US3107647A

US3107647A - Toroidal acoustic reflector

Info

Publication number: US3107647A
Application number: US210298A
Authority: US
Inventors: Robert S Soloff
Original assignee: Astrosonics Inc
Current assignee: Astrosonics Inc
Priority date: 1962-07-09
Filing date: 1962-07-09
Publication date: 1963-10-22
Anticipated expiration: 1980-10-22
Also published as: GB1011002A

Description

Oct. 22, 1963 R. s. SOLOFF TOROIDAL ACOUSTIC REFLECTOR Filed July 9, 1962 INVENTOR T S. SOLOFF @LMMA km;

ATTORNEY I ROBER FIG. I

United States Patent 3,107,547 TGROIDAL AOUSTIC REFLECTUR Robert S. Sololi, Brooklyn, N.Y., assigns: to Astrosonies, line, Syosset, Long Island, NY. Filed Suly 9, 1962, Ser. No. 219,298 2 Qlaims. (til. 116-137) The present invention relates to an improved sonic generator provided with reflector means adapted to focus the sonic output. This results in a large axial intensity of sonic energy as well as redistribution of the gaseous driving medium exhaust, whereby the driving medium gas blast is separated from the sound propagation field.

The sonic generator is adapted to generate a high energy vibratory sound field when a tuned cavity resonator is excited into resonance under the influence of an impinging supersonic jet stream. Such a resonator will periodically load and discharge violently at the imposed resonator frequency. Thus, the high velocity jet stream is converted or transduced into a high intensity sonic output. Devices utilizing such sonic energy have proven very efficient in fields such as spray drying, defoaming, cleaning, atomization, etc., in many instances showing marked advantage over conventional devices utilizing much higher pressures and complex mechanical or electronic components.

The operating frequency may vary over a rather wide range of frequency due to the varying pressure of gas into the resonator. Thus, a typical sonic transducer device utilizing an inlet pressure varying from 35 to 50 p.s.i. will have an operating frequency of 7600 to 9400 c.p.s. It will be appreciated therefore that the configuration of the nozzle and the resonator cavity must be such that sonic waves are generated over a rather wide fluctuation of pressure to permit continuous reliable operation of the device. Reference is made to US. Patent No. 2,519,619, issued to Yellott and Savory, for a description of a suitable acoustic generator. For efficient utilization of the energy, it is desirable in most applications that the sonic waves be reflected and focused in a selected direction. Normally, the sonic shock wave emanates from the periphery of the resonator lip in a semi-spherical wave shape radiating outwardly with equal intensity in all directions. However, it will be appreciated that this involves loss of useful power in the direction of the nozzle. It is therefore customary to provide an accoustical reflector where it is desired to focus the maximum intensity of the sound field away from this point. It should be noted that such a reflector will in effect provide an obstruction for the jet flow discharging from the cavity, which necessarily is evacuated due to pres sure of the incoming jet stream from the nozzle. This discharge stream will normally be redirected towards the nozzle, causing turbulence and pressure instability which, in turn, can lead to frequency instability, as pointed out hereinabove.

It is therefore a primary object of the present invention to provide improved reflector means for a sonic generator while simultaneously providing for improved gas distribution means, whereby increased frequency stability is maintained.

It is a further object of the present invention to provide means for increasing acoustical power in a sonic generator.

These and other objects and advantages of the present invention will be pointed out with further particularity, or will be evident from the following description and the drawings appended thereto in which:

FIG. 1 is a partially sectioned view taken in elevation of a device of the present invention.

FIG. 2 is an end view of the device of the present invention.

FIG. 3 is a fragmentary elevational view of a prior art resonator and a curved reflector, partly in section, showing schematically the interaction between the air stream and sound field.

FIG. 4 is a fragmentary, sectional elevational view of the resonator and the toroidal reflector of this invention showing the independent action between air stream and sound field.

Referring more particularly to the drawings, there is shown in FIGS. 1 and 2 a device of the present invention characterized generally by the numeral 10 comprising a conduit member 12 externally threaded at its upper end 14 for coupling with a suitable pressure source and internally threaded at its lower end 18 for coupling with body member 2% having provided therein a longitudinal bore 22. Rigidly attached to body 20, at its lower end 24, is a tapered sleeve 26 having a tapered inner diameter 28 congruent at its upper and larger end 30 with bore 22 and narrowing down to a lower and smaller end 52.

Force fit within bore 22 of body 20 is a spider 40 having force fit within its own longitudinal bore 42 a supporting stem 44 provided with upper and lower ends as and 48, respectively. Stem 44 may be moved axially by means of adjusting screw 5%), threadedly engaged in the upper end 46 of stem 44. When a suitable axial position is attained, as indicated by a desired spray pattern, a hole is drilled into both stem 44 and screw 50, using a predrilled hole in body 20 and spider 40 as a pilot. Locking pin 52 is used to retain body, spider, stem and screw in a fixed relative position.

A cavity resonator 60 comprising a substantially cylindrical inside wall 62 and a bottom Wall 64 is secured to lower end 43 of stem 44 by means of locking pin 66. At its top or open end, cavity resonator 60 is provided with a beveled edge 63. Adjacent cavity resonator M3 in a particular position, the location of which was hereinbefore described, is a nozzle formed by the closely spaced concentric relationship of sleeve end 32 and stem end 48.

Toroidal reflector 72 is rigidly attached by means of internal threads to the lower end of sleeve 26 and is disposed circumferentially about nozzle 70. Reflector 72 is provided underneath with a concave portion 74 proximate nozzle 70 and on the opposite, or upper, side a convex portion 76. Lip portion 78 of reflector 72 is spherical in cross-section and lies in a plane substantially intermediate nozzle '70 and bevel edge 68 of resonator 66.

The lip portion 73 of the toroidal member is rounded to afiford minimal impedance to the jet stream discharging from resonator oil. This jet stream is also normally redirected axially towards the nozzle. The configuration illustrated in FIG. 1 permits the exhaust gas discharged from the resonator to be diverted away from the region of the nozzle, since the reflector is provided with an aerodynamical contour tending to promote this effect.

The aerodynamical contour of the deflector creates a high velocity laminar discharge over the toroidal configuration which carries the exhaust gas stream away from the sound field.

In FIGS. 3 and 4, the gas discharge flow patterns for a. typical elliptical reflector 73 and the toroidal reflector 72 of this invention are shown for comparison.

In FIG. 3, typical of the prior art, the interaction between the exhausted driving gas G and the sonic energy field S is obvious. On the other hand, the configuration of FIG. 4 provides clear separation of the exhaust gas G and sonic energy field S.

There is an important advantage to this configuration in that the exhaust gas is directed away from work being processed by the sonic energy beam. Further, it has been empirically established that a noticeable increase in acoustic power is observed when this deflection of exhaust is provided. Simultaneously, the concave portion of the toroidal reflector concentrates the sonic energy axially to the area below the resonator, where in many applications it is desired that the maximum intensity of sonic energy be focused.

The position of the toroidal reflector in relation to the nozzle and resonator is critical. Thus, it has been known in the art to provide a dish-like reflector to redirect sonic energy axially. The lip portion 78 of the reflector is substantially coplanar with a point midway between the orifice of the nozzle and the rim of cavity resonator 60. The gain in power of this configuration over a reflector having its lip portion disposed axially beyond the plane of the cavity resonator is 75% to 100%. It will thus be apparent that considerable improvement in the efliciency of the device has been achieved by the present invention.

There has been disclosed heretofore the best embodiment of the invention presently contemplated and it is to be understood that various changes and modifications may be made'by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. An improved sonic generator comprising:

a conduit member adapted to carry gas under pressure, said conduit terminating in a nozzle, whereby said gas is emitted in a supersonic jet stream;

a sonic cavity resonator axially aligned with said nozzle and disposed in spacedtopposition thereto,

said gas being directed at said cavity resonator whereby a sonic wave field is generated, said gas thereafter being normally redirected from said resonator towards said nozzle; and I a toroidal member disposed circumferentially about said nozzle and normal thereto, said toroidal member being formed with a concave portion proximate to said nozzle and a convex portion merging with- 2. A device as in claim 1 wherein said toroidal member comprises an internally threaded annular member disposed circumferentially about said nozzle and said nozzle is provided with an externally threaded portion adapted to register with said internally threaded portion of said toroidal member in the assembled condition.

References Cited in the file of this patent UNITED STATES PATENTS 1,257,863 Hesselbein Feb. 26, 1918 1,980,171 Amy Nov. 13, 1934 2,238,668 Wellenstein Apr. 12, 1941 2,519,619 Yellott et al. Aug. 22, 1950

Claims

1. AN IMPROVED SONIC GENERATOR COMPRISING: A CONDUIT MEMBER ADAPTED TO CARRY GAS UNDER PRESSURE, SAID CONDUIT TERMINATING IN A NOZZLE, WHEREBY SAID GAS IS EMITTED IN A SUPERSONIC JET STREAM; A SONIC CAVITY RESONATOR AXIALLY ALIGNED WITH SAID NOZZLE AND DISPOSED IN SPACED OPPOSITION THERETO, SAID GAS BEING DIRECTED AT SAID CAVITY RESONATOR WHEREBY A SONIC WAVE FIELD IS GENERATED, SAID GAS THEREAFTER BEING NORMALLY REDIRECTED FROM SAID RESONATOR TOWARDS SAID NOZZLE; AND A TOROIDAL MEMBER DISPOSED CIRCUMFERENTIALLY ABOUT SAID NOZZLE AND NORMAL THERETO, SAID TOROIDAL MEMBER BEING FORMED WITH A CONCAVE PORTION PROXIMATE TO SAID NOZZLE AND A CONVEX PORTION MERGING WITH