US3123305A - Hydrodynamic vibrative atomizer - Google Patents

Description

March 3, 1964 B. J. EISENKRAFT HYDRODYNAMIC VIBRATIVE ATOMIZER 2 Sheets-Sheet 1 Filed NOV. 1, 1961 INVENTOR 5 e/waro 1 [/Isenh'a/Y BY 3AM...

ATTORNEY March 3, 1964 B. J. EISENKRAFT 3,123,305

HYDRODYNAMIC VIBRATIVE ATOMIZER 2 Sheets-Sheet 2 Filed Nov. 1, 1961 INVENTOR fie/woro c/ [Assn/ruff ATTORNEY United States Patent 3,123,305 HYDRODYNAMIC VIBRATIVE ATOMIZER Bernard H. Eisenkraft, 10564 Flatlands th St., Brooklyn, N.Y.

Filed Nov. 1, 1961, Ser. No. 149,438 4 Claims. (Cl. 239102) This invention relates to atomizers in general, and specifically to a hydrodynamically vibrative atomizer In many industries, and for many applications, it is necessary to disperse liquids of various properties mto sprays of finely divided droplets, which process is commonly referred to as atomization. The present invention makes use of the principles of the jet edge generator, whereby a stream of fluid issuing from a rectangular orifice causes resonant vibration of a bevel-edged thin plate or disc held at a nodal point or points a short distance from the said orifice, and upon contact of the liquid to be atomized with the antinodal point or points of the plate or discs, atomization of such liquid occurs.

One of the objects of this invention is to provide a hydrodynamically vibrative atomizer for liquids.

Another object of this invention is to provide an atomizer for liquids operated on the principles of the jet edge generator.

A further object of this invention is to provide an atomizer for liquids operated on the principles of the jet edge generator in which a stream of fluid issuing from a rectangular orifice causes resonant vibration of a beveledged thin plate or disc held at a nodal point or points a short distance from the said orifice, the liquid to be atomized contacting the iantinodal point or points of the plate or disc and being atomized therefrom.

Still other and further objects of this invention will become apparent during the course of the following description.

Referring now to the drawings, in which like numerals represent like parts in the several views:

FIGURE 1 represents a perspective view, partially diagrammatic, of one form of hydrodynamically vibrative atomizer.

FIGURE 2 represents a side elevation, partially diagrammatic, of the atomizer of FIGURE 1, showing in phantom the slightly exaggerated mode of vibration of the plate.

FIGURE 31 represents a side elevation, partially diagrammatic, of a hyd-rodynamically vibrative atomizer similar to that of FIGURES 1 and 2, showing in phantom the slightly exaggerated mode of vibration of the plate, and showing further atomization at several antinodal points along the plate.

FIGURE 4 represents a perspective view, partially diagrammatic, of a hydrodynamically vibrative atomizer using a thin bevel-edged disc.

FIGURE 5 represents :a view in plan of another modification of hydrodynamically vibrative atomizer, partially diagrammatic, showing the exciting fluid passing at right angles to the longitudinal axis of the plate, and showing further another modification of nodal support means, utilizing the wall of the vessel in which atomization occurs.

FIGURE 6 represents a section in elevation, taken along the line 66 of FIG. 5.

FIGURE 7 represents a perspective view of the plate, showing an alternate means of nodal support.

In FIGURE 1, a stream of fluid 1 issues from rectangular orifice 2 of nozzle 3 and passes across bevel-edge 4 of thin bar or plate 5. Reservoir 6, with outlet pipe 7 and valve 8, contains the liquid R to be atomized. Plate 5 is shown supported at the center thereof by means of rod 19 passing therethrough and held thereto by nuts 11 threaded on or otherwise secured to the said rod 10.

3,l23,3fi5 Patented Mar. 3, 19%4 ice This point of support is of course a nodal point, and under the proper conditions to be described further on, the bevel-edge 4 and rear edge 12, being unrestrained, will be :antinodal points (FIGURE 2), the latter in the embodiment of FIGURE 1 atomizing liquid 9 into finely divided droplets 13.

In FIGURE 3, reservoir 6 is seen provided with valved line 14 communicating with manifold 15, the latter having several outlet pipes 16, each being located over an :antinodal point of plate 5 which latter, under the proper conditions, has been made to vibrate at the mode'shown in phantom.

In FIGURE 4, the stream of fluid 1 is seen passing over the bevel-edge 17 of circular plate or disc 18, the latter being restrained at the center thereof by means of rod 10 and nuts 11. In this embodiment, the antinode is located at the periphery of disc 18, liquid 9 flowing from the center to the periphery of said disc 13 for atomization. Preferably, that portion of the bevel-edge 17 registering with the length of rectangular orifice 2 is within the range of approximately 0.1 to 1.5 centimeters from the said rectangular orifice 2 so as to be within the zone of oscillation of the fluid stream 1 as explained further on.

In FIGURE 5, plate 19 is provided at one end with bevel-edge 20 facing the stream of fluid 1 at right angles to the longitudinal axis of the plate 19. In this embodiment, the stream of fluid 1 does not pass across the antinodal point at which atomization occurs. Further, in this embodiment, plate '19 is seen to be supported at the center by the wall 21 of the vessel in which the atomization is effected. A weld 22. along both sides of the wall 21 and around the said plate 19 may be provided, if desired. It should be understood that this particular plate 19 may also be supported as shown in the other figures in regard to plate 5.

In FIGURE 7, plate 5 is seen supported at the sides by means of rods 23 secured thereto.

In the apparatus of the foregoing figures the beveledges are positioned with respect to orifice 2 so as to be axially centered or registering relative thereto and to split the stream of fluid 1, it being preferred that the length of orifice 2 be suflicient so that the width of the stream of liquid 1 be at least equal to the width of the beveledges. The angle of the bevel-edges may be from about 5 to about 35 and, while the plate 5 is beveled at both ends for symmetry when 6 inches or less in length, the bevel at the rear edge may be dispensed with in longer plates.

The hydrodynamically vibrative atomizers of this invention operate as previously noted, on the principles of the jet edge generator. While the mechanics of the jet edge generator are still open to discussion, one explanation thereof is presented herewith. A thin fluid sheet, which may be of gas or of liquid, issued from the rectangular orifice with a certain velocity. This sheet, being non-rigid, is unstable. Disturbances originating in the walls of the orifice, and also arising from the entry of the thin sheet into the surrounding quiescent medium, create undulations or weak oscillations in the sheet, which latter acts as a membrane. These undulations or oscillations occur generally within 0.1 to 1.5 centimeters from the orifice, the precise distance being a function of orifice size and roughness, properties of the fluid forming the sheet, and the velocity of the said fluid. If a sharp beveled edge is located within this zone of oscillations of the fluid sheet, indicated in the accompanying figures as 24, the oscillating sheet causes the beveled edge to oscillate. Hydrodynamic feedback occurs when the fluid sheet glances off the beveled edge, a pressure pulse being transmitted back to the orifice through the sheet causing the latter to buckle. The timing of this feedback pulse or buckle will reinforce or amplify a particular frequency of vibration in the fluid sheet, and the fluid sheet will oscillate at this frequency but will not be stable as any change in sheet velocity will establish a new frequency. Now, with the beveled edge vibrating at a particular frequency, it feeds back pressure pulses to the oscillating fluid sheet at that particular frequency to reinforce and amplify that particular frequency in preference to other frequencies. The beveled edge being unrestrained and an antinode of a resonant flexural plate, tLE feedback will be of the resonant frequency. Slight variations in fluid sheet velocity will not alter the resonant frequency. In short, the fluid sheet impinging on tie bevel-edged antinodal portion of the plate disturbs the latter into oscillations, and the dominant one fed back to the sheet will be the resonant mode. Full treatment of this theory may be found in Sonics by Hueter and Bolt (.lohn Wiley, New York), pp. 288-295.

With particular reference to the apparatus of the accompanying figures, the operation thereof comprehends passing fluid, which may be liquid or gas, into nozzle 3, so that a stream 1 of such fluid will issue from rectangular orifice 2,. The stream 1 traverses distance 24 and contacts bevel-edge d of plate (or bevel-edge 17 of circular plate 18, or bevel-edge 2d of plate 19). Small vibrations are set up in the stream if. and in plate 5 (or plates 18 or 19 as the case may be), which vibrations will be audible if in the sonic range. As the rate of flow of fluid through rectangular orifice 2 is increased, the frequency of the resulting tone also increases. A fluid fiow rate will be reached at which the vibrations of stream 1 and of plate 5 (or 18 or 19) will increase sharply, and small variations of fluid flow rate will not affect the stability of these vibrations. In this latter condition, the vibrations of plate 5 (or 18 or 19) are in a resonant mode, controlling and reinforcing similar vibrations in stream 1 by means of hydrodynamic feedback. By proper adjustment of the fluid flow rate through rectangular orifice 2, of distance 24 (nozzle 3 or the nodal support rods for plates 5 or 18 or 19 may be mounted to permit relative movement between said nozzle and plate as by a lead screw arrangement or by any other means well-known in the mechanical arts, so as to permit variation of distance 24 which means need not be shown herein as they would unnecessarily increase the length and complexity of this specification), and/or of the position of the nodal supports, the fundamental and higher resonant modes of the plates 5 or 18 or 19 may be tuned. in. Liquid 9 is fed to the plates 5 or 18 or 19 in thin columns or drops, and is atomized from iantinodal portions thereof to form sprays comprising finely dispersed particles.

During the atomization process, the effective mass of the plates 5 or 18 or 19 mayvary, due to some of the liquid 9 adhering thereto or flowing partially to nodal portions of the said plates 5 or 13 or 19. However, .due to the peculiar properties of the jet edge generator, particularly of the phenomenon of hydrodynamic feedback, resonant flexural vibrations of the plates 5 or18or 19 are maintained. As the effective mass of the plates 5 or. 18 or 19 chan es, a slightly different resonant frequency thereof exists, which new frequency is fed back to. stream It as the dominant frequency, reinforcing and amplifying that particular frequency in stream ll, other frequencies ddamping out as they are not reinforced by hydrodynamic feedback.

Liquid 9 may be, besides a true liquid, a solid heated to the molten state, ora gas cooled to the liquid state, those parts of the atomizer contacting the liquid being maintained at the proper temperature by heating or cooling means Well known in the art to preserve the liquid state until atomization occurs.

While the accompanying drawings show plates 5 or 19 supported at a central node, the said plates 5 or 19 may be supported at other nodal points to permit even or odd harmonic modes.

Typical fluid flow rates and values of distance 24 under which this invention may operate may be found in FIG- URE 7.30 of Sonics, by Hueter and Bolt (John Wiley, New York), p. 290. However, this invention is not to be considered as limited to the operating conditions contemplated by the said FIGURE 7.30, but may also be operated under other conditions.

While I have shown the best embodiments of my invention known to me, 1 do not wish to be limited to the exact constructions disclosed herein, but may use such modifications, equivalents and substitutes as are embraced within the scope of the specification and drawings.

1 claim:

1. A hydrodynamically vibrative atomizer for dispersing a first liquid into fine particles comprising a nozzle, a rectangular orifice in said nozzle, means to introduce second fluid into said nozzle, a stream of second fiuid issuing from said rectangular orifice, a thin circular disc, means supporting said circular disc at the center thereof, a bevel-edge at the periphery of said circular disc and closely adjacent to said rectangular orifice, said beveledge splitting said stream of second fluid, and means to introduce first liquid to be atomized to a face of said circular disc. 2. Apparatus as in claim 1, that portion of said beveled'ge adjacent to and registering with said rectangular orifice being positioned within the range of 0.1 to 1.5 centimeters of said rectangular orifice.

3. Apparatus as in claim 1, that portion of said beveledge adjacent to and registering with said rectangular orifice being positioned within the zone of oscillation of said stream of second fiuid. I v 4. Apparatus as in claim 1, said last-mentioned means being positioned adjacent the center of said circular disc.

Claims (1)

1. A HYDRODYNAMICALLY VIBRATIVE ATOMIZER FOR DISPERSING A FIRST LIQUID INTO FINE PARTICLES COMPRISING A NOZZLE, A RECTANGULAR ORFICE IN SAID NOZZLE, MEANS TO INTRODUCE SECOND FLUID INTO SAID NOZZLE, A STREAM OF SECOND FLUID ISSUING FROM SAID RECTANGULAR ORIFICE, A THIN CIRCULAR DISC, MEANS SUPPORTING SAID CIRCULAR DISC AT THE CENTER THEREOF, A BEVEL-EDGE AT THE PERIPHERY OF SAID CIRCULAR DISC AND CLOSELY ADJACENT TO SAID RECTANGULAR ORIFICE, SAID BEVELEDGE SPLITTING SAID STREAM OF SECOND FLUID, AND MEANS TO INTRODUCE FIRST LIQUID TO BE ATOMIZED TO A FACE OF SAID CIRCULAR DISC.

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