flow, but instead carry on in (or toward) the direction they were travelling prior to encountering the curved streamlines. This may result in a portion of the coolant flow (i.e. the at which downstream of the curvature having a lower concentration of suspended particles than the coolant flow entering the plenum.

[0063] The one or more separation members 105 may also act to separate suspended particles from the coolant flow by causing suspended particles to rebound from the separation members and towards the scavenge flow and scavenge exit. This phenomenon is known as bounce separation or rebound separation. The angle of the separation members (and in particular the angle of the part of the separation members on which oncoming flow impinges) relative to the oncoming coolant flow may allow particles to rebound in a manner in which they are redirected across the separator, entrained in the flow through the separator, and towards the scavenge exit.

[0064] The coolant flow which is laden with particles (i.e. contains the particles separated from the main stream) is directed towards the scavenge exit 106. The main stream flow (i.e. the flow which is not directed towards the scavenge exit) thus has a significantly lower concentration and / or number of suspended particles than both the incoming coolant flow and the scavenge exit flow (and may have substantially none of the particles which are separated from the coolant flow by the separator). It will be understood that some particles suspended in the incoming coolant flow may not be separated by the separator, and thus remain in the mainstream flow (as indicated by the particle track near the top of figure 3). However, in general, the mainstream flow has a lower concentration of particles than the incoming coolant flow. The separators of the present invention may be particularly effective with larger particles, such as those with a diameter of 20 microns and above, more effective with particles with a diameter of 50 microns and above, and most effective with particles with a diameter of 100 microns. Although the separation of smaller particles may be less effective, suchparticles may be of lesser concern as they are less likely to cause blockages and / or damage to the internal structure of the blade.

[0065] The plenum 104 is a sub-section of the internal cavity, and may be defined by a plenum wall which separates the plenum 104 of the separator 103 from the rest of the cavity. It will be understood that the cavity may include other cooling features such as rib turbulators.

[0066] The plenum 104 includes a coolant inlet 109. The coolant inlet 109 may be formed in (or otherwise in fluid communication with) the outer wall of the blade. In some arrangements, the coolant inlet 109 may be in fluid communication with (and may also be formed in) a radially inner surface of the outer wall (and thus in a radially inner surface of the blade). Alternatively or additionally, the coolant inlet 301 may be in fluid communication with another portion of the cavity defined by the outer wall of the blade. In other words, the plenum 104 may receive coolant which has already passed through other upstream cooling passages or other features in the blade. Such features (e.g. rib turbulators) are not described in detail herein, but are well-known in the art.

[0067] The coolant inlet 109 may be disposed radially inward (in the frame of reference of the turbine blade when mounted in a turbine) of the scavenge outlet 106. This may allow the coolant flow to be accelerated from the inlet towards the outlet by the centripetal acceleration imposed by the rotation of the turbine, which may in turn provide improved separation due to a higher flow velocity. In other words, the coolant may be centrifuged outwards by the rotation of the turbine as it moves from the inlet towards the outlet.

[0068] In the arrangements of figures 1-4, the separator 103 comprises a plurality of separation members 105. The separation members 105 are arranged in an array along the plenum 104. That is, the plurality of separation members 105 are distributed (i.e. spaced apart from each other). The array of separation members may extend in any suitable direction such as (in the arrangements of figures 1-4) parallel to the trailing edge of the blade, or (in other arrangements) parallel to one of the walls of the plenum 104 or parallel to the direction of coolant flow through the plenum 104 (which may be defined between the coolant inlet and the scavenge outlet 106).In the arrangements of figures 3 and 4, each of the separation members is disposed at a constant angle of incidence relative to the oncoming flow of coolant (i.e. relative to a coolant flow direction through the plenum). However (and as will be described below in relation to figure 10) the angle of incidence may also vary.

[0069] In the arrangements of figures 1-4, the separation members are arranged in a straight line. That is, the array of separation members forms a straight line. However (and as will be described below in relation to figure 11) the array need not form a straight line.

[0070] In some arrangements, and as shown in figures 1-4, the plenum may be tapered such that the coolant flow area reduces along a flow path of the coolant through the plenum (i.e. from the inlet towards the scavenge outlet). This may result in the coolant flow being accelerated towards the outlet, which may in turn provide improved separation. In some arrangements, the taper angle is acute. The ratio of the width of the inlet to the plenum to the length of the separator may be not more than 0.17 (corresponding to a taper angle of 10.3 degrees).

[0071] As shown in figures 1 and 2, the separator may be located in the trailing 50% (i.e. the trailing half) of the blade. The trailing 50% may be measured with respect to the chord line or the camber line of the blade. In such arrangements, the leading wall (i.e. the part of the plenum wall which is furthest upstream in the coolant flow, in arrangements where the plenum wall is angled) of the plenum may be located at a position which is 50% or less of the chord of the blade from the trailing edge. For cambered blades, the separator may be located in the trailing 50% of the camber line (rather than the chord line). Again, in such arrangements, the leading wall (i.e. the part of the plenum wall which is furthest upstream in the coolant flow, in arrangements where the plenum wall is angled) of the plenum may be located at a position which is in the last 50% of the camber line (i.e. 50% or less of the length of the camber line from the trailing edge, when viewed normal to the camber). The maximum width of the plenum (i.e. the total extent of the plenum inside the blade) may be 30% or less of the chord of the blade.In the arrangements of figures 1-4, a plurality of heat transfer members 107 are disposed in the cavity 102 of the blade (and downstream of the plenum 104, in a part of the cavity 102 which is in fluid communication with the plenum 104, and thus in fluid communication with the separator). These heat transfer members 107 may also be known as heat transfer pedestals. Like the separation members 105, the heat transfer members 107 may extend across the cavity 102 in the thickness direction of the turbine blade (i.e. between the interior of the pressure surface and the interior of the suction surface).

[0072] The separation members 105 are disposed between the plenum 104 and the heat transfer members 107 in the coolant flow path. In other words, the heat transfer members 107 may be downstream of the separation members 105 (i.e. the flow entering the plenum first encounters the separation members, then the heat transfer members).

[0073] In some arrangements, such as those depicted in figures 1-4, the heat transfer members may be circular in cross section. In some arrangements, a matrix (i.e. a two-dimensional array) of heat transfer members may be provided. That is, there may be a plurality of arrays extending substantially in the same direction as the array of separation members, with the arrays being distributed chordwise along the blade (i.e. towards the trailing edge and / or in the direction of main stream coolant flow). As shown in figures 3 and 4, the arrays may also be offset from each other so as to form a “chequerboard” pattern.

[0074] In some arrangements (such as those of figures 1-4), the separation members may have a different cross section to the heat transfer members. Although the primary function of the separation members is to separate suspended particles from the coolant flow, and the primary function of the heat transfer members is to transfer heat from the blade surface to the coolant flowing past the heat transfer members, it will be understood that the separation members may also have some heat transfer function, and vice versa. It will also be understood that (as explained below in relation to figure 12) arrangements are possible in which the separation members and the heat transfer members have the same cross-section.

[0075] Figures 5-11 illustrate further arrangements of separator, which are described in more detail below. Unless stated otherwise, the features of the separator (and the turbine blade in whichthe separator is provided) are substantially similar to those described above in relation to figures 1-4, and any of the features described above in relation to figures 1-4 can equally be applied to the arrangements of figures 5-11 (and vice versa).

[0076] Figure 5 shows a further arrangement of separator, with separation members having a square cross section, similar to the arrangement of figures 1-3, but with more separation members 105. Arrangements which have more, smaller separation members (than arrangements with fewer but larger separation members) may provide improved separation. Further, arrangements where the separation members are similar in size and / or shape to the heat transfer members may provide improved ease of manufacture.

[0077] Figure 6 shows a further arrangement of separator, with separation members having a circular cross section. The circles may be of any suitable size. Further, in arrangements where heat transfer members which are circular in cross section are provided, the separation members may be of the same size and shape as the heat transfer members.

[0078] Figure 7 shows a further arrangement of separator, with separators having a Z shaped cross section (which is defined above in relation to figure 2).

[0079] Figure 8 shows a further arrangement of separator, with separators having an aerofoil shaped cross section. Any suitable aerofoil section may be used. For example, the aerofoil section used in the arrangement of figure 8 is a cambered aerofoil section. However, uncambered aerofoil sections may also be used.

[0080] Although in the arrangements of figures 1-8, the wall of the plenum is a straight line, other plenum wall profiles are possible. For example, the plenum wall may be curved. Figure 9 shows an example of such an arrangement. In particular, in the arrangement of figure 9, the curvature of the plenum wall is such that the upstream end of the plenum has a relatively larger flow area than if the plenum wall between the inlet and the outlet were a straight line, and the downstream end of the plenum has a relatively smaller flow area than if the plenum wall between the inlet and the outlet were a straight line. This may promote flow accelerationthrough the plenum and / or provide improved consistency of flow through the plenum, which may in turn provide improved separation.

[0081] Although in the arrangements of figures 1-9, the angle of incidence of the separation members relative to the coolant flow is constant, arrangements are also possible in which the angle of incidences varies between separation members. Figure 10 shows an example of such an arrangement. In particular, in the arrangement of figure 10, the angle of incidence of the separation members relative to the coolant flow decreases further along the array (i.e. in the downstream direction in the direction of flow through the plenum and closer to the scavenge exit). This may provide improved separation.

[0082] Although in the arrangements of figures 1-10, the separation members are arranged in an array which is a straight line, arrangements are also possible in which the separation members are disposed along a curved line. Figure 11 shows an example of such an arrangement. In this arrangement, the separation members are arranged along a curved (or bowed) line. This may impose a sustained acceleration away from the array of separation members, which may in turn provide improved separation. Although the arrangement of figure 11 shows the separation members having a square cross section, it will be understood that any of the other cross-sectional areas may also be used in conjunction with a curved line.

[0083] It will be understood that any of the separation member cross-sectional shapes described herein may be applied to the variations of figures 9, 10 and 11 (and vice versa).

[0084] Figures 12 and 13 show a further arrangement of separator 103 (with figure 12 depicting particle tracks and figure 13 depicting flow velocity). As with the arrangements described above, an array of separation members 105 and a matrix of heat transfer member 107 is provided. Again, the separation of particles from the incoming coolant flow may be provided by the combination of the separation members (which function as described above), together with the centripetal acceleration resulting from the rotation of the turbine. However, the plenum does not comprise a separate outlet which is configured to exhaust the scavenge stream. Rather, the separator is configured to direct the scavenge stream (labelled S) parallel to the main stream (labelled M), such that the scavenge stream exits the blade in a similarlocation to the main stream (e.g. through an opening in the trailing edge of the blade). The scavenge stream corresponds to the flow in the top most section of the view of figure 12 (which may correspond to the radially outermost portion of the cavity in the blade). There may be no barrier between the main stream and the scavenge stream.

[0085] Thus, in the arrangement of figure 12, the scavenge stream is exhausted from the blade at the trailing edge, rather than at a separate outlet. This may prevent a situation in which a separate scavenge exit might be blocked by particles.

[0086] Although the arrangement of figures 12 and 13 depict the separation members 105 as being circular in cross section, it will be understood that any of the features of figures 1-11 (including but not limited to the cross-sectional shapes, distribution and angle of incidence of the separation members) may be applied to the arrangements of figures 12 and 13 (and vice versa).

[0087] Likewise, in some arrangements, such as that shown in figure 12, the heat transfer members 107 and the separation members 105 may have the same cross section. This may result in improved ease of manufacture (as the manufacturing of multiple shapes inside the blade may not be required). However, arrangements with no separate scavenge outlet (as in figure 12) may be applied to arrangements (such as those depicted in figures 1-4) where the separation members and heat transfer members have different shapes to each other.

[0088] Figure 14 shows a further arrangement of separator 103 having a separate scavenge outlet 106. Unlike the arrangements described above in relation to figures 1-13 (which have a plurality of separation members), in the arrangement of figure 14, the separator includes a single separation member 105. The single separation member 105 is a protrusion extending into the coolant flow. The protrusion is configured to separate the mainstream from the scavenge stream. This single separation member may be aligned so as to receive flow directed by a curved portion 110 of the plenum 104. The curved portion 110 of the plenum may be configured to induce curvature in the coolant flow. Thus, the protrusion may cooperate with the curved portion of the plenum such that coolant flow is split either side of the protrusion, with coolant flow having a higher concentration of particles (separated due to thecurved streamlines of the flow and / or rebound from the protrusion) being directed towards one side of the protrusion, producing the scavenge stream. This may be the radially outer portion of the flow, so that separation is also aided by the centripetal acceleration caused by the rotation of the turbine.

[0089] Thus, in the arrangement of figure 14, the oncoming flow to the single separation member (i.e. the incoming coolant flow) is split by the protrusion into a scavenge flow having a higher concentration of suspended particles than the incoming coolant flow, and a mainstream flow having a lower concentration of suspended particles than the incoming coolant flow.

[0090] Although in the above, the turbine blade as disclosed herein is described in the context of a jet engine (e.g. an aircraft engine), it will be understood that such turbine blades can also be used in other applications, such as ground-based gas turbines (e.g. as used in electricity generation).

[0091] It should be understood by those skilled in the art that while the present invention has been described with reference to exemplary embodiments, it is not limited to the disclosed exemplary embodiments. Various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof. Features from any example or embodiment of the present disclosure can be combined with features from any other example or embodiment of the present disclosure.

Claims

CLAIMS1. A turbine blade comprising:an outer wall defining a cavity, the cavity being configured to receive a coolant flow; anda separator disposed in the cavity and configured to separate suspended particles from the coolant flow, the separator comprising:a plenum configured to receive the coolant flow; and one or more separation members configured to interact with the coolant flow to separate suspended particles therefrom.

2. The turbine blade of any preceding claim, wherein the separator is configured to divide the coolant flow into a scavenge stream comprising the particles separated from the coolant flow, and a main stream having a lower concentration of suspended particles than the scavenge stream.

3. The turbine blade of claim 2, wherein the plenum further comprises an outlet configured to exhaust said scavenge stream.

4. The turbine blade of claim 3, wherein the outlet is in fluid communication with a radially outer surface of the outer wall.

5. The turbine blade of claim 3 or 4, wherein the outlet is configured to exhaust 5% or less of the total mass flow of the coolant through the plenum.

6. The turbine blade of claim 2, wherein the separator is configured to direct the scavenge stream parallel to the main stream.

7. The turbine blade of any preceding claim, wherein the separator comprises a plurality of said separation members.

8. The turbine blade of any of claims 1-7, wherein the one or more separation members have a circular cross-section.

9. The turbine blade of any of claims 1-7, wherein the one or more separation members have a square cross-section.

10. The turbine blade of any of claims 1-7, wherein the one or more separation members have a rectangular cross-section.

11. The turbine blade of any of claims 1-7, wherein the one or more separation members have a z-shaped cross-section.

12. The turbine blade of any of claims 1-7, wherein the one or more separation members have an aerofoil cross-section.

13. The turbine blade of any of claims 7-12, wherein the separation members are arranged in an array along the plenum.

14. The turbine blade of any of claims 7-13, wherein the separation members are arranged in a straight line.

15. The turbine blade of any of claims 7-13, wherein the separation members are arranged along a curved line16. The turbine blade of claim any of claims 7-15, wherein the separation members are disposed at a constant angle of incidence relative to a coolant flow direction through the plenum.

17. The turbine blade of claim any of claims 7-15, wherein the separation members are disposed at a varying angle of incidence relative to a coolant flow direction through the plenum.

18. The turbine blade of claim any of claims 7-17, wherein the separation members are disposed with varying spacing.

19. The turbine blade of any of claims 2-5, wherein the separator includes a single separation member comprising a protrusion configured to separate said scavenge stream from said main stream, and wherein the plenum comprises a curved portion upstream of the separation member configured to induce curvature in the coolant flow.

20. The turbine blade of any preceding claim, wherein the plenum includes a coolant inlet.

21. The turbine blade of claim 3 and 20, wherein the coolant inlet is disposed radially inward of the outlet.

22. The turbine blade of any preceding claim, wherein the plenum is tapered such that the coolant flow area reduces along a flow path of the coolant through the plenum.

23. The turbine blade of any preceding claim, wherein the plenum includes a curved wall.

24. The turbine blade of any preceding claim, wherein the one or more separation members are configured to induce curvature in coolant flow through the cavity25. The turbine blade of any preceding claim, wherein the separator is located in the trailing 50% of the blade.

26. The turbine blade of any preceding claim, further comprising a plurality of heat transfer members disposed in the cavity, wherein the separation members are disposed between the plenum and the heat transfer members.

27. A gas turbine engine comprising the blade of any preceding claim.19

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