Surface heat-exchanger for a cooling system of an aircraft turbojet engine

Abstract

A surface heat-exchanger for a turbojet engine nacelle between a fluid (C) to be cooled down and air (F) includes a circulation duct of the fluid (C) to be cooled down disposed in contact with air. The circulation duct includes a plurality of channels extending substantially in the same direction with a distance (D) between two adjacent channels between two and five times the width (L) of the channels, each channel having a wall with an area intended to be in contact with air and an area opposite to the area intended to be in contact with air.

Claims

1. A surface heat-exchanger for a turbojet engine nacelle, between a fluid to be cooled down and air, the surface heat-exchanger comprising a circulation duct of the fluid to be cooled down disposed in contact with the air, the circulation duct comprising a plurality of channels, each channel of the plurality of channels having a width between 5 and 50 mm, the plurality of channels extending in a common direction with a distance between two adjacent channels between two and five times the width of one of the plurality of channels, wherein each channel of the plurality of channels has a wall comprising an area in contact with the air and an area opposite to the area that is in contact with the air, wherein the width of each channel of the plurality of channels is variable from one channel to another, and wherein the distance between two adjacent channels is between two to five times a maximum width of each channel of the plurality of channels.

2. The surface heat-exchanger according to claim 1, wherein the wall of each channel of the plurality of channels has a thickness between 0.6 and 4 mm.

3. The surface heat-exchanger according to claim 1, wherein at least the area in contact with the air has a thickness between 1.5 and 4 mm.

4. The surface heat-exchanger according to claim 1, wherein each channel of the plurality of channels has a semi-circular shaped section or triangular-shaped section.

5. The surface heat-exchanger according to claim 1, wherein the fluid to be cooled down is a heat-transfer fluid that is less flammable than a lubricant of a turbojet engine, the heat-transfer fluid being a liquid at temperatures between −70° C. and +175° C.

6. The surface heat-exchanger according to claim 5, wherein the heat-transfer fluid is nonflammable at temperatures between −70° C. and +175° C. at a pressure of 10 bars.

7. The surface heat-exchanger according to claim 5, wherein the heat-transfer fluid is a 3-Ethoxyperfluoro(2-methylhexane).

8. A cooling system comprising: a surface heat-exchanger according to claim 1, wherein the surface heat-exchanger is a cold source heat-exchanger; and a hot source heat-exchanger between a lubricant to be cooled down and the fluid being cooled down in the cold source heat-exchanger.

9. A turbojet engine nacelle comprising: an outer structure and an inner structure defining an annular flow path for a secondary cold air flow, the outer structure comprising an outer fairing defining an outer aerodynamic surface and an inner fairing defining an inner aerodynamic surface, the outer and inner fairings being connected upstream by a leading edge wall forming an air inlet lip; and a surface heat-exchanger according to claim 1.

10. The turbojet engine nacelle according to claim 9, wherein the circulation duct comprises at least one circulation area of the fluid to be cooled down formed by a double-wall of the outer fairing or the inner fairing of the turbojet engine nacelle.

11. The surface heat-exchanger according to claim 1, wherein the width of each channel of the plurality of channels is between 6 and 20 mm.

12. The surface heat-exchanger according to claim 1, wherein the width of each channel of the plurality of channels is between 10 and 15 mm.

13. The surface heat-exchanger according to claim 1, wherein at least the area opposite to the area in contact with the air is made of aluminum.

Description

DRAWINGS

(1) In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

(2) FIG. 1 is a schematic view of a nacelle of an aircraft turbojet engine comprising a surface heat-exchanger according to the present disclosure;

(3) FIG. 2 is a schematic view of a cooling system comprising a surface heat-exchanger according to the present disclosure;

(4) FIG. 3 is a schematic view of a portion of the nacelle of FIG. 1, comprising the surface heat-exchanger according to the present disclosure;

(5) FIG. 4 is a schematic longitudinal sectional view of FIG. 3, the nacelle portion being represented as planar; and

(6) FIG. 5 is a schematic view of a variant of the nacelle portion of FIG. 4.

(7) The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

(8) The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

(9) In the following description and in the claims, identical, similar or analogous components will be referred to by the same reference numerals and the terms “upstream,” “downstream,” etc. will be used in a non-limiting manner and with reference to the drawings in order to facilitate the description.

(10) FIG. 1 illustrates a nacelle 100 hanging from a pylon 102 intended to be fastened to a wing (not represented) of an aircraft (not represented). The nacelle 100 comprises an outer structure 103 comprising an upstream section 104 provided with a lip 106 forming an air inlet 108, a middle section 110, and a downstream section 112.

(11) The nacelle further comprises an inner fixed structure 114 surrounding a downstream portion of a turbojet engine (not represented) concentrically with respect to the downstream section 112. The inner fixed structure 114 and the outer structure 103 delimit an annular flow path 115 defining a passage for a secondary cold air flow (not represented).

(12) The nacelle 100 also comprises an ejection conduit 116 comprising a gas ejection plug 118 and a gas ejection nozzle 120. The ejection plug 118 and the ejection nozzle 120 define a passage for a hot air flow (not represented) coming out of the turbojet engine (not represented) 200.

(13) The outer structure 103 comprises an outer fairing 103a defining an outer aerodynamic surface, and an inner fairing 103b defining an inner aerodynamic surface, the outer 103a and inner 103b fairings being connected upstream by a leading edge wall (not represented) forming the air inlet 108 lip 106.

(14) The nacelle comprises a so-called cold source surface heat-exchanger 12 (FIG. 2) between a heat-transfer fluid C (FIG. 2) to be cooled down and a cold air flow F (FIG. 2).

(15) The cold source surface heat-exchanger 12 is disposed within the outer structure 103. It is intended to cooperate with a so-called hot source heat-exchanger 14 (FIG. 2) between an engine lubricant H (FIG. 2) to be cooled down and the heat-transfer fluid C, via a circulation duct 15 (FIG. 2) of the heat-transfer fluid C.

(16) The hot source heat-exchanger 14 is disposed within the turbojet engine (not represented).

(17) The assembly formed by the cold source heat-exchanger 12 and the hot source heat-exchanger 14 forms a cooling system 10 (FIG. 2) of the engine lubricant H.

(18) FIG. 2 illustrates the cooling system 10 of the engine lubricant H.

(19) The cooling system 10 comprises the cold source heat-exchanger 12 and the hot source heat-exchanger 14.

(20) The heat-transfer fluid C circulates in the circulation duct 15 and in the cold source heat-exchanger 12 where it is cooled down by cold air F. The heat-transfer fluid C thus cooled down then circulates in the hot source heat-exchanger 14 where it is heated up by the engine lubricant H.

(21) Thus, the heat-transfer fluid C cooled down by the cold source heat-exchanger allows cooling down the engine lubricant H.

(22) The heat-transfer fluid C is intended to circulate both in the cold source heat-exchanger 12 and in the hot source heat-exchanger 14.

(23) A pump P enables the circulation of the heat-transfer fluid C between the cold source heat-exchanger 12 and the hot source heat-exchanger 14.

(24) An expansion vessel 17 allows accommodating the variation of the volume of the heat-transfer fluid C by the effect of temperature.

(25) The expansion vessel 17 includes a closed tank. Thus, the pressure in the expansion vessel 17 is directly related to the volume occupied by the heat-transfer fluid in the expansion vessel. This feature advantageously allows controlling a maximum and/or minimum pressure in some portions of the circulation duct 15 of the heat-transfer fluid by only tuning the capacity (volume) of the expansion vessel 17.

(26) The expansion vessel 17 is filled with the heat-transfer fluid C and with a volume devoid of heat-transfer fluid, called gaseous sky, which serves as a buffer. It allows limiting the pressure in the circulation duct 15 of the heat-transfer fluid during the expansion of the fluid according to the temperature.

(27) The expansion vessel 17 is a pressurizing means.

(28) FIG. 3 illustrates the outer fairing 103a at the level of the downstream section 112 of a nacelle 100 (FIG. 1) comprising a cold source heat-exchanger 12.

(29) The cold source heat-exchanger 12 comprises a plurality of channels 16 disposed in parallel, in which the heat-transfer fluid C circulates (FIG. 2). The channels 16 are disposed in contact with the outer fairing 103a.

(30) The outer fairing 103a being in contact with a cold outside air flow, the heat exchange is carried out by convection with the cold outside air flow.

(31) In one variant that is not represented, the cold source heat-exchanger 12 is disposed in contact with the outer fairing 103a at the level of the upstream 104 or middle 110 section of the nacelle 100 (FIG. 1).

(32) FIG. 4 shows that the channels 16 are formed by a double-wall 18, 20 of the outer fairing 103a. Thus, the heat-exchanger 12 forms at least partially the outer fairing 103a. This is referred to as structural heat-exchanger.

(33) The double-wall 18, 20 comprises an area 18 intended to be in contact with outside air and an area 20 opposite to the area 18 intended to be in contact with outside air. The area 18 intended to be contact with outside air is smooth. This is referred to as aerodynamic surface. The opposite area 20 is corrugated.

(34) The channels 16 have a semi-circular shaped section and a width L in the range of 10 mm, and the distance D between the channels 16 is in the range of 30 mm.

(35) Thus, the distance D between the channels 16 is comprised between twice and five times the width L of said channels 16.

(36) Each wall 18, 20 of the channels 16 has a thickness E in the range of 2 mm. In this manner, the area 18 intended to be in contact with outside air is adapted to withstand lightning.

(37) FIG. 5 illustrates a variant of channels 16′ in which the channels 16′ have a triangular-shaped section.

(38) The channels 16′ according to this variant are formed by a double-wall 18, 20 of the outer fairing 103a.

(39) In the same manner as before, the double-wall 18, 20 comprises an area 18 intended to be in contact with outside air and an area 20 opposite to the area 18 intended to be in contact with outside air. The area 18 intended to be in contact with outside air is smooth. This is referred to as aerodynamic surface. The opposite area 20 is corrugated.

(40) The channels 16′ further have a width L in the range of 10 mm, and the distance D between the channels 16′ is in the range of 30 mm.

(41) Thus, the distance D between the channels 16′ is comprised between twice and five times the width L of said channels 16′.

(42) Each wall 18, 20 of the channels 16′ has a thickness E in the range of 2 mm. In this manner, the area 18 intended to be in contact with outside air is adapted to withstand lightning.

(43) In one variant that is not represented, the opposite area 20 has a thickness E comprised between 0.6 and 1.5 mm. Indeed, the opposite area 20 is not impacted by lightning.

(44) In one form that is not represented, the cold source heat-exchanger 12 comprises a plurality of channels 16 disposed in parallel, in which the heat-transfer fluid C circulates, the channels 16 being disposed in contact with the inner fairing 103b (FIG. 1). In this form, the heat exchange is carried out by convection with the secondary cold air flow. The area 18 intended to be in contact with air is then intended to be in contact with air from the secondary flow path. In the same manner as before, the area 18 intended to be in contact with air from the secondary flow path is smooth. This is referred to as aerodynamic surface.

(45) In this form, the wall 18, 20 has a thickness E comprised between 0.6 and 1.5 mm. Indeed, the wall 18, 20 is not impacted by lightning.

(46) In another form that is not represented, the cold source heat-exchanger 12 is disposed in contact with the outer fairing 103a and with the inner fairing 103b and the heat exchange is carried out by convection with the cold outside air flow and the secondary cold air flow.

(47) Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

(48) As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

(49) The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.