PLATE HEAT EXCHANGER COMPRISING PROFILED GUIDE ELEMENTS

Abstract

A plate heat exchanger, in particular for an aircraft turbo machine, between a first fluid and a second fluid, the first fluid being intended to circulate in a first direction and the second fluid being intended to circulate in a second direction different from the first direction, the heat exchanger having stacked stages for circulation of the first fluid, and profiled elements at the inlet and outlet of the stages, the profiled elements having a sawtooth-shaped cross-section and defining channels converging at the inlet of the stages and diverging at the outlet of the stages.

Claims

1. A plate heat exchanger, in particular for an aircraft turbomachine, between a first fluid and a second fluid, the first fluid being intended to circulate along a first direction, and the second fluid being intended to circulate along a second direction different from the first direction, said exchanger comprising stacked stages for circulation of the first fluid, each stage comprising: two parallel plates at a distance from each other, so as to define between them a passage for the circulation of the first fluid, a series of fins arranged between said plates, so as to define a series of conduits for the circulation of the first fluid in said circulation passage, first profiled elements for the entry of the first fluid into said circulation passage, these first profiled elements being located at the level of each of the plates, at the entry to said passage, so as to define a first convergent path for guiding said first fluid in this passage, and/or second profiled elements for the outlet of the first fluid from said circulation passage, these second profiled elements being located at the level of each of the plates, at the outlet of said passage, so as to define a second divergent path for guiding said first fluid outside this passage, wherein each of said first and second profiles has in cross-section a sawtooth shape which comprises: a first peripheral edge comprising a substantially straight first end for connection to one of the plates defining a first of said circulation passages, a second end located at a tip of the profiled element, and a convex curved portion extending between the first and second ends, a second peripheral edge comprising a substantially straight third end for connection to one of the plates defining a second of said circulation passages adjacent to said first passage, a fourth end located at the tip of the profiled element and oriented at an angle of less than 90 to the second end, and a concave curved portion extending between the third and fourth ends, the concave and convex curved portions of said first and second profiles having different curvatures so as to define said first and second paths, and in that the convex curved portion has a curvature corresponding to a quarter of an ellipse having a larger radius a1 at the level of the second end and a smaller radius b1 at the level of the first end, and the concave curved portion has a curvature corresponding to a portion of an ellipse having a larger radius a2 at the level of the fourth end and a smaller radius b2 at the level of the third end, the ellipses having a same centre and a2 and b2 being respectively larger than a1 and b1.

2. The heat exchanger according to claim 1, wherein the second end located at the tip of the profiled element forms an angle of between 60 and 95, and preferably between 70 and 90, with the first end.

3. The heat exchanger according to claim 2, wherein the tips of the first and second profiled elements are tapered.

4. The heat exchanger according to claim 1, wherein said first profiled elements are carried by a manifold fitted to the inlet of the plates, and said second profiled elements are carried by a distributor fitted to the outlet of the plates.

5. The heat exchanger according to claim 1, wherein said first and second profiled elements are integrated with said plates.

6. The heat exchanger according to claim 1, wherein said first profiled elements are all identical and said second profiled elements are all identical.

7. The heat exchanger according to claim 1, wherein
a.sub.2=a.sub.1+h.Math.R.sub.d[MATH1] where h is the distance between the plates and Rd is a parameter controlling the variation in cross-section of the corresponding path.

8. The heat exchanger according to claim 7, wherein $\begin{array}{cc}{b}_2=\frac{\mathrm{pitch}}{\sqrt{1-{\left(\frac{a_1}{a_2}\right)}^2}}& \left[\mathrm{MATH2}\right]\\ b_1=b_2-h& \left[\mathrm{MATH}3\right]\end{array}$ where pitch is the pitch between two adjacent circulation passages.

9. The heat exchanger according to claim 1, wherein
a.sub.1,n+1=a.sub.1,n+R.sub.a[MATH4]
or
a.sub.1,n+1=a.sub.1,n.Math.R.sub.g[MATH5] where Ra and Rg are the reasons for these sequences, arithmetic and geometric respectively.

10. The heat exchanger according to claim 1, wherein the second end located at the tip of the profiled element is oriented substantially perpendicular to the first end.

11. The heat exchanger according to claim 1, wherein the fins are arranged substantially perpendicularly between said plates.

12. A turbomachine comprising at least one heat exchanger according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0046] Further characteristics and advantages of the invention will become apparent from the following detailed description, for the understanding of which reference is made to the attached drawings in which:

[0047] FIG. 1 is a schematic perspective view of a plate heat exchanger for an aircraft turbomachine,

[0048] FIG. 2 is a very schematic view of the flowing of a first fluid at the outlet of a heat exchanger according to the prior art,

[0049] FIG. 3 is a very schematic view of a manifold or distributor for a plate heat exchanger according to the invention,

[0050] FIG. 4 is a larger-scale view of a portion of FIG. 3 and shows profiled elements of a heat exchanger,

[0051] FIGS. 5a and 5b are diagrams showing examples of curvature for the profiled elements of the heat exchanger,

[0052] FIG. 6 is a similar view to FIG. 4 and illustrates the flowing of the first fluid out of the exchanger, and

[0053] FIG. 7 is a similar view to FIG. 4 and illustrates the flowing of the first fluid at the inlet of the exchanger.

DETAILED DESCRIPTION OF THE INVENTION

[0054] The invention relates to a heat exchanger 1, an example of which is shown in FIG. 1 and described in the foregoing. The above description therefore applies to a heat exchanger according to the invention.

[0055] In addition to the aforementioned characteristics, the exchanger 1 according to the invention comprises profiled elements 10 at the inlet and outlet of the passages 7, which are designed to optimise the deflection of the flowing of the first fluid while avoiding the appearance of recirculation areas and the generation of pressure losses.

[0056] FIG. 3 illustrates only one portion of a heat exchanger 1 according to the invention and more particularly one side of this exchanger, which corresponds here to a manifold C for the outlet of the first fluid from the aforementioned passages 7. The following description also applies to the distributor D which is mounted at the inlet of the passages to supply these passages 7 with the first fluid.

[0057] As mentioned above, the first fluid is collected by the passages 7 in the manifold C in the direction X and is diverted in the direction X2. In the distributor D, the first fluid flows in the direction X1 and is redirected in the direction X.

[0058] The profiled elements 10 can be carried by the manifold D or the distributor D and, for example, integrated or formed in one piece with the manifold or distributor. Alternatively, the profiled elements 10 can be provided directly at the ends of the plates 6 delimiting the passages 7 between them, and are then independent of the manifold C and of the distributor D.

[0059] The profiled elements 10 are located at the level of the plates 6 and have the function of defining converging paths for guiding the first fluid at the inlet to the passages 7, on the one hand, and diverging paths for guiding the first fluid at the outlet from the passages 7, on the other hand.

[0060] Each of the profiled elements 10 is located on a common side of two adjacent plates 6 and extends along this side. One of these plates 6 defines a first passage 7 and the other of these plates defines an adjacent passage 7. Each of the profiled elements 10 therefore has a generally elongated shape. Each of the profiled elements 10 has a general sawtooth shape in cross-section, as can be seen more clearly in FIG. 4.

[0061] The sawtooth shape comprises: [0062] a first peripheral edge B1 comprising a first substantially straight end B11 for connection to a first of the plates 6 (defining a first circulation passage 7), a second end B12 located at a tip 14 of the profiled element 10 and oriented substantially perpendicular to the first end B11, and a convex curved portion B13 extending between the first and second ends B11, B12, [0063] a second peripheral edge B2 comprising a third substantially straight end B21 for connection to a second of the plates 6 (defining a second circulation passage 7 adjacent to the first passage), a fourth end B22 located at the tip 14 of the profiled element 10 and oriented substantially perpendicular to the third end B21, and a concave curved portion B23 extending between the third and fourth ends B21, B22.

[0064] The concave B13 and convex B23 curved portions of the profiles 10 have different curvatures so as to define the aforementioned converging and diverging paths 12.

[0065] As can be seen in FIG. 4, the tips 14 of the profiled elements 10 are all oriented in the same orientation and are tapered, i.e. as fine as possible. Their thickness is, for example, less than or equal to 0.5 mm.

[0066] The diagram in FIG. 5a illustrates the differences in curvature of the two portions B13 and B23 of the sawtooth shape of each profiled element 10.

[0067] The convex curved portion B13 has a curvature corresponding to a quarter, or even less, of an ellipse E1 having a larger radius a1 at the level of the second end B12 and a smaller radius b1 at the level of the first end B11.

[0068] The concave curved portion B23 has a curvature corresponding to a quarter of an ellipse E2 having a larger radius a2 at the level of the fourth end B23 and a smaller radius b2 at the level of the third end B21.

[0069] As can be seen in FIG. 5a, the ellipses E1 and E2 have the same centre O and the ellipse E2 is larger than the ellipse E1, i.e. a2 and b2 are respectively larger than a1 and b1.

[0070] In the example shown in FIGS. 3 to 7, which represents a first embodiment of the invention, the profiled elements 10 are all identical.

[0071] The following equations allow to calculate the values of a1, a2, b1 and b2 and are given as examples.

a.sub.2=a.sub.1+h.Math.R.sub.d[MATH1]

[0072] where h is the distance between the plates 6 and therefore the height of the passages 7, as shown in FIG. 6,

[0073] and Rd is a parameter controlling the variation in cross-section of the corresponding path 12.

[00002]$\begin{array}{cc}{b}_2=\frac{\mathrm{pitch}}{\sqrt{1-{\left(\frac{a_1}{a_2}\right)}^2}}& \left[\mathrm{MATH2}\right]\\ b_1=b_2-h& \left[\mathrm{MATH}3\right]\end{array}$

[0074] where pitch is the pitch between two adjacent passages 7, as shown in FIG. 6.

[0075] Alternatively, the profiled elements 10 are different and sized according to a predetermined arithmetic or geometric sequence.

a.sub.1,n+1=a.sub.1,n+R.sub.a[MATH4]

or

a.sub.1,n+1=a.sub.1,n.Math.R.sub.g[MATH5]

[0076] with Ra and Rg the reasons for these sequences.

b.sub.1=b.sub.2h[MATH3]

[0077] The profiled elements 10 of the exchanger according to the invention can be produced by additive manufacturing using selective fusion on powder beds, for example. As mentioned above, these profiled elements 10 can be produced with the plates 6 when they are integrated with the plates 6, or produced with the manifold C or the distributor D when they are integrated with the latter.

[0078] FIG. 5b illustrates an alternative embodiment for the ellipses E1 and E2. They have the same centre O and the ellipse E2 is larger than the ellipse E1. b2 is larger than b1 but is larger than a1. a2 is larger than a1.

[0079] Furthermore, the framed portion of FIG. 5b shows that the area of interest chosen for the curvatures of the profiled elements is not necessarily a quarter of the large ellipse but can represent less than a quarter of an ellipse.