Many aircraft heat exchangers operate at high temperatures and are subject to thermal stresses caused by thermal expansion, especially with thermal coefficient mismatch and uneven temperature distribution within the heat exchanger or with abutting components. These thermal stresses can lead to a reduction in the service life of the heat exchanger. In addition, deleterious mechanical stresses due to vibration can arise where components natural frequencies coincide significantly with engine operating frequencies. Particularly high stress regions within aircraft heat exchangers include interfaces between fluid inlets and outlets with the core section.
A core arrangement for a heat exchanger includes a first core layer disposed along a first plane and having an inlet and outlet oriented along a first axis within the first plane and a first core stage disposed in fluid communication between the inlet and the outlet. The first core stage includes a first upstream fluid intersection downstream of and adjacent the inlet and having a first inlet continuation and a first bifurcation. The first core stage further includes a first downstream fluid intersection upstream of and adjacent the outlet and having a first outlet continuation and a first recombination. A plurality of first core tubes fluidly connect the first bifurcation to the first recombination. The first core layer further includes a second core stage disposed in fluid communication between the first inlet continuation and the first outlet continuation. The second core stage includes a second upstream fluid intersection downstream of the first inlet continuation and having a second bifurcation, and a second downstream fluid intersection upstream of the first outlet continuation and having a second recombination. A plurality of independent second core tubes fluidly connect the second bifurcation to the second recombination.
A heat exchanger includes a core having a core arrangement with a plurality of core layers in a stacked arrangement and disposed in a core layer plane. Each of the core layers includes an inlet and outlet oriented along a first axis within the first plane and a first core stage disposed in fluid communication between the inlet and the outlet. The first core stage includes a first upstream fluid intersection downstream of and adjacent the inlet and having a first inlet continuation and a first bifurcation. The first core stage further includes a first downstream fluid intersection upstream of and adjacent the outlet and having a first outlet continuation and a first recombination. A plurality of first core tubes fluidly connect the first bifurcation to the first recombination. The first core layer further includes a second core stage disposed in fluid communication between the first inlet continuation and the first outlet continuation. The second core stage includes a second upstream fluid intersection downstream of the first inlet continuation and having a second bifurcation, and a second downstream fluid intersection upstream of the first outlet continuation and having a second recombination. A plurality of independent second core tubes fluidly connect the second bifurcation to the second recombination.
A heat exchanger with improved performance under thermal and vibrational stresses is disclosed herein. The heat exchanger includes a core having multiple, planar core layers in a stacked configuration. Individual core layers can include a number of tubular flow paths concentrically arranged to give the core layer a leaf-like planar geometry with improved thermal and mechanical properties. The core can be additively manufactured to achieve varied tubular dimensions (e.g., diameter, wall thicknesses, curvature, etc.), which allows for the manufacture of a heat exchanger specifically tailored for a desired operating environment.
Core 12 includes a plurality of core layers 20 stacked along axis A2. Core 12 can further include connecting elements/vanes 22 disposed between adjacent core layers 20. As shown in
Each core layer 20 is in fluid communication with inlet header 14 and outlet header 16 such that each core layer 20 can receive a portion of the flow of first fluid F1. Inlet header 14 and outlet header 16 have a branched configuration and are therefore scalable to fluidly connect to one or more core layers by the addition/omission of branches 24. The branched configuration can for example, exhibit a fractal geometry, with sequential branched stages and intervening bifurcations.
Core stage 26H, the outermost core stage shown in
Each core tube 38A-38H is mechanically independent from other core tubes, and is joined to other components of heat exchanger 10 only at corresponding intersections at either end of the respective core tube (and via vanes 22, in some embodiments). The ability of each core tube to bend independently under thermal loads greatly improves compliance of heat exchanger 10 as a whole, along fluid axis A1. The curvature of core tubes 38A-38H (substantially circular in the illustrated embodiment) provides a degree of stiffness in the plane of each core stage, transverse to fluid axis A1, which can drive the natural vibrational modes of the core along this dimension out of (lower) frequency bands corresponding to engine operating frequencies.
As shown in
The components of heat exchanger 10 can be formed partially or entirely by additive manufacturing. For metal components (e.g., Inconel, aluminum, titanium, etc.) exemplary additive manufacturing processes include powder bed fusion techniques such as direct metal laser sintering (DMLS), laser net shape manufacturing (LNSM), electron beam manufacturing (EBM), to name a few, non-limiting examples. For polymer or plastic components, stereolithography (SLA) can be used. Additive manufacturing is particularly useful in obtaining unique geometries (e.g., varied core tube radii, arcuate core tubes, branched inlet and outlet headers) and for reducing the need for welds or other attachments (e.g., between inlet header 14 and core layers 20). However, other suitable manufacturing process can be used. For example, header and core elements can in some embodiments be fabricated separately, and joined via later manufacturing steps.
The disclosed core arrangement offers improved thermal and mechanical properties. The curved geometry and tailored radii of core tubes 38 reduces pressure drop across each core layer 20. Curved core tubes also provide increased compliance along the first axis F1 to allow for thermal growth of the core layer. Alternative embodiments of core 12 can include core layers 20 having other substantially planar geometries with non-circular (e.g., oval, elliptical, s-shaped) tube curvature, and/or having non-uniform shapes and/or sizes. In addition to aerospace applications, the disclosed core arrangement can be used generally in other transportation industries, as well as industrial applications.
Discussion of Possible Embodiments
The following are non-exclusive descriptions of possible embodiments of the present invention.
A core arrangement for a heat exchanger includes a first core layer disposed along a first plane and having an inlet and outlet oriented along a first axis within the first plane and a first core stage disposed in fluid communication between the inlet and the outlet. The first core stage includes a first upstream fluid intersection downstream of and adjacent the inlet and having a first inlet continuation and a first bifurcation. The first core stage further includes a first downstream fluid intersection upstream of and adjacent the outlet and having a first outlet continuation and a first recombination. A plurality of first core tubes fluidly connect the first bifurcation to the first recombination. The first core layer further includes a second core stage disposed in fluid communication between the first inlet continuation and the first outlet continuation. The second core stage includes a second upstream fluid intersection downstream of the first inlet continuation and having a second bifurcation, and a second downstream fluid intersection upstream of the first outlet continuation and having a second recombination. A plurality of independent second core tubes fluidly connect the second bifurcation to the second recombination.
The core arrangement of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
In the above core arrangement, the first inlet continuation and the first outlet continuation can be oriented along the first axis.
In any of the above core arrangements, the plurality of independent first and second core tubes can be arcuate tubular members disposed within the first plane.
Any of the above core arrangements can further include a third core stage disposed in fluid communication between the first inlet continuation and the first outlet continuation. The third core stage can include a third upstream fluid intersection downstream of and adjacent the first inlet continuation and having a third bifurcation and a second inlet continuation upstream of and fluidly connected to the second upstream fluid intersection. The third core stage can further include a third downstream fluid intersection upstream of and adjacent the first outlet continuation and having a third recombination and a second outlet continuation downstream of and fluidly connected to the downstream fluid intersection. A plurality of independent third core tubes can fluidly connect the third bifurcation to the third recombination.
In any of the above core arrangements, the plurality of independent first, second, and third core tubes can be arranged substantially concentrically within the first plane.
In any of the above core arrangements, the plurality of independent first core tubes can have a first diameter, the plurality of independent second core tubes can have a second diameter, and the plurality of independent third core tubes can have a third diameter.
In any of the above core arrangements, the first diameter can be greater than the second and third diameters.
In any of the above core arrangements, the first core layer can be symmetrical about the first axis.
Any of the above core arrangements can further include a second core layer disposed along a second plane adjacent and parallel to the first plane. The second core layer can include a second inlet oriented along the first axis within the second plane, a second outlet oriented along the first axis, a first core stage of the second core layer similar to the first core stage of the first core layer, and a second core stage of the second core layer similar to the second core stage of the first core layer.
In any of the above core arrangements, the first and second core layers can be formed from one of a metallic and a plastic material.
Any of the above core arrangements can include a plurality of connecting elements disposed between and physically contacting each of the first a second core layers.
A heat exchanger includes a core having a core arrangement with a plurality of core layers in a stacked arrangement and disposed in a core layer plane. Each of the core layers includes an inlet and outlet oriented along a first axis within the first plane and a first core stage disposed in fluid communication between the inlet and the outlet. The first core stage includes a first upstream fluid intersection downstream of and adjacent the inlet and having a first inlet continuation and a first bifurcation. The first core stage further includes a first downstream fluid intersection upstream of and adjacent the outlet and having a first outlet continuation and a first recombination. A plurality of first core tubes fluidly connect the first bifurcation to the first recombination. The first core layer further includes a second core stage disposed in fluid communication between the first inlet continuation and the first outlet continuation. The second core stage includes a second upstream fluid intersection downstream of the first inlet continuation and having a second bifurcation, and a second downstream fluid intersection upstream of the first outlet continuation and having a second recombination. A plurality of independent second core tubes fluidly connect the second bifurcation to the second recombination.
The heat exchanger of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
The above heat exchanger can further include a third core stage disposed in fluid communication between the first inlet continuation and the first outlet continuation. The third core stage can include a third upstream fluid intersection downstream of and adjacent the first inlet continuation and having a third bifurcation and a second inlet continuation upstream of and fluidly connected to the second upstream fluid intersection. The third core stage can further include a third downstream fluid intersection upstream of and adjacent the first outlet continuation and having a third recombination and a second outlet continuation downstream of and fluidly connected to the downstream fluid intersection. A plurality of independent third core tubes can fluidly connect the third bifurcation to the third recombination.
In any of the above heat exchangers, the plurality of independent first, second, and third core tubes can be arranged substantially concentrically within the core layer plane.
Any of the above heat exchangers can further include a plurality of connecting elements disposed between and physically contacting one of the plurality of core layers and an adjacent one of the plurality of core layers.
In any of the above heat exchangers, each of the plurality of core layers can be configured to receive a first fluid along the first axis.
In any of the above heat exchangers, each of the plurality of core layers can be fluidly connected to a first fluid inlet header and a first fluid outlet header.
In any of the above heat exchangers, each of the first fluid inlet header and the first fluid outlet header can be a bifurcated header having fractal geometry.
In any of the above heat exchangers, the core can be configured to receive a flow of a second fluid along a second axis perpendicular to the first axis.
In any of the above heat exchangers, a temperature of the second fluid can be lower than a temperature of the first fluid.
While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
This application claims the benefit of U.S. Provisional Application No. 62/808,068 filed Feb. 20, 2019 for “LEAF-SHAPED GEOMETRY FOR HEAT EXCHANGER CORE” by E. Joseph, M. Maynard, M. Doe, M. Hu, F. Feng, A. Bacene, and G. Ruiz.
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62808068 | Feb 2019 | US |