Fluid flow restrictor

Abstract

A fluid .[.Flow Restrictor.]. .Iadd.flow restrictor .Iaddend.especially suitable for reducing the pressure of gases or liquids is described. The restrictor comprises a series of rows of baffles placed in the path of fluid flow, with the baffles in succeeding rows staggered with respect to those in adjacent rows so that as the fluid flows, it is constrained to change its direction repeatedly. The restrictor is preferably constructed with an increasing cross sectional area along the direction of flow. One suitable physical construction comprises a plurality of thin circular plates with a central bore, arranged in a stack. Each plate has a baffle pattern formed on one or both sides, for example, by etching. Fluid flow is from the central bore, between adjacent plates, to the circumference of the stack.

I.]. .Iadd.We .Iaddend.claim: 
     
       1. A .Iadd.low noise level .Iaddend.restrictor .Iadd.having an inlet .Iaddend.for insertion in a fluid path for controlling the flow of fluid therethrough, comprising, a plurality of spaced apart parallel impervious plates,   means for constraining fluid to flow between adjacent plates, .Iadd.and.Iaddend.   a plurality of unconnected baffles between said plates, .Iadd.each .Iaddend.in engagement with .Iadd.both .Iaddend.facing surfaces of adjacent plates and arranged in rows transverse to the general direction of fluid flow, undeviating spaces between adjacent rows and spaces between adjacent baffles in each row as to define transverse passageways between rows and substantially straight longitudinal passageways between adjacent baffles in each row interconnecting adjacent transverse passageways,   the baffles in succeeding rows being positioned so as to divide the flow arriving from the spaces between adjacent baffles of the preceding row.[...]..Iadd.,.Iaddend.   .Iadd.said restrictor having a first row of baffles at said inlet defining a first longitudinal set of passageways having a first total cross-sectional flow area and each succeeding row of longitudinal passageways having a total cross-sectional flow area greater than the cross-sectional flow area of the preceding row, such that the total cross-sectional flow area of said longitudinal passageways between said baffles at any given distance from said inlet increases with the distance from the inlet as measured along the direction of flow of fluid so as to reduce the noise level caused by the insertion of said restrictor into said fluid path..Iaddend..[.2. A restrictor in accordance with claim 1 in which the sizes, shapes and numbers of said baffles are selected and said baffles are positioned so that the cross sectional flow area does not   
     
     
        decrease in the direction of flow..]. .[.3.  A restrictor in accordance with claim 1 in which the sizes, shapes and numbers of said baffles are selected and said baffles are positioned so that the cross sectional flow area remains substantially constant along the direction of flow..]..[.4. A restrictor in accordance with claim 1 in which the sizes, shapes and numbers of said baffles are selected and said baffles are positioned so that the cross sectional flow area increases in the direction of flow..]. 
     
     
         . A restrictor in accordance with claim 1 in which said baffles are positioned so that a stream of fluid passing between adjacent baffles of one row encounters a baffle in a succeeding row and is thereby constrained 
     
     
        to change its direction of flow. 6. A restrictor in accordance with claim 1 in which said baffles are positioned to define a plurality of series and 
     
     
        parallel flow paths. 7. A restrictor in accordance with claim 1 in which said baffles are positioned so that a stream of fluid encountering a baffle is divided into two streams which then flow in opposite directions, 
     
     
        each at approximately ninety degrees to its former direction. 8. A restrictor in accordance with claim 1 in which said baffles are positioned so as to divide a fluid stream striking it into two streams flowing in 
     
     
        opposite directions approximately parallel to said rows. 9. A restrictor in accordance with claim 8 in which said baffles are positioned so that said streams flowing parallel to said rows encounter and join oppositely flowing streams in turning and flowing between baffles of the next 
     
     
        succeeding row. 10. A .Iadd.low noise level .Iaddend.restrictor for insertion in a fluid flow path for controlling the flow of fluid therethrough, comprising, a plurality of thin plates .[.assembled into a stack.].,   each of said plates being formed with a central aperture,   .Iadd.said plates being assembled into a stack with said apertures aligned and constituting a fluid inlet,.Iaddend.   each of said plates also being formed with a plurality of unconnected baffles on at least one side thereof,   said baffles being arranged in concentric rows about said central aperture with uniform annular spaces between rows and radial spaces between adjacent baffles in each row as to define circular passageways between rows and substantially straight radial passageways between adjacent baffles in each row interconnecting adjacent circular passageways,   whereby .Iadd.fluid entering said fluid inlet flows between adjacent plates and encounters .Iaddend.said baffles .Iadd.which .Iaddend.divide the flow and define a plurality of paths along the surfaces of said plates between baffles interconnecting said central aperture with the outside edge.[...]..Iadd.,.Iaddend.   .Iadd.said restrictor having a first row of baffles at said inlet defining a first radial set of passageways having a first total cross-sectional flow area and each succeeding row of radial passageways having a total cross-sectional flow area greater than the total cross-sectional flow area of the preceding row, such that the total cross-sectional flow area of said radial passageways between said baffles at any given distance from the inlet increases with distance from the inlet as measured along the direction of the flow of fluid so as to reduce the noise level caused by   
     
     
        the insertion of said restrictor into said fluid flow path..Iaddend. 11. A restrictor in accordance with claim 10 in which said plates are formed with baffles on but one side thereof and in which said stack includes one 
     
     
        plate without baffles. 12. A restrictor in accordance with claim 10 in which said plates are formed with baffles on both sides and said stack includes a plurality of plates without baffles alternating with said 
     
     
        plates with baffles. 13. A restrictor in accordance with claim 10 in which said baffles are positioned to define a plurality of series and parallel 
     
     
        paths between said central aperture and said outside edge. 14. A restrictor in accordance with claim 10 in which said plates and said aperture are circular and in which said baffles are positioned so that fluid flowing between adjacent baffles in a row strikes and is deflected 
     
     
        by a baffle in the next succeeding row. .[.15.  A restrictor in accordance with claim 14 in which the sizes, shapes and numbers of said baffles are selected and said baffles are positioned so that the cross sectional flow area increases with radial distance from the center of said plates..]. 
     
     
            A .Iadd.low noise .Iaddend.restrictor for insertion in a fluid flow path for reducing the pressure of a fluid flowing therethrough, comprising, a plurality of thin, circular plates, each formed with a circular, central aperture,   .Iadd.said plates being assembled into a stack with said apertures aligned and constituting a fluid inlet,.Iaddend.   each of said plates being smooth on one side and formed with a plurality of unconnected baffles on the other side so arranged in concentric circular rings with a continuous annular space between adjacent rings and radial spaces .[.and.]. between adjacent baffles in each ring for the flow of fluid as to define concentric circular passageways between rows and substantially straight radial passageways between adjacent baffles in each row connecting adjacent circular passageways,   the baffles in each ring being positioned so that fluid .Iadd.entering said inlet and .Iaddend.flowing radially outwardly between adjacent baffles strikes a baffle in the next succeeding ring and is divided thereby .[...]..Iadd.,.Iaddend.   .Iadd.said restrictor having a first row of baffles at said inlet defining a first radial set of passageways having a first total cross-sectional flow area and each succeeding row of radial passageways having a total cross-sectional flow area greater than the total cross-sectional flow area of the preceding row, such that the total cross-sectional flow area of said radial passageways between said baffles at any given distance from said inlet increases with the distance from the inlet as measured along the direction of flow of fluid, so as to reduce the noise level caused by the insertion of said restrictor into said fluid flow path..Iaddend.   
     
     
        .[.     A restrictor in accordance with claim 16 in which the sizes, shapes and number of said baffles are selected and said baffles are positioned so that the cross sectional flow area increases with the radial distance from the center of said stack..].