FR2486222A1 - Aircraft jet engine air reheater - has heat exchanger block with flanged ends for connection between divided air collector boxes - Google Patents

Abstract

The heat exchanger used as an air reheater for an aircraft jet engine has a set of heat exchanger tubes (121), formed by holes through a block (10) between two collectors (20,30). The tubes form two sets, so that currents can pass through them in counter flow. The complete heat exchanger can form a cylinder enclosing a cylindrical part of the engine. The block has flanges (11) at each end for connection to the two collectors. Each collector is divided into two sections (21A,B;31A,B) by a partition with a sloping part (33) connected to an outer part (32) at right angles to the outer end of the collector. These sections form an inlet for one medium and an outlet for the second medium, and each collector has an inlet connection (25A,35B) and an outlet connection (25B,35A).

Description

FIXED HEAT EXCHANGER WITH SOLID BLOCK AND APPLICATION
TO AN AIR HEATER FOR TURBOMACHINE
The invention relates to a fixed heat exchanger for fluids which can be used in particular as a diaphragm heater for a combustion turbomachine.

The heat exchanger of the invention is of the type comprising
- a massive heat exchanger block in which are formed end to end. end of the parallel channels divided into two groups of channels respectively traversed by one and the other fluid, said channels being arranged in rows of channels belonging alternately to one and to the other group,
- two collectors arranged on either side of the exchanger block and each comprising two chambers, one of which communicates with all the channels of a group and the other with all the channels of the other group.

Modern drilling methods (electrolytic, electro-erosion, electron bombardment, laser beam, etc.) allow the production of efficient massive exchanger blocks because they include dense networks of fine channels for the passage of fluids through the liquid or gaseous state. These heat exchanger blocks are also waterproof, compact and rigid, and therefore not very sensitive to vibrations. However, the addition of collectors partly destroys these advantages because, whatever the relative arrangement of the two chambers of each collector, the communication conduits between these chambers and the channels of the block necessarily intersect. This results in an increase in size and in the difficulties of production (assembly, counter, etc.). These drawbacks are particularly significant when it comes to air heaters for aeronautical turbomachines, these heaters having to respond to special requirements for mass and reliability.

The object of the invention is to provide a fixed heat exchanger for fluids (and in particular a diapir heater for an aeronautical turbomachine) of the aforementioned type but having, to a greater degree, compared to known exchangers of the same kind, the following advantages : compactness, reliability, lower mass, ease of construction and counter.

The fixed fluid heat exchanger of the invention is essentially characterized in that each collector has a flat wall applied against one of the faces of the exchanger block through which the channels open, in that the two chambers of each collector are contiguous and separated by a dividing partition parallel to the direction of the channels and in that each of these chambers communicates with the totality of the channels of a group by as much light provided in said dividing partition and in the planar wall that said group comprises of rows of channels, each light putting said chamber in communication with all the channels in a row.

The rows of one of the groups of channels of the exchanger block alternating with the rows of another group, it follows that the lights communicating in each manifold one of the chambers with the channels of a group alternate with the lights communicating the another room with the channels of the other group.

In a particularly advantageous embodiment, the dividing partition of each collector opens out towards the exchanger block to form a volume of triangular current section, the base of which forms the flat face which is applied against the exchanger block and in which are alternately arranged. the communication lights with the rows of one and the other group of channels. It will be seen that it then suffices with a simple milling operation to spare each light.

As already indicated, the invention makes it possible to produce an air heater for a combustion turbomachine, this heater being in fact an exchanger according to the invention in which the two groups of channels are respectively traversed by the air to be heated and by combustion gases.

 Slil is an annular heater intended to surround a cylindrical wall of the turbomachine, the exchanger block is then of annular shape, the channels are parallel to the axis of revolution of the block, the two collectors are also annular and the dividing partition of each exchanger is an annular partition separating the two chambers which are annular and concentric. We can then adopt for the annular partition the flourishing configuration already mentioned, the volume of triangular section becomes a ring of triangular section whose base is applied against the block and in which are alternately formed the communication lights with the rows of channels of one and the other group. These lights are simple prismatic millings of oblong current section, the median plane of each light obviously coinciding with the plane passing through the axis of the channels of the corresponding row.

A final advantageous arrangement consists in aligning the channels of each row and the corresponding lumen of each collector in a plane oriented obliquely (advantageously at 450) relative to the plane passing through the axis of the annular exchanger block and through the axis of a middle channel of this row. It will be seen that this arrangement makes it possible to increase the density of the network of channels and / or to decrease the number of lights required while facilitating the drilling of the channels.

The invention will be better understood on reading the descriptions of exemplary embodiments which follow and which refer to the appended drawings in which
- Figure 1 is a longitudinal section of an exchanger according to the invention.

FIGS. 2, 3 and 4 are cross sections of said exchanger taken respectively along planes 2-2, 3-3, and 4-4 of FIG. 1,
FIG. 5 is an axial half-section of an annular air heater according to the invention intended for an aeronautical turbomachine,
FIGS. 6, 7, 8 and 9 are respectively partial cross sections of said heater taken respectively according to the planes 6-6, 7-7, 8-8> and 9-9 of FIG. 5.

In order to facilitate the examination of the drawings, we have deliberately omitted to represent therein the elements or bodies whose mention is not useful for understanding the invention, such as the pins or cords for locating or centering, the fixing bolts, seals or sealing cords, etc ...

First consider Figures 1,2, 3 and 4 simultaneously.

They represent an exchanger traversed by a hot fluid A gas or liquid and by a cold fluid B gas or liquid. The arrows show the directions of circulation of these fluids. We see that it is a countercurrent exchanger.

The exchanger block 10 proper consists of a matrix of parallelepipedal shape joined by its flat faces diextrwemite respectively to flat faces of the collectors 20 and 30. The fixing of the collectors to the matrix is ensured by means of flanges 11 (for the matrix) and 26 or 36 (for collectors). If, taking into account its transverse dimensions (dimensions, diameter and no channels!), The matrix is too long to be produced in one piece, it is obviously sufficient to fragment it into at least two sections.

Parallel channels 12A (intended for the circulation of the fluid A) and 12B (intended for the circulation of the fluid B) are formed at constant pitch throughout the length of the block 10.

They form vertical rows 13A of channels 12A alternating with vertical rows 133 of channels 12B. There is between rows 13A on the one hand and 13B on the other hand an offset of half a step in order to ensure a general arrangement of the channels in staggered rows. The diameter and pitch of the channels have been significantly exaggerated in the figures and their number has been reduced accordingly.

The collector 20 and the collector 30 both have a generally parallelepiped shape. The collector 20 is divided into two superimposed chambers 21A and 21B (21B being arranged above 21A) by a dividing partition 22. This opens out towards the block 10 to form a prism 23 of isosceles triangular vertical current section whose base coincides with the face of the collector 20 which is applied against the block 10. In this prism 23 are provided alternately on the one hand by the vertical lights 24A each of which puts the lower ch-amber 21A in communication with the channels 12A of the same vertical row 13A and on the other hand of the vertical lights 24B, each of which puts the upper chamber 213 in communication with the channels 12B of the same vertical row 133. Finally, an intake manifold 25A admits the fluid A into the chamber 21A while a united outlet tube 25B allows the fluid B to exit from the chamber 213.

The constitution of the collector 30 is identical to that of the collector 20. In the figure there is shown by way of example the chamber 31A, from which the fluid A is extracted by the tube 35A and which communicates with the green rows: 13A of channels 12A by as many vertical lights (not shown) formed in the triangular prism 33 which forms part of the separating partition 32, disposed above the chamber 313 in which the tube 35B admits the fluid B and which communicates with the vertical rows 13B of channels 12B by as many vertical slots 34B formed in the prism 33 between the ports for passage of the fluid A which are not shown.

The following remarks will be made at this stage of the description.
the fluid conduits between the block and the collectors being openings made in the mass of the collectors and the latter being linked with the block by wide flat faces, the assembly thus produced has compactness and maximum rigidity, whence arises from the rest a minimum mass;
- It suffices with a simple tilting of a collector during machining to mill a series of lights (for example the lights 243) after having produced the other series (for example 24A);
- The exchanger that has been described is against the current but can be made "equi-current" (same direction of circulation of the two fluids in the channels) by simple permutation of the direction of circulation of one of the fluids; ;
- It suffices, in a collector, to impose on the two series of lights translations in opposite directions to permute the communications between the two chambers and the two groups of channels (to put for example in the collector 20 the chamber 21A in communication with channels 12B and chamber 213 with channels 12A);
- In each collector, the separating partition 22 or 32 and especially the sails formed in the prism 23 or 33 by lluination of the lights form significant surfaces of heat exchange; each collector therefore also constitutes an additional exchanger.

We now consider simultaneously Figures 5, 6, 7, 8 and. 9. It is an equi-current air heater (that is to say that the air and the heating gases circulate therein in the same direction) of annular shape since it is intended to surround a primary nozzle (not shown) for an aeronautical turbomachine.

The exchanger block 50 is a ring of rectangular axial section, the two faces of which are respectively attached to the upstream annular collector 60 and to the downstream annular collector 70 by annular flanges 51.

Channels 52A and 52B parallel to the axis of the exchanger block run through said block. Channels 52A are intended for the circulation of gases and channels 52B for the circulation of air. The channels 52A are distributed in equidistant rows 53A. The plane determined by the axis of the channels of the same row forms a dihedral of 45 with the axial plane passing in the vicinity of the median channel (s) of this row. The channels 52B are distributed in equidistant rows 53B having the same angular arrangement, the same number of channels and the same between channels as the rows 53A and interposed therebetween.

We will now describe the collectors 60 and 70. In order to condense the description, the indications relating to these two collectors will be combined by mentioning in brackets the references of the elements of the collector 70 and, outside the parentheses, the references of the elements of the collector 60.

The collector 60 (70) is divided into two concentric annular chambers 61A (71A) and 61B (71 B) by an adjoining annular partition 62 (72). The annular bottom 66 (76) consists of a removable cover carrying a part of the partition 62 (72) in order to facilitate the making and maintenance of the collector. The partition 62 (72) opens out in the direction of the annular exchanger block 50 to form a ring of isosceles triangular section 63 (73), the base of which forms the face of the manifold 60 (70) which is applied against the exchanger block 50. In this ring 63 (73) are provided alternately, dune. part of the oblong slots 64A (74A) inclined in the proper direction so that each puts the internal chamber 61A (71A) into communication with the channels 52A in the same row 53A, on the other hand the oblong slots 64B (74B) inclined in the same direction so that each puts in communication the external chamber 613 (71 B) with the channels 52B of a same row 53B. It is only to facilitate the reading of FIG. 5 that lights 64A and 74A are represented therein whole in the plane of the figure as well as all the channels 52A of the same row.

The manifold 60 carries at least one pipe 65A for admitting hot gases into the chamber 61A and at least one pipe 65B for admitting fresh air into the chamber 613. The manifold 70 carries at least one pipe 75A for the outlet of the cooled gases from chamber 71A and at least one tube 75B for leaving the heated air from chamber 713. These tubes can of course be multiplied as necessary.

The same remarks can be made with respect to the air heater which has just been described with reference to FIGS. 5, 6, 7, 8 and 9 as those already made with regard to the heat exchanger of FIGS. 1, 2, 3 and 4, but it is also necessary to draw attention to the arrangements of the rows of channels of the block 50 and of the lights of the collectors 60 and 70. The fact of tilting these rows and these lights has 1 advantage for the same not radial and the same circumferential pitch between channels, to increase the number of channels in communication with the same light, that is to say to reduce the number of lights required. In addition, the fact of fixing the inclination precisely at 450 relative to the axial planes simplifies the machining of the channels.

It can be seen in FIG. 8 that the channels are present in the section of the exchanger block not only aligned in inclined rows, but also in staggered radial rows.

Claims (8)

 - each of these chambers (21A, 21B, 31A, 313; 61A, 61 B, 71A, 713) communicates with all the channels (12A, 12B; 52A, 52B) of a group by as many lights (24A, 24B , 34B; 64A, 64B, 74A, 74B) formed in the dividing partition and in the planar wall which said group comprises of channels, each light (24A) putting said chamber in communication with all the channels (12A) of a row ( 13A).  - the two chambers (21A, 21B, 31A, 31B; 61A, 61B, 71A, 713) of each collector (20, 30; 60, 70) are contiguous and separated by a dividing partition (22, 32; 62, 72 ) parallel to the direction of the channels1  each collector has a flat wall applied against one of the faces of the exchanger block (10; 50) through which the channels open,  - two collectors (20, 30; 60, 70) arranged on either side of the exchanger block and each comprising two chambers (21A, 21B, 31A, 313; 61A, 61B, 71A, 713), one of which (21A ; 61A) communicates with all channels (12A; 52A) of one group and the other (21B; 613) with all channels (12B; 52B) of the other group, characterized in that  - a massive exchanger block (10; 50) in which its arranged from end to end parallel channels divided into two groups (12A, 12B; 52A, 52B) of channels respectively traversed by one and the other fluid, said channels being arranged in rows of channels belonging alternately to one and to the other group,  fixed fluid heat exchanger of the type comprising: 2 - Heat changer according to claim 1, characterized in that in each collector (20, 30) the dividing partition (22, 32) opens out towards the exchanger block (10) to form a volume (23, 33) of triangular current section, the base of which forms the flat face which is applied against the exchanger block (10) and in which the lights (24A, 24B, 34B) for communication with the rows (13A, 133) are alternately provided and the other group of channels. 3 - Air heater for combustion turbomachine according to claim 1, characterized in that the two groups of channels (52B, 52A) being respectively traversed by the air to be heated and by combustion gases, the heat exchanger block (50 ) is of annular shape, the channels (52) are parallel to the axis of the block, the two collectors (60, 70) are annular and the dividing partition (62, 72) of each exchanger is an annular partition separating two annular spaces (61A, 61B, 71A, 71B) concentric. 4 - Air heater according to claim 3 characterized in that the annular partition of each collector opens out towards the exchanger block to form a triangular ring (63, 73) whose base is applied against the block ( 50) and in which the communication lights (64A, 64B; 74A, 743) are alternately arranged with the rows (53A, 53B) of channels of one and the other group. 5 - Air heater according to claim 4, characterized in that each lumen is a prismatic milling of oblong current section whose median plane coincides with the plane passing through the axis of the channels of the corresponding row. 6 - Air heater according to claim 5, characterized in that the channels of each row (53A, 53B) and the corresponding lumen (64A, 64B, 74A, 74B) of each manifold (6G, 70) are aligned in a plane oriented obliquely to the plane passing through a median channel of this row and through the axis of the annular exchanger block (50). 7 - Air heater according to claim 6, characterized in that the value of the dihedral formed by the two planes is 450. 8 - Aeronautical turbomachine, characterized in that it is equipped with an air heater according to any one of claims 3 to 7.