Asymmetric fluid flow device

Abstract

A fluid flow assembly for disposition along a fluid flow axis within an inward-facing surface extending between upstream and downstream ends. At least two damper blades extend from associated blade axes transverse to the flow axis. The damper blades include perimeter sections opposite the respective blade axes which are matching-in-shape to sections of the inward-facing surface. The damper blades are selectively driven by actuators to independently pivot about the respective blade axes between a closed position blocking fluid flow from the upstream end to the downstream end, to an open position angularly displaced therefrom. In a form, at least two damper blades have different cross-section areas between their respective blade axes and matching-in-shape perimeter sections. In a form, at least one damper blade is configured as an orifice plate.

What is claimed is: 
     
         1 . A fluid flow assembly for disposition along a central fluid flow path extending along a fluid flow axis and defining a flow region bounded by an inward-facing surface extending along the fluid flow axis from an upstream end to a downstream end, comprising:
 A. a plurality of damper blades disposed within the flow region, including:
 i. a first end blade characterized by a blade area A 1 , and
 a. extending from a first end blade axis extending transverse to the flow axis and across the flow region, to a first end blade perimeter section opposite the first blade axis, wherein at least a portion of the perimeter section matches in shape a corresponding portion of the inward facing surface, and 
 b. adapted for pivotal motion at angle ϕ 1  about the first end blade axis from a closed position whereby the matching portions of the first end blade perimeter section and inward facing wall are adjacent, thereby blocking fluid flow past the perimeter section of the first end blade along the flow path to an open position angularly offset therefrom, 
 wherein the matching in shape portion of the perimeter section of the first end blade 
 and the matching in shape portion of the inward facing surface opposite thereto define a first adjustable variable aperture through which at least a portion of the flow path passes when ϕ 1  is offset from the closed position, and wherein the cross section area of fluid flow through the first adjustable variable aperture normal to the flow is A o1 , 
 
 ii. a second end blade characterized by a blade area A 2 , and
 a. extending from a second end blade axis parallel to the first end blade axis, and extending transverse to the flow axis and across the flow region, to a second end blade perimeter section opposite the second blade axis wherein at least a portion of the perimeter section matches in shape a corresponding portion of the inward facing surface, and 
 b. adapted for pivotal motion at angle ϕ 2  about the second end blade axis wherein the second end blade axis extends across the second end blade and transverse to the flow path from a closed position whereby the matching portions of the second end blade perimeter section and inward facing wall are adjacent, thereby blocking fluid flow past the perimeter section of the second end blade along the flow path, to an open position angularly offset therefrom, 
 wherein the matching in shape portion of the perimeter section of the second end blade and the matching in shape portion of the inward facing surface opposite thereto define a second adjustable variable aperture through which at least a portion of the flow path passes when ϕ 2  is offset from the closed position, and wherein the cross section area of fluid flow through the second adjustable variable aperture normal to the flow is A o2 , and 
 
   B. an actuator assembly including a plurality of actuators operatively connected with the first end blade and the second end blade, including:
 i. a first actuator coupled to the first end blade and adapted to effect actuator-driven pivotal motion of the first end blade, and 
 ii. a second actuator coupled to the second end blade and adapted to effect actuator-driven pivotal motion of the second end blade, and 
   wherein the actuator assembly is adapted to effect independent pivotal motion of the first end blade and pivotal motion of second end blade thereby effecting independent control of ϕ 1  and ϕ 2 .   
     
     
         2 . The fluid flow assembly according to  claim 1 , wherein A 1  is greater than A 2 . 
     
     
         3 . The fluid flow assembly according to  claim 2 , further comprising:
 A. in a downstream portion of the flow region between downstream-facing portions of the first end blade and the second end blade and the downstream end,
 a fluid flow separator extending from a blade support structure at or between the first end blade axis and the second blade axis, toward the downstream end, and 
 wherein the fluid flow separator is adapted to prevent fluid flow in directions transverse to the fluid flow axis between points in the downstream portion of the flow region proximal to the first end blade and points in the downstream portion of the flow region proximal to the second end blade, 
 thereby establishing:
 i. a first downstream static fluid region of the fluid flow region characterized by a first static pressure adjacent to the downstream facing portion of the first end blade, and 
 ii. a second downstream static fluid region of the fluid flow region characterized by a second static pressure adjacent to the downstream facing portion of the second end blade, and the second end blade, 
 
   B. at least one upstream sensor adapted for sensing upstream pressure at a first upstream pressure sense locus in a portion of the flow region upstream with respect to and displaced distal in the direction of the flow axis from an upstream facing side of at least one of the first end blade and the second end blade,   C. at least one downstream sensor adapted for sensing downstream pressure in at least one first downstream pressure sense locus disposed in the first downstream static fluid region,   D. at least one upstream sensor adapted for sensing upstream pressure at a second upstream pressure sense locus in a portion of the flow region upstream with respect to and displaced distal in the direction of the flow axis from an upstream facing side of the second end blade,   E. at least one downstream sensor adapted for sensing downstream pressure in at least one second downstream pressure sense locus disposed in the first downstream static fluid region,   F. variable aperture sensors associated with the actuator assembly and adapted to characterize cross-section areas A o1  and A o2  of the respective first and second variable apertures normal to the direction of the flow path therethrough as the cross-section areas vary pursuant to the effected pivotal motion, and   G. a processor responsive to:
 i. the sensed upstream pressures and sensed downstream pressures to generate pressure signals representative of differential pressures ΔP 1  and ΔP 2  along the flow axis across the first end blade and second end blade respectively, 
 ii. the variable aperture sensors of the actuator assembly to generate aperture signals representative of the areas of the respective apertures associated with the first end blade and the second end blade normal to flow paths of fluid flowing therethrough, 
 iii. the pressure signal and the aperture signal to generate respective blade area control signals, and apply the blade area control signals to the actuator assembly in a closed loop manner, 
 whereby fluid flows from the upstream end, through the first and second adjustable variable apertures characterized by respective cross section areas A o1  and A o2  normal to the flows therethrough, and to the downstream end wherein the fluid flowing between the respective apertures and the downstream end, is characterized by associated vena contractae having respective cross section areas A c1  and A c2  normal to the fluid flows therethrough, 
 wherein for the vena contractae associated with the first adjustable variable aperture and the second adjustable variable aperture,
 a. A c1 <A o1 , and A c1  is less than the cross section area normal to fluid flow elsewhere between the vena ccontracta associated with the first adjustable variable aperture and the downstream end, and 
 b. A c2 <A o2 , and A c2  is less than the cross section area normal to fluid flow elsewhere between the vena ccontracta associated with the second adjustable variable aperture and the downstream end, 
 
 thereby establishing a contraction coefficients C 1  and C 2  for the adjustable variable apertures of the first end blade and the second end blade for fluid flowing from the upstream end, through the respective variable apertures, and to the downstream end, wherein 
   
       
         
           
             
               
                 C 
                 1 
               
               = 
               
                 
                   
                     
                       A 
                       
                         c 
                          
                         
                             
                         
                          
                         1 
                       
                     
                     
                       A 
                       
                         o 
                          
                         
                             
                         
                          
                         1 
                       
                     
                   
                    
                   
                       
                   
                    
                   and 
                    
                   
                       
                   
                    
                   
                     C 
                     2 
                   
                 
                 = 
                 
                   
                     A 
                     
                       c 
                        
                       
                           
                       
                        
                       2 
                     
                   
                   
                     A 
                     
                       o 
                        
                       
                           
                       
                        
                       2 
                     
                   
                 
               
             
           
         
         
           where A c1  and A c2  are representative of cross section areas of vena contractae of fluid flowing through the respective first adjustable variable aperture determined by the first end blade and second adjustable variable aperture determined by the second end blade, 
           whereby the processor is responsive to contraction coefficients C 1  and C 2 , the respective aperture signals and the respective pressure signals, to regulate the variable apertures of the first end blade and the second end blade over time in a closed loop manner so that a set point is attained with respect to the first end blade and the second end blade. 
         
       
     
     
         4 . The fluid flow assembly according to  claim 3 , wherein the at least one upstream pressure sense locus is disposed upstream of portions of the flow region between the upstream pressure locus and the first side of the damper assembly in which fluid flow is disturbed by the damper assembly. 
     
     
         5 . A fluid flow assembly according to  claim 3  wherein:
 i. ϕ 1  is defined with respect to a plane traversing the flow region normal to the flow axis so that ϕ 1 =0 when the first adjustable variable aperture is at the closed position, and 
 ii. ϕ 2  is defined with respect to a plane traversing the flow region normal to the flow axis so that ϕ 2 =0 when the second adjustable variable aperture is at the closed position. 
 
     
     
         6 . The fluid flow assembly according to  claim 2 , wherein the first end blade axis and the second end blade axis are coaxial. 
     
     
         7 . The fluid flow assembly according to  claim 2 , wherein the first end blade axis and the second end blade axis are spaced apart by a distance L in a direction transverse to the flow axis. 
     
     
         8 . The fluid flow assembly according to  claim 7 , wherein a fluid flow impervious element is disposed between the first end blade and the second end blade, blocking fluid flow therethrough from portions of the flow region upstream with respect to the first end blade and the second end blade to regions downstream thereof. 
     
     
         9 . The fluid flow assembly according to  claim 8 , wherein the fluid flow impervious element is a static pressure regain element extending along the flow axis. 
     
     
         10 . The fluid flow assembly according to  claim 7 , wherein n intermediate blades are disposed successively between the first end blade and the second end blade, wherein n is an integer, and wherein the n intermediate blades:
 i. are each adapted for pivotal motion at an angle ϕn about an associated intermediate blade axis parallel to the first end blade axis and second blade axis, from a closed position wherein ϕn=0, to an angle offset therefrom, and   ii. each have lateral boundaries which are adjacent to lateral boundaries of the intermediate blades adjacent thereto when ϕn=0,
 whereby the adjacent lateral boundaries of the intermediate blades block fluid flow therebetween when ϕn=0, and permit fluid flow therebetween along the fluid flow pathway when ϕn is non-zero. 
   
     
     
         11 . The fluid flow assembly according to  claim 2 , wherein the inward-facing surface defines a circular cross-section in a portion adjacent to the first end blade and the second end blade, and the first end blade and the second end blade are characterized by chord-truncated circular shapes. 
     
     
         12 . The fluid flow assembly according to  claim 2 , wherein the inward-facing surface defines an elliptical cross-section in a portion adjacent to the first end blade and the second end blade, and the first end blade and the second end blade are characterized by chord-truncated elliptical shapes. 
     
     
         13 . The fluid flow assembly according to  claim 2 , wherein the inward-facing surface defines an oval cross-section in a portion adjacent to the first end blade and the second end blade, and the first end blade and the second end blade are characterized by chord-truncated oval shapes. 
     
     
         14 . The fluid flow assembly according to  claim 2 , wherein the inward-facing surface defines a rectangular cross-section in a portion adjacent to the first end blade and the second end blade, and the first end blade and the second end blade are characterized by rectangular shapes. 
     
     
         15 . The fluid flow assembly according to  claim 1 , wherein A 1  equals A 2 . 
     
     
         16 . The fluid flow assembly according to  claim 15 , further comprising:
 A. in a downstream portion of the flow region between downstream-facing portions of the first end blade and the second end blade and the downstream end, a fluid flow separator extending from a blade support structure at or between the first end blade axis and the second blade axis, toward the downstream end, and
 wherein the fluid flow separator is adapted to prevent fluid flow in directions transverse to the fluid flow axis between points in the downstream portion of the flow region proximal to the first end blade and points in the downstream portion of the flow region proximal to the second end blade, 
 thereby establishing:
 i. a first downstream static fluid region of the fluid flow region characterized by a first static pressure adjacent to the downstream facing portion of the first end blade, and 
 ii. a second downstream static fluid region of the fluid flow region characterized by a second static pressure adjacent to the downstream facing portion of the second end blade, and the second end blade, 
 
   B. at least one upstream sensor adapted for sensing upstream pressure at a first upstream pressure sense locus in a portion of the flow region upstream with respect to and displaced distal in the direction of the flow axis from an upstream facing side of at least one of the first end blade and the second end blade,   C. at least one downstream sensor adapted for sensing downstream pressure in at least one first downstream pressure sense locus disposed in the first downstream static fluid region,   D. at least one upstream sensor adapted for sensing upstream pressure at a second upstream pressure sense locus in a portion of the flow region upstream with respect to and displaced distal in the direction of the flow axis from an upstream facing side of the second end blade,   E. at least one downstream sensor adapted for sensing downstream pressure in at least one second downstream pressure sense locus disposed in the first downstream static fluid region,   F. variable aperture sensors associated with the actuator assembly and adapted to characterize cross-section areas A o1  and A o2  of the respective first and second variable apertures normal to the direction of the flow path therethrough as the cross-section areas vary pursuant to the effected pivotal motion, and   G. a processor responsive to:
 i. the sensed upstream pressures and sensed downstream pressures to generate pressure signals representative of differential pressures ΔP 1  and ΔP 2  along the flow axis across the first end blade and second end blade respectively, 
 ii. the variable aperture sensors of the actuator assembly to generate aperture signals representative of the areas of the respective apertures associated with the first end blade and the second end blade normal to flow paths of fluid flowing therethrough, 
 iii. the pressure signal and the aperture signal to generate respective blade area control signals, and apply the blade area control signals to the actuator assembly in a closed loop manner, 
 whereby fluid flows from the upstream end, through the first and second adjustable variable apertures characterized by respective cross section areas A o1  and A o2  normal to the flows therethrough, and to the downstream end wherein the fluid flowing between the respective apertures and the downstream end, is characterized by associated vena contractae having respective cross section areas A c1  and A c2  normal to the fluid flows therethrough, 
 wherein for the vena contractae associated with the first adjustable variable aperture and the second adjustable variable aperture,
 a. A c1 <A o1 , and A c1  is less than the cross section area normal to fluid flow elsewhere between the vena ccontracta associated with the first adjustable variable aperture and the downstream end, and 
 b. A c2 <A o2 , and A c2  is less than the cross section area normal to fluid flow elsewhere between the vena ccontracta associated with the second adjustable variable aperture and the downstream end, 
 
 thereby establishing a contraction coefficients C 1  and C 2  for the adjustable variable apertures of the first end blade and the second end blade for flu id flowing from the upstream end, through the respective variable apertures, and to the downstream end, wherein 
   
       
         
           
             
               
                 C 
                 1 
               
               = 
               
                 
                   
                     
                       A 
                       
                         c 
                          
                         
                             
                         
                          
                         1 
                       
                     
                     
                       A 
                       
                         o 
                          
                         
                             
                         
                          
                         1 
                       
                     
                   
                    
                   
                       
                   
                    
                   and 
                    
                   
                       
                   
                    
                   
                     C 
                     2 
                   
                 
                 = 
                 
                   
                     A 
                     
                       c 
                        
                       
                           
                       
                        
                       2 
                     
                   
                   
                     A 
                     
                       o 
                        
                       
                           
                       
                        
                       2 
                     
                   
                 
               
             
           
         
         
           where A c1  and A c2  are representative of cross section areas of vena contractae of fluid flowing through the respective first adjustable variable aperture determined by the first end blade and second adjustable variable aperture determined by the second end blade, 
           whereby the processor is responsive to contraction coefficients C 1  and C 2 , the respective aperture signals and the respective pressure signals, to regulate the variable apertures of the first end blade and the second end blade over time in a closed loop manner so that a set point is attained with respect to the first end blade and the second end blade. 
         
       
     
     
         17 . The fluid flow assembly according to  claim 16 , wherein the at least one upstream pressure sense locus is disposed upstream of portions of the flow region between the upstream pressure locus and the first side of the damper assembly in which fluid flow is disturbed by the damper assembly. 
     
     
         18 . A fluid flow assembly according to  claim 16  wherein:
 i. φ 1  is defined with respect to a plane traversing the flow region normal to the flow axis so that φ 1 =0 when the first adjustable variable aperture is at the closed position, and 
 ii. ϕ 2  is defined with respect to a plane traversing the flow region normal to the flow axis so that ϕ 2 =0 when the second adjustable variable aperture is at the closed position. 
 
     
     
         19 . A fluid flow assembly according to  claim 2  where A 1 >A 2 , wherein, when ϕ 1 =ϕ 2 , and pressure drop across the first blade ΔP 1  and across the second blade ΔP 2  are the same, fluid flow past the first blade is at a relatively high rate and fluid flow past the second blade is at a relatively low rate. 
     
     
         20 . A fluid flow assembly according to  claim 15  where A 1 =A 2 , wherein, when (ϕ 1 >ϕ 2 , and pressure drop across the first blade Δ P1  and across the second blade ΔP 2  are the same, fluid flow past the first blade is at a relatively high rate and fluid flow past the second blade is at a relatively low rate.