Contemporary engines used in aircraft can produce substantial amounts of heat needing to be transferred away from the engine. Heat exchangers provide a way to transfer heat away from such engines. For example, one type of heat exchanger that may be used is an annular surface cooler that is mounted to an aft fan casing. Integral fins formed from parent material in the heat exchanger can have a significantly higher heat transfer coefficient versus fins which may be brazed or otherwise attached to the parent material. The fins of such heat exchangers provide large surface areas beneficial for transferring heat to the surrounding air. In addition, thermal transfer enhancing features may be provided within the heat exchanger.
In one aspect, a method of forming a heat exchanger includes providing a metal body having a first surface and a second surface opposite and spaced from the first surface, removing material from the first surface of the metal body to partially create a set of cooling passages having open faces within the metal body, filling the partially created set of cooling passages via the open faces with sacrificial material such that the sacrificial material forms an exposed surface, forming a remainder of the set of cooling passages such that the exposed surface is covered and the open faces are closed and a set of fully formed cooling passages for the heat exchanger are defined, and removing the sacrificial material from the set of fully formed cooling passages. The heat exchanger can be configured to operate in a high pressure environment of 0.7 MPa or more and a high temperature environment of 150° C. or more.
In another aspect, a method of forming a heat exchanger includes forming a set of cooling passages in a metal body by providing a metal body having a first surface and a second surface opposite and spaced from the first surface, removing material from the first surface of the metal body to partially create a set of cooling passages having open faces within the metal body, filling the partially created set of cooling passages via the open faces with sacrificial material such that the sacrificial material forms an exposed surface, electroforming a remainder of the set of cooling passages such that the exposed surface is covered and the open faces are closed and a set of fully formed cooling passages for the heat exchanger are defined and removing the sacrificial material from the set of fully formed cooling passages, and forming at least one fin projecting from the second surface. Fluid may be passed through the set of fully formed cooling passages and heat from the fluid may be dissipated through the fin.
In yet another aspect, a method of forming a heat exchanger includes providing a nickel metal body having a first surface and a second surface opposite and spaced from the first surface, machining nickel material from the first surface of the nickel metal body to partially create a set of cooling passages having open faces within the nickel metal body, filling the partially created set of cooling passages via the open faces with sacrificial material such that the sacrificial material forms an exposed surface, electroforming nickel over the exposed surface to close the open faces such that a set of fully formed cooling passages for the heat exchanger are defined, and removing the sacrificial material from the set of fully formed cooling passages.
In the drawings:
Jet engines, such as turbine engines, pose unique thermal management challenges and in cases where compressor bleed air is used within the heat exchanger, the thermal management challenges are quite extreme. In such a situation, a surface cooler, which is a type of heat exchanger, can be designed to accept a flow of compressor bleed air through a series of tubes to transfer the heat from the compressor bleed air through the heat exchanger to a surrounding environment. The surrounding environment can include a cooler air flow, such as that from fan bypass air which is provided over the top of the heat exchanger. It will be understood that the present disclosure is not limited to the environment of a turbine engine and may have general applicability in non-aircraft applications, such as other mobile applications and non-mobile industrial, commercial, and residential applications as well.
As used herein, the term “forward” or “upstream” refers to moving in a direction toward the engine inlet, or a component being relatively closer to the engine inlet as compared to another component. The term “aft” or “downstream” used in conjunction with “forward” or “upstream” refers to a direction toward the rear or outlet of the engine or being relatively closer to the engine outlet as compared to another component. Additionally, as used herein, the terms “radial” or “radially” refer to a dimension extending between a center longitudinal axis of the engine and an outer engine circumference. Further, “a set” as used herein can include any number including only one.
All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of the disclosure. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and can include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary.
Portions of the nacelle 20 have been cut away for clarity. The nacelle 20 surrounds the turbine engine 16 including the inner cowl 32. In this manner, the nacelle 20 forms an outer cowl 34 radially surrounding the inner cowl 32. The outer cowl 34 is spaced from the inner cowl 32 to form an annular passage 36 between the inner cowl 32 and the outer cowl 34. The annular passage 36 characterizes, forms, or otherwise defines a nozzle and a generally forward-to-aft bypass airflow path. A fan casing assembly 37 having an annular forward casing 38 and an annular aft casing 52 can form a portion of the outer cowl 34 formed by the nacelle 20 or can be suspended from portions of the nacelle 20 via struts (not shown).
In operation, air flows through the fan assembly 18 and a first portion 40 of the airflow is channeled through compressor(s) 24 wherein the airflow is further compressed and delivered to the combustion section 26. Hot products of combustion (not shown) from the combustion section 26 are utilized to drive turbine(s) 28 and thus produce engine thrust. The annular passage 36 is utilized to bypass a second portion 42 of the airflow discharged from fan assembly 18 around engine core 22.
The turbine engine assembly 11 can pose unique thermal management challenges and a heat exchanger or surface cooler, illustrated herein as an annular surface cooler 50, can be attached to the turbine engine assembly 11 to aid in the dissipation of heat.
Turning to
The surface cooler 50 can include a circumferential and axial profile that is substantially similar to the circumferential and axial profile of the peripheral wall 54, and can cover any portion of the circumference of the peripheral wall 54 as shown in
During operation, arrows 56 (
Regardless of where the heat exchanger or surface cooler 50 is utilized, it will be understood that there may be a need for a more durable material to form the heat exchanger including that of nickel. It will now be described how a metal heat exchanger can be formed that can withstand higher temperatures and pressures.
A set of sacrificial fillings 76 can be provided in the cavities 73 as shown in
In
The same material as the metal body 60 can be used for the cover wall 78; by way of non-limiting example, if the metal body 60 is nickel, the cover wall can also be nickel. Thus, in the illustration no distinction or separation has been shown between the metal body 60 and the cover wall 78. The deposition of material to form the cover wall 78 defines a remainder of the cooling passages 70 and allows for the heat exchanger or surface cooler 50 to not have joints, which can be prone to failure at high pressures.
Turning to
Further still, the set of fins 80 can be created from the ridges 90 using any suitable method including, but not limited to, skiving.
In the illustrated example of
A method of forming the heat exchanger 50 is illustrated in a flowchart in
It can be appreciated that the method of electroforming more durable metals such as nickel over the sacrificial fillings to fully enclose the cooling passages can provide for the creation of a heat exchanger that can withstand higher ambient temperatures or pressures than traditional heat exchangers made from the extrusion of relatively softer materials such as aluminum or that of heat exchangers having welded or fastened joints. It is contemplated that the heat exchangers of the present disclosure may be used in environments having temperatures of 150° C. or higher and pressures of 0.7 MPa or more.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.