초록

A device comprises a sensor tube for placement in a process flow and a flow-modifying element. The flow-modifying element is formed on the sensor tube, in order to reduce flow-induced vibrations by reducing coherent vortex shedding in the process flow.

대표청구항 ▼

The invention claimed is: 1. A device comprising: a sensor tube for placement in a process flow, the sensor tube having an inside wall and an outside wall; and a flow-modifying element formed along a helical path on the outside wall of the sensor tube; wherein the flow-modifying element is shaped t

The invention claimed is: 1. A device comprising: a sensor tube for placement in a process flow, the sensor tube having an inside wall and an outside wall; and a flow-modifying element formed along a helical path on the outside wall of the sensor tube; wherein the flow-modifying element is shaped to reduce flow-induced vibrations of the sensor tube by modifying flow at a boundary layer of the sensor tube, such that coherent vortex shedding is disrupted in the process flow. 2. The device of claim 1, wherein the flow-modifying element follows the helical path about the outside wall of the sensor tube, such that the flow-modifying element disrupts the coherent vortex shedding by encouraging detachment at aperiodic intervals. 3. The device of claim 2, wherein the helical path is right handed. 4. The device of claim 2, wherein the helical path is left handed. 5. The device of claim 1, wherein the flow-modifying element comprises a groove formed in the outside wall of the sensor tube, along the helical path. 6. The device of claim 1, wherein the flow-modifying element comprises a deformable shape wound onto the outside wall of the sensor tube, along the helical path. 7. The device of claim 1, wherein the flow-modifying element comprises a set of notches shaped into the outside wall of the sensor tube, along the helical path. 8. The device of claim 1, wherein the flow-modifying element comprises a rough surface fashioned on the outside wall of the sensor tube, along the helical path. 9. The sensor of claim 1, wherein the sensor tube comprises a thermowell and further comprising a temperature sensor positioned in thermal communication with the thermowell. 10. The sensor of claim 1, wherein the sensor tube comprises a Pitot tube and further comprising a Pitot sensor positioned in pressure communication with the Pitot tube. 11. The device of claim 1, further comprising a cantilevered mounting assembly for mounting the sensor tube in a conduit. 12. The device of claim 1, further comprising a sensor positioned for communication with the sensor tube in order to sense a fluid parameter in the process flow, wherein the flow-modifying element reduces signal noise generated by the sensor by reducing mechanical, thermodynamic or electronic noise effects associated with the flow-induced vibrations. 13. A sensor comprising: a sensor element for generating a sensor signal as a function of a process parameter; a sensor tube for communicating the process parameter to the sensor; a mounting assembly for mounting the sensor tube in a process flow; and a vibration-reducing element formed along a helical path on an outside wall of the sensor tube; wherein the vibration-reducing element is shaped for reducing vibrations induced by the process flow by modifying flow at a boundary layer of the sensor tube, such that coherent vortex shedding is disrupted. 14. The sensor of claim 13, wherein the vibration-reducing element reduces the coherent vortex shedding from the sensor tube by controlling a detachment point to modify a frequency spectrum of vortices in a downstream wake field. 15. The sensor of claim 14, wherein the vibration-reducing element further reduces signal noise generated by the sensor element by reducing mechanical, thermodynamic or electronic noise effects associated with the flow-induced vibrations. 16. The sensor of claim 13, wherein the vibration-reducing element forms a spiral about the outside wall of the sensor tube, along the helical path. 17. The sensor of claim 16, wherein the spiral is formed as a groove in the outside wall of the sensor tube. 18. The sensor of claim 16, wherein the spiral is formed as a protrusion from the outside wall of the sensor tube. 19. The sensor of claim 16, wherein the spiral is formed as a surface finish on the outside wall of the sensor tube. 20. The sensor of claim 16, wherein the spiral is formed as a set of discrete structures, wherein each individual structure in the set of discrete structures is formed along part of the helical path and wherein the set of discrete structures is discontinuous in at least one location along the sensor tube. 21. The sensor of claim 13, wherein the vibration-reducing element forms a number of generally parallel, laterally-spaced spirals about the sensor tube, as characterized by an overall helicity that is either right-handed or left-handed, but not both. 22. The sensor of claim 13, wherein the vibration-reducing element forms at least one right-handed spiral about the sensor tube and at least one left-handed spiral about the sensor tube. 23. The sensor of claim 13, wherein the sensor element is positioned adjacent to the sensor tube and further comprising a transmitter for transmitting an output representative of the sensor signal generated by the sensor element. 24. A method of making a sensor tube, the method comprising: forming a sensor tube for mounting in a process flow, the sensor tube having an inside wall and outside wall; and forming a spiral flow-modifying element along a helical path on the outside wall of the sensor tube, such that the flow-modifying element follows the helical path about the sensor tube; wherein the flow-modifying element is shaped to reduce flow-induced vibrations of the sensor tube by modifying flow at a boundary layer of the sensor tube and disrupting coherent vortex shedding from the sensor tube when mounted in the process flow. 25. The method of claim 24, wherein forming the sensor tube comprises forming a thermowell and further comprising positioning a thermal sensor within the thermowell, adjacent the inside wall of the sensor tube. 26. The method of claim 24, wherein forming the sensor tube comprises forming a Pitot tube and further comprising positioning a Pitot sensor in pressure communication with the Pitot tube. 27. The method of claim 24, wherein forming the spiral flow-modifying element comprises forming a groove in the outside wall of the sensor tube, and further comprising mapping a pitch and thickness of the groove to a geometry of the sensor tube such that the coherent vortex shedding is disrupted. 28. The method of claim 24, wherein forming the spiral flow-modifying element comprises forming a protrusion in the outside wall of the sensor tube, and further comprising mapping a pitch and width of the protrusion to a geometry of the sensor tube such that the coherent vortex shedding is disrupted. 29. A method of monitoring a process parameter, the method comprising: positioning a sensor tube in a process flow, the sensor tube having an inside wall, an outside wall and a helical flow-modifying element formed on the outside wall, the helical flow-modifying element configured to disrupt coherent vortex shedding and reduce flow-induced vibrations of the sensor tube; and sensing the process parameter with a sensor positioned for communication with the sensor tube; wherein the flow-modifying element disrupts the coherent vortex shedding by modifying flow at a boundary layer of the sensor tube; and wherein the flow-modifying element controls a detachment point to prevent periodic shedding of alternating vortices on opposites sides of the sensor tube. 30. The method of claim 29, wherein the flow modifying element comprises at least one of a groove in the outside wall of the sensor tube, a protuberance from the outside wall of the sensor tube, or a machined surface on the outside wall of the sensor tube, and further comprising mapping a pitch of the helical flow-modifying element to the geometry of the sensor tube such that the coherent vortex shedding is disrupted. 31. The method of claim 29, wherein sensing the process parameter comprises sensing a temperature with a temperature sensor positioned inside the sensor tube, adjacent the inside wall. 32. The method of claim 29, wherein sensing the process parameter comprises sensing a flow rate with a Pitot sensor positioned in pressure communication with the sensor tube. 33. The method of claim 29, further comprising transmitting an output signal representative of the process parameter sensed by the sensor, wherein the helical flow-modifying element reduces signal noise generated by the sensor by reducing mechanical, thermodynamic or electronic noise effects associated with the flow-induced vibrations of the sensor tube. 34. The device of claim 1, wherein the flow-modifying element disrupts the coherent vortex shedding by controlling a detachment point to prevent periodic shedding of alternating vortices on opposites sides of the sensor tube. 35. The device of claim 1, wherein the flow-modifying element reduces the flow-induced vibrations of the sensor tube by encouraging detachment at intervals that do not correspond to resonant frequencies or natural modes of the sensor tube.