ARRANGEMENTS FOR DRAWING IN AIR AND TRAPPING FOREIGN BODIES IN AN AIRCRAFT PROPULSION ASSEMBLY

Abstract

The invention relates to an arrangement, in a pod of an aircraft propulsion assembly, for drawing in air and trapping foreign bodies. Said arrangement includes a main air inlet duct (11) separating into, on one hand, a channel (13) for leading air to a compressor and, on the other hand, a bypass channel (12) capable of trapping foreign bodies (5) that enter said main duct (11). Said arrangement comprises a heat exchanger (6) that extends along a section of the bypass channel (12). Said heat exchanger (6) carries out surface heat exchange along said section and is coupled with an external oil system in order to cool the oil thereof by heat exchange with the air (4) flowing in the bypass channel (12). Said bypass channel (12) has an air outlet (12a) acting as a means for discharging the foreign bodies (5).

Claims

1. An air inlet and foreign bodies trapping arrangement in a pod of an aircraft propulsion assembly, comprising a main air inlet duct separating on the one hand into a channel for leading air to a compressor and on the other hand into a bypass channel capable of trapping foreign bodies penetrating into said main duct, wherein it includes a heat exchanger which extends along a section of the bypass channel, said heat exchanger accomplishing surface heat exchange along said section and being coupled to an external oil circuit to cool the oil therein by heat exchange with the air circulating in the bypass channel, said bypass channel having an air outlet used for discharging foreign bodies.

2. The arrangement according to claim 1, wherein the air outlet of the bypass channel is positioned in confluence with an outlet of the exhaust nozzle of the propulsion assembly, the flow of air circulating in the bypass channel being accelerated by the low pressure created by the flow of the exhaust gases at the outlet of the nozzle.

3. The arrangement according to claim 1, wherein the bypass channel being formed with a deflection with respect to the main duct, the heat exchanger is positioned in a zone of the bypass channel outside the continuation of the main duct in said bypass channel, so that a foreign body circulating in the bypass channel cannot directly impact the heat exchanger.

4. The arrangement according to claim 1, wherein the heat exchanger is a surface heat exchanger of the plate-and-fin type, and in that the fins of said plate are oriented in the direction of the flow of air which circulates in said bypass channel, so as to maximize heat exchange.

5. The arrangement according to claim 1, wherein said heat exchanger uses an internal wall of the section of said bypass channel to accomplish the heat exchange with the air circulating in the bypass channel.

6. The arrangement according to claim 5, wherein the heat exchanger consists of a pipe inside which the oil circulates, said pipe being wound along an external wall of the section of the bypass channel.

7. The arrangement according to claim 6, wherein the section of the bypass channel consists of a metallic material.

8. The arrangement according to claim 7, wherein said pipe is in close contact with and rigidly attached to the section of the bypass channel so as to reinforce the stiffness of said section, in particular in zones of said section likely to be impacted directly by foreign bodies circulating in the bypass channel, and to increase heat exchange.

9. The arrangement according to claim 8, wherein said pipe comprises a truncated tube extending in a serpentine path along the section, said tube being attached in a fluid-tight manner to the bypass channel in such a manner that the external wall of said section forms a wall of the pipe.

10. A turbine engine pod including an arrangement according to claim 1.

Description

DESCRIPTION OF THE FIGURES

[0024] Other features, aims and advantages of the present invention will appear upon reading the detailed description which follows, and referring to the appended drawings, given by way of non-limiting examples wherein:

[0025] FIG. 1 shows schematically an air inlet and bypass channel arrangement of a propulsion assembly of an aircraft according to one possible embodiment of the invention;

[0026] FIG. 2 illustrates the arrangement of the surface exchanger with respect to the trajectory of foreign bodies in the bypass channel;

[0027] FIG. 3 illustrates a preferred arrangement of the outlet of the bypass channel with respect to the outlet flow of the exhaust nozzle of the propulsion assembly of an aircraft;

[0028] FIG. 4 illustrates schematically a turboprop including an arrangement of the type of that illustrated in FIGS. 1 through 3;

[0029] FIG. 5 illustrates a variant embodiment of the surface exchanger wherein said heat exchanger consists of a pipe wound around the bypass channel;

[0030] FIG. 6 shows a particular embodiment of a surface exchanger with a channel wound around the bypass channel.

DESCRIPTION OF ONE OR MORE EMBODIMENTS

[0031] The arrangement 1 according to a first embodiment illustrated in FIG. 1 includes an air inlet duct 11 which is divided into two separate channels, on (bypass channel 12), in the lower portion, which constitutes a channel serving as a trap for foreign bodies, the other (air inlet channel 13) which provides for leading air to the compressor.

[0032] With such an arrangement, possible foreign bodies 5 which are carried by an air flow 4 which enters into the air inlet arrangement of the propulsion assembly through the duct 11, are directed toward the bypass channel 12 forming a trap and do not enter into the air inlet channel 13. The aircraft propulsion assembly is thus protected from potential damage which foreign bodies 5 can cause.

[0033] The arrangement also includes, inside the bypass channel 12, a heat exchanger 6 which is of the surface type (for example an exchanger of the “SACOC” (surface air cooler oil cooler) type) which is arranged to be flush with an internal wall of a section of said bypass channel 12.

[0034] This surface heat exchanger 6 serves to cool the oil of a lubricating oil circuit, in the case of a turbine engine for example, the oil circuit of the reduction gearbox between the compressor and the propeller. In the embodiment shown in FIG. 1, it is for example constituted of a plate with fins on the inner wall of the channel 12, at the bottom thereof. The oil circulation fins of said plate are then oriented in the direction of the air flow 4 which circulates in said bypass channel 12 so as to maximize heat exchange between the oil and the air 4.

[0035] This surface heat exchanger 6 accomplishes a surface heat exchange along the section of the bypass channel 12. In fact, the heat exchange takes place at the surface of the section which is covered by the surface heat exchanger 6, and not in the entire volume of said section. In fact, volume heat exchangers occupy the entire volume of the section of the channel in which they are situated, thus accomplishing heat exchange over the entire volume of said section, which makes them sensitive to the impacts of foreign bodies 5.

[0036] Surface heat exchange (and therefore a surface heat exchanger 6) offers the advantage of not requiring a removal flap upstream of the heat exchanger 6. The heat exchanger 6 can consequently benefit from the entire flow in the bypass channel 12 which serves as a trap for foreign bodies. Thus the cooling performance of the lubricating oil is improved. Moreover, the fact of not using a dedicated system for protecting the heat exchanger 6 from foreign bodies 5 makes it possible to simplify the structure of the arrangement 1.

[0037] In addition, given that the heat exchanger 6 is selected as a surface type, and therefore does not occupy or occupies only a small portion of the interior space of the bypass channel 12, the impacts with foreign bodies 5 are minimized, these leaving the bypass channel 12 by a single air outlet 12a which said bypass channel 12 includes.

[0038] Moreover, so as to limit the impacts of foreign bodies 5 on the heat exchanger 6, said heat exchanger 6 is placed in a zone of the bypass channel 12 which has little likelihood of being impacted directly by foreign bodies 5.

[0039] In particular, the bypass channel 12 has a dropping curvature with respect to the air inlet 11 and the surface heat exchanger 6 is situated in the bottom of this dropping curvature, so as not to be in the direct continuation of the air inlet duct 11.

[0040] In FIG. 2, the chain-dotted lines 7 show schematically the continuation of said inlet duct 11 and the general direction of the flow of air 4 when it enters into the bypass channel 12 forming a trap for foreign bodies. The zone 8a below this air flow is a zone protected from impacts by foreign bodies 5, while the zone 8b between the lines 7 is, for its part, impacted directly by said foreign bodies 5.

[0041] With such an arrangement where the heat exchanger 6 is placed in the zone protected from impacts 8a, in the portion located outside the continuation lines 7 of the air inlet 11, the foreign bodies 5 cannot directly impact the heat exchanger 6.

[0042] Moreover, as illustrated in FIG. 3, so as to increase the flow speed of cooling inside the bypass channel 12 forming a trap for foreign bodies 5, the air outlet 12a thereof is provided not at the body of the exhaust nozzle 9, but in confluence with the outlet 9a of the nozzle 9 of the propulsion assembly.

[0043] In this manner, the air flow leaving the outlet 9a of the nozzle 9 creates a vacuum at the air outlet 12a of the bypass channel 12 and the air flow 4 circulating in the bypass channel 12 is accelerated by the outlet flow of the nozzle 9 thanks to an effect of the “jet ejector” type.

[0044] Thus, the flow in the channel 12 has a constant high speed which ensures effective cooling of the oil at the heat exchanger 6, including during phases wherein the airplane is at low speed.

[0045] As will have been understood, and as illustrated in FIG. 4, an arrangement of the type of that which has just been described is advantageously utilized within the framework of a turboprop. That is what FIG. 4 illustrates, on which has been shown a turboprop TP including a propeller H, as well as a reducer R and its oil circuit C. This oil circuit is cooled there by a surface heat exchanger 6 positioned on the inner wall of the bypass channel 12.

[0046] According to a variant embodiment, which can be accomplished for example by an arrangement like that illustrated in FIG. 5, the surface heat exchanger 6 uses an internal wall of the section of said bypass channel 12 to accomplish the heat exchange with the air 4 circulating in the bypass channel 12. More precisely, in this variant, the heat exchange between the air 4 and the heat exchanger 6 occurs at the inner wall of the section in which the heat exchanger is positioned.

[0047] According to a variant embodiment illustrated in FIG. 5, the heat exchanger 6 can consist of a pipe 60 which is wound in the form of a serpentine along an outer wall of a section of the bypass channel 12. The lubricating oil which is to be cooled circulates inside the pipe 60, thus forming a cooling surface 7 which covers the perimeter of the section on which the pipe 60 is wound. Thus, the heat exchanger 6 according to such a variant accomplishes surface heat exchange along the section of the bypass channel 12.

[0048] In the variant illustrated in FIG. 5, the heat exchanger 6 is such that the heat exchange with the air 4 is accomplished through an inner wall of the section of the bypass channel 12.

[0049] In order to improve heat exchange between the oil circulating in the pipe 60 and the air 4 circulating inside the bypass channel 12, the section of the bypass channel 12 consists of a metallic material.

[0050] According to an advantageous feature, the pipe 60 is in close contact with and rigidly attached to the section of the bypass channel 12, thus making it possible, on the one hand, to increase heat exchange between the oil and the air 4, and on the other hand to reinforce the stiffness of the section of the bypass channel 12, in particular in the zones of said section which are likely to be impacted directly by foreign bodies 5.

[0051] The advantage of such a variant is that the heat exchanger 6 is not positioned inside the bypass channel 12, and thus that the heat exchanger 6 is much less vulnerable to foreign bodies 5. Moreover, the heat exchanger 6 does not perturb the air flow 4 that circulates inside the bypass channel 12.

[0052] According to a particular embodiment of the variant of the heat exchanger 6 using a pipe 60 wound around the bypass channel 12 which is presented in FIG. 6, the pipe 60 comprises a truncated tube 61 which is attached in a fluid-tight manner on the section of the bypass channel 12 along a serpentine path, so as to form a cavity wherein circulates the lubricating oil to be cooled. Thus, the lubricating oil circulates between the truncated tube 61 and the section of the bypass channel 12, and the external wall of said section forms a wall of the pipe 60.

[0053] More precisely, the truncated tube 61 is a hat-shaped wall the concavity whereof is directed toward the bypass channel 12, so as to form the cavity wherein circulates the lubricating oil to be cooled.

[0054] The truncated tube 61 can be attached to the bypass channel 12 by welding or by riveting, and with seals.

[0055] It is understood that the invention is applicable not only to turboprops but also to other types of turbine engines. In particular, the invention is of interest in turbine engines with un-ducted contra-rotating propellers, also called “open rotor,” and more particularly in architectures called “puller,” that is those wherein the dual contra-rotating propellers are positioned ahead of the engine.