Bluff body flowmeter

Abstract

Flowmeters utilizing nonstreamlined, bluff bodies and sensors are disclosed for generating oscillating wakes in a fluid flowing through a pipe to produce high signal-to-noise signals which are free from intermittency and are sensed outside of the wake in the flow near and upstream from the bodies. Each of the bodies comprises prescribed geometric configurations and includes a base surface facing the flow and downstream surfaces to control the oscillatory flow. The bodies each have sharp upper and lower corners at the edges of the facing base surface for defining separation lines for the flow. The facing base surfaces are selectively blunt or convex for reducing pressure loss in the pipe due to the bluff body.

What is claimed is: 
     
       1. In combination, a conduit having means defining a hollow inner chamber containing a flowing fluid,   said chamber having a longitudinal axis .Iadd.and an inner diameter dimension in a plane normal to said longitudinal axis.Iaddend.,   and a stationary bluff body positioned within said chamber .Iadd.and spanning said inner diameter .Iaddend.transverse to said longitudinal axis thereof, said body having a first surface facing upstream in said flowing fluid and second surfaces extending from said first surface downstream in said flow through said chamber, said first surface having .Iadd.a predetermined height dimension with respect to said inner diameter dimension of said chamber and .Iaddend.a prescribed .Iadd.axial .Iaddend.dimension .[.with respect to dimensions.]. of said second surfaces, .Iadd.the ratio of said height dimension to said diameter dimension being between the limits of 0.15 and 0.4 and the ratio of said axial dimension to said height dimension being between the limits of 1 and 2, said first surface having upper and lower edges each of which is contiguous to an individual corresponding one of said second surfaces to define a fixed line along which said fluid flow past said body separates, .Iaddend.and said first and second surfaces by interacting with said flowing fluid producing in said chamber an oscillating fluid flow free of intermittency and of a frequency corresponding to said flowrate.   
     
     
       2. The combination in accordance with claim 1 wherein said bluff body surfaces interact with said flowing fluid to produce said oscillating fluid flow free of intermittency outside of an oscillating wake generated by the interaction of said flowing fluid and said body surfaces,   and further comprising means sensing outside of said wake said oscillating fluid flow which is free of intermittency.   
     
     
       3. The combination in accordance with claim 2 wherein said sensing means senses said oscillating fluid flow which is free of intermittency within predetermined distances of said body and which is within prescribed areas of said body outside of said oscillating wake. .[.4. The combination in accordance with claim 2 wherein   said conduit comprises a circular pipe means having a wall means with an inner surface defining said hollow inner chamber cylindrically with a defined diameter dimension relationship to a height dimension of said first surface,   and said bluff body is positioned along said diameter dimension transverse to said longitudinal axis of said chamber..]. .[.5. The combination in accordance with claim 4 wherein said first surface has a height dimension, said second surfaces have an axial dimension, and the ratio of said axial dimension to said height dimension is within the limits of 1 and 2..]. .[.6. The combination in accordance with claim 5 wherein   the ratio of said height dimension of said first surface to said diameter dimension of said inner chamber is between the limits of 0.15 and 0.4..]. .[.7. The combination in accordance with claim 6 wherein   said first surface has upper and lower edges each of which is contiguous to an individual one of said second surfaces to form a respective sharp corner segment that defines a fixed line along with said fluid flow past   
     
     
        said body separates..]. 8. The combination in accordance with claim .[.7.]. .Iadd.2 .Iaddend.wherein said first surface has a convex surface with an axial dimension 0.3 or less   
     
     
        than said height dimension of said first surface. 9. The combination in accordance with claim .[.5.]. .Iadd.2 .Iaddend.wherein said bluff body comprises a cross-section substantially of triangular shape with said first surface being a base surface and said second surfaces being side 
     
     
        surfaces of said stationary bluff body. 10. The combination in accordance with claim 9 wherein said base surface is substantially flat, said body further comprises another substantially flat surface, and said side surfaces terminate at said other flat surface downstream from said base 
     
     
        surface. 11. The combination in accordance with claim .[.5.]. .Iadd.2 
     
     
        .Iaddend.wherein said bluff body comprises a T shaped cross-section. 12. The combination in accordance with claim .[.5.]. .Iadd.2 .Iaddend.wherein said bluff body comprises a substantially symmetrical cross shaped cross-section for measurement of flow in both directions 
     
     
        through said chamber. 13. In a flowmeter arrangement having a conduit having means defining a hollow inner chamber for containing a flowing fluid and   said chamber having a longitudinal axis and an inner diameter dimension .Iadd.in a plane normal to said longitudinal axis.Iaddend.,   the invention comprising a stationary bluff body positionable within said chamber .Iadd.and spanning said inner diameter .Iaddend.transverse to said longitudinal axis thereof, said body having triangularity in its shaped cross-section, a base surface with a prescribed height dimension facing upstream in said fluid flow through said chamber and side surfaces facing from said base surface downstream in said fluid flow,   said height dimension of said base surface to said diameter dimension being a prescribed ratio .Iadd.between the limits of 0.15 and 0.4.Iaddend.,   said body having a downstream length dimension,   said height dimension of said base surface to said length dimension being a predetermined ratio between the limits of 1 and 2,   and interaction of said base and side surfaces with said fluid flow producing in said chamber an oscillating fluid flow free of intermittency   
     
     
        and of a frequency corresponding to said flowrate. 14. .[.The invention defined in claim 13 wherein.]. .Iadd.In a flowmeter arrangement having a conduit having means defining a hollow inner chamber for containing a flowing fluid and   said chamber having a longitudinal axis and an inner diameter dimension,   the invention comprising a stationary bluff body positionable within said chamber transverse to said longitudinal axis thereof, said body having triangularity in its shaped cross-section, a base surface with a prescribed height dimension facing upstream in said fluid flow through said chamber and side surfaces facing from said base surface downstream in said fluid flow,   said height dimension of said base surface to said diameter dimension being a prescribed ratio between the limits of 0.15 and 0.4, said base surface having a convex surface with an axial dimension 0.3 or less than said height dimension of said first surface,   and interaction of said base and side surfaces with said fluid flow producing in said chamber an oscillating fluid flow free of intermittency and of a frequency corresponding to said flowrate, .Iaddend.   said side surfaces comprise an axial dimension and   said axial dimension to said height dimension being a predetermined ratio .Iadd.between the limits of 1 and 2 .Iaddend.whereby interaction of said base and side surfaces with said fluid flow produce in said chamber said oscillating fluid flow free of intermittency and of a frequency   
     
     
        corresponding to said flowrate. 15. The invention defined in claim 14 wherein said flowmeter arrangement further has means for sensing said oscillatory fluid flow free of intermittency and outside of an oscillating wake generated by the interaction of said flowing fluid and said base and 
     
     
        side surfaces of said stationary bluff body. 16. A fluid mechanical arrangement of a .Iadd.stationary .Iaddend.bluff body having a first surface for facing upstream in a fluid flowing through a hollow conduit and having second surfaces .Iadd.with a downstream axial dimension, said hollow conduit having an inner diameter dimension and said bluff body spanning said inner diameter, .Iaddend.characterized in that .Iadd.said first surface has a height dimension, the ratio of said height dimension to said inner diameter dimension is between the limits of 0.15 and 0.4, and .Iaddend.said first and second surfaces have a prescribed dimensional ratio .Iadd.between said height dimension and said axial dimension lying in the range between the limits of 2 and 1 .Iaddend..[.therebetween.]. for enabling said surfaces to interact with said flowing fluid through said hollow conduit to produce therein an oscillating fluid flow free of 
     
     
        intermittency and of a frequency corresponding to the flowrate. 17. .[.The invention set forth in claim 16.]. A fluid mechanical arrangement of a bluff body having a first surface for facing upstream in a fluid flowing through a hollow conduit and having second surfaces, characterized in that said bluff body is transverse to a longitudinal axis of said hollow conduit said first and second surfaces have a prescribed dimensional ratio therebetween for enabling said surfaces to interact with said flowing fluid through said hollow conduit to produce therein an oscillating fluid flow free of intermittency and of a frequency corresponding to the flowrate, further characterized in that said first surface has a predetermined height dimension having a prescribed ratio relationship to an inner diameter dimension of said conduit.Iadd., said prescribed ratio being between the limits of 0.15 and 0.4, further characterized in that said second surfaces have an axial dimension and the ratio of said axial dimension to said height dimension being between the limits of 1 and 2, and further characterized by said first surface having upper and lower edges defining fixed lines of fluid flow separation.Iaddend.. .[.18. A bluff body for use in a pipeline flowmeter in which said body comprises a first surface having a height dimension and for facing upstream in a fluid flow through said pipeline,   second surfaces having an axial dimension and for facing from said first surface downstream in said fluid flow through said pipeline,   and the ratio of said axial dimension to said height dimension being within the limits of 1 and 2..]. .[.19. A bluff body for use in a pipeline flowmeter for interacting with a fluid through said pipeline to produce an oscillating fluid flow free of intermittency and of a frequency corresponding to the flowrate and in which said body comprises   a surface having a height dimension and for facing upstream in said fluid flow through said pipeline,   said pipeline having an inner diameter dimension,   and the ratio of said height dimension of said facing surface to said inner diameter dimension being between the limits of 0.15 and 0.4..]. .Iadd. 20. In combination,   a circular pipe means having a wall means with an inner surface defining a hollow inner chamber cylindrically with a defined diameter dimension,   said chamber having a longitudinal axis, and   a stationary bluff body positioned within said chamber along said diameter dimension transverse to said longitudinal axis,   said body having a first surface facing upstream in said flowing fluid and second surfaces extending from said first surface downstream in said flow through said chamber,   said first surface having a height dimension,   said second surfaces having an axial dimension,   said height dimension having a prescribed ratio relationship to said axial dimension and being between the limits of 1 and 2,   said height dimension having a prescribed ratio relationship to said diameter dimension of said chamber and being between the limits of 0.15 and 0.4,   said first surface having upper and lower edges each of which is contiguous to an individual one of said second surfaces to form a respective sharp corner segment that defines a fixed line along which said fluid flow past said body separates, and   said first and second surfaces by interacting with said flowing fluid producing in said chamber an oscillating fluid flow free of intermittency and of a frequency corresponding to said flowrate. .Iaddend. .Iadd. 21. The combination in accordance with claim 20 wherein said bluff body comprises a T-shaped cross-section. .Iaddend..Iadd. 22. The combination in accordance with claim 20 wherein said bluff body comprises a substantially symmetrical cross shaped cross-section for measurement of flow in both directions through said chamber. .Iaddend. .Iadd. 23. In a flowmeter arrangement having   a conduit having means defining a hollow inner chamber for containing a flowing fluid and   said chamber having a longitudinal axis and an inner dimension,   the invention comprising   a stationary bluff body positioned within said chamber spanning the inner diameter and transverse to said longitudinal axis,   said body having substantially a T-shaped cross section with a front surface facing upstream in said fluid flow through said chamber,   said front surface having a height dimension measured transversely to said longitudinal axis and first and second edges defining respective fixed lines along which said fluid flow past said body separates, said body further having side surfaces facing from said front surface downstream in said fluid flow and said body having an axial streamwise dimension,   said height dimension of said front surface to said diameter dimension being between the limits of 0.15 and 0.4,   said axial dimension to said height dimension being between the limits of 1 and 2,   and interaction of said front and side surfaces with said fluid flow producing in said chamber an oscillating fluid flow free of intermittency and of a frequency corresponding to said flowrate. .Iaddend.