Abstract:
A fluid cooled system includes a first heat generating component. A first airflow pathway directs a first flow of air across a first heat exchanger. A second airflow pathway directs a second flow of air across a second heat exchanger. A first working fluid is flowed from the first heat generating component, through the first heat exchanger and through the second heat exchanger and returned to the first heat generating component.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present disclosure relates to vehicles, for example, rotorcraft with fluid cooled engines. More specifically, the present disclosure relates to redundant cooling systems for vehicles with fluid cooled engines or fluid cooled systems. 
         [0002]    Fluid cooled systems, for example, internal combustion engines, require a cooling system that forces air across a heat exchanger to reject thermal energy from a working fluid that circulates through the engine. The cooling system must function during normal engine operation to prevent the engine from overheating that leads to engine failure. Such a cooling system is prone to failure of any one of the multiple components of the system, such as a fan, duct, heat exchanger or fluid distribution system including pumps and piping network Failure or malfunction of any of these components could lead to cooling system failure and, consequently, engine failure. 
         [0003]    In some applications, aircraft have multiple engines for redundancy to meet safety and reliability requirements if a failure of one of the engines occurs. It is difficult to meet safety and reliability requirements if a failure of one of the above components of the cooling system can result in cooling system failure. To overcome this difficulty, the individual components, such as the fan, duct and heat exchanger are robustly designed to increase damage and flaw tolerance, with the penalty of additional weight, increased cost, larger component size, and loss of mission capability of the aircraft. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    A fluid cooled system includes a heat generating component. A first airflow pathway directs a first flow of air across a first heat exchanger. A second airflow pathway directs a second flow of air across a second heat exchanger. A working fluid is flowed from the heat generating component, through the first heat exchanger and through the second heat exchanger and returned to the heat generating component. 
         [0005]    A rotorcraft includes an airframe and a rotor assembly operably connected to the airframe including a plurality of rotor blades operably connected to a rotor shaft. The rotorcraft further includes a fluid cooled engine system operably connected to the rotor assembly. The fluid cooled engine system includes an engine, a first airflow pathway to direct a first flow of air across a first heat exchanger, and a second airflow pathway to direct a second flow of air across a second heat exchanger. A working fluid is flowed from the engine, through the first heat exchanger and through the second heat exchanger and returned to the engine. 
         [0006]    A method of operating a fluid cooled engine system includes urging a flow of a working fluid from a heat generating component and urging the flow of working fluid through a first heat exchanger. A first airflow is urged across the first heat exchanger via a first airflow pathway thereby transferring thermal energy between the flow of working fluid and the first airflow. The flow of working fluid is conveyed through a second heat exchanger and a second airflow is conveyed across the second heat exchanger via a second airflow pathway thereby transferring thermal energy between the flow of working fluid and the second airflow. The flow of working fluid is returned to the heat generating component. 
         [0007]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0009]      FIG. 1  is a schematic view of an embodiment of a rotary wing aircraft; 
           [0010]      FIG. 2  is a schematic embodiment of an embodiment of a fluid cooled engine system; 
           [0011]      FIG. 3  is a schematic of coolant flow in a fluid cooled engine system; 
           [0012]      FIG. 4  is another schematic of coolant flow in a fluid cooled engine system; 
           [0013]      FIG. 5  is a schematic of lubricant flow in a fluid cooled engine system; 
           [0014]      FIG. 6  is another schematic of lubricant flow in a fluid cooled engine system; and 
           [0015]      FIG. 7  is a schematic of fluid flow in a fluid cooled engine system. 
       
    
    
       [0016]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 1  is a schematic illustration of a rotary wing aircraft  10  having a main rotor assembly  12 . The aircraft  10  includes an airframe  14  having an extending tail  16  at which is mounted a tail rotor  18 . The main rotor assembly  12  is driven by two or more fluid cooled engines  20  connected to the main rotor assembly via a gearbox  22 . 
         [0018]    Referring now to  FIG. 2 , in some embodiments the aircraft  10  has two engines  20 , identified as  20   a  and  20   b  in the FIG. and is cooled via a cooling system  24 . It is to be appreciated that while the system  24  described herein is for cooling two engines  20   a  and  20   b,  the system  24  may be arranged to cool any number of engines  20 . Further, while the system  24  is described herein as applied to a rotary wing aircraft  10 , it may be applied to any use of a fluid cooled engine arrangement  20 . Also, while the system  24  described herein is utilized to cool engines, it is to be appreciated that the system  24  may be utilized to cool other heat generating components or machines. 
         [0019]    A first engine  20   a  is operably connected to a first fan  26   a  which urges a flow of inlet air  28  into a first duct  30   a.  A first coolant heat exchanger  32   a  and first engine oil heat exchanger  34   a  are arranged at the first duct  30   a  upstream of a first duct outlet  36   a.  Further, first engine  20   a  is operably connected to a first coolant pump  38   a  and a first oil pump  40   a.    
         [0020]    Similarly, a second engine  20   b  is operably connected to a second fan  26   b  which urges a flow of inlet air  28  into a second duct  30   b.  A second coolant heat exchanger  32   b  and second engine oil heat exchanger  34   b  are arranged at the second duct  30   b  upstream of a second duct outlet  36   b.  Further, second engine  20   b  is operably connected to a second coolant pump  38   b  and a second oil pump  40   b.    
         [0021]    Flow of coolant and engine oil for engines  20   a  and  20   b  during normal operation of engines  20   a  and  20   b  and cooling system  24  is illustrated in  FIGS. 3-6 . Referring to  FIG. 3 , when the first engine  20   a  is operating, the first fan  26   a,  the first coolant pump  38   a  and the first oil pump  40   a,  driven by the first engine  20   a  are also operating. The first fan  26   a  urges inlet air  28  through the first duct  30   a  and across the first coolant heat exchanger  32   a  and the first engine oil heat exchanger  34   a.  The first coolant pump  38   a  pumps a first engine coolant flow  42   a  from the first engine  20   a.  The first coolant pump  38   a  urges this first engine coolant flow  42   a  through the first coolant heat exchanger  32   a,  where thermal energy is transferred from the first engine coolant flow  42   a  to the inlet air  28  flowing through the first duct  30   a.  The first engine coolant flow  42   a  is then urged to the second coolant heat exchanger  32   b  and flowed therethrough to transfer thermal energy from the first engine coolant flow  42   a  to inlet air  28  flowing through the second duct  30   b.  After flowing through the second coolant heat exchanger  32   b,  the first engine coolant flow  42   a  is flowed into the first engine  20   a  where thermal energy is transferred from the first engine  20   a  to the first engine coolant flow  42   a  to cool the first engine  20   a.  Directing the first engine coolant flow  42   a  through both the first coolant heat exchanger  32   a  and the second coolant heat exchanger  32   b  allows for effective cooling of the first engine  20   a  even with failure of components such as the first coolant heat exchanger  32   a,  the first fan  26   a  or first duct  30   a.    
         [0022]    Similarly, and referring now to  FIG. 4 , a second engine coolant flow  42   b  is pumped from the second engine  20   b  by the second coolant pump  38   b.  The second coolant pump  38   b  urges the second engine coolant flow  42   b  through the second coolant heat exchanger  32   b,  where thermal energy is transferred from the second engine coolant flow  42   b  to the inlet air  28  flowing through the second duct  30   b.  The second engine coolant flow  42   b  is then urged to the first coolant heat exchanger  32   a  and flowed therethrough to transfer thermal energy from the second engine coolant flow  42   b  to inlet air  28  flowing through the first duct  30   a.  After flowing through the first coolant heat exchanger  32   a,  the second engine coolant flow  42   b  is flowed into the second engine  20   b  where thermal energy is transferred from the second engine  20   b  to the second engine coolant flow  42   b  to cool the second engine  20   b.  Directing the second engine coolant flow  42   b  through both the second coolant heat exchanger  32   b  and the first engine coolant heat exchanger  32   a  allows for effective cooling of the second engine  20   b  even with failure of components such as the second coolant heat exchanger  32   b,  the second fan  26   b  or second duct  30   b.    
         [0023]    Referring to  FIG. 5 , the first oil pump  40   a  pumps a first engine oil flow  44   a  from the first engine  20   a  and through the first engine oil heat exchanger  34   a,  where thermal energy is transferred between the first engine oil flow  44   a  and the inlet flow  28  through the first duct  30   a.  The first engine oil flow  44   a  then proceeds through the second engine oil heat exchanger  34   b  and thermal energy is transferred between the first engine oil flow  44   a  and the inlet flow  28  through the second duct  30   b.  The first engine oil flow  44   a  is then flowed into the first engine  20   a  to lubricate and transfer thermal energy from the first engine  20   a  to the first engine oil flow  44   a  to cool the first engine  20   a.  Directing the first engine oil flow  44   a  through both the first engine oil heat exchanger  34   a  and the second engine oil heat exchanger  34   b  allows for effective cooling of the first engine oil flow  44   a  even with failure of components such as the first engine oil heat exchanger  34   a,  the first fan  26   a  or the first duct  30   a.    
         [0024]    Referring to  FIG. 6 , the second oil pump  40   b  pumps a second engine oil flow  44   b  from the second engine  20   b  and through the second engine oil heat exchanger  34   b,  where thermal energy is transferred between the second engine oil flow  44   b  and the inlet flow  28  through the second duct  30   b.  The second engine oil flow  44   b  then proceeds through the first engine oil heat exchanger  34   a  and thermal energy is transferred between the second engine oil flow  44   b  and the inlet flow  28  through the first duct  30   a.  The second engine oil flow  44   b  is then flowed into the second engine  20   b  to lubricate and transfer thermal energy from the second engine  20   b  to the second engine oil flow  44   b  to cool the second engine  20   b.  Directing the second engine oil flow  44   b  through both the second engine oil heat exchanger  34   b  and the first engine oil heat exchanger  34   a  allows for effective cooling of the second engine oil flow  44   b  even with failure of components such as the second engine oil heat exchanger  34   b,  the second fan  26   b  or the second duct  30   b.    
         [0025]    Referring now to  FIG. 7 , the system  24  is still operable to serve a remaining engine in the case of failure of one engine. For example, as shown in  FIG. 7 , in the case of a failure of the second engine  20   b,  the system  24  would still serve the first engine  20   a  with sufficient cooling capacity for continued normal operation. In the case of failure of the second engine  20   b,  first engine coolant flow  42   a  is not routed to second coolant heat exchanger  32   b,  but is diverted back through first coolant heat exchanger  32   a  for a second pass by operation of first coolant valve  46   a.  Similarly, the first engine oil flow  44   a  is not routed to second oil heat exchanger  34   b,  but is diverted for a second pass through first oil heat exchanger  34   a  by first oil valve  48   a.  Second coolant valve  46   b  and second oil valve  48   b  (shown in  FIG. 2 ) are provided to similarly divert the second engine coolant flow  42   b  and the second engine oil flow  44   b  in the case of a failure of the first engine  20   a.  In some embodiments, sensors such as temperature sensors  50  and/or pressure sensors  52  are provided in the system  24  to assist in determining functionality of the system  24 . In some embodiments, the sensors are connected to a health monitor  54  or other controller that utilizes inputs from the sensors to determine if valves  46   a,    46   b,    48   a  or  48   b  should be used to divert the flows  42   a,    42   b,    44   a,    44   b  from their respective normal paths. 
         [0026]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.