Patent Publication Number: US-2019170455-A1

Title: Heat exchanger bell mouth inlet

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This disclosure claims priority to U.S. Provisional Patent Application No. 62/593,402 filed Dec. 1, 2017. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with government support under contract number FA8626-16-C-2139 awarded by the United States Air Force. The government has certain rights in the invention. 
    
    
     BACKGROUND 
     A plate and fin heat exchanger includes alternating layers of passages formed by flat sheet metal material and corrugated preformed structures. The entire structure is brazed together to form a unitary brazed assembly. Inlet and outlet openings typically are blunt shaped and can create significant pressure losses as airflow transitions from large spaces within an inlet manifold into the much smaller passages defined by the preformed structures or plates. Similarly, airflow exiting the heat exchanger is subject to pressure losses due to undefined transition from the passages to an open area of a manifold. 
     Turbine engine manufactures utilize heat exchangers throughout the engine to cool and condition airflow for cooling and other operational needs. Improvements to turbine engines have enabled increases in operational temperatures and pressures. The increases in temperatures and pressures improve engine efficiency but also increase demands on all engine components including heat exchangers. 
     Turbine engine manufacturers continue to seek further improvements to engine performance including improvements to thermal, transfer and propulsive efficiencies. 
     SUMMARY 
     In a featured embodiment, a heat exchanger includes at least one passage defining a flow path for airflow. A manifold includes a transition region including at least two rib portions defining a smoothly curved transition surface into the at least one passage. 
     In another embodiment according to the previous embodiment, the manifold includes a housing with an inlet opening and the transition region is adjacent the at least one passage. 
     In another embodiment according to any of the previous embodiments, the at least two rib portions extend across the transition region of the manifold. 
     In another embodiment according to any of the previous embodiments, the at least two rib portions include a support portion supporting the at least one passage. 
     In another embodiment according to any of the previous embodiments, a plate defining the at least one passage, the plate abutted against the support portion of the at least two rib portions so as to continue the smoothly curved transition surface through the at least one passage. 
     In another embodiment according to any of the previous embodiments, a seal disposed between the plate and the at least two rib portions. 
     In another embodiment according to any of the previous embodiments, the plate includes a unitary part without joints. 
     In another embodiment according to any of the previous embodiments, the smoothly curved transition surface includes a bell mouth shape. 
     In another embodiment according to any of the previous embodiments, a plurality of passages for airflow and the manifold includes an inlet manifold at one end of the plurality of passages and an outlet manifold at an opposite end of the plurality of passages. 
     In another featured embodiment, a heat exchanger includes at least two plates defining a first flow passage. The at least two plates include an inlet region. The inlet region includes a smoothly curved transition region. A manifold includes an inlet opening and a transition region supporting the at least two plates. 
     In another embodiment according to any of the previous embodiments, the plate includes a first end portion spaced apart from a second end portion. A cavity defines a first flow path between the first end portion and the second end portion. An outer surface portion defines a second flow path. The plate includes a single unitary part without a joint between any two portions. 
     In another embodiment according to any of the previous embodiments, each of the first end portion and the second end portion include the smoothly curved transition region. 
     In another embodiment according to any of the previous embodiments, the at least two plates includes a plurality of plates stacked atop each other and supported within the transition region of the manifold. 
     In another embodiment according to any of the previous embodiments, the manifold includes a first manifold at an inlet end of the at least two plates and a second manifold at the outlet end of the at least two plates. 
     In another embodiment according to any of the previous embodiments, the smoothly curved transition surface includes a bell mouth shape. 
     In another featured embodiment, a method of assembling a heat exchanger includes defining a manifold to include a plurality of ribs extending across a transition region. Each of the plurality of ribs include a smoothly curved transition surface. A plate defining an airflow passage is inserted between two of the plurality of ribs to hold the plates within the transition region and define a smoothly curved transition surface into the airflow passage. 
     In another embodiment according to any of the previous embodiments, inserting a seal between an end of the plate and at least two ribs. 
     In another embodiment according to any of the previous embodiments, the manifold includes an inlet manifold and an outlet manifold and the method includes inserting the plate into both the inlet manifold to define an inlet transition surface into the airflow passage and the outlet manifold to define an outlet transition surface for airflow exiting the airflow passage. 
     Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     These and other features disclosed herein can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an example heat exchanger embodiment. 
         FIG. 2  is a cut away view of the example heat exchanger embodiment. 
         FIG. 3  is a sectional cut away view of a portion of the example heat exchanger. 
         FIG. 4  is a cross sectional view of a portion of the heat exchanger. 
         FIG. 5  is a perspective view of an example plate embodiment. 
         FIG. 6  is a perspective view of another example plate embodiment. 
         FIG. 7  is a partial sectional view of a portion of another heat exchanger embodiment. 
         FIG. 8  is a cross sectional view of the heat exchanger embodiment illustrated in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , an example heat exchanger  10  includes an inlet manifold  15  and an outlet or exhaust manifold  20 . The inlet manifold  15  includes an inlet  14  for a first airflow  28 . The inlet manifold  15  and the outlet manifold  20  are disposed on the ends of a plurality of plates  12 . The plates  12  define an airflow passage between the inlet  14  and an outlet  24 . The plates  12  also define a plurality of passages for a cooling airflow  30  that passes through channels defined by the plurality of plates  12 . 
     The inlet manifold  15  includes a transition region  16  defining an opening or series of openings  18  at the end of the manifold  15  that receives the plates  12  and where airflow schematically indicated at  28  is dispersed and transitions into the airflow passages defined by the plates  12 . The outlet manifold  20  includes a similar transition region  22  where airflow exiting the passages defined within the plates  12  transition towards the outlet  24 . 
     The example heat exchanger  10  is an air to air heat exchanger where a hot airflow indicated at  28  is injected through the inlet  14  and flows through passages within the plates  12  towards the exhaust manifold  20 . Airflow exhausted through the outlet  24  as is indicated at  32  is cooled to a desired temperature. A cooling airflow schematically indicated at  30  flows through the passages defined between the plates  12  by channels between fins. The airflow through the inlet  14  is desired to maintain a desired pressure and avoid excessive pressure losses. Accordingly, the transition region  16  includes features to improve flow into the cooling passages in a more controlled and less turbulent manner to reduce pressure losses that can degrade thermal transfer efficiencies. By controlling transition of airflow into the passages defined by the plates  12 , the pressure losses produced through this transition region can be significantly reduced. 
     Referring to  FIG. 3  with continued references to  FIGS. 1 and 2 , the example intake manifold  15  is shown in an enlarged cross sectional view. The example intake manifold  10  includes a plurality of ribs  36  that extend from a first wall  34  shown in  FIG. 3  to a second wall not shown in  FIG. 3 . Each of the ribs  36  include a smoothly curved transition surface  40 . The ribs  36  further include a support portion  42 . Each of the plates  12  are supported between two of the ribs  36  such that the smoothly curved transition surface indicated at  40  is disposed above and below each intake passage of each plate  12 . The smooth surfaces  40  define a bell mouth shape forward of the inlet to the plate  12  that improves flow properties into the flow passage. 
     In this example, the plate  12  defines a first flow passage  44  through the plate  12  and a second flow passage  46  that flows over an outer surface of the plate  12  between fins  56 . As appreciated, the fins  56  cooperate with fins  56  in an adjacent plate  12  to define channels through which the cooling airflow  30  flows. 
     Referring to  FIGS. 4 and 5  with continued reference to  FIG. 3 , each of the plates  26  are trapped between at least two of the ribs  36 . In the cross section illustrated in FIG.  4 , a first plate  26   a  is trapped between rib  36   a  and  36   b.  A portion of a second plate  26   b  is also illustrated and trapped between the rib  36   b  and  36   c.    
     The example plate  26  is shown in perspective view includes a first end  52  and a second end  54 . The first end  52  defines an inlet  48  that leads to the first flow passage  44 . The outer surface includes the fins  56  that define the second airflow passage  46  for the cooling airflow that flows perpendicular to the hot airflow communicated through the intake manifold  15 . A seal  50  is disposed between each of the plates  26   a,    26   b  and  26   c  and the corresponding ribs  36   a,    36   b  and  36   c.    
     Each of the ribs includes the support portion  42  that accepts the first end portion  52  of a corresponding plate  26 . By defining the ribs  36  within the intake manifold transition region  16  and providing the ribs  36  with the smooth curved transition portions  40 , the bell mouth is created forward of the inlet to the plates  26  to provide a more uniform and smooth transition of airflow from the manifold into each of the corresponding first passages  44 . 
     Referring to  FIGS. 6, 7 and 8 , another example heat exchanger  60  is illustrated and includes a plurality of plates  64  that are stacked atop each other and that are in communication with a transition region  66  of an intake manifold  62 . Each of the plates  64  includes ribs  70  that are disposed within the cooling air flow. As appreciated, the example manifold  60  is shown by way of an example and only the intake manifold  62  is illustrated. A corresponding exhaust manifold would be provided at the exit end of each of the plurality of plates  64  in a similar arrangement to that of the intake manifold  62 . 
     In this example, each of the plates  64  include a bell mouth surface  68 . The bell mouth surfaces  68  mate to one another to define a smoothly curved surface that transitions airflow into the air passages through the plates  64 . In this embodiment, the manifold  62  is not required to have a plurality of ribs. Instead, each of the plates  64  include features that define the bell mouth shape that provide the smooth transition of airflow from the manifold into the airflow passage defined through the plates. 
     In the disclosed example embodiments, the plates  26  and  64  are one piece unitary structures that are cast as a one piece item that do not include joints between any of the portions. The unitary structure of the plate eliminates the need for welded or brazed joints that can cause problems during operation or that may be susceptible to mechanical strains and stresses caused by extreme thermal gradients. 
     The example heat exchanger manifold includes features that tailor airflow and transition that airflow through the plates to enable higher pressure capabilities that in turn increase the overall efficiency of the heat exchanger to enable use and higher temperature and pressure applications. 
     Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the scope and content of this disclosure.