US2705972A - Apparatus for reducing turbulence - Google Patents

Description

April 12, 1955 D. VAWTER 2,705,972 APPARATUS FOR REDUCING TURBULENCE Filed Aug. 25, 1952 United States Patent O F APPARATUS FOR REDUCING TURBULENCE Dale Vawter, Harrison, Wis. Application August 25, 1952, Serial No. 306,216

2 Claims. (Cl. 138-47) The present invention is concerned with an apparatus for reducing turbulence in flowing liquid streamsparticularly where the streams are being directed from a higher level to a lower level.

In many industrial processes it is necessary to transfer a flowing liquid stream from a higher level to a lower level and to do so with a minimum amount of turbulence being produced in the liquid stream. A good example of this type of process occurs in the paper making industry where pulp suspensions must be transferred from various portions of the paper making assembly, and foaming, agitation, splashing, and turbulence resulting from the free fall of the liquid suspension in conduits or channels presents a very distinct problem. In handling such suspensions, it is desirable to have a very low velocity head so that the composition of the suspension is maintained more uniform, the liquid flow can be controlled more readily, and the liquid is free of air entrainment resulting from the turbulence.

In addition to its use in the paper making industry, the apparatus of the present invention will find use generally where the problems ofexcessive agitation, splashing, and turbulence are to be controlled.

An object of the present invention is to provide means for minimizing or reducing turbulence in flowing liquid streams.

Another object of the invention is to provide an apparatus for dissipating much of the kinetic energy contained in a flowing stream so as to leave the stream in a quiescent condition.

Still another object of the present invention is to provide an apparatus for reducing turbulence in a liquid stream and thereby leave said stream with a relatively low velocity head.

Other objects and features of the present invention will be apparent to those skilled in the art from the following description of the attached sheet of drawings which illustrate the preferred embodiment of this invention.

Figure 1 is a front elevational view of an assembly for reducing turbulence embodying the principles of the present invention; Figure 2 is a side elevational view of the assembly illustrated in Figure 1; and Figure 3 is a cross-sectional view taken substantially along the line III-III of Figure 2.

In the form of the invention illustrated in the drawings, the assembly includes a generally circular hollow casing which is provided at its upper end with an inlet generally indicated at numeral 11. A conduit 12 introduces the flowing stream through the inlet 11 and into the interior of the casing 10.

The casing 10 also has centrally located bearing supports 13 and 14 at opposite ends thereof, the bearing supports 13 and 14 receiving a shaft 16 for rotation within the casing 10. As best seen in Figure 3, a circular core 17 is secured to the shaft 16 within the casing 10. A plurality of circumferentially spaced vanes 18 are located in spaced relation along the periphery of the core 17, or the vanes 18 may be integral with the core 17. The specific shape or contour of the vanes 18 will vary with each installation but in general may include a contoured foil or scoop portion 18a for minimizing the amount of turbulence created by the fluid stream as it strikes the vanes 18. The circumferentially spaced vanes 18 and the core 17 thereby provide a rotatable impeller whichis acted upon by the flow of liquid through the casing to dissipate some of the kinetic energy contained in the flow stream originally and developed during the fall of the 2,705,972 Patented Apr. 12, 1955 liquid from a higher level to a lower level. As best seen in Figure 2, the edges of the vanes 18 extend into close proximity to the walls of the casing 10 so that little or no liquid is able to flow through the casing without engaging the surface of one of the vanes 18.

As the liquid enters the hollow casing through the inlet 11 and falls through the casing, some of the energy originally present as potential energy is transformed into kinetic energy in the flowing stream. In order that the turbulence of the stream may be minimized and the velocity head reduced to a sufliciently low value, most of this kinetic energy must be absorbed before the stream passes to the outlet in the casing. The liquid stream in rotating the impeller consisting of the vanes 18 and the core 17 loses some of its kinetic energy, but for most purposes the amount of energy thus dissipated would be insufl'icient to reduce the turbulence to the desired degree. In order to increase the resistance or the work of the impeller, the assembly is provided with a braking means which supplies a predetermined and adjustable braking torque on the movement of the impeller. In the form of the invention illustrated, these braking means take the form of a pair of shoes 19 and 20, each of which has complementary recesses through which the shaft 16 extends. The brake is fixedly secured to the casing 10 by means of a support arm 21. The braking torque applied by the brake shoes 19 and 20 can be varied by adjustment of a pair of bolts 22 and 23 which determine the pressure exerted by the brake shoes 19 and 20 on the shaft 16. The showing of specific brake means in the drawings is purely by way of example, and other means for securing the desired braking torque will suggest themselves to those skilled in the art.

The liquid stream in passing through the casing and in rotating the impeller dissipates much of its kinetic energy and the resulting quiescent stream is withdrawn from the casing through an outlet 24 in open communication with the interior of the casing 10.

As previously mentioned, the assembly of the present invention is particularly adapted for use in the paper making industry where it is desired to transfer liquid streams from one level to a lower level without causing an excessive amount of turbulence or agitation. In operating the apparatus described, I find it possible to reduce the velocity heads of a stream to extremely low values on the order of 1 to 2 inches of water. Other assemblies for achieving turbulence reduction, such as those employing restrictions of various types in the stream do not operate satisfactorily at low flow velocities and are generally inefiicient at the range of velocities on which the present apparatus is particularly effective.

Many modifications can be made to the disclosed apparatus without departing from the scope of the present invention. It is not my intention to limit the invention to the specific apparatus employed, but only as necessitated by the scope of the appended claims.

I claim:

1. Apparatus for reducing turbulence in a free falling liquid stream comprising a casing having a circular chamber, a liquid inlet leading downward and tangentially into the chamber, a shaft extending axially through the chamber, a circular core in the chamber carried by and rotatable with the shaft, the core being peripherally spaced from and concentric with the circular wall of the chamber and extending the full axial length of the chamber, radial vanes extending from the periphery of the core the full radial extent between the core and the circular wall of the chamber, said vanes having a width to extend the said axial length of the chamber, said inlet discharging into the space between the core periphery and the circular wall, an outlet directed axially of the chamber in the lowest part thereof between the core and the circular wall of the chamber, and means for applying regulated frictional rotational restraint to the core and vanes during rotation of the latter, said rotation of the vanes being effected by force applied to the vanes by liquid entering the chamber through the inlet.

2. The method of reducing turbulence in a stream of liquid flowing from a high level to a low level which comprises eflecting the successive introduction of retarding vanes into the stream between said levels, supporting the vanes for movement in a circular path t; which the strezfin References Cited in the file of this patent is tangent, enc osing the vanes on all si es to su stantia y prevent escape of the liquid past said sides as it impinges UNITED STATES PATENTS the vanes, effecting the retarding of the downward move- 165,290 Williams July 6, 1875 ment of the vanes under the weight of the liquid imping- 5 600,737 Monroe Mar. 15, 1898 ing thereon to pass the liquid off of the vanes without 2,544,813 Wall Mar. 13, 1951 turbulence as it reaches the lower level, and diverting the direction of flow of the stream to an outlet, said outlet Q PATENTS providing a path at a substantial angle to the axis of the 247,718 Great Brltalfl 1926 circular path of the retarding vanes. 10 864,124 France Apr. 19, 1941

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