HEAT EXCHANGER OF A GAS TURBINE ENGINE OF AN AIRCRAFT

Abstract

A heat exchanger of a gas turbine engine includes a casing having a stepped incident-flow profile. An air volume flow is, in the region of the incident-flow profile, diverted such that a recirculation zone with a separation bubble forms in the flow. Downstream of the incident-flow profile, is a further stepped incident-flow profile. The flow is diverted such that, downstream of the further incident-flow profile, a further recirculation zone forms in which a separation bubble is present. In the region of the incident-flow profile and/or the further incident-flow profile, is an inlet of a flow duct which runs in the casing in the direction of a mouth. An air volume flow conducted through the flow duct emerges from the mouth at such an angle relative to the flow direction of the air volume flow that, downstream of the mouth, a recirculation zone with a separation bubble forms.

Claims

1. A heat exchanger of a gas turbine engine of an aircraft having a casing, wherein the casing has a step-like incident-flow profile in a region facing toward a flow of an air volume flow, and the air volume flow is, in the region of the incident-flow profile, in relation to an outer side of the casing, diverted perpendicularly with respect to the outer side, over which flow passes, of the casing in a growing manner in such a way that, downstream of the incident-flow profile and above an outer side of the casing, a recirculation zone with at least one separation bubble forms in the air volume flow, and wherein, downstream of the incident-flow profile, there is provided at least one further step-like incident-flow profile which, in relation to the outer side downstream of the step-like incident-flow profile and in relation to the outer side of the casing, rises outwardly, is impinged on by the air volume flow at least in an axial direction, and diverts the air volume flow in such a way that, downstream of the further incident-flow profile, above a further outer side of the casing, a further recirculation zone forms in which in each case at least one separation bubble is present, and/or, in the region of the incident-flow profile and/or in the region of the further incident-flow profile, there is provided an inlet of at least one flow duct which runs in the casing in the direction of a mouth which is arranged at least approximately in the region of the outer side or which are arranged in each case in the region of the outer sides of the casing, wherein the air volume flow conducted through the flow duct or the air volume flows conducted through the flow ducts emerges from the mouth or emerge from the mouths in each case at such an angle relative to the flow direction of the air volume flow that, downstream of the mouth or downstream of the mouths, in each case one recirculation zone with at least one separation bubble forms above the outer side(s) of the casing.

2. The heat exchanger according to claim 1, wherein the recirculation zones each have a defined length in the flow direction of the air volume flow, which lengths are dependent on heights of the effective areas of the incident-flow profiles, which correspond in each case to an area of the incident-flow profiles in each case projected into a plane which is perpendicular to the flow direction of the air volume flow.

3. The heat exchanger according to claim 1, wherein the air volume flow is, in the region of the incident-flow profile or in the region of the incident-flow profiles and/or in the region of the mouth or in the region of the mouths, diverted relative to the outer side of the casing in a growing or expanding manner such that, in the flow direction of the air volume flow, the recirculation zones are adjoined by in each case one reattachment region of the air volume flow.

4. The heat exchanger according to claim 3, wherein the mouth or the mouths is arranged in each case at least approximately in the region of the outer side or are arranged in each case in the region of the outer sides of the casing in which the reattachment region is present or in which the reattachment regions are present.

5. The heat exchanger according to claim 4, wherein the air volume flow is, in the region of the incident-flow profile or in the region of the incident-flow profiles and/or in the region of the mouth or in the region of the mouths, diverted relative to the outer side of the casing in a growing or expanding manner such that, in the flow direction of the air volume flow, the reattachment regions are adjoined by in each case one turbulent flow region.

6. The heat exchanger according to claim 1, wherein, on the outer side of the casing, there are provided cooling fins which extend substantially outward in relation to the outer side of the casing and which run at least approximately in the flow direction of the air volume flow and which are spaced apart from one another in a direction which is perpendicular to the flow direction of the air volume flow.

7. The heat exchanger according to claim 6, wherein the incident-flow profile or the incident-flow profiles and/or the outer side or the outer sides of the casing is or are arranged, in the flow direction, upstream of or at least regionally between the cooling fins.

8. The heat exchanger according to claim 6, wherein a height of the cooling fins proceeding from the outer side or proceeding from the outer sides of the casing is in each case constant, or increases at least regionally in the flow direction of the air volume flow, over the length of the cooling fins.

9. The heat exchanger according to claim 8, wherein the height of the fins increases linearly or parabolically.

10. The heat exchanger according to claim 1, wherein a spacing between in each case two incident-flow profiles in the flow direction of the air volume flow lies in a range between one and ten times the height of the effective area of the in each case front incident-flow profile in the flow direction of the air volume flow, preferably in a range between four and five times the height of the effective area of the front incident-flow profile.

11. The heat exchanger according to claim 6, wherein the cooling fins end, in the flow direction of the air volume flow, upstream of that region of the outer side or upstream of those regions of the outer sides of the casing in which the mouth of the flow duct is arranged or in which the mouths of the flow ducts are arranged, and/or begin downstream of the region or downstream of the regions.

12. The heat exchanger according to claim 1, wherein the step-like incident-flow profiles extend at least approximately transversely with respect to the flow direction of the air volume flow.

13. The heat exchanger according to Clam 1, wherein the step-like incident-flow profiles are formed at least regionally with a convex and/or planar face area directed counter to the flow direction of the air volume flow, which face areas enclose in each case an angle of between 0° and 90° with the outer sides of the casing.

14. The heat exchanger according to claim 1, wherein the casing of the heat exchanger, in the assembled operating state, extends in a circumferential direction of the gas turbine engine and is of curved form in the circumferential direction and, in the circumferential direction, delimits a flow region of the air volume flow.

15. The heat exchanger according to claim 14, wherein the casing of the heat exchanger is formed as a closed ring-shaped body or as a ring segment.

Description

IN THE FIGURES

[0031] FIG. 1 shows a highly schematic longitudinal section through a gas turbine engine of an aircraft having a heat exchanger;

[0032] FIG. 2 shows a sectional view of a first embodiment of the heat exchanger of the gas turbine engine as per FIG. 1;

[0033] FIG. 3 shows an illustration corresponding to FIG. 2 of a further embodiment of the heat exchanger;

[0034] FIG. 4 shows a plan view of a region IV of the heat exchanger as per FIG. 3;

[0035] FIG. 5 shows an illustration corresponding to FIG. 2 of a further embodiment of the heat exchanger;

[0036] FIG. 6 shows a plan view of a region VI of the heat exchanger as per FIG. 5;

[0037] FIG. 7 shows a longitudinal sectional view of a further embodiment of the oil-air heat exchanger;

[0038] FIG. 8 shows a three-dimensional partial illustration of a further embodiment of the oil-air heat exchanger;

[0039] FIG. 9 shows an illustration corresponding to FIG. 8 of a further embodiment of the heat exchanger;

[0040] FIG. 10 shows an illustration corresponding to FIG. 8 of a further embodiment of the heat exchanger;

[0041] FIG. 11 shows an illustration corresponding to FIG. 8 of a further exemplary embodiment of the heat exchanger; and

[0042] FIG. 12 shows an illustration corresponding to FIG. 8 of a further embodiment of the heat exchanger.

[0043] FIG. 1 shows a gas turbine engine 10 with a main axis of rotation 9. The gas turbine engine 10 comprises an air inlet 12 and a fan 23 that generates two air flows: a core air flow A and a bypass air flow B. The gas turbine engine 10 furthermore comprises an engine core 11 that receives the core air flow A. In the axial flow direction, the engine core 11 comprises a low-pressure compressor 14, a high-pressure compressor 15, a combustion device 16, a high-pressure turbine 17, a low-pressure turbine 19, and a core thrust nozzle 20. An engine nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass thrust nozzle 18. The bypass air flow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low-pressure turbine 19 by way of a shaft 26 and an epicyclic gear box 30.

[0044] During operation of the gas turbine engine 10, the core air flow A is accelerated and compressed by the low-pressure compressor 14 and directed into the high-pressure compressor 15, where further compression takes place. The compressed air expelled from the high-pressure compressor 15 is directed into the combustion device 16, where it is mixed with fuel and the mixture is combusted. The resulting hot combustion products then propagate through the high-pressure and the low-pressure turbines 17, 19 and thereby drive said turbines, before they are expelled through the nozzle 20 to provide a certain propulsive thrust. The high-pressure turbine 17 drives the high-pressure compressor 15 by means of a suitable connecting shaft 27. The fan 23 generally provides the major part of the propulsive thrust. The epicyclic gear box is a reduction gear box.

[0045] Attention is drawn to the fact that the expressions “low-pressure turbine” and “low-pressure compressor”, as used herein, can be taken to mean the lowest-pressure turbine stage and lowest-pressure compressor stage (i.e. not including the fan 23), respectively, and/or the turbine and compressor stages that are connected together by the connecting shaft with the lowest rotational speed in the gas turbine engine (i.e. not including the gear box output shaft that drives the fan 23). Alternatively, there is furthermore also the possibility that the low-pressure turbine and the low-pressure compressor to which reference is made here are the medium-pressure turbine and the medium-pressure compressor. Where such alternative nomenclature is used, the fan can be referred to as a first, or lowest-pressure, compression stage.

[0046] Other gas turbine engines in which the present disclosure can be used may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of connecting shafts. As a further example, the gas turbine engine shown in FIG. 1 has a split flow nozzle 20, 22. This means that the flow through the bypass duct 22 has a dedicated nozzle which is separate from the engine core nozzle 20 and radially on the outside thereof. However, this is not restrictive, and any aspect of the present disclosure can also apply to engines in which the flow through the bypass duct 22 and the flow through the core 11 are mixed or combined before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) can have a fixed or variable area. Although the example described relates to a turbofan engine, the disclosure can be applied, for example, to any type of gas turbine engine, such as, for example, an open rotor engine (in which the fan stage is not surrounded by an engine nacelle) or a turboprop engine. In some arrangements, the gas turbine engine 10 may not comprise a gear box 30.

[0047] The geometry of the gas turbine engine 10, and components thereof, is or are defined using a conventional axis system which comprises an axial direction (which is aligned with the axis of rotation 9), a radial direction (in the direction from bottom to top in FIG. 1), and a circumferential direction (perpendicular to the view in FIG. 1). The axial, radial and circumferential directions run so as to be mutually perpendicular.

[0048] Additionally, the gas turbine engine 10 as per FIG. 1 comprises a heat exchanger 35, which is arranged in the present case on the inner diameter of the bypass duct 22 on an intermediate casing 36 and surrounds the intermediate casing 36 in a circumferential direction of the gas turbine engine 10.

[0049] As an alternative to this, the heat exchanger 35 may also be arranged in the region of the outer diameter of the bypass duct 22, which is the same as the diameter of the inner side of the engine nacelle 21. Furthermore, it is also possible for at least one heat exchanger 35 to be provided both on the inner diameter and on the outer diameter of the bypass duct 22.

[0050] FIG. 2 to FIG. 12 show various embodiments of the heat exchanger 35, which in the present case is designed as an oil-air heat exchanger. Here, oil of an oil circuit of the gas turbine engine 10 is conducted through an inner region 37 of a casing 38 of the heat exchanger 35. An outer side 39 of the heat exchanger 35 is impinged on by the bypass air flow B. The heat exchanger 35 may be designed as a concurrent-flow, counterflow or cross-flow heat exchanger, or else may have any desired combination of the latter structural forms. In the present case, the oil is, in relation to the main flow direction of the bypass air flow B through the bypass channel 22, oil conducted transversely or in a cross-flow configuration with respect to the bypass air flow B or the air volume flow through the casing 38.

[0051] The heat exchanger 35 constitutes a device of the gas turbine engine 10, in the region of which the fluid or oil that can be conducted through the casing 38 is temperature-controlled by means of the bypass air flow B impinging on the housing 38 or by means of the air volume flow conducted through the bypass duct 22.

[0052] The casing 38 has a first step-like incident-flow profile 41 in a region 40 facing toward the flow of the air volume flow B. Here, the air volume flow B is, in the region of the incident-flow profile 41, diverted outward in relation to the inner region 37 or the outer side 39 of the casing 38 such that a recirculation zone 42 with at least one separation bubble 43 forms downstream of the incident-flow profile 41 and above the outer side 39 of the casing 38 in the air volume flow B.

[0053] In the present case, the flow of the air volume flow B is, downstream of the incident-flow profile 41, diverted radially outward in relation to the main axis of rotation 9 and the outer side 39 of the casing 38.

[0054] If the heat exchanger 35 is arranged in the region of the outer diameter of the bypass channel 22, the air volume flow B is, downstream of the incident-flow profile 41 in relation to the main axis of rotation 9 and in relation to the then radially inwardly directed outer side 39 of the heat exchanger 35, diverted radially inward in relation to the main axis of rotation 9 and the outer side 39 of the casing 38.

[0055] The separation bubble 43 and the recirculation zone 42 have a defined length L. The defined length L of the recirculation zone 42 and of the separation bubble 43 is dependent on a height H41 of the effective area of the incident-flow profile 41. The effective area of the incident-flow profile 41 corresponds to an area 44 of the incident-flow profile 41 projected into a plane which is perpendicular to the flow direction of the air volume flow B. The recirculation zone 42 is adjoined by a reattachment region 45. In the reattachment region 45, the flow of the air volume flow B re-attaches to the outer surface 39 of the heat exchanger 35. Additionally, the reattachment region 45 is adjoined by a turbulent flow region 85, in which the flow of the air volume flow B, above the outer side 39 of the casing 38, expands again or grows over the further flow path.

[0056] Downstream of the incident-flow profile 41, there is provided a further step-like incident-flow profile 46. The further step-like incident-flow profile 46 rises, relative to the outer side 39 between the incident-flow profile 41 and the further incident-flow profile 46, outwardly in relation to the inner region 37 of the casing 38. The further incident-flow profile 46 or the area 47 thereof is impinged on by the air volume flow B and diverts the air volume flow B outward to the extent illustrated in FIG. 2. Here, the air volume flow B is diverted by the further incident-flow profile 46, which is designed substantially similarly to the incident-flow profile 41, such that, downstream of the further incident-flow profile 46, above a further outer side 48 of the casing 38, there is formed a further recirculation zone 49 with a defined length L in the flow direction, in which in turn there is situated a separation bubble 50.

[0057] The recirculation zone 49 and the separation bubble 50 are adjoined firstly in turn by a reattachment region 51 and, adjoining this, in turn, a turbulent flow region 91. The further turbulent flow region 91 extends as far as an additional incident-flow profile 52, which in turn substantially corresponds to the incident-flow profile 41. The additional incident-flow profile 52 is in turn impinged on by the air volume flow B and diverts this to the extent described in more detail above, such that, downstream of the incident-flow profile 52, in turn, there is formed a recirculation zone 53 with a separation bubble 54. Downstream of the recirculation zone 53, in turn, there is formed firstly a further reattachment region 55 and, adjoining this, a further turbulent flow region 95, which extends as far as a further incident-flow profile 56.

[0058] The heat exchanger 35 is thus formed with incident-flow profiles 41, 46, 52 and 56 which follow one another at least approximately in a stepped or staircase-like manner, in order to generate, downstream of each of the incident-flow profiles 41, 46, 52 and 56, recirculation zones 42, 49, 53, 59 and separation bubbles 43, 50, 54, 60 and, adjoining each of these, reattachment regions 45, 51, 55, 70 and, adjoining these, turbulent flow regions 85, 91, 95 and 100, which in each case improve a heat transfer coefficient.

[0059] Here, the heights of the incident-flow profiles 41, 46, 52 and 56 and also the axial spacings between the incident-flow profiles 41, 46, 52 and 56 are in the present case of equal magnitude. In a manner dependent on the respectively present usage situation, it is however also possible for the heights of the incident-flow profiles 41, 46, 52 and 56 and also the axial spacings between the incident-flow profiles 41, 46, 52 and 56 to differ from one another in each case, or to be only partially identical.

[0060] FIG. 3 shows an illustration corresponding to FIG. 2 of a further exemplary embodiment of the heat exchanger 35. The heat exchanger 35 as per FIG. 3 has substantially the same construction as the heat exchanger 35 as per FIG. 2. However, the heat exchanger 35 as per FIG. 3 is, in the region of the incident-flow profiles 41, 46, 52 and 56, formed in each case with an inlet 41A, 46A, 52A and 56A of flow channels 41B, 46B, 52B and 56B. The flow channels 41B to 56B run in the casing 38 of the heat exchanger 35 in each case in the direction of mouths 41C, 46C, 52C and 56C which are arranged at least approximately in regions of outer sides 39, 48, 57 and 58 of the heat exchanger 35 in which the recirculation zones 85, 91, 95 and 100 are respectively present.

[0061] Via the inlets 41A to 56A of the flow channels 41B to 56B, in each case one air volume flow is conducted in the direction of the mouths 41C to 56C. In the exemplary embodiment considered here, the air volume flows in the flow channels 41B to 56B are each diverted through 90° in relation to the main flow direction of the air volume flow B in the bypass duct 22 and introduced into the turbulent boundary layers or flow regions 45, 51, 55, 70 of the air volume flow B above the outer sides 39 to 58 at a defined angle α relative to the main flow direction of the air volume flow B which the air volume flow B has in particular upstream of the incident-flow profile 41. This so-called passive injection has the effect that respective further recirculation zones 46A, 49A, 53A and 59A with separation bubbles 43A, 50A, 54A and 60A form downstream of the mouths 41C to 56C. Thus, the heat transfer coefficient is further improved in each case in the region of the outer sides 39, 48, 57 and 58 of the heat exchanger 35.

[0062] Here, the defined angle α may have values between 80° and 140°.

[0063] In further embodiments of the heat exchanger, it is possible for the air volume flows in the flow channels 41B to 56B to be diverted by angular values greater than or less than 90° between the inlets 41A to 56A and the mouths 41C to 56C.

[0064] FIG. 4 shows a plan view of a region IV, indicated in more detail in FIG. 3, of the heat exchanger 35, which region comprises the incident-flow profile 56, the mouth 56C and the two recirculation zones 59 and 59A.

[0065] FIG. 5, shows, in turn, an illustration corresponding to FIG. 2 of a further exemplary embodiment of the heat exchanger 35, which in turn substantially corresponds to the heat exchanger 35 as per FIG. 2. The heat exchanger 35 as per FIG. 5 comprises respective cooling fins 61 to 64 in each case on the outer sides 39, 48, 57 and 58. The cooling fins 61 to 64 extend in each case outward in relation to the inner region 37 or the outer sides 39 to 58 of the casing 38 of the heat exchanger 35, and run at least approximately in the flow direction of the air volume flow B. Additionally, the cooling fins 61 to 64 are spaced apart from one another in the circumferential direction of the heat exchanger 35 in the manner illustrated in more detail in FIG. 6. Here, FIG. 6 shows the cooling fins 64 and a region VI, indicated in more detail in FIG. 5, in a view from above. It can be seen from the illustrations as per FIG. 5 and FIG. 6 that the recirculation zones 42, 49, 53, 59, the reattachment regions 45, 51, 55 and 70 and the turbulent flow regions 85, 91, 95 and 100 are divided in the circumferential direction of the heat exchanger 35, or in the flow direction of the oil in the casing 38, by the cooling fins 61 to 64.

[0066] FIG. 7 shows a further exemplary embodiment of the heat exchanger 35 in a schematic longitudinal sectional view. Here, the heat exchanger 35 as per FIG. 7 is formed only with the incident-flow profile 41. The recirculation zone 42 and the separation bubble 43 form, in turn, downstream of the incident-flow profile 41. The recirculation zone 42 is adjoined, in turn, by the reattachment region 45. In the reattachment region 45, there are provided first cooling fins 61, which extend in the main flow direction of the air volume flow B as far as a short distance upstream of the mouth 41C of the flow channel 41B. The air volume flow B which emerges through the mouth 41C substantially perpendicularly outward from the casing 38 in relation to the outer side 39 of the casing 38 leads, in turn, to a breakup of the boundary layer of the air volume flow B downstream of the cooling fins 61, which in turn generates a further recirculation zone 65 and a further separation bubble 66. In a further reattachment region 105, there are provided further cooling fins 67, the height of which, like the height of the cooling fins 61, is substantially constant in the main flow direction of the air volume flow B.

[0067] FIG. 8 shows a schematic three-dimensional partial view of a further exemplary embodiment of the heat exchanger 35. The heat exchanger 35 as per FIG. 8 is designed with an incident-flow profile 41, the area 44 of which encloses, with the outer side 39, an angle β which corresponds to approximately 90°. Thus, the heat exchanger 35 has an obtuse-angled edge at the transition between the area 44 and the outer side 39.

[0068] By contrast to this, the heat exchanger 35 as per FIG. 9 is formed with a rounded edge between the area 44 of the incident-flow profile 41 and the outer side 39, whereby the area 44 encloses an angle β equal to 0° with the outer side 39 in the transition region. The configuration of the heat exchanger 35 as per FIG. 8 has the effect that the recirculation zone 42 adjoining the incident-flow profile 41, and the separation bubble 43, have a greater length L than the recirculation zone 42 and the separation bubble 43 downstream of the incident-flow profile 41 of the heat exchanger 35 as per FIG. 9.

[0069] An axial spacing x in the main flow direction of the air volume flow B between the incident-flow profile 41 and the start of the cooling fins 61 is equal, in both embodiments of the heat exchanger 35 as per FIG. 8 and FIG. 9, to the product of the height H41 of the incident-flow profile 41 and a factor, which in the present case is equal to 4.5.

[0070] FIG. 10 is a three-dimensional partial view of the heat exchanger 35, the design of which substantially corresponds to the embodiment described in more detail with regard to FIG. 7.

[0071] FIG. 11, in turn, shows an illustration, corresponding to FIG. 8, of a further exemplary embodiment of the heat exchanger 35, which differs from the exemplary embodiment of the heat exchanger 35 illustrated in FIG. 8 by the fact that a height of the cooling fins 61 increases linearly in the main flow direction of the air volume flow B.

[0072] Additionally shown in FIG. 12 is a further exemplary embodiment of the heat exchanger 35, which substantially corresponds to the exemplary embodiment of the heat exchanger 35 illustrated in FIG. 10. That region of the cooling fins 61 of the heat exchanger 35 which extends between the incident-flow profile 41 and the mouth 41C in FIG. 12 is formed with a height which is constant in the main flow direction of the air volume flow B. That region of the cooling fins 69 which adjoins the mouth 41C in a downstream direction rises in the present case linearly in the main flow direction of the air volume flow B. As an alternative to this, it is in turn possible for the height of the cooling fins 67 to rise parabolically in the main flow direction of the air volume flow B.

LIST OF REFERENCE SIGNS

[0073] 9 Main axis of rotation

[0074] 10 Gas turbine engine

[0075] 11 Engine core

[0076] 12 Air inlet

[0077] 14 Low-pressure compressor

[0078] 15 High-pressure compressor

[0079] 16 Combustion device

[0080] 17 High-pressure turbine

[0081] 18 Bypass thrust nozzle

[0082] 19 Low-pressure turbine

[0083] 20 Core thrust nozzle

[0084] 21 Engine nacelle

[0085] 22 Bypass duct

[0086] 23 Fan

[0087] 26 Shaft

[0088] 27 Shaft

[0089] 30 Epicyclic gear box

[0090] 35 Heat exchanger

[0091] 36 Intermediate casing

[0092] 37 Inner region of the casing of the heat exchanger

[0093] 38 Casing of the heat exchanger

[0094] 39 Outer side of the casing

[0095] 40 Region

[0096] 41 Incident-flow profile

[0097] 41A Inlet of the flow duct

[0098] 41B Flow duct

[0099] 41C Mouth

[0100] 42 Recirculation zone

[0101] 42A Further recirculation zone

[0102] 43 Separation bubble

[0103] 43A Further separation bubble

[0104] 44 Area of the incident-flow profile 41

[0105] 45 Reattachment region

[0106] 46 Further incident-flow profile

[0107] 46A Inlet

[0108] 46B Flow duct

[0109] 46C Mouth

[0110] 47 Effective area of the further incident-flow profile

[0111] 48 Outer side of the casing

[0112] 49 Further recirculation zone

[0113] 49A Further recirculation zone

[0114] 50 Separation bubble

[0115] 50A Further separation bubble

[0116] 51 Further reattachment region

[0117] 52 Additional incident-flow profile

[0118] 52A Inlet

[0119] 52B Flow duct

[0120] 52C Mouth

[0121] 53 Recirculation zone

[0122] 53A Further recirculation zone

[0123] 54 Separation bubble

[0124] 54A Further separation bubble

[0125] 55 Further reattachment region

[0126] 56 Further incident-flow profile

[0127] 56A Inlet

[0128] 56B Flow duct

[0129] 56C Mouth

[0130] 57 Outer side

[0131] 58 Outer side

[0132] 59 Recirculation zone

[0133] 59A Further recirculation zone

[0134] 60 Separation bubble

[0135] 60A Separation bubble

[0136] 61 to 64 Cooling fins

[0137] 65 Further recirculation zone

[0138] 66 Further detachment bubble

[0139] 67 Cooling fins

[0140] 70 Reattachment region

[0141] 85, 91, 95, 100 Turbulent flow region

[0142] 105 Reattachment region

[0143] A Core flow

[0144] B Bypass flow

[0145] L Length of the recirculation zone or of the detachment bubble

[0146] H41 Height of the incident-flow profile 41

[0147] x Axial spacing

[0148] α, β Angle