CA1157067A - Liquid oscillator device - Google Patents

Abstract

ABSTRACT
The liquid spray includes an oscillator for produc-ing a fan spray with liquid droplets of uniform size.
The oscillator is constituted by a power nozzle. a pair of side walls forming a pair of vortice spaces offset from the power nozzle, a pair of inwardly extending pro-tuberances or deflectors downstream of which are a pair of inlets to passages leading to exits adjacent the power nozzle, and an outlet throat or aperture having a pair of short wall surfaces defining an exit throat of any value selected from about 30° to about 160° so that the fan angle can be selected to be from about 30° to 160°. This structure results in an oscillator which has a relatively low threshold of pressure at which oscil-lations are initiated and, most importantly, the liquid is issued in a much more uniform fan pattern than here-tofore possible. In a preferred embodiment the liquid is a windshield washer fluid and the oscillator is incorporated in a nozzle for an automobile windshield washer assembly for issuing a fan spray of washer fluid onto the windshield.

Description

~L57(~7 This invention relates to a liquid oscillator and to a method of causing a liquid jet to sweep back and forth.
In the prior art liquid oscillator nozzles as disclosed in the Canadian application of Harry C. Bray, Jr. r entitled "Cold Weather Fluidic Fan Spray Devices And Method"
Canadian Patent Application Serial No. 339,~59 filed November 8, 1979, and the oscillators disclosed in Bauer patents 4,157,161, 4,184,636 and Stouffer et al patents 4,1Sl,955 and 4,052,002, and Engineering World, December 1977, Vol. 2, No.
4 Page 1, (all of which are incorporated herein by reference) liquid oscillator systems are disclosed in which a stream of liquid is cyclically deflected back and forth, and in the case of patent 4,157,161, Engineering World, and the above application of Bray, the liquid is a cleaning liquid compound directed upon the windshield of an automobile system. In those which have the coanda effect wall attachment, or lock-on (Engineering World, for example) there is a dwell at the ends of the sweep which tends to make the fan spray heavier at ends of the sweep than in the middle. Such system works very well where a single nozz]e is used to provide a fan spray from the center of the windshield as in the system disclosed in Engineering World system.
The basic object of the present invention is to provide a liquid oscillator element which produces a fan spray in which the liquid is relatively uniform throughout the fan spray thereby resulting in a more uniform dispersal of the liquid.
For example, in a preferred embodiment, the liquid is a windshield washer fluid which is sprayed on an automobile ~,,. 1 `~h`~
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" ~57067 windshield and the uniform droplets provide a better cleaning action. In addition, the oscillator in the present invention retains the desirable low pressure start features of the prior art as well as the cold weather start characteristics of the oscillator disclosed in the above mentioned Bray patent application.
Thus, a further object of the invention is to provide an improved liquid oscillator for automobile windshield washer systems.
One aspect of the present invention resides in a liquid oscillator having an oscillation chamber, a power nozzle for introducing a liquid power jet into the chamber, an outlet throat downstream of the power nozzle and a pair of passages having inlet openings in the respective sides of the outlet throat and exit openings adjacent the power nozzle. The oscillation chamber includes a pair of mirror image wall surfaces beginning immediately downsteam of the exit openings and extending to downstream therefrom and defining vortex forming chambers, the downstream end of each wall surface being shaped to permit vortices formed in the vortex forming chambers to move thereover into the inlet openings, respectively, whereby the liquid power jet is caused to oscillate back and forth in the oscillation chamber.
Another aspect of the invention resides in a method of causing a liquid jet to sweep ~ack and forth, the method including the steps of issuing a liquid jet into a chamber having mirror image vortex forming spaces to create oppositely rotating vortices, and an outlet, and causing the vortices to alternately move downstream to block respective entranceways pc~, - ~57~67 to passages leading to exits adjacent the point of issuance of the liquid jet into the chamber. The jet is caused to alternately aspirate the exits until the vortice blocking the entrance is swallowed into the passage it is blocking so that the liquid jet is caused to deflect back and forth in the chamber and sweep back and forth on passing through the outlet.

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- , , BRIEF DESCRIPTION OF THE D~A~INGS
__ The above and other objects advan~ages and features of the invention will become more apparent when con-sidered with the accompanying drawings wherein:
Figure l(a) is a silhouette of a preferred form of the oscillator, and Figure l(b) is a sectional side ele-vationsl view of Figure l(a), Figure 2 is a view similar to Figure l(a~, but wherein l~gendq have been applied and some of the num-10 bering deleted for clarity and there is shown the posi-tions of three of the vortices and the locati~n of the power jet at a particular instance during operation thereof, Figures 3a-3h diagrammatically illustrate a sequence 15 of vortex formation and movement and resulting flow condi-tions in.an oscillator i~corporating the inven~ion and, 7 Figure 4 illustrates the droplet formation due to the sweeping action of the power jet.
.~ DETAILED DESCRIPTION OF THE INVENTION
The invention will be described in relation to auto-mobile windshield washer assemblies, the oscillator of the present invention is constit-uted by a molded plastic body member 10 which would typically be inserted into a housing or holder member 11 (shown in section Figure 2) 25 which ha~ a fitting 12 which recei~es ~ubing 13 connec-tlon to the outle~ of the windshield washer pump ~not shown). Liquid washing compound is thus introduced to the device via power nozzle inlet 14 which thus issues fluid through power nozzle 15. The liquid issues fr~m the power 30 nozzle 15 which at its exit EP has a width W, the liquid : flowing initially past the exit ports 16 and 17 of liquid passages 18 and 19 respectively. Elements 20 and 21 basically form the boundaries of the interaction chamber and th~ liquid passages 18 and lg, respectively. This ~5'7(~67 , chamber structure is defined by a pair of walls 20-N
and 21-N which are noxmal to the cen~ral axis through the p~wer nozzle 15 and outlet throat 24, which connect with wall elements 20-P and 21-P which are parallel to the direction of fluid flow9 the wall elements normal and parallel wall elemen~s being ~oined by curved sec-tion 20-C and 21-C respectively so that the liquid passages fxom the inl~ts 18-I and l9-I respec~iYely are of substantially unifonm width and about equal to the 10 width W of the power nozzle. An important feature o the invention are the bulbous protuberances or proJec-tions 20-B and 21-B at the downstream ends o~ parallel portions 20-P and 21-P which preferably have smoothly rounded surfaces. Protuberances 20-B and 21-B with outer wall portions 36 and 37 de~ine the entranceways 38 and 39 ~o inlets 18-I and l9-I, respectively. The outlet throat 24 has a pair o~ very short diverging fan angle limiting walls 26-~ and 26-R, which in this embodiment are set at an angle o~ about 110 a~d which 20 thereby defines the maximum ~an angle.
While the basic structural features of the inv~n~ion have been described above in relation to the invention;
the ~ollowin~ description relates to the :func-tional characteristics of each o~ the major components of the invention ~a ~
Figure 1 shows that in the device the walls WP of the power nozzle, are not parallel to the power jet centerline, but converge increasingly all ~he way 30 to the power nozzle exit EP, so that the power jet st~eam will continue to conver~e (and increase velo-city) until the internal pressure in the jet overides and expansion begins.

THE MAIN OSCILLATOR CHAMBER
The main oscillator chamber MOC includes a pair of left and right vortex supporting or generating volumes which vortices avoid wall attachment and boundary layer 5 effects and hence avoids dwell of the power jet at either extremity of its sweep; the chamber is more or less square. The terms "left" and "right" are solely with refere~ce to the drawi~g and A~e not intended to be limiting.
FEEDBACX PASSAGES
Exits (16', 17') The feedback passage exits 16 and 17 (Figures 1 and

2) are not reduced in flow area. A reduction in flow area is sometimes uaed in prior art oscillatars to in-15 crease the velocity of feedback flow where it interacts with the power jet; to restrict entrainment flow out of the feedback passage; or as part of an RC feedback system to determ~ne power jet dwell time at an attach-ment wall. In the preferred embodiment of the inven-20 tion, the feedback passage exits 16 and 17 of the oscil-lator are the same size as the passages 19 and 20. No aid to wall attachment is neces3ary because there are no walls on which attachment might occur.
Inlet (18-I and l9-I) The feedback inletq in many prior art oscillators are sharp edged diviters placed so that they intercept part of the power jet flow when ~he power jet iq at ei.ther the right or left extreme of it9 motion. The dividers used in prior art oscillators at the feedback 30 inlet direct a known percentage o~ the flow to the ~eedback exit (or feedback nozzle in some cases) in order to force the power jet to move or switch to the other s~de of the device. The feedback passages some-times contain "capacitors" to delay the build-up of , .

, ~7~7 eedback pressure in order ~o lengthen ~he ~ime the power jet dwells at either e~reme. In con~rast the feedback inlets 18-I and l9-I O~ this invention are rotated 90 relative to the usual configuration, and thus do not intercept any power jet flow. In fact, as will be described later under t~e ~eading "Method of OscillatIon", there is no power jet flow in the feed-back passages 19 and 20.
DEFLFCTORS (PROTUBER~NCES 20B AND 21B) .. . .
The partition tha~ separates ~eedback passage ~rom the main chamber MOC o the oscillator may also be seen in Figure 2, this partition is terminated at the feed-bac~ passage inlet by rounded protrusion or de~lector members 20-B and 21-B. This par~ of the partition has three functions; to deflect the power je~ streamj to provide a do~s~re2m seal for the vortex generatio~ cham-ber; and to ~orm part of the'feedback passage inlet.
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METHO~ OF OSCILLATION
__ , Initially as the supply pressure applied to the 20 inlet 14 of the oscillator is increased, the power jet leaving via EP becomes turbulent. Liquid ~rom the power nozzle EP issues therefrom toward the outlet throat and expa~ds to fill the oscillation chamber MOC. The turbu-lence which begins on the free sides of the jet causes - some entrainment o local 1u~d in the main chamber M0~, and eventually su~ficient instability in the pressure - surrounding the jet to cause it to begin to undulate.
This movement increases with increased pressure until the jet impacts the deflectors and then the normal oscil-30 lation pattern for this device begins.
In this invention there are ~our places where vor-texes can exist. These locations, (30, 31, 32, 33), may be se~n in FIgures 1 and 2. However,only thxee vortexes ;
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~ 57 ~ 67 exist during most of the cycle, only two during thefeedback por~ion o~ the cycle, and never four at the same time.
Assuming the power jet has just arrived at ~he left side o~ the device in Figures 2 a~d 3a, the vortex formation in left vorte~ generation chamber has just begun. The de~lector 20B has formed a seal between the power jet a~d the rest of ~he chæmber, so th~t the only place cha~ber MOC can get a supply o~ flow to relieve 10 the low pressure genera~ed there would be from the ~eed~
back passage FBl. With normal feedback this would occur because the feedbac~ inlet would be receiving flow at a rate greater than the entrainment ~low out o the feed-bac~ exi~, and the power jet would move toward the opposi~e side. However, in this in~ention the inlet 18-I to the feedbac~ passage is sealed by a strong vor-.
tex 32 in entranceway 38. T~is vortex at entranceway 38was larger (like the one at entranceway 39) until it was confined in the ~eedback inlet by the power iet.
20 Being suddenly reduced in size, its rotational speed increased, enhancing its ability to seal the feedback inlet 18-I and to deflect the power jet toward the out-let of the device to ambiænt-. ~eanwhile, since the vortex fo~ming in the let vortex chambex has no flow to re-lieve the low pressure but the power jet, it builds in intensity. The increasing pressure unbalance across the p~wer je~ and the motion of the vortex cause the power jet to move fur~her l~t (Fi~ures 3b~ 3c and 3d) and to begin to impact the de1ector 20B more on the 30 upstre~m side. As this condition increases the power Jet deflects off the deflector at a more shallow angle permitting the vortex 32 at entranceway 3~ to expand.
; Thus, the outlet stream begins to move before eedback begins.
As the po~er jet moves into the left vortex chamber ~ . :
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~ 7 it flows right across the lower end of the partitionforming the feedback passage exit 16 following the con-tour of the partition 20P and at the same time, by aspiration, greatly reducing the pressure in feedback 5 passage 20. The continual lowering of the pressure in the feedback passage, combined with the loss in energy of the vortex 32, results in the vortex suddenly being "swallowed" (Figure 3e) into the feedback passage 20 and dis 9 ipating there.
When the vortex 32 is i'swallowed", flow can take place in 20 The motivation for this flow is not from the usual positive pressure at the feed~ack inlet, generated by splitting of~ part of the power jet, but it is due to a L~w pressure in the feedback passage 20 15 generated by the high velocity power jet aspirating fluid from 20 at 16. The effect of feedbac~ flow is:
1. Permits the power jet to receive entrained fl~w (through 20), so it can begin to move away from ~he partition at 16.
2. The additional flow (power jet plus entrained flow) ten~s to push the vortex 30 in the left vortex : chamber downstream.

3. The flow through 20 to 16 creat~s a low pressure at 18 thus initiating a circulating flow from 16 co 25 18-I on the chamber side of the partitions 20P with the return through passageway 20 (Figures 3c~ 3~ and 3g).
~ . The fluid motion described above, generates a pressure difference across the vortex 20 in the left vor-.~ 30 tex chamber. This push-pull effect causes th~ vortex 30 to cros~-over deflector 20B and to move into the low pressure zone at entranceway 38 (Figures 3f, 3g, and 3h) : 5. The i~let 18-I is thus sealed once more upon the arrival of the vortex 32 (Figure 3~). Feedbac~ flow exists only during that period of time from the ..

' ' annihilation of the vortex at inlet 18-I until the next vortex, from 30, moves into 18-I. During the remainder of the oscillator's cycle there is essentially no net flow through 20.
S 6. As the vortex 30 generated in the left vortex chæmber moves across deflector 20B, it forces the power jet to the right side (Figure 3g) where the power jet encounters the vortex 32 at entranceway 39 and the de-flector 21B.
7. The CCW motion of the "new" vortex 32, as it crosses over deflector 20B, and the CW motion of the "old" ~ortex 32 at entranceway 39 cause the power jet ~o bend sharply and exit to the left. (OppositP to the condition shown in Figure 2).
8. When the power jet encounters the deflector 21B
(Figure 3h)~ a vortex 31 begins to form at the right vortex generation chamber (inlet lg-I is sealed by the "old" vortex 33) and the entire process described above is repeated.
The vement of the outlet stream is depicted in Figures 3a through 3h. As is shown in these figures, the outlet stream begins to move or sweep in an opposite direction by virtue of generation and movement of the vortices 30 and 31 and hence before fluid flow in the 25 feedback passages. Therefore; the motion and position of the outlet stream is not entirely dependent on feed-back, whereas the opposite is true, in astable m~ltivi-hrators. The angular relationship (~weeping mo~ion) of the output stre~m versus time is more closely related to 30 sinusoidal oscillation than lt is to astable oscillation.
This is evideneed by the fact that ~he output stream does not "linger" at either extreme of its angular move-ment.
DROP~E~ FOgMATION
The mechanism by which the droplets are formed begins ~lQ~

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~ 67 in the power nozzle. The convergency of the power noz-zle generates turbulence in the power jet. Vortex shedding on the free sides of the power jet combines with the internal turbulenee of the jet to generate an 5 "organized" instability within the power jet. This instability or undulation wi~hin the power jet contin-ues to build uniformly as the power jet approaches and passes through the exit. The frequency of the ~ndula-tion being much higher than the frequency at which the 10 power jet sweeps from side to side, provides a pattern ~ery similar to that shown in Figure 4. This figure shows a calculated displacement versus time plot OI the motion of the power jet stream as it exits the oscilla-tor. For clarity the frequency ratio of the undulation 15 in the power jet to the fre~uency of the power jet was set to 10:1 and the amplitude ratio 3:10. Figure 4 shows only one sweep of the power ~et from left to right.
The various maxim~ and minima that occur during the motion from left to right are labeled a through h. The 20 number of degrees of motion of the jet that occurs between successive letters is quite different, however, the time between each is the same. It is therefore obvious that if the flow rate is constant, (which i~ is), then the amount of liquid distributed between C and 3, 25 for instance, is the same a~ between D and E. Since the amound of liquid distributed along these two paths is the s~me, then the size of the s~ream and thus the cohesi~e forces will be greater be~een D and E ~-han between C ant D. Applyin~ the above argument to ~he 30 entire picture, one would predict that as the liquid progressed away from the outlet tha stream would part between A and B, C and D, E and F, and G and H. This is reasonable be ause of the higher tensile stress that exists between these points as com~ared to B and C, D and G and G and F. Therefore, the droplets would form ~ ~¢~7~367 from the liquid contained in the latter group and the remaining liquid that flows into each ar~a from the break points in the stream.
SUM~ARY
The power nozzle design purposely generates turbu-lence in the power ~et stream prior to the nozzle exit, rather than attempt to generate a "low" turbulence nozzle design with a controlled and stable velocity profile. Moreover, the power nozzle allows the power 10 jet flow within the power nozzle to "hug" one or the other of the power nozzle's sidewalls in order to cause a closer interaction between the power jet and the exits 16 and 17 of the feedbac~ passages 19 and 20, thus, enha~cing the generation of very low pressures in the 15 feedback passages.
The feedback pa~sage e~its 16 and 17 are unrestricted so there is no RC storage (e.g. capacitance or resistance efrects) and permit maximum flow from the ~eedback pass-age. The large exits 16 and 17 also permit maximum 20 aspiration to occur as a result of the power jet flowing across the exits. The feedbac~ passages l9 and 20 are at a "low pressure-no flow" condition for most of the oscillator cycle.
Feedback is controlled by low pressure and vortex 25 mov~ment rather than intercepting a portion of the power jet. In act, there i9 no power jet flow in the feedback passage. The entranceways 38 and 39 to feedback passage inlets 18-I and l~-I are designed to provide containment of a vortex for sealing the inlet to the feedback passage 30 against flow.
The vortices produced in le~t and right vortex generation ch~mbers dominate t~eiprocess of oscilla~ion and also prov~de a ne~ vortex thàt moves into the inlet of a feedback passage to terminate each feedback occur-enee.
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It is the vorte~ aided power jet control (asopposed to boundary layer or stream interaction) which is the dominant oscillatory mechanism controlling all major aspects. When a vortex moves across one of the 5 deflectors, it forces the power jet toward the opposite deflector. In addition, this vortex, with help from a counter rotating ~ortex on the other side of the power jet, causes the power jet to bend sharply around the firs~ vor~ex.
Since there is no wall loc~-on or coanda efect utilized, there is essentially no dwell, a uniformity of fan pattern is achieved at the relatively wide angle (in the disclosed embodiment 110 to 120 however, I
wish it to be understood that the fan angle can be any 15 value from 30 to 160) needed for good wetting , for example of a windshield, especially where separate driver and passenger nozzles are used. The fan is in the direct line of vision. At the same t~me, the device retains the low threshold pressure for initiation of oscillation ~o 20 in the case of a windshield washer assembly for automo-biles, there is no need to increase pump sizes for cold weather operation when the viscosity and surface tension of the liquid has increased. If desired, the oscillation chamber can have the top (roof) and bottom (floor~ walls 25 thereof diverging from each other in the direction of the outlet throat so a3 to e~pand the power jet in cold weather but it is not necessary in regards to the pre~ent invention.
The device illustrated i~ an actual operating 30 devlce. Variations of the output characteristics can be achieved b~ varying the cur~ature of protuberances 20-B and 21-B. In addition, the fan angle can be de-creased by shortening the distance between the power nozzle 15 and outlet throat 24. In ~he drawing~, the distance between the power nozæle 15 and the outlet throat ~3~

57~67 ~4 is about 9W and ~he distance between side walls 20 and 21 is slightly more than 6W, ~he distance between protuberances 20-B and 21-B is slightly greater than ~W.
While the preferred embodiment of the invention has been illustrated and described in detail, it will be appreciated that various modifications and adapta-tions ~f the basic invention will be obvious to those skilled in the art and it is intended that such modifi-10 cations and adaptations as come within the spirit andscope of the appended claims be covered thereby.

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Claims (19)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a liquid oscillator having an oscillation chamber, a power nozzle for introducing a liquid power jet into said chamber, an outlet throat downstream of said power nozzle and a pair of passages having inlet openings to the respective sides of said outlet throat and exit openings adjacent said power nozzle, the improvement wherein said oscillation chamber includes a pair of mirror image wall surfaces beginning immediately downstream of said exit openings and extending to downstream therefrom and defining vortex forming chambers, the downstream end of each said wall surfaces being shaped to permit vortices formed in said vortex forming chambers to move thereover into said inlet openings, respectively, whereby said liquid power jet is caused to oscillate back and forth in said oscillation chamber.

2. The liquid oscillator defined in claim 1 wherein said downstream ends are smoothly curved.

3. The liquid oscillator defined in claim 1 wherein said power nozzle has converging sides and said power jet expands in said oscillation chamber.

4. The liquid oscillator defined in claim 1 wherein said oscillation chamber has top and bottom walls which diverge, relative to each other.

5. The liquid oscillator defined in claim 1 wherein said power jet creates a suction at the exit opening of the one of said pair of passages having a vortex residing in the inlet opening thereof.

6. The liquid oscillator defined in claim 1 wherein said downstream ends are smoothly curved to merge into said inlet opening.

7. The liquid oscillator defined in claim 6 wherein said power nozzle has converging walls such that said power jet expands in said oscillation chamber.

8. The liquid oscillator defined in claim 7 wherein said power jet alternatively creates suction at the exit opening of one of said pair of passages having a vortex residing in the inlet opening thereof respectively.

9. The liquid oscillator defined in claim 1 wherein said oscillation chamber is generally rectangular in shape, said vortex forming chambers being to each side of said power nozzle, respectively.

10. The liquid oscillator defined in claim 8 wherein said oscillation chamber is generally rectangular in shape.

11. In an automobile windshield washer system having a supply of windshield washer liquid coupled to an oscillating spray nozzle and a pump for causing washer liquid from said supply to flow to said nozzle for issuing a jet of washer liquid upon the windshield at selected fan angle the improvement wherein said nozzle includes an oscillator as defined in claim 1, and an outlet wall at each side of said outlet throat for limiting the fan angle of the liquid spray upon the windshield of the automobile.

12. In a windshield washer system having liquid fan spray nozzle, said nozzle including an oscillator having an oscillation chamber, a power nozzle for introducing a liquid power jet into said chamber, outlet throat downstream of said power nozzle for issuing the liquid of said power jet in a fan spray, and a pair of passages having inlet openings to the sides of said outlet throat and exit openings adjacent the power nozzle, the improvement comprising, a pair of mirror image wall surfaces, each mirror image wall surface extending along one side of the axis of said power nozzle and beginning immediately downstream of said exit openings and shaped to define a vortex forming chamber, and a pair of spaced apart protuberances connected to the downstream ends, respectively, of said mirror image wall surfaces, the upstream surfaces of said protuberances being shaped to permit vortices formed in each said vortex forming chamber to move downstream thereover into inlet openings of said passages, whereby the liquid of said power jet is caused to oscillate in said chamber and does not lock-on to any wall surface and the pattern of liquid in said fan spray is substantially uniform.

13. The invention defined in claim 12 wherein at least the upstream surface portions of said protuberances are smoothly curved.

14. The invention defined in claim 12 wherein said protuberances are shaped to form vortex supporting entranceways between said outlet throat and the inlet openings to said passages, respectively.

15. In a windshield washer system having a liquid fan spray nozzle for issuing a sweeping jet of wash fluid on a windshield, wherein said nozzle includes an oscillator having a chamber, a power nozzle for introducing a liquid power jet into said chamber, outlet throat downstream of said power nozzle and a pair of passages having inlets adjacent said outlet throat and openings adjacent the power nozzle, said sweeping jet being issued from said outlet throat, the improvement comprising, a first pair of walls normal to the axis of said power nozzle and located immediately downstream of said exit openings, a second pair of walls parallel to the axis of said power nozzle connected to said first pair of walls immediately downstream thereof, and a pair of spaced apart, protuberances connected to the downstream end of said second pair of walls, whereby the liquid of said power jet does not lock-on to any wall surface and the pattern of liquid in said fan spray is substantially uniform.

16. The invention defined in claim 15 wherein said protuberances are smoothly curved.

17. The invention defined in claim 15 wherein said protuberances are bulbous and are shaped to form vortex support-ing entranceways between said outlet throat and the inlet openings to said passages, respectively.

18. A fluid oscillator comprising in combination, a power nozzle, an oscillation chamber for receiving fluid from said power nozzle and being constituted by a pair of vortex inducing spaces, each vortex inducing space having an upstream end, a downstream end an element connecting said downstream end with said upstream end, means forming a pair of passages at each side of said chamber, each passage having an inlet opening end adjacent the downstream end of said vortex inducing space and an exit opening adjacent to said power nozzle, means forming an outlet throat downstream of inlet opening end, whereby vortices rythmically induced in said vortex spaces move to said inlet openings and a negative pressure is induced at the exit openings of said passageways by fluid flow from said power nozzle until the vortex in said inlet opening is swallowed into said passage.

19. A method of causing a liquid jet to sweep back and forth comprising, issuing a liquid jet into a chamber having mirror image vortex forming spaces to create oppositely rotating vortices, and an outlet, causing said vortices to alternately move downstream to block respective entranceways to passages leading to exits adjacent the point of issuance of said liquid jet into said chamber and causing said jet to alternately aspirate said exits until the vortice blocking said entranceway is swallowed into the passage it is blocking, whereby said liquid jet is caused to deflect back and forth in said chamber and sweep back and forth on passing through said outlet.