US2270033A - Nozzle - Google Patents

Description

Jan. 13, 1942. c. H. CARR 2,270,033

ATTdRNEY Patented Jan. 13, 1942 STATES PAI'rs'r rFlCE- NOZZLE Clifford H. Carr, Kansas City, Mo.

Application January 30, 1939, Serial No. 253,611

3 Claims.

My invention relates to liquid spray nozzles and particularly to spray nozzles for spraying liquid in a hollow conical spray. This type of nozzle is particularly adapted for use in spray cooling systems, such as cooling ponds, cooling towers, or in systems for washing, humidifying or dehumidifying air, aeration of sewage and chemical spraying. Such nozzles may, of course, be used in other types of heat exchange systems.

Generally speaking, the type of nozzle to which the present invention is directed, comprises a whirl chamber having an inlet usually entering the chamber substantially tangent to the outside wall thereof so that the velocity of the incoming liquid imparts a whirling motion which subjects the liquid to centrifugal force. The liquid is discharged through an outlet orifice whose axis is at right angles to the inlet. In devices prior to my invention it has been the usual practice to so relate the size of the inlet and outlet that throttling, and consequently high discharge velocity of the liquid, is obtained at the outlet directly under the influence of the pressure from the inlet source, the whirling action being primarily relied upon to spread the discharge. In such prior devices considerable difiiculty has been experienced in producing an even discharge, which is highly important in order to obtain most efiicient operation, because of the interaction between the incoming liquid and the whirling liquid in the whirl chamber.

The present invention represents a departure from this usual practice in that it provides a construction which converts a major part of the energy of the incoming pressure head into kinetic energy of rotation and the areas of the inlet and outlet are so related that substantially no back pressure develops in the whirl chamber, the projections of the liquid from the outlet being due substantially entirely to the centrifugal force urging a thin film of the liquid over the inside surfaces of the outlet orifice.

One of the major objects of my invention is to provide an improved nozzle having improved efficiency in which the cross sectional area of the smallest passage for a nozzle of a given capacity will be greater than heretofore.

Another object is to provide a nozzle which will produce a uniform spray at low pressure heads.

Another object is to provide a nozzle which will obtain a fine, even spray with a minimum of energy loss in the nozzle.

A more specific object is to provide a nozzle having unusually large passages for given capacities to permit foreign particles to readily pass, but in which the entering water is given a whirling action and the resulting centrifugal force, in conjunction with the walls of the whirl chamber, restrict the water to a continuously diminishing cross section to produce progressively increasing velocity and a consequent conversion of the pressure head into kinetic energy of rotation to obtain efiicient distribution of fine droplets. Another related object is to provide a spray nozzle having a whirl chamber with an end wall having an outlet orifice andwall at the opposite end uniformly spiralling toward the first end wall over substantially one revolution and beginning and terminating at the same side of theinlet.

Another object is to provide an improved nozzle which accomplishes the above results and which at the same time can be cast in one piece.

Other and further objects of my invention will become apparent from the following description taken in connection with the accompanying drawing, in which:

Figure 1 is an elevational view of a nozzle embodying the present invention, looking from the inlet side of the nozzle; and

Figure 2 is a plan section on the lines 22 of Figure 1.

Nozzles of the type under consideration must be capable of handling large quantities of water in which there may be present a large amount of foreign matter or particles as well as chemicals which may deposit on the interior surfaces. Despite the above conditions which must be met, it is necessary and essential that high discharge velocities be obtained in order to produce the required break-up of the water, which is the major factor in determining the efficiency of the nozzle. At the same time the nozzle must produce an even distribution of comminuted liquid evenly and symmetrically projected with respect to the axis of the outlet. A further rigid requirement is that all of the above conditions must be met when the pressure head on the water is low. It will be readily apparent that low pressure, large orifices and high discharge velocities are usually considered to be the antithesis of each other.

The present invention contemplates a spray nozzle in which the physical passages of the nozzle are comparatively large but in which centrifugal force is utilized in such a manner that the force cooperates with the shape of the whirl chamber to obtain the throttling effect of small passages with an accompanying increase in outlet velocity. The returning water is so directed as to effectively produce a restricted orifice to maintain a high whirl velocity without the usual physical restrictions which readily clog with foreign matter. Furthermore, the present nozzle accomplishes the objects set forth above primarily through conversion of the pressure head into kinetic energy of rotation whereby the water is distributed substantially entirely by centrifugal force which, so to speak, squeezes the water out of the outlet orifice in a thin film rotating at very high velocity.

Referring more particularly to the drawing, an embodiment of the invention is illustrated by a nozzle I having an annular whirl chamber 2, an inlet 3 and an outlet 4, the axes of the inlet and outlet being at substantially right angles to each other and laterally displaced from each other. The whirl chamber 2 is provided with a plane end wall 6 which is arranged at a right angle to the axis of the outlet 4 and has a smooth inner surface I. The opposite end wall 8 of the whirl chamber is in the form of a helix. The beginning of the helix is at the inner surface of one side of the inlet as indicated at 9 and the terminus is at the same surface but at a point ll removed from the beginning by a distance equal to the height of the opening in the whirl chamber connected to the inlet 3. The pitch of the helix is illustrated as being equal to the height of the opening into the whirl chamber.

The inlet 3 is preferably round and fitted with threads for coupling to standard pipe connections, but progressively changes in shape to a substantially square shape and merges into the opening in the whirl chamber, and is so disposed relative to the opening in the whirl chamber that the outer wall of the inlet 3 is substantially tangent to the annular wall of the whirl chamber 2 and the upper inside surface of the inlet 3 is flush with the inner upper surface of the opening in the whirl chamber. The lower part of the inlet merges into the beginning of the helix. For the purpose of obtaining some increase in velocity of the water, the cross sectional area of the opening into the whirl chamber is less than the maximum cross sectional area of the inlet 3.

It will be noted from the drawing that the incoming water is progressively confined in a direction transversely of the whirl chamber but is unconfined in an axial direction as soon as the water passes inwardly beyond where the inlet 3 passes through the wall of the whirl chamber 2. This permits the water to spread upon the inner surface of the whirl chamber. As the water continues in the circular path inside of the whirl chamber, the center of mass of the layer of water gets farther from the center and the centrifugal force increases and this in turn still further flattens the water. While the water is held against the inside of the whirl chamber wall, the water is progressively confined in a direction parallel to the axis of the outlet by the helical bottom wall 8 and the upper end wall 6. This action effectively obtains a throttling action with a consequently increased velocity, all without using small physical orifices. The centrifugal force of the whirling water effectively squeezes the water out in a thin film on the inside surface of the outlet 4 and obtains very efficient break-up of the water into fine droplets.

From the foregoing description, it will be readily apparent that as the water passes through the inlet 3 it is immediately allowed to rise upwardly, when looking at the front of Figure 2, and

spread out on the inside surface of the whirl chamber wall, being restricted on the upper surface by the water returning from the end of the helical bottom 8. The incoming water will spread over the inner surface of the annular whirl chamber wall 2 and after leaving the inlet will be confined only on three sides by physical walls, that is, by the wall 2 and the plane upper end 6 and the helical bottom 8, while centrifugal force effectively serves as the inner fourth wall or confining surface. Since the bottom wall 8 spirals toward the plane end 6, the water is progressively confined by the physical "surfaces and the centrifugal force acting against the inner surface of the water effectively produces a throttling action and consequently an increase in velocity of the whirling water with the result that the water is, so to speak, squeezed out along the inner surface of the outlet 4 in a thin film and the high whirl velocity produces efficient comminution of the water into fine droplets. The cross sectional area of the outlet 4 is preferably greater than that of the smallest passage of the inlet so that no back pressure builds up in the whirl chamber and therefore the force which produces the spray is substantially entirely that due to the kinetic energy in the whirling water. Also the highest velocity occurs at the most effective point, that is, at the discharge orifice or outlet 4 so that high friction losses are minimized. The whirling water in the whirling chamber passes over the incoming water and no distortion of the spray discharge occurs. The inclined terminus of the floor 8 produces streamlining and blending of the returning water with the incoming water and keeps eddy currents at this point at a minimum. This effectively reduces the energy loss and permits spraying of liquids Where only very low pressure heads are available, and where auxiliary pumping is not possible.

The design of the present nozzle to accomplish the above results also permits same to be cast in one piece, with a resultant reduction in cost.

It is to be understood that various modifications and changes may be made in the apparatus described without departing from the spirit of the invention and, therefore, the foregoing description is intended as illustrative and is not to be construed as a limitation of the invention thereto.

What I claim is:

1. A spray nozzle of the type described comprising means forming a cylindrical whirl chamber, a plane end wall perpendicular to the axis of said whirl chamber and having a circular discharge orifice opening concentric with said axis, a helical end wall closing the opposite end of said whirl chamber, an inlet tangent to and merging into the intersection of said whirl chamber and the beginning of said helical wall, the pitch of said helical wall being substantially equal to the dimension of said inlet measured in a direction parallel to the axis of said outlet and said latter wall terminating at, and flush with, the inner side of said inlet, the cross sectional area of said outlet being at least as great as the cross sectional area of the smallest passage of said inlet.

2. A spray nozzle of the type described comprising means forming a cylindrical whirl chamber, a plane end wall perpendicular to the axis of said whirl chamber and having a circular discharge orifice opening concentric with said axis,

a helical end wall closing the opposite end of said whirl chamber, an inlet tangent to and merging into the intersection of the Wall of said whirl chamber and the beginning of said helical end Wall, the termination of said helical end wall being displaced axially of said chamber by such an amount that the water completing the whirl in the whirl chamber passes over the incoming water, the area of said outlet being greater than the smallest passage of said inlet.

3. A spray nozzle of the type described comprising means forming a cylindrical whirl chamber, a plane end wall perpendicular to the axis of said whirl chamber and having a circular discharge orifice opening concentric with the axis of said whirl chamber, a helical end wall closing the opposite end of said whirl chamber, an inlet to said whirl chamber tangent to and merging into the annular wall of said whirl chamber and merging into the beginning of said helical end wall and entirely disposed between the beginning and termination of said helical wall, the cross sectional area of said outlet opening being at least as great as the cross sectional area of the effective area of said inlet.

I CLIFFORD H. CARR.

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