US2693943A - Liquid-siren sonic agitator - Google Patents

Description

Nov. 9, 1.954 A. A. FOWLE 2,693,943

LIQUID-SIREN SONIC AGITATOR Filed May 5, 1951 2 Sheets-Sheet l Fig. l

OUTLET g 42 INLET 1 HIGH 54 PRESSURE 38 SUPPLY @Y T 34 32 I0 P /50 /48 I8 46 LOW PRESSURE SUPPLY HVVENIUR.

B M M, j mvmm ATTORNEYS United States Patent 6 M The" present invention relates:- to apparatus for treat=- ingzbulkiliquidsr with: sound waves: and comprises, in: one aspect, a liquid siren.

Ithas long been'recognizedf that sound-waves of proper frequencies may be utilized to accomplish many valu+- ableresultsawhen appliedto liquids. For exarnpleg. sound wavesmay be employed to kill bacteria; .to accelerate the chemical: processes involved in the ageing: of alcoholbeverages; to form emulsions; and otherwise improve the'characteristics'of mans liquids; Attempts havebeen madeto-utilize piezo-electric crystals and magnetostriction: rodsas the-sourceof'sound waves in liquids, buttheineffi'ciency of suchoperations onza' large scale has pre-- eluded economic commercial use:thereof;

The-primary object of theinvention is to provide simple" and efficient apparatus' for generating-high intensity sound waves in bulk liquids and thereby to'render commercially feasiblethe sonic treatment thereof.

An important feature of the invention resides in a rotor-stator combination wherein a liquid is introduced" into the rotor and passed through thestator in bursts which. generate pressure waves at sonic orultrasonicfr'equencies, the arrangement of' the rotor with respect toa surrounding housing being such that liquid discharged from the rotor drops at once into a drainage chamber beneath the rotor; whereby the=rotor spins in air and'is not subject to significant frictional. drag of 'th'e' liquid.

Still another important: feature of the invention resides in a duplex conduit or which one-half serves asa passage for the supply of liquid to the rotor as well as for the passage of' back-generated'pressure waves; while the other part of the conduit serves for the passage of the liquid to be treated as well as'a continuation of the passage for the pressure waves, the twoportions of the conduit being separated by a plug "having anacoustic irn pedance comparable to that of the'liquid' supplied: to' the rotor.

Another feature of the' invention resides in a rotor havingslots so formed that the passage of pressurized fluid therethrough' serves to' spin the rotor..

A very important feature of the invention resides in the=combinationof a hollow'rotor: and a surrounding stator so designed as. to utilize the: pressure. waves generated within. the body of the rotoritself, these. waves traveling backthroughthe rotor and into-a treating chame her. This contrasts with. conventional;operationiin-which 6O thepressure wavesemanating? from the. stator are: applied to do the'desiredwork. While-using. the back-generated waves, itbecomes possible. to spin the rotor inv air. in stead ofliquid in. order to reduce significant frictional drag. Furthermore the flow passages inthe. rotor. maybe. designed so that turbulence within the rotor is avoided; thus increasing the effective amplitude of the backgenerated waves; Moreoverby supplying" liquid to the rotor under pressure, cavitation. aflfecting the; back-generated waves is entirely eliminated, with the result that pressure wanes of relatively large intensity may begenerated and applied to do=useful work.

These and other objects and features of the invention will be more readily understood and appreciated from the following? detailed description ofa preferred embodiment thereof. selected for purposes of illustration and shown in the accompanying drawings in which:

Fig. 1 is a: diagrammatic view of.- a' complete liquid siren and sonic treating system,

Fig. 2. is aview in cross sectionthrough the elements 0 of. the rotor-stator combination,

may therefore be 2,693,943 Patented Nov. 9, 1954 Fig: 3:: is a: plan; view of: the: rotor-stator combination; witlr portions .shownzimsectiom.v

Fig;vv 4' is; awiew irr crossssection". onarr-enlarged scale through :a: rotor slot; and" Fig.5

stator ports;

The general organization ofxa'sonic. treating system incorporating an improveddiquidfsiren" isrshown in Fig.1 1 wherein it'wilI. bewevident' that-there is pro.vided a large casing eor housing: 102 of; generally cylindrical shape havmga massive central-boss: 12-.andialso having in its in.- terior anzintegral upstandingtannular flange. 14' provided at its-upper? endi witha series-of: slots: 16;. this serves' as astator;

A' shaft; 18=extendsz through thevboss 12 and. is coupled at itsxlower'xend tosarvariablespeed drive: motor'20'resting'iupon a suitable: base 22'.

Registering: with-.and' secured to the housing 10." is an upper; casing 24* having a massive central boss: 26. A hol'low 'rotor-28 is. secured to the upper endof'theshaft 18 within the'wchamben formed by'the housings 10 and 24. and'ha'sa. 'ollow chamber S'Oand a series: of peripheral slots' ot portssadapted to register with the slots 16 in the stator ringz14 and to open and close them. as the rotor turns. The rotor is also provided on i'tsupper surface with a centrally'locatedf aperture: 34 surrounding which is a. sealf36 by'means of which thepassage 34 is'coupled in? watertight relation: to; the. flanged end of a. vertical pipe 38 passing throughthe: boss 26.

A- conduit" 40: connected toarpressure gauge 42. leads to: the. pipe: 38? from. a, highpressure: tank. served by" a variable drive pump driven: by a motor? 44- and arranged to'supplyliquid. to the: high pressuretank from a sumpor low-pressuretanki connected to the bottom of the housing; 10by'a drain-conduit 46 and'connected to the pump by a. conduit: 48; A. by-pass: conduit 50. connects the low pressure or sump tank torthe highpressure tank and is: provided with a. pressure". operated relief valve 52: which maybemanually set to bleed the high pressuretank into the; low pressure tank; at a predetermined pressure; and thereby automatically control the rate of flow of liquid fromthe: high pressure-tank into the pipe 38- and the: rotor28; There is provided in the pipe 38 abovewtheconduit 40 a plug 54- of'solid'material' having a compressibilitysimilarto thatof'the-liquidin the supply circuitv and-thereby exhibiting anacoustic impedance similarto-that of" the: liquid, which may be oil of the sort commonly used' in' hydraulic systems. The plug 54 composed of a rubber-like substance bondedrto the.- pipe-walls;

Above the plug 5'4 there is providedrin the-pipe 38 an inlet, and the upper end of the pipe 38 leads to a large surge tank provided? with a pressure gauge 56- and also having. an outlet or discharge pipe so that liquid to be treated. may'ber circulated. through the pipe- 38 and into the surge tank incontinuous fashion. The pressure gauge 56 permits observation astothe pressure in the treating system. v

The. rotor. maybe turned by themotor 20 as liquidis suppliedto it. The flowof liquid through the rotor is intermittently interrupted as the rotor slots 32. pass iii and: out of registry with the stator slots 16. This periodic interruption of the flow of liquid. generates, compression and'rarefaction. waves both outwardly and inwardly with respect to. the rotor slots. The inwardly directed pressure waves travel back through. the pipe 38; passing easily through" the plug 54" and thence into the liquid flowing in' the upper part of the pipe and through the surge tank.

It is important to note that the rotor 28 spins in air, since-liquid passing through the rotor slots and through: the stator slots drops into the lower housing 10' from which it is immediately. drained into the. pressure supply tanlc. Consequently the movement ofthe; rotor is. not impeded by' the frictional; dragwhich would be presentif; the-entire. system were: immersed in liquid. This feature isofqgreat significance. from the standpoint of the efliciency; with which. the. system is operated;

Asbest-showniin Fig. 3rthe rotor maytake. thezformis-a view intcrosssectionwon; amenlargedscale showln'gthe: relationship. between: the rotor slots and sump: or low of a reaction turbine, in which case it supplies its own motive power from the pressure of the liquid and the motor may be eliminated. Where the motor is used to drive the rotor, the frequency of the sonic compression waves is a function of the speed of the motor and the number of slots in the rotor and stator, the rotor speed being the variable factor. Where the rotor is self-driven as a reaction turbine, the frequency will depend also upon the speed of the rotor, and that in turn will depend upon the pressure of the liquid supplied to it as well as the rate at which it is supplied, these factors being controlled by the setting of the relief valve 52 and the speed at which the pump is driven.

In Figs. 25 the rotor-stator combination is shown in greater detail. As before, there is provided a lower housing 60 having vertical reinforcing webs 62 terminating in an appropriately formed base 64. The housing 60 is provided with a centrally located tubular bearing housing 66 having an upper bearing assembly 68 and a lower bearing assembly '70, both being provided with suitable means for lubrication thereof. A shaft 67 is supported in the bearings and connected at its lower end to a motor shaft 69. Propecting upwardly from the bottom of the housing 60 there is an integral annulus 72 upon which there is mounted a stator ring 74 having a plurality of outwardly flaring ports or slots 76 and secured in position by a series of bolts 78. It should be noted that the stator is so constructed as to be readily removable and replaceable by one having slots of different configuration. In this way the shape of the generated sound wave may easily be varied and controlled. Change in the wave shape is accomplished by varying the flare angle of the stator slots. Within the stator and secured to the shaft 67 there is mounted a rotor consisting of a bottom disk 80 secured by two rows of screws 84 and 85 to an upper disk or plate 82. The bottom 80 of the rotor is machined to provide a circular central chamber from which radiate a plurality of milled slots 86 each of which terminates at the periphery of the rotor in tangentially inclined jets 83, the jets being inclined rearwardly with respect to the direction of rotation of the rotor.

A hollow casing 90 fits over the rotor and is secured to the lower housing 60 by a circumferential row of bolts 92. The housing 90 has a central tubular portion enclosing a sleeve 96 which bears at its lower end upon an annular sealing ring 94 resting upon the upper surface of the rotor disk 82 and flanged at its lower end to accommodate the lower end of a compression spring 98 which bears at its upper end against a plate 100. A pipe 102 pierces the plate 100 and is received within the interior of the sleeve 94. The spring 98 presses the flanged lower end of the sleeve 96, the seal 94 and the top of the rotor 82 in watertight relation. A packing gland or other suitable sealing arrangement may be employed in place of the system herein shown and described.

When liquid under pressure is supplied through the pipe 102 and into the interior of the rotor 8082, it is forced outwardly of the rotor through the jets 88, and the reaction of this pressure through the jets 88 serves to spin the rotor with the shaft 67.

As the rotor turns the flow of liquid therethrough it is interrupted as the stator slots are opened and closed. Preferably the speed of the rotor is governed to produce pressure pulses at a frequency equal to that of the natural frequency of the system including the pipe 102 and the tank which is coupled to it, since maximum amplitude is attained at this natural frequency. The sound waves traveling up the pipe 102 are reflected at the junction between the pipe and the surge tank, the result being that standing waves of considerable amplitude are established in the pipe.

Emphasis is laid upon the fact that the rotor spins in air, a fact which makes it possible to employ high rotor speeds, high frequencies, and high flow rates without wasting energy imparting angular momentum to fluid leaving the rotor. If it is desirable to produce cavitation in the liquid undergoing treatment, the supply system to the rotor may be operated under pressure while the pressure in the treating circuit is low; if cavitation is not desired, the treating circuit can be operated under suflicient pressure to prevent it and thereby to establish the standing wave field in the pipe. Preferably the pipe is tuned to the siren either by adjustment or by precalculation.

Several important facts follow from the use of the back-generated pressure pulses instead of the more conventional utilization of the down stream generated waves. If the down stream generated waves were to be employed, the chamber surrounding the stator would have to be completely immersed in liquid. This liquid would exert a considerable frictional drag upon the rotor and thereby increase the work required to turn it. With the arrangement herein shown and described the rotor is spun in air, the most efficient manner of operation. Moreover, the flow passages in the rotor are streamlined to avoid turbulence within them, and the pressure pulses travel efliciently back through the rotor passages and into the treating system. By pressurizing the liquid supplied to the rotor cavitation within it is effectively suppressed, whereas the elimination of cavitation within the slots of the stator is diflicult to avoid. Moreover it is practically impossible to avoid turbulence Within the stator slots.

It is also important to note that the system herein shown and described makes it convenient to treat liquids in a confined system without passing them through the rotor-stator combination. Corrosive fluids or liquids of high viscosity could not for practical reasons be passed through the rotor-stator combination, but there is no impediment to passing them through a properly designed conduit and tank. As before stated the separation of the treating circuit from that of the rotor-stator combination also allows choice as to whether or not cavitation will be permitted within the treating circuit. Moreover the treating circuit may be separately tuned to resonance by increasing or decreasing the length of the conduit.

While there has been shown here a system designed for operation with a confined treating circuit, it is equally possible to employ the liquid siren as a means of generating pressure within an unconfined liquid. In such a case the inlet and surge tank are replaced by a suitable acoustic horn or other radiating device secured to the conduit.

A liquid siren of the type herein disclosed is useful to produce sound waves of high intensity and, generally, in the frequency range of from to 1,000 cycles per second, although frequencies as high as 10,000 cycles may be obtained. The maximum sound output into water will exceed 10 kilowatts.

Having now described and illustrated a preferred embodiment of the invention, what I claim as new and desire to secure by Letters Patent is:

1. A liquid siren comprising a hollow rotor having peripheral openings, a stator surrounding said rotor and having ports adapted to be opened and closed by the rotation of the rotor, a first conduit connected to the rotor, a housing encasing said stator and providing a drainage chamber of large capacity beneath said rotor, means for supplying liquid to said conduit, 2. second conduit connected to said first conduit, a solid plug separating said conduits, said plug having an acoustic impedance comparable to that of said liquid, said first conduit and plug providing acoustical communication between said rotor and said second conduit, and means for passing liquid through said second conduit.

2. A liquid siren comprising a slotted rotor, a stator surrounding said rotor and having ports adapted to be opened and closed by the rotor, a first conduit connected to said rotor, means for supplying liquid to said first conduit and rotor, a second conduit connected to the first conduit, and a solid plug separating the first and second conduits, said plug having an acoustic impedance approximately equal to that of said liquid said first conduit and plug providing acoustical communication between said rotor and said second conduit.

3. A liquid siren comprising an elongated pipe, a hollow rotor connected to one end of said pipe, a stator surrounding said rotor, said rotor and stator having cooperating ports, a plug of solid material disposed in said pipe to separate it into two compartments, means for supplying liquid to the compartment nearest the rotor, and means for passing a liquid to be treated through the other compartment, said compartment nearest the rotor and said plug providing acoustical communication between said rotor and said other compartment, the

material of the plug having an acoustic impedance comparable to that of the liquid supplied to said rotor.

4. A liquid siren comprising an elongated pipe, a hollow rotor connected to one end of said pipe, a stator surrounding said rotor, said rotor and stator having cooperating ports, a plug of solid material disposed in said pipe to separate it into two compartments, a tank connected to the other end of said pipe, means for supplying liquid to the compartment nearest the rotor, and means for passing a liquid to be treated through the other compartment and tank, said compartment nearest the rotor, said plug and said other compartment providing acoustical communication between said rotor and said tank, the material of the plug having an acoustic impedance comparable to that of the liquid supplied to said rotor.

5. A liquid siren comprising a hollow rotor mounted for rotation upon a vertical shaft, a motor connected to said shaft, a housing surrounding said rotor and providing a chamber beneath it, a drain connected to said chamber, a stator disposed within said housing and surrounding said rotor, said rotor and stator having cooperating ports, a conduit mounted above and connected to said rotor, a plug of solid material disposed in said conduit to separate it into two compartments, means for supplying liquid to said rotor through one of said compartments, whereby liquid may be passed through the rotor and stator and chamber to said drain permitting 6 minimum frictional drag upon the rotor and means for passing a liquid to be treated through the other of said compartments in the said conduit, whereby said plug and the first-named compartment provide an acoustical communication between said rotor and said other compartment.

6. A liquid siren comprising a slotted rotor, a stator surrounding said rotor and having ports adapted to be opened and closed by the rotor, a first conduit connected to said rotor, means for supplying liquid to said first conduit and rotor, a second conduit connected to the first conduit, and a solid plug separating the first and second conduits, the first conduit and plug providing acoustical communication between said rotor and said second conduit, said plug having an acoustic impedance approximately equal to that of said liquid.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,475,385 Hecht et al. Nov. 27, 1923 2,163,650 Weaver June 27, 1939 2,248,459 Kiesskalt July 8, 1941 2,560,728 ee July 17, 1951 2,565,159 Williams Aug. 21, 1951 2,570,081 Szczeniowski Oct. 2, 1951 2,632,634 Williams Mar. 24, 1953

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