The present invention relates generally to sonoluminescence and, more particularly, to a port assembly for use with a sonoluminescence cavitation chamber.
Sonoluminescence is a well-known phenomena discovered in the 1930's in which light is generated when a liquid is cavitated. Although a variety of techniques for cavitating the liquid are known (e.g., spark discharge, laser pulse, flowing the liquid through a Venturi tube), one of the most common techniques is through the application of high intensity sound waves.
In essence, the cavitation process consists of three stages; bubble formation, growth and subsequent collapse. The bubble or bubbles cavitated during this process absorb the applied energy, for example sound energy, and then release the energy in the form of light emission during an extremely brief period of time. The intensity of the generated light depends on a variety of factors including the physical properties of the liquid (e.g., density, surface tension, vapor pressure, chemical structure, temperature, hydrostatic pressure, etc.) and the applied energy (e.g., sound wave amplitude, sound wave frequency, etc.).
Although it is generally recognized that during the collapse of a cavitating bubble extremely high temperature plasmas are developed, leading to the observed sonoluminescence effect, many aspects of the phenomena have not yet been characterized. As such, the phenomena is at the heart of a considerable amount of research as scientists attempt to not only completely characterize the phenomena (e.g., effects of pressure on the cavitating medium), but also its many applications (e.g., sonochemistry, chemical detoxification, ultrasonic cleaning, etc.).
In order to study the sonoluminescence phenomena, it is clearly important to be able to closely monitor the cavitating bubbles as well as the intensity, frequency and timing of the resultant sonoluminescence. Additionally, some research may require probing the cavitating liquid. Lastly, many cavitation experiments utilize external means of introducing the bubbles into the liquid, for example bubble tubes or hot wires, thus requiring further means of entering the cavitating medium.
Although access to the liquid within a cavitation chamber is typically required before, during and after a cavitation experiment, typically this does not present a problem as most cavitation research is performed at relatively low pressure. As such, glass or other transparent material is generally used for the chamber, thus providing an easy means of monitoring on-going experiments. Additionally, such experiments often use standard beakers or flasks as the cavitation chamber, allowing convenient access to the cavitation medium.
U.S. Pat. No. 4,333,796 discloses a cavitation chamber that is generally cylindrical although the inventors note that other shapes, such as spherical, can also be used. As disclosed, the chamber is comprised of a refractory metal such as tungsten, titanium, molybdenum, rhenium or some alloy thereof and the cavitation medium is a liquid metal such as lithium or an alloy thereof. Surrounding the cavitation chamber is a housing which is purportedly used as a neutron and tritium shield. Projecting through both the outer housing and the cavitation chamber walls are a number of acoustic horns. The specification only discloses that the horns, through the use of flanges, are secured to the chamber/housing walls in such a way as to provide a seal. Similarly, although the specification discloses the use of a tube to distribute H-isotopes into the host material during cavitation, the specification does not disclose how the tube is to be sealed as it passes through the chamber/housing walls. Similarly U.S. Pat. No. 4,563,341, a continuation-in-part of U.S. Pat. No. 4,333,796, does not disclose means for the inclusion of a port with the disclosed cylindrical chamber.
U.S. Pat. No. 5,659,173 discloses a sonoluminescence system that uses a transparent spherical flask. The spherical flask is not described in detail, although the specification discloses that flasks of Pyrex®, Kontes®, and glass were used with sizes ranging from 10 milliliters to 5 liters. As the disclosed flask is transparent, the PMT used to monitor the sonoluminescence was external to the chamber. The drivers as well as a microphone piezoelectric were epoxied to the exterior surface of the chamber. The use of a transparent chamber also allowed the use of an external light source, e.g., a laser, to determine bubble radius without requiring the inclusion of a window in the chamber walls.
U.S. Pat. No. 5,858,104 discloses a shock wave chamber partially filled with a liquid. The remaining portion of the chamber is filled with gas which can be pressurized by a connected pressure source. Acoustic transducers are used to position an object within the chamber. Another transducer delivers a compressional acoustic shock wave into the liquid. A flexible membrane separating the liquid from the gas reflects the compressional shock wave as a dilation wave focused on the location of the object about which a bubble is formed. The patent simply discloses that the transducers are mounted in the chamber walls without stating how the transducers are to be mounted. Similarly, there is no discussion of mounting ports (e.g., view ports) within the chamber walls.
U.S. Pat. No. 6,361,747 discloses an acoustic cavitation reactor in which the reactor chamber is comprised of a flexible tube. The liquid to be treated circulates through the tube. Electroacoustic transducers are radially distributed around the tube, apparently coupled to the flexible tube by being pressed against the exterior surface of the tube. The heads of the transducers have the same curvature as the tube, thus helping to couple the acoustic energy. A film of lubricant interposed between the transducer heads and the wall of the tube further aid the coupling of the acoustic energy to the tube.
Although not in the field of sonoluminescence, U.S. Pat. No. 4,448,743 discloses a confinement chamber for use with an ultra-high temperature steady-state plasma. The specification refers to the plasma as a plasmasphere but is unclear as to whether the confinement chamber is spherical or cylindrical in nature. The disclosed chamber includes multiple transparent ports, for example made of germanium or sodium chloride, but does not disclose how the ports are fabricated or installed within the chamber.
One approach to fabricating a high pressure spherical cavitation chamber is disclosed in co-pending patent application Ser. No. 10/925,070, filed Aug. 23, 2004, entitled Method of Fabricating a Spherical Cavitation Chamber. In order to provide optimum high pressure performance, in addition to being spherically shaped, the inside spherical surface has only a very minor fabrication seam. Such a chamber, however, provides a challenge as to port mounting, especially if the smooth inside surface and the high pressure aspects of the chamber are to be maintained.
Accordingly, what is needed is a means of including one or more ports in a high pressure cavitation chamber. The present invention provides such a port assembly.
The present invention provides a method of assembling a port assembly in a cavitation chamber, typically a spherical chamber. The method is comprised of the steps of boring a port in a cavitation chamber wall, positioning a cone-shaped member within a corresponding cone-shaped surface of a mounting ring, positioning the mounting ring within the port, and locking the mounting ring within the port with a retaining ring. The largest diameter of the cone-shaped member corresponds to the cavitation chamber internal surface. The member can be a window, gas feed-thru, liquid feed-thru, mechanical feed-thru, sensor, sensor coupler, transducer coupler or plug. The member can be secured within the mounting ring with an adhesive. The retaining ring can be coupled to the cavitation chamber external surface with one or more bolts.
The port in the cavitation chamber is preferably cone-shaped with the largest diameter of the port corresponding to the cavitation chamber external surface. In one embodiment in which the mounting ring and the retaining ring are combined into a single retaining coupler, thereby combining the functionality of the mounting ring and the retaining ring, the cavitation chamber port can be either cone-shaped with the largest diameter of the port corresponding to the cavitation chamber external surface or the port can be cylindrically shaped.
In one embodiment, the inner chamber surface of the mounting ring (or retaining coupler) and the central member are shaped to match the curvature of the internal surface of the cavitation chamber. Alternately, only one of either the mounting ring (or retaining coupler) inner chamber surface or the central member inner chamber surface are shaped. Alternately, neither the mounting ring (or retaining coupler) inner chamber surface nor the central member inner chamber surface are shaped.
In one embodiment, the surface of the retaining ring (or retaining coupler) adjacent to the external surface of the cavitation chamber is shaped, preferably shaped to form a curved surface, and more preferably shaped to form a curved surface that matches the curvature of the external surface of the cavitation chamber.
In one embodiment a malleable material, preferably of a metal, and more preferably of brass, is interposed between the internal cone-shaped surface of the mounting ring (or retaining coupler) and the external cone-shaped surface of the member. In one embodiment a malleable material, preferably of a metal, and more preferably of brass, is interposed between the port and the corresponding surface of the mounting ring (or retaining coupler).
In one embodiment a sealant is interposed between the internal cone-shaped surface of the mounting ring (or retaining coupler) and the external cone-shaped surface of the member. In one embodiment a sealant and/or adhesive is interposed between the port and the corresponding surface of the mounting ring (or retaining coupler). In one embodiment a sealant and/or adhesive is interposed between the surface of the retaining ring (or retaining coupler) adjacent to the external surface of the cavitation chamber and the external surface of the cavitation chamber.
In one embodiment one or more o-rings are interposed between the port and the corresponding surface of the mounting ring (or retaining coupler). In one embodiment one or more o-rings are interposed between the surface of the retaining ring (or retaining coupler) adjacent to the external surface of the cavitation chamber and the external surface of the cavitation chamber. In one embodiment one or more o-rings are interposed between the internal cone-shaped surface of the mounting ring (or retaining coupler) and the external cone-shaped surface of the member.
A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.
Chamber 101 can be fabricated from any of a variety of materials, depending primarily on the desired operating temperature and pressure, as well as the fabrication techniques used to make the chamber. Typically the chamber is fabricated from a metal; either a pure metal or an alloy such as stainless steel.
With respect to the dimensions of the chamber, both inner and outer diameters, the selected sizes depend upon the intended use of the chamber. For example, smaller chambers are typically preferable for situations in which the applied energy (e.g., acoustic energy) is somewhat limited. Similarly, thick chamber walls are preferable if the chamber is to be operated at high static pressures. For example, the prior art discloses wall thicknesses of 0.25 inches, 0.5 inches, 0.75 inches, 1.5 inches, 2.375 inches, 3.5 inches and 4 inches, and outside diameters in the range of 2-10 inches.
Although the present invention is not limited to a particular chamber configuration, for illustration purposes only spherical chambers are described in detail. It will further be appreciated that with respect to spherical chambers, the present invention is not limited to a particular outside chamber diameter, inside chamber diameter, chamber material, chamber shape, transducer type, transducer number, or transducer mounting location. Such information, as provided herein, is only meant to provide exemplary chamber configurations for which the present invention is applicable.
The prior art means of providing a port, as well as the prior art means of attaching a window or other member to the port, suffers from several problems. First, the edge 311 of the port presents a significant discontinuity along surface 313 of wall 301, the discontinuity affecting the cavitation process. Second, for high pressure systems the window of this port assembly is prone to failure as there is minimal contact area between window 305 and wall 301 (i.e., area 315) and minimal contact area between window 305 and flange 307 (i.e., area 317). Third, it is difficult to achieve an adequate seal between the window (or similar port member) and wall 301.
One approach to alleviating at least some of the issues of the prior art port assembly is illustrated in
One benefit of the assembly shown in
Although the assembly shown in
Although the embodiment shown in
Port 701 can either be bored into chamber wall 301 before assembly of the cavitation chamber is complete, or after. The benefit of boring the port prior to chamber completion is that it is easier to clean the inside chamber surfaces before the final chamber assembly. Depending upon the method used to bore port 701, it may also be easier to bore the hole prior to chamber assembly.
After chamber completion, for example as described in co-pending application Ser. No. 10/925,070, filed Aug. 23, 2004, entitled Method of Fabricating a Spherical Cavitation Chamber, the disclosure of which is incorporated herein for any and all purposes, member 705 is placed within the cone-shaped port 707 of mounting ring 703. Preferably member 705 is locked into place, for example using one of the means described below (e.g., an adhesive). The combination of mounting ring 703 and member 705 is then placed within port 701 after which a retaining ring 801 (shown in
The primary benefit of the port assembly of the present invention over an assembly such as those illustrated in
It should be appreciated that there are countless minor variations to the embodiment illustrated in
Regardless of the exact shape of the retaining ring, it will be appreciated that the retaining ring can be used to push the external cone-shaped surface of the mounting ring against the adjacent cone-shaped port surfaces, thus improving the seal between the two pieces. In the embodiment shown in
In the embodiments shown in
Although the embodiments shown above distribute the force on the central member (e.g., member 705 and member 1207), thus minimizing deformation and/or breakage of the central member, in a preferred embodiment of the invention a thin sheet or foil of malleable material 1211, for example brass or other malleable metal, is interposed between member 1207 and retaining coupler 1203. Although the inclusion of malleable material 1211 is only indicated in
In one preferred embodiment, a sealant and/or adhesive is interposed between one or more adjoining port assembly surfaces. For example, a sealant and/or adhesive can be interposed between adjoining surfaces of the central member and the mounting ring (or retaining coupler), thus holding the central member in place during port assembly and when the chamber is evacuated (e.g., during degassing or operation). Alternately, or in addition to, a sealant and/or adhesive can be interposed between the adjoining surfaces of the mounting ring (or retaining coupler) and the port. Alternately, or in addition to, a sealant and/or adhesive can be interposed between the adjoining surfaces of the retaining ring (or retaining coupler) and the external chamber surface.
In one preferred embodiment, one or more o-rings are interposed between the adjoining surfaces of the mounting ring (or retaining coupler) and the port (and/or external chamber surface).
In one embodiment, one or more o-rings are interposed between the adjoining surfaces of the mounting ring (or retaining coupler) and the central member. As opposed to an adhesive (e.g., epoxy), o-rings will not hold the central member in place during chamber evacuation, accordingly o-rings are preferably used with the central member only when the central member can be secured using other means, for example one or more bolts.
The inventors have also found that if the central member is not fragile (e.g., a quartz window), in many instances a simpler assembly can be obtained by using a single piece port cover as illustrated in
For clarity,
The present invention, as described in detail above, not only provides a strong, load distributing port assembly which can be easily assembled/disassembled, it also provides a means of assembling/disassembling a port assembly such as that shown in
As will be understood by those familiar with the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/926,602, filed Aug. 25, 2004 now abandoned.
Number | Name | Date | Kind |
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4333796 | Flynn | Jun 1982 | A |
4448743 | Bass | May 1984 | A |
4563341 | Flynn | Jan 1986 | A |
5659173 | Putterman et al. | Aug 1997 | A |
5858104 | Clark | Jan 1999 | A |
6361747 | Dion et al. | Mar 2002 | B1 |
Number | Date | Country | |
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20060042088 A1 | Mar 2006 | US |
Number | Date | Country | |
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Parent | 10926602 | Aug 2004 | US |
Child | 10941601 | US |