Fluidic oscillator with resonant inertance and dynamic compliance circuit

Abstract

The fluidic oscillator consists of a resonant fluid circuit having a fluid inertance and a dynamic fluid compliance. The inertance is a conduit interconnecting two locations of a chamber on each side of a working fluid jet issuing into one end of the chamber, the inertance conduit serving to transfer working fluid between the two locations. Through one or more output orifices located approximately at the opposite end of the chamber, the fluid exits from a chamber exit region which is shaped to facilitate formation of a vortex (the dynamic compliance) from the entering fluid. The flow pattern in the chamber and particularly the vortex in the chamber exit region provide flow aspiration on one side and surplus of flow on the opposite side of the chamber, which effects accelerate and respectively decelerate the fluid in the inertance conduit such as to cause reversal of the vortex after a time delay given by the inertance. The vortex in the chamber exit region will thus cyclically alternate in the velocity and direction of rotation to direct outflow through the output orifice such as to produce a cyclically repetitive side-to-side sweeping stream our spray pattern whose direction is determined, at any instant in time, as a function of the vectorial sum, at the output orifice, of the tangential vortex flow spin velocity vector and the static pressure vector as well as the dynamic pressure component, both directed radially from the vortex. By changing these parameters by suitable design measures and operating conditions and by appropriately configuring the oscillator, sweep angle, oscillation frequency, distribution, outflow velocity, break up into droplets, etc. can be readily controlled over large ranges.

What I claim is: .[.1. A fluidic oscillator having a chamber, an inlet opening for issuing a jet of working fluid into said chamber, and an outlet opening for issuing working fluid from said chamber into the ambient environment, characterized by a fluid inertance flow conduit transferring working fluid between first and second locations on opposite sides of said jet and near said inlet opening in said chamber, and a dynamic compliance in the form of a vortex region defined between sidewalls of said chamber which generally converge towards said outlet opening and near said outlet opening such that working fluid in the jet forms in said vortex region a vortex which alternately flows in opposite directions, the vortex alternately aspirating fluid from and supplying fluid to said first and second locations in opposite phase and thereby through said inertance in alternately opposite directions..]. .[.2. The oscillator according to claim 1 further including an adjustment for 
     
        changing the inertance of said flow conduit..]. 3. The oscillator according to claim .[.1.]. .Iadd.25 .Iaddend.further including a pressure control device for permitting adjustment of the static working fluid pressure in said vortex region to change the frequency and/or outlet spray 
     
     
        pattern of said oscillator. 4. The oscillator according to claim .[.1.]. .Iadd.25 .Iaddend.further including a first adjustment for the oscillator frequency in the form of an adjustment for the length of said inertance flow conduit, and a second adjustment for the oscillator frequency in the form of a control of the static pressure in said vortex region, the effect on oscillator frequency of the first and second adjustments being 
     
     
        multiplicative. 5. A showerhead employing the oscillator of .[.claims 1, 
     
     
        2, 3, or 4.]. .Iadd.claim 25.Iaddend.. 6. The oscillator according to .[.claims 2 or 4.]. .Iadd.claims 26 .Iaddend.wherein .Iadd.at least a portion of .Iaddend.the inertance flow conduit is the closed end of a hollow cylinder open at one end and closed at the other end with a cylindrical piston axially slidable therein, the closed end of the cylinder being of greater diameter than the portion of the cylinder immediately adjacent thereto and being pressure sealed therefrom, whereby the axial movement of the piston in the cylinder varies the volume and the 
     
     
        shape of the volume of the closed end and hence the inertance thereof. 7. The oscillator according to .[.claims.]. .Iadd.claim .Iaddend.3 .[.or 4.]. wherein control of static pressure in the vortex region is provided by a valve which controllably supplies pressurized working fluid to said 
     
     
        vortex region through an opening therein. 8. A fluidic spray device in the form of a fluidic oscillator having a power nozzle issuing a jet of working liquid into a chamber, an outlet opening for issuing working liquid spray from said chamber, and means in said chamber for oscillating the issued liquid spray back and forth transverse to the general direction of the jet, said device being characterized by means for adjusting the shape of the pattern formed by said issued spray by controlling the static 
     
     
        pressure in said chamber downstream of said nozzle. 9. The fluidic spray device according to claim 8 wherein said means for adjusting is a valve for supplying pressurized working fluid into said chamber through another 
     
     
        opening therein. 10. The fluidic spray device according to claim 8 wherein said chamber includes a vortex region in which a vortex flow of said working fluid alternately flows in opposite directions at the frequency of said oscillator and wherein said means for adjusting includes an opening in said chamber at said vortex region and means for controllably admitting pressurized working fluid into said vortex region through said opening. .[.11. A fluidic spray device comprising: a chamber;   inlet means for issuing a jet of working fluid into said chamber;   outlet means for issuing working fluid from said chamber in a flow pattern and direction determined by the static pressure and flow velocity of working fluid in said chamber;   dynamic compliance means in the form of sidewalls which converge toward said outlet opening and near said outlet opening for establishing a vortical flow of the working flow issued into said chamber; and   fluid inertance means for cyclically reversing said vortical flow between first and second flow directions, said fluid inertance means interconnecting first and second locations in said chamber on opposite sides of said jet proximate said inlet means such that vortical flow in said first flow direction aspirates fluid from said fluid inertance means at said first location and feeds fluid into said fluid inertance means at said second location, and such that vortical flow in said second direction aspirates fluid from said fluid inertance means at said second locations and feeds fluid into said fluid inertance means at said first location, said fluid inertance means including means establishing a flow inertia for delaying changes in flow conditions through said fluid inertance means in response to differential pressure changes across said first and second locations..]. .[.12. The spray device according to claim 11, further comprising frequency control means for permitting selective control of the frequency at which said vortical flow reverses direction..]. .[.13. The spray device according to claim 12 wherein said fluid inertance means comprises a flow passage of small cross-section extending between said first and second locations, and wherein said frequency control means comprises means for selectively adjusting the length of said flow   
     
     
        passage..]. 14. The spray device according to claim .[.12.]. .Iadd.29 .Iaddend.wherein said frequency control means comprises further means for selectively controlling the static working fluid pressure in said vortical 
     
     
        flow. 15. The spray device according to claim 14 wherein said further means comprises valve means for supplying pressurized fluid to said 
     
     
        chamber at a location downstream of said inlet means. 16. The spray device according to claim 15 further comprising means for simultaneously adjusting the flow rates of working fluid through said inlet means and 
     
     
        said valve means. 17. The spray device according to claim .[.11.]. .Iadd.25 .Iaddend.wherein said fluid inertance means comprises a flow passage of small cross-section extending between said first and second locations, said device further comprising first and second independently adjustable frequency control means having a combined multiplicative effect on the frequency at which said vortical flow reverses directions, said first frequency control means comprising means for selectively adjusting the length of said flow passage .Iadd.and.Iaddend., said second frequency control means comprising means for selectively controlling the static 
     
     
        pressure in said chamber. 18. The spray device according to claim .[.11.]. .Iadd.25 .Iaddend.wherein .Iadd.at least a portion of .Iaddend.said fluid inertance means comprises the closed end of a hollow cylinder open at one end and closed at the other end and having a cylindrical piston axially slidable therein, the closed end of the cylinder being of greater diameter than the portion of the cylinder immediately adjacent thereto and being .[.pressure sealed.]. .Iadd.pressure-sealed .Iaddend.sealed therefrom, whereby the axial movement of the piston in the cylinder varies the volume and the shape of the volume of the closed end and hence the inertance 
     
     
        thereof. 19. The spray device according to claim .[.11.]. .Iadd.25 .Iaddend.wherein said outlet means includes an opening in said chamber positioned at the periphery of said vortical flow to issue working fluid from said vortical flow in the form of a swept jet which oscillates between two extreme diverging sweep positions as a function of the changing vortical flow velocity and static pressure within said chamber, said device further comprising control means for selectively controlling 
     
     
        the angle between said two extreme sweep positions. 20. The spray device according to claim 19 wherein said control means comprises means for selectively varying the static pressure in said chamber .[.from.]. 
     
     
        .Iadd.at .Iaddend.a location downstream of said inlet means. 21. The spray device according to claim .[.11.]. .Iadd.25 .Iaddend.wherein said outlet means comprises a plurality of outlet openings for issuing individual 
     
     
        spray patterns of working fluid from said chamber. 22. The combination according to claim .[.11.]..Iadd.25 .Iaddend.comprising two of said spray devices and further including further means for synchronizing the two spray devices in frequency of vortical flow reversal, said further means comprising: a first flow conduit interconnecting said first locations in said two spray devices; and a second flow conduit interconnecting said second locations   
     
     
        in said two spray devices. 23. The combination according to claim 22 
     
     
        disposed in a shower head. 24. The combination according to claim .[.11.]. .Iadd.25 .Iaddend.wherein a plurality of said spray devices are part of a spray assembly, comprising: a common supply passage for delivering working fluid to all of said plurality of spray devices, said spray devices being positioned at   1ocations along said common supply passage and oriented to issue outlet spray generally toward a common location. .Iadd.25. A fluidic oscillator comprising:   a chamber having sidewalls forming an upstream end and a downstream end thereof;   an inlet opening for issuing a jet of working fluid directly into the upstream end of said chamber;   an outlet opening for issuing working fluid from said chamber into the ambient environment;   an inertance flow conduit for transferring working fluid between first and second locations in the upstream end of said chamber and on opposite sides of said jet;   said sidewalls in the upstream end of said chamber converging toward said jet and being substantially spaced therefrom;   said inertance flow conduit entering said upstream end of said chamber so that the transferred working fluid from said inertance conduit enters into said upstream end of said chamber at a location substantially spaced from said jet; and,   dynamic compliance means in the form of a vortex region defined between the downstream sidewalls which generally converge toward said outlet opening near said outlet opening for establishing a vortical flow of the working fluid issued into said chamber so that working fluid in the vortex region alternately flows in opposite vortical directions to alternately aspirate fluid from and supply fluid to said first and second locations in said upstream end of said chamber in opposite phase and thereby through said inertance flow conduit in alternately opposite directions..Iaddend.   
     
     
        .Iadd. 6.  The oscillator according to claim 25 further including an adjustment for changing the inertance of said flow conduit during operation of said oscillator..Iaddend. .Iadd.27. The oscillator according to claim 4 wherein at least a portion of the inertance flow conduit is the closed end of a hollow cylinder open at one end and closed at the other end with a cylindrical piston axially slidable therein, the closed end of the cylinder being of greater diameter than the portion of the cylinder immediately adjacent thereto and being pressure-sealed therefrom, whereby the axial movement of the piston in the cylinder varies the volume and the shape of the volume of the closed end and hence the inertance thereof..Iaddend. .Iadd.28. The oscillator according to claim 4 wherein control of static pressure in the vortex region is provided by a valve which controllably supplies pressurized working fluid to said vortex region through an opening therein..Iaddend. .Iadd.29. The spray device according to claim 25, further comprising frequency control means for permitting selective control of the frequency at which said vortical flow reverses direction..Iaddend. .Iadd.30. The spray device according to claim 29 wherein said fluid inertance means comprises a flow passage of small cross-section extending between said first and second locations, and wherein said frequency control means comprises means for selectively adjusting the length of said flow passage during operation of said 
     
     
        oscillator..Iaddend. .Iadd.31.  The oscillator of claim 25 wherein said chamber has an hour-glass shape..Iaddend. .Iadd.32. The oscillator of claim 25 wherein said chamber includes a transition section between the upstream and downstream ends thereof, said transition section being necked-down to have a transverse dimension at the necked-down portion that is smaller than the widest dimension in either said upstream or said downstream end..Iaddend. .Iadd.33. The oscillator of claim 32 wherein said upstream and downstream ends are of a generally U-shaped configuration and wherein said inlet opening enters the base of the "U" in the upstream end and said outlet opening is in the base of the "U" in the downstream end..Iaddend. .Iadd.34. The oscillator of claim 25 wherein said inertance flow conduit lies in the plane of said chamber..Iaddend. .Iadd.35. The oscillator of claim 25 wherein said inertance conduit follows a generally circular path..Iaddend. .Iadd.36. The oscillator of claim 25 wherein said jet issues from said inlet opening along a longitudinal axis of said chamber and wherein said sidewalls in the upstream end of said chamber have initial portions that are essentially parallel to said longitudinal axis followed by the converging sidewall portions which are inwardly curved in a downstream direction to a transition point in said downstream end where said downstream sidewalls move sharply inwardly toward said outlet opening..Iaddend. .Iadd.37. The oscillator of claim 25 wherein said sidewalls continually converge toward said outlet opening..Iaddend. 
     
     
        .Iadd. 8.  The oscillator of claim 25 including a transition region between the upstream and downstream ends of said chamber, said upstream sidewalls continually converging toward said transition region and said downstream sidewalls initially diverging in a downstream direction prior to reconvergence toward said outlet opening..Iaddend. .Iadd.39. The oscillator of claim 38 wherein said jet issues from said inlet opening along a longitudinal axis of said oscillator; and, the downstream sidewalls have portions between said diverging and converging portions thereof that are essentially parallel to said longitudinal axis..Iaddend. .Iadd.40. The oscillator of claim 25 wherein said inertance flow conduit enters the upstream end of said chamber essentially parallel to said sidewalls in said upstream end..Iaddend. .Iadd.41. A fluidic spray device comprising: a chamber having sidewalls forming an upstream end and a downstream end thereof;   fluid inlet means;   inlet means for issuing a jet of working fluid into aid chamber;   said sidewalls in the upstream end of said chamber converging toward said jet and substantially spaced therefrom;   said inertance means including an inertance flow conduit having an entry portion thereof entering directly into said upstream end of said chamber so that working fluid from said inertance means enters directly into said upstream end of said chamber at a location substantially spaced from said jet;   outlet means for issuing working fluid from said chamber in a flow pattern and direction determined by the static pressure and flow velocity of working fluid in said chamber;   dynamic compliance means including sidewalls which converge toward said outlet opening and near said outlet opening for establishing a vortical flow of the working flow issued into said chamber; and   fluid inertance means for cyclically reversing said vortical flow between first and second flow directions, said fluid inertance means interconnecting first and second locations in said chamber on opposite sides of said jet proximate said inlet means such that vortical flow in said first flow direction aspirates fluid from said fluid inertance means at said first location and feeds fluid into said fluid inertance means at said second location, and such that vortical flow in said second direction aspirates fluid from said fluid inertance means at said second locations and feeds fluid into said fluid inertance means at said first location, said fluid inertance means including means establishing a flow inertia for delaying changes in flow conditions through said fluid inertance means in response to differential pressure changes across said first and second locations..Iaddend. .Iadd.42. The oscillator of claim 41 wherein said inertance flow conduit enters the upstream end of said chamber essentially parallel to said sidewalls in said upstream end..Iaddend.