EP0085583A2 - Liquid atomizing method and apparatus - Google Patents
Liquid atomizing method and apparatus Download PDFInfo
- Publication number
- EP0085583A2 EP0085583A2 EP83300921A EP83300921A EP0085583A2 EP 0085583 A2 EP0085583 A2 EP 0085583A2 EP 83300921 A EP83300921 A EP 83300921A EP 83300921 A EP83300921 A EP 83300921A EP 0085583 A2 EP0085583 A2 EP 0085583A2
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- European Patent Office
- Prior art keywords
- liquid
- throat
- gas flow
- throats
- downstream
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B17/00—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups
- B05B17/04—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods
- B05B17/06—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations
- B05B17/0692—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by a fluid
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B11/00—Single-unit hand-held apparatus in which flow of contents is produced by the muscular force of the operator at the moment of use
- B05B11/01—Single-unit hand-held apparatus in which flow of contents is produced by the muscular force of the operator at the moment of use characterised by the means producing the flow
- B05B11/04—Deformable containers producing the flow, e.g. squeeze bottles
- B05B11/042—Deformable containers producing the flow, e.g. squeeze bottles the spray being effected by a gas or vapour flow in the nozzle, spray head, outlet or dip tube
- B05B11/043—Deformable containers producing the flow, e.g. squeeze bottles the spray being effected by a gas or vapour flow in the nozzle, spray head, outlet or dip tube designed for spraying a liquid
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
- F23D11/34—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space by ultrasonic means or other kinds of vibrations
Definitions
- the invention relates to a method and apparatus for achieving atomization of a liquid characterized by extremely small droplets within a narrow size range. More particularly, the invention employs a shock wave technique for creating sonic and/or ultrasonic vibrations to shatter a confined column of liquid into a mist composed of droplets of a narrow size range below 50 microns in diameter.
- Hand sprayers of pump or squeeze bottle type are in very common use for spraying liquids such as deodorants, hair spray, cologne, etc.
- Typical hand sprayers produce droplets ranging in size from 0 to 250 microns in diameter.
- psig pounds per square inch gauge
- Hughes U.S. Patent No. 3,240,253 and Hughes U.S. Patent No. 3,240,254 which refer back to earlier Hughes Patents No. 3,230,923 and No. 3,230,924.
- Hughes patents disclose the use of convergent-divergent nozzles to achieve supersonic air flow in conjunction with Hartmann generators to create sonic resonance into which streams of liquid are injected for atomization purposes.
- the lowest mean droplet size achieved by Hughes was approximately 60 microns at substantial input air pressures, approximately 100 pounds per square inch absolute (psia). Hughes discloses that mean droplet size increases essentially geometrically with reduced input pressure, showing mean droplet size over 100 microns at an input pressure of approximately 19.7 psia. It is noted that since Hughes discloses mean droplet size, by definition, half of the droplets at any particular point on the Hughes curves would be of a larger size. Although most of the examples given by Hughes relate to atomization of fuel oil, it is noted that the droplet size achieved by Hughes is stated by him to be relatively independent of the viscosity (e.g., Hughes Patent No. 3,240,253, column 10, lines 9-20).
- Hughes discloses that the liquid to be atomized is introduced into the gas stream prior to or at about the time of acceleration to sonic velocity.
- Hughes Patent No. 3,354,443 Hughes also employs a Helmholtz resonator to reinforce the shock waves in the supersonic stream.
- Joeck U.S. Patent No. 2,532,554 An earlier device for atomizing a liquid by supersonic sound vibrations is disclosed in Joeck U.S. Patent No. 2,532,554. Joeck talks in terms of "breaking up" a liquid stream into finely divided droplets by introducing the liquid into a high velocity gas stream, assertedly supersonic.
- Applicant obtains extremely small droplet sizes by creating shock waves in a high speed air flow in diverging passages (that is, passages of successively increasing cross-sectional areas)- and causing these shock waves to impact against a wall surface to trigger sonic and/or ultrasonic vibrations which are directed into a confined column or stream of liquid such as water.
- the sonic and/or ultrasonic vibrations in the confined column of liquid cause it to fracture and to emerge as a fog-like flow comprised of droplets of extremely small size.
- shock waves in the air flow are achieved even though the input air pressure is as low as 1 to 2 psi, and these shock waves occur in a passage between a composite inlet or upstream throat and a single outlet or downstream throat, with the effective cross-sectional flow area of the outlet throat being approximately one-third larger than the effective cross-sectional flow area of the composite inlet throat.
- the shock wave and sonic and/or ultrasonic vibration phenomena which cause the liquid to fracture into a mist of extremely small droplets is approximately equally operative when the effective cross-sectional flow area of the downstream throat is in the range of from 1.25 to 1.5 times the effective cross-sectional flow area of the composite throat. From observation of models and from high speed photography, it has been determined that shock waves are indeed formed during operation even though the input pressure is so low as to indicate against the achievement of supersonic flow between the composite upstream throat and the downstream throat.
- the resulting flow is ejected from the downstream throat as a fine spray at a substantial forward velocity in the form of droplets in a very narrow size range of 50 microns or less.
- the atomizing apparatus of the present invention is generally designated by the reference numeral 20 in Figure 1.
- the apparatus includes a deformable plastic container 22 which incorporates a spray apparatus designated as 24.
- the container 22 is of the "squeeze bottle” type partly filled with a liquid to be sprayed, such as water, deodorant, hairspray, cologne or the like generally designated 26.
- the remainder of the bottle is filled with air at atmospheric pressure.
- pressure is created in the bottle causing the liquid to be ejected by the spray apparatus 24 in the form of a fine mist, the main body of which is designated by the reference numeral 28.
- a few droplets 28a are carried 9 to 10 inches away from the main spray, as shown, by the force of exiting shock waves as described in more detail subsequently herein.
- the spray apparatus 24 includes a spray plug 30 to which is connected a rigid liquid supply pipe 32 and which is in turn connected to a flexible dip tube 34, the bottom portion of which is immersed in the liquid 26.
- a spray plug 30 to which is connected a rigid liquid supply pipe 32 and which is in turn connected to a flexible dip tube 34, the bottom portion of which is immersed in the liquid 26.
- the dip tube has an en-. larqed upper end portion 36 in which the lower end portion of the supply pipe 32 is inserted and secured in liquid-tight fashion.
- a ball check valve is located within the tube enlargement 36 and comprises a ball member 38 normally seated against an annular valve seat 40.
- the ball 38 normally is urged in fluid-tight fashion against the seat 40 by means of gravity and a light compression spring 42 which is compressed between the ball member 38 and the lower end of the liquid supply pipe 32.
- the spray plug 30 is similar in general external configuration to the discharge nozzle device shown and described in applicant's above mentioned patent No. 3,316,559.
- the pluq 30 is preferably molded of semirigid plastic such as polyethylene or polypropylene, but it may be formed of metal or some other rigid material if desired.
- the pluo includes a cylindrical outer annular portion 44, a dome portion 46 and a cylindrical inner annular sleeve portion 48, all integral.
- the outer cylindrical portion 44 is adapted for being secured in the upper end portion of the squeeze bottle 22, as shown in Figure 1.
- the present invention resides in the configuration and coaction of the'cooperating portions of the spray plug 30 and the liquid supply pipe 32.
- the arrangement provides air passages which when the bottle 22 is squeezed, coact to achieve acceleration of air flow sufficient to create shock waves which are impinged against a wall surface to create sonic and/or ultrasonic vibrations which are reflected into the confined liquid flow before it emerges from the supply pipe 32, causinq fracturing of the confined liquid into extremely fine droplets of a narrow size range.
- the upper end portion of the liquid supply pipe 32 is snuqly held in a central cylindrical cavity 50 of the sleeve portion 48.
- Six longitudinal grooves 52 are formed in the inner wall of the cavity 50 and are equally spaced around the periphery.
- the grooves 52 are 'slightly tapered inwardly from their bottom ends toward the top.
- the grooves 52 With the pipe 32 secured within the cavity 50 as shown, the grooves 52. provide six air flow passages which are circumferentially spaced about the outer periphery of the pipe.
- a central liquid flow passage 54 is formed within the pipe 32, terminating at an opening at an upper end surface 55 of the pipe.
- the outer surface of the upper end portion of the liquid supply pipe 32 is scarfed or chamfered, with two an q ularly disposed flat chamfers 56 formed at each side. Consequently, the outer periphery of the end portion of the pipe is generally diamond shaped in cross-section as best seen in Figures 5 and 12, and the diamond shape gradually fairs into the round cross-sectional configuration of the outer surface of the pipe below the chamfers 56.
- the arrangement is such as to form three air flow passages on each side of the pipe 32, the center one of each group of three being the main or primary passage generally designated by the reference numeral 58, and the two flanking passages of each group being side or auxiliary passages generally designated by the reference numeral 60.
- the air flow passages 58 and 60 are of a convergent-divergent form.
- the passages 52 are sliqhtly flared toward their bottom ends, so that the passages 58 and 60 formed by grooves 52 and the circumferential surface of the liquid supply pipe 32 are slightly convergent in the direction of air flow until the chamfers 56 are encountered. At this point the narrowest constriction in each passage is reached.
- each of the primary passages 58 the point of narrowest constriction constitutes a throat 58t (at the phantom line shown), and in each of the auxiliary passages 60 the point of narrowest constriction constitutes a throat 60t (a,t the phantom lines shown).
- the portions of the primary and secondary passages upstream of the throats 58t and 60t are designated 58a and 60a, respectively, and the common diverging passage downstream of the throats is designated 61.
- the air flow passages 58 and 60 are constructed in convergent-divergent nozzle form, with the convergent section being the portion upstream of the respective throats 58t and 60t and the divergent section beinq the common diverging passage 61.
- the grooves 52 are .013 inches deep.
- the grooves 52 defining the orimary air flow passages 58 encounter the scarfed surfaces 56 at a point where the width of the grooves 52 is .032 inches.
- the auxiliary passages 60 do not reach the scarfed surfaces 56 until farther downstream, so that because of the taper in the grooves 52 the width at that point is approximately .025 inches.
- each of the throats 58t of the primary air flow passages 58 is .013 inches by .032 inches in dimension
- each auxiliary air flow passages 60 has a slightly smaller throat 60t of .013 by .025 inches in dimension. Downstream of the throats 58t and 60t the air passages open into the common diverging passage 61 defined by the scarfed surfaces 56.
- the cavity 50 in the sleeve portion 48 terminates at an end wall 62.
- a ramp 64 is formed in the central portion of the end wall and extends angularly upwardly from riqht to left as seen in Fiqures 4, 9, and 11.
- Parallel side walls 66 join the ramp 64 to define a ramped channel 67 leadinq to an exit orifice 68 exiting to the atmosphere.
- the exit orifice 68 is formed in an exterior surface 69 of a depressed region of the dome portion 46, with the surface disposed at about a 45° angle to the central axis of the spray plug.
- the outside diameter of the liquid supply pipe 32 below the scarfed surfaces 56 is .114 inches, while the diameter of the liquid passage ⁇ 54 is .042 inches.
- the liquid supply pipe 32 is secured in the cavity with its end surface 55 spaced .015 to .020 inches from the end wall 62 of the cavity.
- the exit orifice 68 is provided with relatively sharp or feather edges 68a and 68b, top and bottom, respectively. It has been determined experimentally that at least two of the edges of the orifice 68 must be relatively sharp or else the spray which is ejected hecomes much poorer, that is, droplet size becomes substantially larger than the desired 50 microns maximum. It has been determined experimentally that a rectangular orifice with all four edges no greater than .025 inches in thickness in the flow direction will work satisfactorily, but if the edge thickness is increased to .040 inches or over, the spray becomes unsatisfactory.
- the exit orifice edge if relatively thick, impedes or prevents the reflected shock waves from passing out the exit orifice.
- a relatively thick orifice may serve . to reduce the mass flow through the exit which in turn decreases the velocity between the two throats.
- the exit orifice 68 is of rectangular configuration .040 inches wide (the same as the distance between the side walls 66) and .036 inches deep (the distance between the sharp ednes 68a and 68b).
- the ramped channel 67 leading to the exit orifice 68 is open at its bottom. Accordingly, the combined cross-sectional open area of the ramped channel 67 and the connected space below the end wall 62 and above the end surface 55 of the liquid supply pipe 32 is considerably larger than the cross-sectional area of the exit orifice 68, particularly as the exit orifice is approached.
- the dimensions and configuration of the liquid supply pipe 32, the scarfed surfaces 56 of the liquid supply pipe, the spacing of the upper end of the liquid supply pipe from the end wall 62 of the cavity 50, the width and depth of the grooves 52, the continuous length of the grooves 52 throughout the cavity 50, and the size of the exit orifice 68 are deliberately chosen to create the effect of two throats in series in the air flow system from the interior of the squeeze bottle 22 to the atmosphere.
- the six throats 58t and 60t comprise a composite upstream throat, while the exit orifice 68 forms a single downstream throat.
- each of the upstream throats 58t is .000416 square inches, while the physical cross-sectional area of each of the upstream throats 60t is .000325 square inches, for a total of .002132 square inches for the composite upstream throat.
- the physical cross-sectional area of the downstream orifice or throat 68 is .00144 square inches.
- the effective cross-sectional flow area of the downstream throat is larger than the effective cross-sectional flow area of the composite upstream throat. This is because of the configuration and size of the long tapered inlet passages 52 and the fact that the composite upstream throat is made up of six throats 58t and 60t of small cross-sectional area, whereas the downstream throat comprises a single orifice 68. Because of the length of the inlet passages 58 and 60, the four wall surfaces forming each passage and the small cross-sectional area of each, there is substantial boundary layer build-up in each passage. In contrast, there is comparatively little boundary layer build-up at the single downstream orifice 68, particularly because of the sharp edges 68a and 68b.
- the ratio of the effective cross-sectional flow area of the downstream throat to the effective flow area of the composite upstream throat is approximately 1.33 to 1 for optimum operation.
- a water flow test is employed to determine experimentally the actual flow per unit time through the downstream throat 68 as compared with the actual flow per unit time through the composite upstream throat 58t and 60t.
- flow of a measured amount of water through the composite upstream throat is timed.
- the pipe 32 is removed, and flow of the same measured amount of water through the downstream throat 68 is timed.
- the comparative flow per unit time so determined defines the effective cross-sectional flow area ratio according to the concepts of the invention. It has been determined that the effective cross-sectional flow area ratio can vary between 1.5 and 1.25 and still achieve the uniform range of extremely small droplet sizes according to the invention.
- the configuration and location of parts is such that the space between the upper end 55 of the liquid supply pipe 32 and the end wall 62 is considerably greater in effective cross-sectional flow area than the effective cross-sectional flow area of the exit orifice 68. Accordingly, the flow is in no way restricted between the composite upstream throat 58t and 60t and the downstream throat 68.
- squeezing of the squeeze bottle 22 creates an internal pressure of 1 to 2 psig which causes liquid to flow upwardly in the passage 54 and causes air to flow upwardly into the grooves 52 comprising the initial portions of the air flow passages 58 and 60.
- the speed of the flow rapidly accelerates, apparently to supersonic speed. Acceleration to supersonic speed is concluded because shock waves form in the diverqent portions 61 of the passage before the air flow reaches the upper end of the liquid pipe 32.
- the shock waves which form in the diverging.passage 61 are schematically illustrated in Figures 9, 10 and 11.
- the shock waves when formed travel at several times the speed of sound.
- Some shock waves initially strike the ramp 64 and then are reflected to the opposed upper end surface 55 of the liquid supply pipe 32, such as the shock waves 70, 72, 74 and 76 schematically illustrated in Figures 9, 10 and 11.
- Some reflected shock waves, not illustrated, strike the side walls 66 of the ramped passage 67.
- other shock waves may first strike the end wall 62 of the cavity 50 and then be reflected against the end surface 55 of the liquid supply pipe from which .they are again reflected upwardly to strike the ramp surface 64.
- Applicant has found that providing a primary air flow as in the air flow passages 58 along with at least one secondary air flow as in the passages 60 is advantageous.
- the air flow in the primary passage 58 passes the throat 58t it tends to fan outwardly as depicted, and the same occurs with respect to the air flow through the auxiliary passages 60 as they pass the throats 60t.
- the secondary air flow appears to assist in acceleratin q the primary flow through entrainment, and in addition it is believed that the secondary flow provides energy to the boundary layer to reduce the flow-impeding effect of boundary layer growth.
Abstract
Description
- The invention relates to a method and apparatus for achieving atomization of a liquid characterized by extremely small droplets within a narrow size range. More particularly, the invention employs a shock wave technique for creating sonic and/or ultrasonic vibrations to shatter a confined column of liquid into a mist composed of droplets of a narrow size range below 50 microns in diameter.
- Hand sprayers of pump or squeeze bottle type are in very common use for spraying liquids such as deodorants, hair spray, cologne, etc. Typical hand sprayers produce droplets ranging in size from 0 to 250 microns in diameter. With the very low upstream input or back pressure available in typical hand sprayers, 1 to 2 pounds per square inch gauge (psig), it has not been possible heretofore to achieve droplet sizes in a very narrow size range no greater than 50 microns in diameter.
- Even with atomizing devices employing higher upstream input pressure the achievement of uniform droplet sizes below 50 microns is difficult and usually entails substantial back pressure and the use of baffles, screens or other mechanical devices to assist in droplet breakup.
- For a number of years those working in the atomization arts have employed sonic and supersonic wave generators to assist in atomization. Typical of such prior art devices are those disclosed in Hughes U.S. Patent No. 3,240,253 and Hughes U.S. Patent No. 3,240,254 (which refer back to earlier Hughes Patents No. 3,230,923 and No. 3,230,924). These Hughes patents disclose the use of convergent-divergent nozzles to achieve supersonic air flow in conjunction with Hartmann generators to create sonic resonance into which streams of liquid are injected for atomization purposes.
- With specific reference to Huqhes Patent 3,240,253, Figures 4 and 5, the lowest mean droplet size achieved by Hughes was approximately 60 microns at substantial input air pressures, approximately 100 pounds per square inch absolute (psia). Hughes discloses that mean droplet size increases essentially geometrically with reduced input pressure, showing mean droplet size over 100 microns at an input pressure of approximately 19.7 psia. It is noted that since Hughes discloses mean droplet size, by definition, half of the droplets at any particular point on the Hughes curves would be of a larger size. Although most of the examples given by Hughes relate to atomization of fuel oil, it is noted that the droplet size achieved by Hughes is stated by him to be relatively independent of the viscosity (e.g., Hughes Patent No. 3,240,253,
column 10, lines 9-20). - Other examples of atomization devices employinq supersonic qas streams are disclosed in Hughes U.S. Patents No. 3,531,048, No. 3,542,291, No. 3,554,443 and No. 3,558,056. In the devices of all four of these later patents Huqhes assertedly obtains supersonic gas velocity through boundary layer "sculpting". According to Hughes, the build up and then the deterioration of the boundary layer in a straight-sided nozzle causes the gas stream to accelerate to supersonic, with the boundary layer forming what is akin to a convergent-divergent supersonic nozzle. In each of these patents, Hughes discloses that the liquid to be atomized is introduced into the gas stream prior to or at about the time of acceleration to sonic velocity. In Hughes Patent No. 3,354,443, Hughes also employs a Helmholtz resonator to reinforce the shock waves in the supersonic stream.
- An earlier device for atomizing a liquid by supersonic sound vibrations is disclosed in Joeck U.S. Patent No. 2,532,554. Joeck talks in terms of "breaking up" a liquid stream into finely divided droplets by introducing the liquid into a high velocity gas stream, assertedly supersonic.
- The Hughes patents and the Joeck patent disclosed above are the closest prior art known to applicant and his attorney relative to the present invention.
- Applicant obtains extremely small droplet sizes by creating shock waves in a high speed air flow in diverging passages (that is, passages of successively increasing cross-sectional areas)- and causing these shock waves to impact against a wall surface to trigger sonic and/or ultrasonic vibrations which are directed into a confined column or stream of liquid such as water. The sonic and/or ultrasonic vibrations in the confined column of liquid cause it to fracture and to emerge as a fog-like flow comprised of droplets of extremely small size.
- The shock waves in the air flow are achieved even though the input air pressure is as low as 1 to 2 psi, and these shock waves occur in a passage between a composite inlet or upstream throat and a single outlet or downstream throat, with the effective cross-sectional flow area of the outlet throat being approximately one-third larger than the effective cross-sectional flow area of the composite inlet throat. The shock wave and sonic and/or ultrasonic vibration phenomena which cause the liquid to fracture into a mist of extremely small droplets is approximately equally operative when the effective cross-sectional flow area of the downstream throat is in the range of from 1.25 to 1.5 times the effective cross-sectional flow area of the composite throat. From observation of models and from high speed photography, it has been determined that shock waves are indeed formed during operation even though the input pressure is so low as to indicate against the achievement of supersonic flow between the composite upstream throat and the downstream throat.
- The resulting flow is ejected from the downstream throat as a fine spray at a substantial forward velocity in the form of droplets in a very narrow size range of 50 microns or less.
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- Figure 1 is an elevational view of a spray device incorporating the atomizing method and apparatus of the present invention;
- Figure 2 is an enlarged fragmentary sectional view of a portion of the apparatus of Figure 1 taken along line 2-2 thereof;
- Figure 3 is an enlarged elevational view of the top end of the apparatus taken along line 3-3 of Figure 1;
- Figure 4 is a sectional view taken along line 4-4 of Figure 3;
- Figure 5 is a fragmentary section view taken along line 5-5 of Figure 4;
- Figure 6 is a sectional view taken along line 6-6 of Figure 4;
- Figure 7 is a fragmentary sectional view taken along line 7-7 of Figure 4;
- Figure 8 is a fragmentary elevational view, partly in section, taken along line 8-8 of Figure 4;
- Figure 9 is a further enlarged fragmentary sectional view taken along line 9-9 of Figure 6, schematically illustrating the atomization phenomenon in operation;
- Figure 10 is a fragmentary sectional view taken along line 10-10 of Figure 9 and to the same scale as Figure 9, further schematically illustrating the atomization phenomenon in operation;
- Fiqure 11 is an enlarged fragmentary sectional view similar to Figure 9 and to the same scale but showing the end portion of the liquid pipe in elevation, further schematically illustrating the atomization phenomenon in operation; and
- Figure 12 is a fragmentary perspective view partly in section and partly schematic and to the same scale as Figures 9 and 10, with the atomization phenomenon further schematically illustrated.
- The atomizing apparatus of the present invention is generally designated by the
reference numeral 20 in Figure 1. The apparatus includes a deformableplastic container 22 which incorporates a spray apparatus designated as 24. Thecontainer 22 is of the "squeeze bottle" type partly filled with a liquid to be sprayed, such as water, deodorant, hairspray, cologne or the like generally designated 26. The remainder of the bottle is filled with air at atmospheric pressure. When the bottle is squeezed or deformed by the user, pressure is created in the bottle causing the liquid to be ejected by thespray apparatus 24 in the form of a fine mist, the main body of which is designated by thereference numeral 28. Afew droplets 28a are carried 9 to 10 inches away from the main spray, as shown, by the force of exiting shock waves as described in more detail subsequently herein. - The
spray apparatus 24 includes aspray plug 30 to which is connected a rigidliquid supply pipe 32 and which is in turn connected to aflexible dip tube 34, the bottom portion of which is immersed in theliquid 26. Aside from the novel construction and operation of the spray apparatus to be described, the general arrangement described thus far is quite similar to the squeeze bottle spray apparatus shown in Montenier U.S. Patent No. 2,642,313. - As best seen in rigure 2, the dip tube has an en-. larqed
upper end portion 36 in which the lower end portion of thesupply pipe 32 is inserted and secured in liquid-tight fashion. A ball check valve is located within thetube enlargement 36 and comprises a ball member 38 normally seated against anannular valve seat 40. The ball 38 normally is urged in fluid-tight fashion against theseat 40 by means of gravity and alight compression spring 42 which is compressed between the ball member 38 and the lower end of theliquid supply pipe 32. When thesqueeze bottle 22 is deformed, the air above theliquid 26 is compressed forcing the liquid to rise in thedip tube 34. When the liquid rises in the dip tube sufficiently to open the ball check valve, the liquid can pass upwardly into theliquid supply pipe 32 and into thespray plug 30. When the squeeze bottle is released, thesupply pipe 32 will remain completely filled by reason of the well-known closing action of the ball check valve. The dip tube and check valve arranqement is very similar to that of the spray apparatus shown in Ewing et al U.S. Patent No. 3,316,559, an invention of the present applicant with another. - The
spray plug 30 is similar in general external configuration to the discharge nozzle device shown and described in applicant's above mentioned patent No. 3,316,559. Thepluq 30 is preferably molded of semirigid plastic such as polyethylene or polypropylene, but it may be formed of metal or some other rigid material if desired. As seen in Figures 3-6 the pluo includes a cylindrical outerannular portion 44, adome portion 46 and a cylindrical innerannular sleeve portion 48, all integral. The outercylindrical portion 44 is adapted for being secured in the upper end portion of thesqueeze bottle 22, as shown in Figure 1. - The present invention resides in the configuration and coaction of the'cooperating portions of the
spray plug 30 and theliquid supply pipe 32. As described in detail hereinafter, the arrangement provides air passages which when thebottle 22 is squeezed, coact to achieve acceleration of air flow sufficient to create shock waves which are impinged against a wall surface to create sonic and/or ultrasonic vibrations which are reflected into the confined liquid flow before it emerges from thesupply pipe 32, causinq fracturing of the confined liquid into extremely fine droplets of a narrow size range. - As best seen in Figures 4, 5 and 6 the upper end portion of the
liquid supply pipe 32 is snuqly held in a centralcylindrical cavity 50 of thesleeve portion 48. Sixlongitudinal grooves 52 are formed in the inner wall of thecavity 50 and are equally spaced around the periphery. Thegrooves 52 are 'slightly tapered inwardly from their bottom ends toward the top. With thepipe 32 secured within thecavity 50 as shown, thegrooves 52. provide six air flow passages which are circumferentially spaced about the outer periphery of the pipe. A centralliquid flow passage 54 is formed within thepipe 32, terminating at an opening at anupper end surface 55 of the pipe. - The outer surface of the upper end portion of the
liquid supply pipe 32 is scarfed or chamfered, with two anqularly disposedflat chamfers 56 formed at each side. Consequently, the outer periphery of the end portion of the pipe is generally diamond shaped in cross-section as best seen in Figures 5 and 12, and the diamond shape gradually fairs into the round cross-sectional configuration of the outer surface of the pipe below thechamfers 56. The arrangement is such as to form three air flow passages on each side of thepipe 32, the center one of each group of three being the main or primary passage generally designated by thereference numeral 58, and the two flanking passages of each group being side or auxiliary passages generally designated by thereference numeral 60. - With specific reference to Figures 5 and 11, the
air flow passages passages 52 are sliqhtly flared toward their bottom ends, so that thepassages grooves 52 and the circumferential surface of theliquid supply pipe 32 are slightly convergent in the direction of air flow until thechamfers 56 are encountered. At this point the narrowest constriction in each passage is reached. With reference to Figure 11, in each of theprimary passages 58 the point of narrowest constriction constitutes a throat 58t (at the phantom line shown), and in each of theauxiliary passages 60 the point of narrowest constriction constitutes athroat 60t (a,t the phantom lines shown). The portions of the primary and secondary passages upstream of thethroats 58t and 60t are designated 58a and 60a, respectively, and the common diverging passage downstream of the throats is designated 61. Accordingly, theair flow passages respective throats 58t and 60t and the divergent section beinq the common divergingpassage 61. - In an operatinq embodiment of the invention as shown and described the
grooves 52 are .013 inches deep. Thegrooves 52 defining the orimaryair flow passages 58 encounter the scarfed surfaces 56 at a point where the width of thegrooves 52 is .032 inches. Theauxiliary passages 60 do not reach the scarfed surfaces 56 until farther downstream, so that because of the taper in thegrooves 52 the width at that point is approximately .025 inches. Accordingly, each of the throats 58t of the primaryair flow passages 58 is .013 inches by .032 inches in dimension, while each auxiliaryair flow passages 60 has a slightlysmaller throat 60t of .013 by .025 inches in dimension. Downstream of thethroats 58t and 60t the air passages open into the common divergingpassage 61 defined by the scarfed surfaces 56. - The
cavity 50 in thesleeve portion 48 terminates at anend wall 62. Aramp 64 is formed in the central portion of the end wall and extends angularly upwardly from riqht to left as seen inFiqures 4, 9, and 11.Parallel side walls 66 join theramp 64 to define a rampedchannel 67 leadinq to anexit orifice 68 exiting to the atmosphere. Theexit orifice 68 is formed in anexterior surface 69 of a depressed region of thedome portion 46, with the surface disposed at about a 45° angle to the central axis of the spray plug. - In the embodiment of the invention being described the outside diameter of the
liquid supply pipe 32 below the scarfed surfaces 56 is .114 inches, while the diameter of the liquid passage` 54 is .042 inches. Theliquid supply pipe 32 is secured in the cavity with itsend surface 55 spaced .015 to .020 inches from theend wall 62 of the cavity. - It will be noted that the
exit orifice 68 is provided with relatively sharp orfeather edges 68a and 68b, top and bottom, respectively. It has been determined experimentally that at least two of the edges of theorifice 68 must be relatively sharp or else the spray which is ejected hecomes much poorer, that is, droplet size becomes substantially larger than the desired 50 microns maximum. It has been determined experimentally that a rectangular orifice with all four edges no greater than .025 inches in thickness in the flow direction will work satisfactorily, but if the edge thickness is increased to .040 inches or over, the spray becomes unsatisfactory. The same occurs with respect to a round exit orifice, that is, an edge thickness of .040 inches or over causes a much poorer spray while an edge thickness below .025 inches results in a satisfactory spray. It is believed that the exit orifice edge, if relatively thick, impedes or prevents the reflected shock waves from passing out the exit orifice. A relatively thick orifice may serve . to reduce the mass flow through the exit which in turn decreases the velocity between the two throats. In the particular embodiment of the invention depicted theexit orifice 68 is of rectangular configuration .040 inches wide (the same as the distance between the side walls 66) and .036 inches deep (the distance between thesharp ednes 68a and 68b). - As best seen in Figures 9 and 10, the ramped
channel 67 leading to theexit orifice 68 is open at its bottom. Accordingly, the combined cross-sectional open area of the rampedchannel 67 and the connected space below theend wall 62 and above theend surface 55 of theliquid supply pipe 32 is considerably larger than the cross-sectional area of theexit orifice 68, particularly as the exit orifice is approached. - The dimensions and configuration of the
liquid supply pipe 32, the scarfed surfaces 56 of the liquid supply pipe, the spacing of the upper end of the liquid supply pipe from theend wall 62 of thecavity 50, the width and depth of thegrooves 52, the continuous length of thegrooves 52 throughout thecavity 50, and the size of theexit orifice 68 are deliberately chosen to create the effect of two throats in series in the air flow system from the interior of thesqueeze bottle 22 to the atmosphere. The sixthroats 58t and 60t comprise a composite upstream throat, while theexit orifice 68 forms a single downstream throat. In the embodiment shown the physical cross-sectional area of each of the upstream throats 58t is .000416 square inches, while the physical cross-sectional area of each of theupstream throats 60t is .000325 square inches, for a total of .002132 square inches for the composite upstream throat. The physical cross-sectional area of the downstream orifice orthroat 68 is .00144 square inches. - Notwithstanding the physical dimensions, the effective cross-sectional flow area of the downstream throat is larger than the effective cross-sectional flow area of the composite upstream throat. This is because of the configuration and size of the long tapered
inlet passages 52 and the fact that the composite upstream throat is made up of sixthroats 58t and 60t of small cross-sectional area, whereas the downstream throat comprises asingle orifice 68. Because of the length of theinlet passages downstream orifice 68, particularly because of thesharp edges 68a and 68b. - The ratio of the effective cross-sectional flow area of the downstream throat to the effective flow area of the composite upstream throat is approximately 1.33 to 1 for optimum operation. In order to determine the effective cross-sectional flow area ratio at higher Reynolds numbers, a water flow test is employed to determine experimentally the actual flow per unit time through the
downstream throat 68 as compared with the actual flow per unit time through the compositeupstream throat 58t and 60t. First, with thepipe 32 in place, flow of a measured amount of water through the composite upstream throat is timed. Next, thepipe 32 is removed, and flow of the same measured amount of water through thedownstream throat 68 is timed. The comparative flow per unit time so determined defines the effective cross-sectional flow area ratio according to the concepts of the invention. It has been determined that the effective cross-sectional flow area ratio can vary between 1.5 and 1.25 and still achieve the uniform range of extremely small droplet sizes according to the invention. - The configuration and location of parts is such that the space between the
upper end 55 of theliquid supply pipe 32 and theend wall 62 is considerably greater in effective cross-sectional flow area than the effective cross-sectional flow area of theexit orifice 68. Accordingly, the flow is in no way restricted between the compositeupstream throat 58t and 60t and thedownstream throat 68. - In operation of applicant's invention, squeezing of the
squeeze bottle 22 creates an internal pressure of 1 to 2 psig which causes liquid to flow upwardly in thepassage 54 and causes air to flow upwardly into thegrooves 52 comprising the initial portions of theair flow passages respective throats 58t and 60t into the divergingportion 61 of the passages, the speed of the flow rapidly accelerates, apparently to supersonic speed. Acceleration to supersonic speed is concluded because shock waves form in thediverqent portions 61 of the passage before the air flow reaches the upper end of theliquid pipe 32. - The shock waves which form in the
diverging.passage 61 are schematically illustrated in Figures 9, 10 and 11. The shock waves when formed travel at several times the speed of sound. Some shock waves initially strike theramp 64 and then are reflected to the opposedupper end surface 55 of theliquid supply pipe 32, such as theshock waves side walls 66 of the rampedpassage 67. Also, it is believed that other shock waves (not shown) may first strike theend wall 62 of thecavity 50 and then be reflected against theend surface 55 of the liquid supply pipe from which .they are again reflected upwardly to strike theramp surface 64. The fact that the energy of the shock waves is not fully dissipated and that reflected waves pass out theexit orifice 68 is determined by visual observation of the external spray, which contains somedroplets 28a carried 9 or 10 inches to.each side of themain spray 28, as illustrated in Figures 1, 9 and 12. - In ascertaining the presence of shock waves applicant has taken hiqh speed photographs of the phenomenon, and in many of these photographs the area of impact of the shock waves aaainst various wall surfaces is quite pronounced. The phenomenon shown in the photographs is schematically illustrated in Figure 9 wherein the
shock wave 70 is shown as first impacting theramp 64 and then reflecting against theupper end surface 55 of theliquid supply pipe 32. Theincident shock 70 causes theboundary layer 78 to separate from thewall surface 64, and it reattaches downstream as shown. As theshock wave 70 reflects against theupper end surface 55 of theliquid supply pipe 32, it also causes theboundary layer 80 to separate from that surface as shown. The shock wave reflected from theend surface 55 then passes out theexit orifice 68 as shown. Since only a relatively strong shock wave causes boundary layer separation, the high speed photographs indicate the presence of strong shock waves. Applicant believes that the boundary layer separation phenomenon occurs each time a sufficiently strong shock wave impacts a wall or is reflected against another wall, as explained for example in Boundary Layer and Flow Control, Vol. 2, Edited by G.V. Lachmann, Perqamon Press, 1961, Chapter by H.H. Pearcey. For the sake of simplicity the boundary layer separation phenomenon is not shown in Figures 10 and 11, but it will be understood that boundary layer separation occurs as theshock waves 72, 74 and 76 impact thesurfaces - The high speed photographs were taken at eight microseconds exposure, and yet the motion of the flow adjacent the
end surface 55 of theliquid supply pipe 32 was not completely stopped. This appears to indicate an area of very low pressure and high velocity along thesurface 55. This is to be expected because of the high velocity of the air flow in the divergingpassages 61 on each side of theliquid supply pipe 32. As the air flow reaches theend surface 55, which is at almost 90° to the planes of the scarfed surfaces 56, extreme turbulence and very low pressure are created adjacent thesurface 55 because of the abrupt discontinuity of the surfaces. This creates a strong "suction" which tends to create tension in the column of liquid in theliquid flow passage 54. - While the presence of rapidly recurring shock waves has been established through testing and high speed photography, the underlying physical-phenomenon which creates the shock wave is not fully understood. As stated earlier, the presence of shock waves seems to indicate acceleration of the air flow in the diverging
passages 61 to supersonic speeds. Also, since only a strong shock wave will cause boundary layer separation, the separation which does occur (Figure 9) seems to point to air flow velocities which are strongly supersonic. However, the back pressure of only 1 to 2 psig would make it necessary that the pressure at theupstream throats 58t and 60t drop to approximately 8.82 psia in order to achieve a critical pressure ratio of .528 (ratio of pressure at the throat divided by back pressure) which is agreed by the authorities as necessary to achieve sonic velocity at a single throat. Achievement of such a low pressure at thethroats 58t and 60t seems unlikely. Nevertheless, because of the rapidly recurring shock waves which are present, it is assumed that during operation of the spray device the air flow in the divergingpassages 61 must turn supersonic and remain supersonic. - Applicant has found that providing a primary air flow as in the
air flow passages 58 along with at least one secondary air flow as in thepassages 60 is advantageous. With specific reference to Figure 11, as the air flow in theprimary passage 58 passes the throat 58t it tends to fan outwardly as depicted, and the same occurs with respect to the air flow through theauxiliary passages 60 as they pass thethroats 60t. The secondary air flow appears to assist in acceleratinq the primary flow through entrainment, and in addition it is believed that the secondary flow provides energy to the boundary layer to reduce the flow-impeding effect of boundary layer growth. - As illustrated in Figures 9 and 10, when the shock waves impact against a surface they create sonic or ultrasonic vibrations, such as the
vibrations ramp surface 64 as shown in Figures 9 and 10 are directed toward thepassage 54 causing sonic vibrations to be transmitted downwardly into the liquid confined within the passage before it reaches theend surface 55. The sonic vibrations created in the confined liquid column cause it to fracture before it emerges from the exit aperture of thepassage 54, so that when the liquid emerges from the aperture at thesurface 55 it does so in the form of amist 88 comprised of extremely small droplets, schematically illustrated in Figure 12. As the flow is ejected out theexit orifice 68, it appears that some recombining of droplets has taken place. Nevertheless, it has been determined that thespray 28 which is ejected is composed of droplets of a narrow size range not greater than 50 microns in diameter. As previously mentioned, somedroplets 28a are ejected as far as 9 to 10 inches to the side of the central ormain core spray 28, indicating that reflected shock waves are exiting with the spray. - It has been determined experimentally that in order to provide sonic vibrations effective for fracturing the confined liquid column, the wall surface or surfaces from which the sonic vibrations emanate must be relatively close and opposed to the liquid exit aperture. It will be seen from Figures 9, 10 and 11 that this is indeed the case with the positioning and attitude of the
ramp surface 64 relative to the exit aperture of theliquid passage 54 at theend surface 55 of thewater pipe 32. - The mechanism by which the sonic vibrations (such as 82, 84 and 86 shown in Figure 9 and 10) cause fracturing of the confined liquid column is not fully understood. It may be that the fracturing is related to and a step beyond the phenomenon of ultrasonically induced cavitation as explained in Ultrasonically Induced Cavitation in Water: A Step-by-Step Process, by G. W. Willard, which appeared in Volume 25,
Number 4 of the Journal of the AcousticalSociety of America for July, 1953, or as explained in Hiqh-Intensity Ultrasonics, by Basil Brown and John E. Goodman, copyright 1965, published in the U.S.A. by D. Van Nostrand Company, Inc. - Although the present invention has been described as embodied in a hand sprayer in which the input pressure is very low, the concepts of the invention are equally applicable to spray devices in which higher input pressures are achieved.
- Variations and modifications may be effected without departing from the scope of the novel concepts of the present invention.
Claims (23)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT83300921T ATE39747T1 (en) | 1983-02-22 | 1983-02-22 | METHOD AND DEVICE FOR FINE ATOMY OF LIQUIDS. |
EP83300921A EP0085583B1 (en) | 1983-02-22 | 1983-02-22 | Liquid atomizing method and apparatus |
DE8383300921T DE3378842D1 (en) | 1983-02-22 | 1983-02-22 | Liquid atomizing method and apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP83300921A EP0085583B1 (en) | 1983-02-22 | 1983-02-22 | Liquid atomizing method and apparatus |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0085583A2 true EP0085583A2 (en) | 1983-08-10 |
EP0085583A3 EP0085583A3 (en) | 1983-09-14 |
EP0085583B1 EP0085583B1 (en) | 1989-01-04 |
Family
ID=8191072
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83300921A Expired EP0085583B1 (en) | 1983-02-22 | 1983-02-22 | Liquid atomizing method and apparatus |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0085583B1 (en) |
AT (1) | ATE39747T1 (en) |
DE (1) | DE3378842D1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0610853A1 (en) * | 1993-02-09 | 1994-08-17 | Elhanan Tavor | Atomizer |
US5513798A (en) * | 1993-08-08 | 1996-05-07 | Tavor; Elhanan | Atomizer |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3240253A (en) * | 1963-02-25 | 1966-03-15 | Sonic Dev Corp | Sonic pressure wave atomizing apparatus and methods |
US3240254A (en) * | 1963-12-23 | 1966-03-15 | Sonic Dev Corp | Compressible fluid sonic pressure wave apparatus and method |
US3741484A (en) * | 1970-09-30 | 1973-06-26 | Decafix Ltd | Atomisers |
US4084934A (en) * | 1972-02-05 | 1978-04-18 | Mitsubishi Precision Co., Ltd. | Combustion apparatus |
US4316580A (en) * | 1979-07-13 | 1982-02-23 | Sontek Industries, Inc. | Apparatus for fragmenting fluid fuel to enhance exothermic reactions |
-
1983
- 1983-02-22 EP EP83300921A patent/EP0085583B1/en not_active Expired
- 1983-02-22 DE DE8383300921T patent/DE3378842D1/en not_active Expired
- 1983-02-22 AT AT83300921T patent/ATE39747T1/en not_active IP Right Cessation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3240253A (en) * | 1963-02-25 | 1966-03-15 | Sonic Dev Corp | Sonic pressure wave atomizing apparatus and methods |
US3240254A (en) * | 1963-12-23 | 1966-03-15 | Sonic Dev Corp | Compressible fluid sonic pressure wave apparatus and method |
US3741484A (en) * | 1970-09-30 | 1973-06-26 | Decafix Ltd | Atomisers |
US4084934A (en) * | 1972-02-05 | 1978-04-18 | Mitsubishi Precision Co., Ltd. | Combustion apparatus |
US4316580A (en) * | 1979-07-13 | 1982-02-23 | Sontek Industries, Inc. | Apparatus for fragmenting fluid fuel to enhance exothermic reactions |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0610853A1 (en) * | 1993-02-09 | 1994-08-17 | Elhanan Tavor | Atomizer |
AU684728B2 (en) * | 1993-02-09 | 1998-01-08 | Elhanan Tavor | Atomizer |
US5513798A (en) * | 1993-08-08 | 1996-05-07 | Tavor; Elhanan | Atomizer |
Also Published As
Publication number | Publication date |
---|---|
EP0085583B1 (en) | 1989-01-04 |
ATE39747T1 (en) | 1989-01-15 |
EP0085583A3 (en) | 1983-09-14 |
DE3378842D1 (en) | 1989-02-09 |
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