阅读说明：本技术 用于飞行器的热交换器 (Heat exchanger for an aircraft ) 是由 保罗·皮萨尼 费代里科·蒙塔尼亚 斯特凡诺·波吉 于 2019-07-26 设计创作，主要内容包括：描述了一种用于飞行器(1)的传动装置的热交换器(10),该热交换器包括：限定用于待冷却的第一流体的第一供给路径(P)的第一模块(23)；限定用于第二冷却流体的第二供给路径(T)的第二模块(33)；第一供给路径和第二供给路径彼此热耦合；每个第二模块(33)包括：由用于第二冷却流体的入口(39)形成的至少一个单元(45)；用于第二冷却流体的出口(40),该出口沿着第一方向(X)布置在与入口(39)相对的一侧上；热耦合至第一路径(P)的第一壁(35)；一对第二壁(36a、36b)；以及从第一壁(35)以悬臂的方式突出的多个散热片(55)。热交换器(10)还包括散热片(55)的至少第一排(61),该第一排的散热片位于与第一方向(X)正交的平面上,第一排(62)的散热片(55)沿着与第一方向(X)正交的第二方向(Y)从第二壁(36a、36b)中的一个第二壁(36a)以逐渐增加的距离延伸。(A heat exchanger (10) for a transmission of an aircraft (1) is described, comprising: a first module (23) defining a first supply path (P) for a first fluid to be cooled; a second module (33) defining a second supply path (T) for a second cooling fluid; the first supply path and the second supply path are thermally coupled to each other; each second module (33) comprises: at least one cell (45) formed by an inlet (39) for a second cooling fluid; an outlet (40) for the second cooling fluid, arranged on the opposite side to the inlet (39) along the first direction (X); a first wall (35) thermally coupled to the first path (P); a pair of second walls (36a, 36 b); and a plurality of fins (55) projecting in a cantilevered manner from the first wall (35). The heat exchanger (10) further comprises at least a first row (61) of fins (55), the fins of the first row lying on a plane orthogonal to the first direction (X), the fins (55) of the first row (62) extending at a gradually increasing distance from one (36a) of the second walls (36a, 36b) along a second direction (Y) orthogonal to the first direction (X).)

1. A heat exchanger (10) for a transmission of an aircraft (1), the heat exchanger comprising:

-a first module (23) defining a first feed path (P) for a first fluid to be cooled;

-a second module (33) defining a second feed path (T) for a second cooling fluid; said first supply path (P) and said second supply path (T) being thermally coupled to each other in use;

each of said second modules (33) comprises at least one cell (45) formed by:

-an inlet (39) for a second cooling fluid;

-at least one outlet (40) for the second cooling fluid, arranged along a first direction (X) on the opposite side to the inlet (39);

-at least one first wall (35) thermally coupled to said first path (P);

-a pair of second walls (36a, 36b) transversal to said first wall (35);

-a plurality of fins (55) projecting in a cantilevered manner from said first wall (35) and adapted to increase, in use, the heat exchange between said second cooling fluid and said first wall (35); and

-at least a first row (61) of said fins (55), said fins (55) of said first row (61) lying on a plane orthogonal to said first direction (X);

-said fins (55) of said first row (62) extend at progressively increasing distances from one (36a) of said second walls (36a, 36b) along a second direction (Y) orthogonal to said first direction (X) when going from said inlet (39) to said at least one outlet (40) along said first direction (X);

characterized in that said unit (45) comprises at least a second row (62) of said fins (55);

the fins (55) of the second row (62) extend at a gradually increasing distance from the other one (36b) of the second walls (36a, 36b) along the second direction (Y).

2. A heat exchanger according to claim 1, wherein the fins (55) are spaced apart along the first direction (X) and form a plurality of channels (56) extending along the second direction (Y).

3. A heat exchanger according to claim 1 or 2, wherein the fins (55) of the first row (61) that are mutually adjacent along the first direction (X) partially overlap along the second direction (Y).

4. Heat exchanger according to claim 2 or 3, wherein the sum of the areas of the sections of said channels (56) orthogonal to said second direction (Y) is greater than the area of said inlet (39).

5. The heat exchanger according to any of the preceding claims, wherein the unit (45) comprises at least two of the outlets (40);

the first row (61) and the second row (62) defining between them a first chamber (52) delimited by the inlet (39);

one (36a) of said second walls (36a, 36b) and said first row (61) defining a second chamber (53) delimited by one said outlet (40);

the other (36b) of said second walls (36a, 36b) and said second row (62) defining a third chamber (53) bounded by the other said outlet (40);

said first chamber (52) and said second chamber (53) being in fluid communication with each other via a first said passage (56) defined between respective mutually adjacent first fins (55) of said first row (61);

the first chamber (52) and the third chamber (53) being in fluid communication with each other via a second said passage (56) defined between respective mutually adjacent first fins (55) of the second row (62).

6. The heat exchanger according to claim 5, characterized in that the first row (61) and the second row (62) of units (45) converge with each other when going from the inlet (39) to the outlet (40).

7. Heat exchanger according to any one of the preceding claims, wherein said second module (33) comprises a plurality of said units (45) placed side by side along said second direction (Y).

8. Heat exchanger according to any one of the preceding claims, wherein said units (45) have a diamond-shaped perimeter in a section orthogonal to said first direction (X).

9. The heat exchanger according to claim 8, characterized in that said first wall (35) and one of said second walls (36a, 36b) form an acute angle (a) smaller than 45 degrees.

10. The heat exchanger of any of the preceding claims, wherein the heat exchanger is made in one piece.

11. The heat exchanger of any preceding claim, wherein the heat exchanger is manufactured using additive manufacturing techniques.

12. The heat exchanger according to any of the preceding claims, wherein the first fluid is a liquid, in particular an oil, and the second fluid is a gas, in particular air.

13. A helicopter (1) comprising:

-a power plant;

-a rotor;

-a transmission (3) operatively interposed between said power unit and said rotor;

-a lubrication circuit of said transmission (3); and

-a heat exchanger (10) according to any of the preceding claims, connected to the lubrication circuit.

14. A method of cooling a first fluid to be cooled by means of heat exchange with a second cooling fluid of an aircraft (1), the method comprising the steps of:

i) -feeding said first fluid to be cooled along a first path (P);

ii) supplying the second cooling fluid along a second path (T) thermally coupled to the first path (P);

-said second path (T) comprises at least one inlet (39) and at least one outlet (40), said at least one inlet (39) and said at least one outlet (40) being arranged along a first direction (X) at two ends opposite each other and being delimited by at least one wall (35) thermally coupled to said first path (P) and by a pair of second walls (36a, 36b) transversal to said first wall (35);

the step ii) comprises the following steps:

iii) feeding said second cooling fluid through said inlet (39) with a main component of motion parallel to said first direction (X);

iv) striking a plurality of fins (55) projecting in a cantilevered manner from the first wall (35) with the second cooling fluid;

v) feeding said second cooling fluid through said outlet (40) with a main component of motion parallel to said first direction (X);

characterized in that the method comprises the following steps:

vi) supplying said second cooling fluid along said second direction (Y) and through a plurality of channels (56) defined between said mutually adjacent fins (55) of the first row (61) and mutually adjacent fins (55) of the second row (62); and

vii) slowing down the second fluid during said step vi) and at the end of said step iii);

-said fins (55) of said first row (61) extend at progressively increasing distances from one (36a) of said second walls (36a, 36b) along a second direction (Y) orthogonal to said first direction (X) when going from said inlet (39) to said outlet (40) along said first direction (X);

the fins (55) of the second row (62) extend at a gradually increasing distance from the other one (36b) of the second walls (36a, 36b) along the second direction (Y).

Technical Field

The invention relates to a heat exchanger for an aircraft, in particular a helicopter.

More specifically, the heat exchanger is a liquid-to-air heat exchanger, in the case shown an oil-to-air heat exchanger.

Background

As is known, helicopters are generally equipped with a plurality of transmissions adapted to transmit, for example, the driving force from one or more turbines to the main and/or tail rotors and/or from the turbines to a plurality of auxiliary devices (i.e. distribution) to provide the power required for the operation of the flight instruments.

In a known manner, a lubricating fluid, usually oil, circulates inside the transmission to lubricate the moving parts of the transmission and to cool them.

To ensure the effectiveness of lubrication and cooling, it is necessary to cool the lubricating fluid circulating inside the transmission.

To this end, helicopters are equipped with a cooling system essentially comprising:

-a heat exchanger for heat exchange between the oil of the transmission and the air circulating inside the cooling system; and

-a fan adapted to create air circulation from the heat exchanger to the fan.

In a known solution, the heat exchanger comprises:

-an oil delivery circuit extending from the first inlet station to the first outlet station; and

-an air delivery circuit extending from the second inlet station to the second outlet station.

In particular, the oil has a first temperature value at the first inlet station and a second temperature value lower than the first temperature value at the first outlet station.

Instead, the air has a third temperature value at the second inlet station and a fourth temperature value higher than the first temperature value at the second outlet station.

In other words, the oil outputs heat into the air, cooling itself inside the heat exchanger, while the air heats up at the same time.

The heat exchangers of known type also comprise a plurality of modules, each formed by:

-walls struck by oil and air on respective mutually opposite faces;

-a plurality of first fins facing the inside of the oil delivery circuit and projecting in a cantilevered manner from the first face; and

-a plurality of second fins facing the inside of the air delivery circuit and projecting in a cantilevered manner from the second face.

In particular, the second fin extends perpendicular to the wall and has a length along a first direction from the second inlet station to the second outlet station.

The second fins are also arranged to form adjacent rows along the first direction.

The second fins of the mutually adjacent rows are staggered in a second direction orthogonal to the first direction.

In particular, the fins of each row are arranged on the intermediate section of the immediately adjacent row.

Due to the above configuration, the air is partially heated at the end of each row, thereby reducing the remaining heat exchange capacity of the air.

More specifically, the peripheral area of the portion of the air flow that hits the second heat sink becomes hot by heat conduction, while the central area of the portion becomes hot when it hits the second heat sink of the next row.

This local heating is repeated at the end of each row until a condition is reached where the air reaches substantially the same temperature as the second fin of the row with which it impinges. In this case, there is substantially no heat exchange between the air and the second fin, and therefore, the oil is not cooled.

Thus, it has been recognized in the industry that for the same heat exchanger weight and the same pressure drop between the second inlet section and the second outlet section, there is a need to optimize the heat exchange between the air and the oil.

Furthermore, heat exchangers of known type are made by brazing, i.e. by welding the various components together.

The use of this technique defines constraints on the shape and configuration achievable with the first and second heat sinks.

It is also recognized in the industry that there is a need to provide a heat exchanger that is particularly flexible in terms of the shape and arrangement of the first and second fins.

US2016/0115864, EP-B-2712805, FR-A-29988822 and WO2016/018498 describe heat exchangers for aircraft of known type.

GB-a-2496692 discloses a heat exchanger according to the preamble of claim 1.

Disclosure of Invention

The object of the present invention is to provide a heat exchanger for an aircraft which satisfies at least one of the above-identified needs in a simple and inexpensive manner.

The above object is achieved by the present invention in that it relates to a heat exchanger for a transmission of an aircraft according to claim 1.

The invention also relates to a method of cooling a first fluid to be cooled by means of heat exchange with a second cooling fluid inside an aircraft according to claim 14.

Drawings

For a better understanding of the invention, preferred embodiments are described below, by way of non-limiting example only, with reference to the accompanying drawings, in which:

figure 1 is a partially exploded perspective view of a helicopter comprising a heat exchanger made according to the teachings of the present invention;

fig. 2 is a highly enlarged front view of the heat exchanger of fig. 1, with some parts removed for clarity;

figure 3 is an exploded perspective view of the heat exchanger of figures 1 and 2, with some parts removed for clarity;

figure 4 is a cross-sectional view along the line IV-IV of figure 2; and

FIG. 5 is a section along the line V-V of FIG. 2.

With reference to fig. 1, reference numeral 1 denotes a helicopter (not fully shown) comprising a pair of turbines, a main rotor and a tail rotor.

Detailed Description

Helicopter 1 further comprises:

a main transmission 3 adapted to transmit power from the turbine to a mast 4 driving the main rotor; and

a plurality of auxiliary transmissions 6, known per se and only schematically illustrated, suitable for transmitting (i.e. distributing) the power coming from the main transmission 3, for example, to provide the power required to operate the drive shaft 5 of the respective on-board equipment or tail rotor.

Helicopter 1 further comprises:

a heat exchanger 10 for cooling the lubricating fluid, in the case illustrated as oil, circulating inside the transmission 3; and

a fan 11 (only schematically shown in fig. 1) adapted to generate air circulation through the heat exchanger 10.

In the case shown, the heat exchanger 10 is a gas-liquid heat exchanger, in particular an air-oil heat exchanger.

In other words, the heat exchanger 10 effects heat exchange between the cooled oil stream and the heated air stream.

In the figure, the flow of the oil to be cooled and the flow of the air heated after heat exchange with the oil are indicated by respective grey arrows.

In contrast, the flow of the oil cooled after heat exchange with the air and the flow of the cool air are indicated by the respective white arrows.

The heat exchanger 10 basically comprises:

-an oil feed circuit 20; and

an air supply circuit 30.

The circuit 20 in turn comprises:

an inlet 21 for oil to be cooled;

an outlet 22 for cooled oil; and

a plurality of oil feeding modules 23 (fig. 2, 3 and 5) fluidly connected to the inlet 21 and the outlet 22.

The circuit 30 in turn comprises:

an inlet 31 for air still to be heated, fluidly connected to the fan 9;

an outlet 32 for heated air, fluidly connected to the fan 9; and

a plurality of air supply modules 33 (fig. 2 to 4) fluidly connected to the inlet 31 and the outlet 32.

Referring to fig. 2 and 3, the modules 23 and 33 alternate with each other along the direction Z and are elongated along the direction Y orthogonal to the direction Z.

The oil flows inside each module 23 along a respective U-shaped path P formed by a pair of delivery sections Q and return sections R, both parallel to direction Y (fig. 5).

Each path P also includes a section S between sections Q and R.

Referring to fig. 3 and 5, each module 23 comprises an inlet section 24 fluidly connected to the inlet 21 and an outlet section 25 fluidly connected to the outlet 22.

Each module 23 comprises:

a pair of parallel walls 26 opposite each other along direction X and lying on respective planes orthogonal to direction X;

walls 27 interposed between walls 26, walls 27 being opposite sections 24 and 25 along direction Y and lying on a plane orthogonal to direction Y.

A divider 28 orthogonal to wall 27, extending from sections 24 and 25 towards wall 27 along the Y direction and spaced apart from wall 27; and

a pair of walls 29 extending between the walls 26 and between the walls 27 and the sections 24 and 25.

In particular, the walls 29 are opposite each other and orthogonal to the direction Z.

The divider 28 is also parallel to the wall 26.

Each module 23 also comprises a plurality of fins 15 elongated along direction Z and extending between walls 29.

The divider 28, the wall 29 and the portion of the wall 26 that delimits the section 24 of each module 23 delimit a conveying branch Q of the path P of the oil inside the module 23.

The divider 28, the wall 29 and the portion of the wall 26 that delimits the section 25 of each module 23 delimit the return branch R of the path P of the oil inside the module 23.

The divider 28, the wall 27, the wall 29 and the portion of the wall 26 immediately adjacent to the wall 27 define a curved branch S of the path P.

The fins 15 are arranged in the section S with a lower density with respect to the branches Q and R so as not to obstruct the tortuous path of the oil inside the relative module 23.

The inlet 31 and the outlet 32 of the circuit 30 are opposite to each other along the direction X.

Referring to fig. 2 to 4, each module 33 includes:

a pair of parallel walls 35 opposite each other along direction Z, lying on respective planes orthogonal to direction Z, and thermally coupled to respective walls 29 of modules 23 immediately adjacent to each other along direction Z;

a plurality of walls 36a and 36b extending between the walls 35 and along the direction X; and

a pair of mutually opposite and parallel walls 37 and 38, which lie on respective planes orthogonal to direction X and define a plurality of respective air inlets 39 and outlets 40 spaced along direction Y.

In particular, the walls 29 and 35 of the respective modules 23 and 33, which are mutually adjacent along the direction Z, are superimposed on one another.

Each module 33 defines a plurality of cells 45, these cells 45 being placed side by side along direction Y and having an extension mainly extending along direction X.

Each cell 45 is bounded by:

a pair of walls 36a and 36b parallel to each other and opposite along direction X;

respective sections of a pair of walls 35 along direction Z; and

respective sections of walls 37 and 38 extending between respective walls 36a and 36 b.

Each cell 45 further comprises:

an inlet 39 defined by a respective section of the wall 37; and

a pair of air outlets 40 defined by respective sections of the wall 38.

The inlet 39 and outlet 40 of each cell 45 are fluidly connected to the inlet 31 and outlet 32 of the circuit 30, respectively.

The modules 33 also comprise a plurality of fins 55 interposed between the walls 36 and adapted to assist the heat exchange between the air flowing in each module 33 and the oil flowing in the module 23 immediately adjacent to the module 33.

Advantageously, each unit 45 comprises a row 61 of fins 55, the fins of which lie on respective planes orthogonal to direction X; the fins 55 of the row 61 extend at progressively increasing distances from the wall 36a along the direction Y as they pass along the direction X from the respective inlet 39 to the respective outlet 40.

Each cell 45 also includes a row 62 of further fins 55, which further fins 55 extend in the Y direction at progressively increasing distances from the wall 36b as one moves in the X direction from the respective inlet 39 to the respective outlet 40.

The rows 61 and 62 of fins 55 of each unit 45 converge towards each other when going parallel to the direction X from the respective inlet 39 to the respective outlet 40.

Each cell 45 defines:

a chamber 52 delimited by the relative inlet 39 and the relative rows 61, 62; and

a pair of chambers 53, each chamber 53 being delimited by a relative wall 36a, a relative row 61 or 62 and a relative segment 51. The fins 55 of each cell 45 extend between the relative walls 35 along the direction Z.

The fins 55 of each cell 45 have a thickness along the X-direction and a length along the Y-direction.

In particular, mutually adjacent fins 55 of each unit 45 are spaced apart along direction X by respective air channels 56.

Mutually adjacent fins 55 along the direction X of the same row 61 and 62 partially overlap each other along the direction Y.

Passage 56 fluidly communicates chamber 52 with chamber 53.

Each channel 56 extends along direction Y, is open at its opposite end with respect to direction Y, and is closed along directions X and Z.

Thanks to this configuration, the air flows inside each module 33 along a path T comprising (fig. 4):

a section U substantially parallel to direction X and described inside chamber 52 starting from inlet 39;

a section V substantially parallel to direction Y and described inside channel 56;

a section W substantially parallel to direction X and described starting from inside chamber 53 to respective outlet 40.

The sum of the areas of the sections of the channels 56 orthogonal to the direction Y is greater than the area of the inlet 39 of each cell 45.

As a result, the air slows as it flows from the chamber 52 to the channel 56 and strikes the fins 55 along the section V of the respective path T.

The area of each outlet 40 is less than the area of the associated inlet 39.

In the case shown, the perimeter of each cell 45 in a section orthogonal to direction X is diamond-shaped.

In particular, wall 35 and walls 36a and 36b defining each cell 45 form an acute angle α (fig. 2) therebetween of less than 45 degrees.

Furthermore, the heat exchanger 10 is made in one piece.

In particular, the heat exchanger 10 is made of aluminum.

In the illustrated case, the heat exchanger 10 is manufactured using additive manufacturing techniques.

In particular, the printing direction of the heat exchanger 10 is parallel to the direction Y.

In use, operation of the transmission 3 causes overheating of the lubricating oil it contains.

The heat exchanger 10 performs heat exchange between the air flow and the lubricating oil, thereby cooling the lubricating oil.

In more detail, the oil enters the heat exchanger 10 through an inlet 21, follows the circuit 20 inside the module 23 and leaves the heat exchanger 10 through an outlet 22.

Inside each module 23, the oil flows from relative section 24 along branches Q, R and S of relative path P until it reaches relative section 25, and from there returns through outlet 22.

Due to the presence of the fins 15, the oil gives off heat to the wall 29 when it flows inside the module 23.

At the same time, after the operation of the fan 11, the still cold air enters the heat exchanger 10 through the inlet 31, follows the circuit 30 inside the module 33 and leaves the heat exchanger 10 in a heated state through the outlet 32.

Inside each module 33, the air flows along a respective path T inside the relative cell 45 between the respective inlet 39 and the respective outlet 40.

In addition, air strikes the fins 55 of rows 61 and 62 of each module 33.

These fins 55 extend from the relative wall 29 and are therefore heated by the oil flowing in the module 23 adjacent to each module 33.

In other words, heat is transferred by the oil in each module 23 to the fins 15 and the wall 29, from the wall 29 to the fins 55, and from the fins 55 to the air flowing in the module 33 adjacent to the above-mentioned module 23.

In more detail, the still cold air flows inside each module 33 first along the section U of the relative path T inside the chamber 52 with a main component of velocity substantially parallel to the direction X.

The air is then diverted and flows in the channels 56 between the fins 55 along the section V of the relative path T with a main component of velocity substantially parallel to the direction Y.

In this case, the air is slowed down, thereby improving the heat exchange efficiency with the heat radiation fins 55.

Finally, the air is again diverted and flows in the chamber 53 of each module 33 along the section W of the relative path T with a main component of velocity substantially parallel to the direction X, until it leaves the module 23 through the section 52.

The heated air then flows from section 51 to outlet 32.

The advantages that can be achieved thereby are evident by examining the heat exchanger 10 and the cooling method implemented according to the present invention.

In particular, the fins 55 of the rows 61 and 62 lie on respective planes orthogonal to the direction X and extend at progressively increasing distances from the respective walls 36a and 36b along the direction Y, when going from the relative inlet 39 to the relative outlet 40 along the direction X.

As a result, the trajectory of each air particle flowing from the inlet 39 to one of the outlets 40 passes through a single passage 56 and strikes a single heat sink 55.

It follows that, contrary to what happens in the previously described known solutions, the air is substantially always at a temperature lower than that of the heat sink 55 it strikes.

This further improves the efficiency of the heat exchange between oil and air with respect to the known solutions described at the beginning of the present description, for the same weight of the heat exchanger 10 and the same pressure drop of the air between the inlet 31 and the outlet 32.

Furthermore, the sum of the areas of the cross sections orthogonal to the direction Y of the channel 56 is greater than the area of the inlet 39 of each cell 45.

As a result, the air not only turns, but also slows down as it hits the heat sink 55.

This further improves the efficiency of the heat exchange between the oil and the water with respect to the known solutions described at the beginning of the present description, for the same weight of the heat exchanger 10 and the same pressure drop of the air between the inlet 31 and the outlet 32.

Finally, the unit 45 is free of undercuts, so that the heat exchanger 10 is suitable for being made in one piece using a technique known as additive manufacturing. This technique is particularly flexible with respect to the possibility of manufacturing differently shaped heat sinks 55.

Finally, it is clear that modifications and variants can be made to the heat exchanger 10 and to the cooling method described and illustrated herein, without departing from the scope defined by the claims.

In particular, each cell 45 may include only one of rows 61 and 62 of fins 55.

Module 33 may be formed of a single unit 45 rather than a plurality of units 45.

The transmission 3 may be a transmission 6. The heat exchanger 10 may be applied to other types of aircraft than the helicopter 1, for example, a thrust reverser aircraft or an airplane.