WO1999002302A1 - Procede et appareil permettant de produire des courants de particules a grande vitesse - Google Patents

Procede et appareil permettant de produire des courants de particules a grande vitesse Download PDF

Info

Publication number
WO1999002302A1
WO1999002302A1 PCT/US1997/012055 US9712055W WO9902302A1 WO 1999002302 A1 WO1999002302 A1 WO 1999002302A1 US 9712055 W US9712055 W US 9712055W WO 9902302 A1 WO9902302 A1 WO 9902302A1
Authority
WO
WIPO (PCT)
Prior art keywords
particles
stage
velocity
stream
air
Prior art date
Application number
PCT/US1997/012055
Other languages
English (en)
Inventor
Y. H. Michael Pao
Peter Maddona
Ross T. Coogan
Original Assignee
Waterjet International, Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Waterjet International, Inc. filed Critical Waterjet International, Inc.
Priority to AU36574/97A priority Critical patent/AU3657497A/en
Priority to PCT/US1997/012055 priority patent/WO1999002302A1/fr
Publication of WO1999002302A1 publication Critical patent/WO1999002302A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts
    • B24C7/0046—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier
    • B24C7/0076—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier the blasting medium being a liquid stream
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C5/00—Devices or accessories for generating abrasive blasts
    • B24C5/02—Blast guns, e.g. for generating high velocity abrasive fluid jets for cutting materials
    • B24C5/04—Nozzles therefor

Definitions

  • This invention relates to a process and apparatus for producing a high- velocity particle stream suitable for use in a variety of settings including, but not limited to, surface preparation, cutting, and painting.
  • high- velocity particle streams for surface preparation such as the removal of coatings, rust and millscale from ship hulls, storage tanks, pipelines, etc.
  • a high- velocity gas stream such as air
  • such systems are compressed-air driven, and comprise: an air compressor, a reservoir for storing abrasives particles, a metering device to control the particle-mass flow, a hose to convey the air-particle stream, and a stream delivery converging-straight or converging-diverging nozzle.
  • hot-cutting thermal-based methods of alloys, ceramic, glass and laminates, etc.
  • a high-velocity stream of liquid such as water
  • a focusing nozzle onto the target to be cut.
  • such systems are high-pressure water driven, and comprise: a high-pressure water pump, a reservoir for storing abrasives particles, a metering device to control the particle mass flow, a hose to convey the particles, a hose to convey high-pressure water, and a converging nozzle within which a high- velocity fluidjet is formed to entrain and accelerate the particle stream onto the target to be cut.
  • micromachining Whether the particle stream is delivered for the purpose of surface preparation or cutting, the mechanism of action, known to the skilled artisan as "micromachining," is essentially the same. Other effects occur, but are strictly second-order effects.
  • the principle mechanics of micromachining are simple.
  • m x dv/dt Upon impact, the resulting momentum change versus time (m x dv/dt) delivers a force (F) which is proportional to the square of the particle impact velocity (v 2 ) times its mass.
  • any major increase in their abrading or cutting performance must come from an increase in velocity.
  • increasing a particle's velocity is the single most effective way to improve its abrading or cutting performance, which, as described above, is proportional to the square of any increase in a particle's impact velocity.
  • particle stream abrasive cutting (using abrasive particles to cut low- cost materials such as steel, concrete, wood, etc.) requires a much higher power input relative to other current methods such as: torch, plasma, laser or diamond- blade cutting, for instance.
  • torch, plasma, laser or diamond- blade cutting for instance.
  • air or water jet-driven abrasive cutting requires a higher power input, making it cost-prohibitive for most applications other than for special situations which mandate cold-cutting and/or contour cutting of thermally sensitive materials.
  • the problem facing the skilled artisan is to design an apparatus or method that delivers an evenly distributed, diffuse stream of abrasive particles to a surface to be cleaned (or a focused stream of abrasive particles to a surface to be cut) at the highest velocity, at the lowest possible power input, and without the generation of unacceptable levels of airborne dust.
  • One object of the present invention is to provide a method for producing a stream of particles moving at high velocity through a chamber by accelerating the particles to subsonic velocity using one or more jets of gas, and then accelerating the particles to supersonic velocity using one or more jets of liquid.
  • a second object of the present invention is to provide a method for producing a stream of particles moving at high velocity through a chamber by accelerating the particles to subsonic velocity using one or more jets of gas, and then accelerating the particles to supersonic velocity using one or more jets of liquid and inducing radial motion to the particles.
  • a third object of the present invention is to provide a method for increasing the concentration of particles having a higher density than their surrounding fluid, in a high-velocity fluid stream, by introducing the particles into a fluid stream having radial flow, and then contacting the particles with a high-velocity fluid stream.
  • a fourth object of the present invention is to provide an apparatus for producing a fluid jet stream of abrasive particles in a fluid matrix.
  • a method for producing a stream of particles moving at high velocity in a chamber comprising the steps of accelerating said particles to subsonic velocity using one or more jets of gas; thereafter, accelerating said particles to supersonic velocity using one or more jets of liquid by contacting said stream at an oblique angle with one or more jets of ultra-high pressure water within the chamber.
  • the method comprises the additional step of inducing radial motion to said particles by the downstream injection of one or more jets of fluid.
  • the method comprises the additional step of inducing radial motion to said particles by narrowing the internal radius of the chamber.
  • the method comprises the additional step of amplifying said radial motion to said particles by narrowing the internal radius of the chamber.
  • the method comprises the additional step of amplifying said radial flow into said stream by using a variable-radius chamber.
  • the method referred to above comprises the additional step of increasing the concentration of particles having a higher density than their surrounding fluid, in a high-velocity fluid stream further comprising the steps of introducing said particles into a fluid stream having radial flow; and thereafter, contacting said particles with a high-velocity fluid stream.
  • a method for producing a stream of particles moving at high velocity in a chamber comprising the steps of accelerating particles to subsonic velocity using one or more jets of gas; thereafter, accelerating said particles to supersonic velocity using one or more jets of liquid by contacting said stream at an oblique angle with one or more jets of ultra-high pressure water within the chamber; thereafter inducing radial motion to said particles by the downstream injection of one or more jets of fluid.
  • the method referred to above further comprises the additional step of amplifying said radial flow into said stream by narrowing the internal radius of the chamber.
  • the method referred to above further comprises inducing spreading of said stream by downstream widening of the internal radius of the chamber.
  • the abrasive particle stream referred to above is accelerated to a velocity of greater than about 600 ft/sec. In still another embodiment of the aforementioned aspect of the present invention, the abrasive particle stream is accelerated to a velocity of greater than about 1000 ft/sec. In yet another embodiment of the aforementioned aspect of the present invention, the abrasive particle stream is accelerated to a velocity of greater than about 2000 ft/sec.
  • the abrasive particle stream is accelerated to a velocity of greater than about 3000 ft/sec.
  • a method for increasing the concentration of particles having a higher density than their surrounding fluid, in a high-velocity fluid stream comprising the steps of introducing said particles into a fluid stream having radial flow; thereafter, contacting said particles with a high-velocity fluid stream.
  • the method referred to above comprises the additional step of passing said particles through a chamber of decreasing radius.
  • the method referred to above comprises the additional step of passing said particles through the chamber of decreasing radius, and thereafter passing said particles through a chamber of increasing radius.
  • an apparatus for producing a fluid jet stream of abrasive particles in a fluid matrix comprising a mixing chamber; an air/particle inlet means at one end of said mixing chamber for delivering an air/particle stream into the mixing chamber at subsonic velocity; one or more ultra-high pressure water inlet means fluidly and obliquely engaging said mixing chamber for accelerating said air/particle stream to supersonic velocity; and one or more air inlet means upstream, at or downstream from the water inlet means and fluidly engaged to the mixing chamber for inducing or amplifying radial flow to said stream.
  • the mixing chamber referred to above comprises a converging portion and a diverging portion.
  • the mixing chamber comprises a converging portion. In still another embodiment of the aforementioned aspect of the present invention, the mixing chamber comprises a diverging portion.
  • the mixing chamber comprises a diverging portion and a focusing tube.
  • the current apparatus and method provides many advantages over currently available systems. Again, the central problem facing the skilled artisan is how to propel the particles to their highest possible practical velocity using the least power using an apparatus of practical dimensions.
  • the present invention achieves this goal of maximizing particle velocity with relatively low input power and within an embodiment of practical size.
  • the abrasive particles are accelerated in the present invention to a velocity exceeding about 1,200 ft/sec while requiring substantially less input power than conventional systems.
  • a second advantage of the present invention directed to embodiments for surface preparation or coating removal— is that it achieves uniform particle spreading. This increases the amount of surface that can be treated per pound of abrasives, and results in higher productivity and lower costs per area treated, and in lower spent-abrasives clean-up and disposal costs. (Disposal costs can be substantial for spent-abrasives- containing hazardous waste.)
  • the embodiments induce and deploy a vortex, which imposes a controlled radial momentum, in addition to the forward axial momentum upon the particles.
  • a third advantage of the present invention pertains to underwater cutting and cleaning, or, in general, to situations where the high-velocity particle stream propelled from the chamber, must travel through a fluid other than a gas or air as it moves towards its intended target. It is well known to the skilled artisan that efficacy of high-velocity water jet and particle stream cleaning and cutting underwater decrease dramatically with stand-off distance, i.e., the distance between nozzle exit and target. The reason is the presence of a liquid media, such as water, which has a density about 800 times that of air in the region between the chamber exit and the target. Conventional high-velocity fluid jets, having to penetrate such media to reach their intended target, become entrained within the surrounding water.
  • air is discharged from the chamber in a swirling manner, forming a rotating, hence stabilized, zone of gas projecting from the chamber exit.
  • a localized, air environment in the form of a stabilized, rotating, vortex-driven air pocket is generated between nozzle and target. Consequently, high-velocity particle and water jets can now pass through this stabilized air pocket, delivering unimpaired cutting or cleaning at "in-air" performance, yet obtained underwater.
  • a fourth, advantage of the present invention is that it eliminates the generation of dust and related environmental, health, occupational and operational safety hazards inherent to dry particle stream surface preparation (commonly referred to as sandblasting) in open air.
  • Sandblasting is well known to generate dust clouds which can spread for miles containing particles small enough to constitute a significant breathable health hazard and cause eye irritation, not only to the operator, but to nearby persons.
  • This dust contains not only pulverized abrasive particles, but may contain material particles removed from the treated surface.
  • It may contain pigments and other surface-corrosion and anti-fouling compounds, such as heavy-metal oxides (e.g., lead oxide), organometals (particularly organotins) and other toxic compounds, perhaps applied to the surface years ago and long since outlawed. Dry sandblasting, while being fast and cost-effective, and with the exception of the present invention, without economical alternative, is being closely monitored and regulated by environmental protection and health-hazard control agencies.
  • heavy-metal oxides e.g., lead oxide
  • organometals particularly organotins
  • other toxic compounds perhaps applied to the surface years ago and long since outlawed. Dry sandblasting, while being fast and cost-effective, and with the exception of the present invention, without economical alternative, is being closely monitored and regulated by environmental protection and health-hazard control agencies.
  • the present invention controls both dust formation and dust liberation.
  • the discharging particles are accompanied by a fine mist of water droplets, resulting from the break-up of the ultra-high velocity water jet as it interacts with the particles and air in the mixing chamber.
  • a fifth advantage of the present invention is that the much lower rearward thrust is generated by the apparatus and method of the present invention. This is a result of the far lower particle mass flow rate per unit of surface cleaned (or cut) with fewer but much faster particles. Hence operating the apparatus causes less fatigue to the operator and should result in safer working conditions. Also, it makes the method and apparatus more amenable to incorporation into low cost automated systems.
  • FIGURE 1 is a cross-sectional view showing a nozzle representing a preferred embodiment of the present invention.
  • FIGURE 2 is a cross-sectional diagram showing the internal features of the nozzle of FIGURE 1, but stylized to emphasize the geometry of the nozzle chamber, and the path of the abrasive particles through the nozzle chamber.
  • FIGURE 3 is a cross-sectional diagram showing the internal features of another preferred embodiment of the present invention, also stylized to emphasize the geometry of the nozzle chamber, and the path of the abrasive particles through the nozzle chamber.
  • FIGURE 4 is a cross-sectional diagram depicting the formation of a rotating (vortex-driven) air environment between nozzle exit and target to maintain cutting and cleaning efficiency for underwater applications.
  • the present invention is directed to a method and apparatus for delivering abrasive particles via a high-velocity fluid stream for the purpose of treating or cutting a surface.
  • abrasive particles for instance, quartz sand
  • a pressurized gas such as air
  • induction / aspiration through a hose leading into a nozzle having a hollow chamber or "mixing chamber.”
  • the velocity of the abrasive particles reach a maximum of about 600 ft/sec, which is close to some practical maximum velocity.
  • air is a poor medium to propel the abrasive particles due to its low density; that is, above a certain point, further increase to the velocity of the air will have only a negligible effect on the particle velocity. Yet air is a very cost effective means to accelerate the particle to about this velocity, but not much beyond.
  • the air/particle stream next passes through the mixing chamber where it encounters one or more inlets, for the introduction of ultra-high velocity liquid jets (such as water jets) into the air/particle stream.
  • ultra-high velocity liquid jets such as water jets
  • the water jet or jets having a relative velocity of up to 4,000 ft/sec with respect to the gas-jet pre- accelerated particles (moving at a velocity of up to about 600 ft/sec), further accelerates the particles through direct momentum transfer and entrainment to supersonic velocity, or greater than about 1100 ft/sec, up to about 3,000 ft/sec.
  • the ultra-high velocity water inlets are positioned such that the water impacts the air/particle stream at an oblique angle relative to the axis formed by the air/particle stream.
  • a vortex, or swirling motion of the air/particle/water stream is created within the mixing chamber. This vortex motion causes the abrasive particles to move radially outward, due to their larger mass (relative to the air and water), by centrifugal force creating an annular zone of high particle concentration.
  • the ultra-high velocity water jets are directed at this zone to accomplish efficient momentum transfer to and entrainment of the particles, resulting in effective acceleration and a maximized particle velocity.
  • the introduction of the ultra-high velocity water jets serves three principal functions: (1) a second-stage acceleration of the particles; (2) the creation of a vortex within the air/particle/water stream; and (3) the creation of a zone of high particle concentration for preferential and effective contacting of the particle stream with the ultra-high velocity water jets, resulting in more efficient acceleration and a higher particle velocity.
  • the vortex motion created in the fluid stream is then amplified in one of several ways.
  • the stream (now comprising air, particles, and water) passes through a final portion of the nozzle where it is subjected to tangentially introduced air.
  • This air may be inducted into the nozzle chamber due to the negative pressure created in the chamber by the movement of the stream.
  • the air may be injected into the chamber at a pressure greater than atmospheric pressure.
  • the internal diameter of the mixing chamber is narrowed (to increase the radial velocity of the particles, hence amplify the vortex motion).
  • the internal diameter of the mixing chamber is then subsequently widened to achieve uniform particle spreading.
  • What exits the nozzle is a high-velocity stream of evenly distributed, abrasive particles traveling at a supersonic velocity, propelled to such velocity in two acceleration stages, the first one being driven by a gas (compressed air) and the second one by a liquid (ultra-high pressure water).
  • a gas compressed air
  • a liquid ultra-high pressure water
  • the surface removal rate (or cutting rate) is a function of two broad sets of parameters.
  • the first set of parameters (aside from the abrasive particles themselves) relates to the initial air velocity that delivers the abrasive particles into the mixing chamber, the location and angle of the ultra-high velocity water jets that converge with the air/particle stream, and similar parameters for the vortex- promoting air injection (if used in the particular embodiment).
  • the second set of parameters relates to the geometry of the mixing chamber itself. For instance, a small diameter may be preferable at one location within the chamber to increase the rotational velocity of the abrasive particles, and hence increase particle interaction with the ultra-high velocity water jet or jets. The chamber may then widen downstream to produce controlled spreading of the particle stream.
  • the particular geometry (internal radii) of the mixing chamber can be optimized experimentally for given air/water/particle flow rates and velocities.
  • Ultra-High Pressure refers to a particular type of pump capable of delivering water at pressures greater than about 15,000 psi, to about 60,000 psi.
  • Ultra-High Velocity refers to velocity of a fluidjet (such as a water jet) having a velocity greater than 600 ft/sec up to about 4,000 ft/sec.
  • Abrasive Particle refers generally to any type of particulate relied upon in the blasting industry for the purpose of ejecting from a device. Substances commonly used include quartz sand, coal slag, copper slag, and garnet. "BB2049" is the industry designation for one common. The suffix 2049 refers to the particle size; the particles are retained by a 20-49 mesh, U.S. Standard Sieve series. Another common type is StarBlast.
  • Figure 1 depicts one particularly preferred embodiment of the present invention.
  • the device shown is preferably constructed from commonly available materials known to the skilled artisan. Modifications for extreme applications, e.g., underwater use, may be made to the device, and which are well known to the skilled artisan.
  • the air/particle stream travels via an inlet hose 10 into the nozzle 20, where it encounters a mixing chamber 40.
  • the device can be subdivided functionally into two stages, a first stage 12, and a second stage 14.
  • the particles are accelerated by pressurized gas, preferably, but not exclusively, air.
  • the second stage 14 the particles are further accelerated by ultra-high pressure water.
  • the approximate velocity of the air/particle stream at this point in the system is about 600 ft/sec.
  • the air/particle stream moves through the mixing chamber 40, it encounters one or more ultra-high pressure water inlets 50, which introduce ultra-high velocity water jets into the mixing chamber at an oblique angle relative to the central axis formed by the movement of the air/particle stream.
  • the jets of water from the inlets 50 converge with the air/particle stream, thereby accelerating the particles to greater than about 1,200 ft/sec.
  • a second function of the ultra-high velocity water jets by virtue of their oblique and/or skewed position, is to alter the direction of the stream, from purely axial to a vortex or swirling motion, thereby enhancing interaction of the particles within the fluid stream.
  • the stream comprising air, particles, and water, exits the downstream end of the nozzle 80.
  • the fluid stream is further manipulated to enhance the vortex motion before exiting the nozzle.
  • the air/particle/water fluid stream travels downstream within the nozzle where it is further mixed with air.
  • the air may be introduced into the mixing chamber 40 by one of several means.
  • the air enters the mixing chamber 40 by simple aspiration or passive induction through one or more holes 60, 62 placed in the nozzle and which allows ambient air to penetrate the mixing chamber.
  • the air is inducted into the mixing chamber through the holes 60, 62 due to the negative pressure created by the movement of the fluid stream through the mixing chamber.
  • the air may be actively injected (under pressure) into the mixing chamber 40.
  • the air enters the mixing chamber 40 through holes 60, 62 located upstream from the ultra-high water injection ports 52, 54, which introduce ultra-high pressure water into the chamber from an inlet 50.
  • the air may enter the chamber upstream from the water injection ports 52, 52.
  • the air and water may enter the chamber simultaneously.
  • the air enters the mixing chamber through passive movement, across a positive pressure gradient from outside to the mixing chamber and commingles with the air/particle/water fluid stream, further enhancing the vortex motion, hence facilitating particulate acceleration.
  • the air is not passively inducted into the mixing chamber, but is actively pumped into the mixing chamber under pressure, e.g., at pressures ranging from approx. 10 to 150 psi gauge.
  • the vortex motion is created (without the aid of air inflow into the mixing chamber 40) or further enhanced by altering the internal geometry of the mixing chamber.
  • the air/water/particulate stream moving through the mixing chamber 40 encounters a converging passage 42 (i.e., the mixing chamber diameter decreases).
  • the radial velocity of the particles increases due to the principle of conservation of angular momentum. Increased radial velocity results in increased particle concentration in a zone upon which the ultra-high velocity water jets are directed, enhancing impingement and entrainment, hence the particle acceleration process within the chamber.
  • the radius increases 44 which causes the abrasive particles to spread, i.e., due to movement towards the walls of the chamber resulting from the radial momentum imposed on the particles.
  • the mixing chamber is comprised of a converging portion 42, followed by a diverging portion 44.
  • controlled and uniform spreading is desirable for surface preparation applications, because it increases the surface area impinged upon by the abrasive particles.
  • the vortex motion is created or enhanced by the placement of grooves or ridges or vanes on all or a portion of the interior wall of the mixing chamber.
  • Figure 3 shows an additional preferred embodiment of the present invention.
  • the mixing chamber diameter decreases (converging portion 42) to increase radial velocity and concentrate the particles in a zone for effective interaction with the ultra-high velocity water jets, but does not subsequently diverge to produce spreading. Instead, the nozzle tapers to form a focusing tube 72.
  • this embodiment is more suitable for cutting, in contrast to the embodiment shown in Figure 2, which is more suitable for surface removal.
  • the optimum removal or cutting rates may be obtained by optimizing the internal geometry of the mixing chamber, i.e., the internal radii, vortex enhancing geometry's, the configuration of vortex enhancing air induction or injection ports, as well as the placement of the converging/diverging portions relative to the water and air inlets.
  • the device depicted in Figure 1 has a skew angle of 0, though it cannot be shown in Figure 1.
  • This parameter is analogous to the previous one, except that the latter describes the spatial relationship between the two stages with respect to positioning of one stage relative to the other, in a plane perpendicular to the page on which the drawing appears.
  • the "Acceleration Power Ratio” is the ratio of the horspower in stage 2 to the horsepower in stage 1, or the hydraulic horsepower to the air horsepower. This parameter is informative because, as evidenced by Figure 1, the particles are accelerated by two sources: air via an inlet hose 10 in the first stage, and water via injection ports 52, 54 in stage 2. Each input requires a power source, hence the "Acceleration Power Ratio" paremeter.
  • 'Vortex Power Ratio is similar to the parameter immediately above it, and is the horsepower applied to generate or enhance the vortex over the horsepower in stage 1 (air horsepower).
  • the next paremeter is the 'Vortex Air Jet Ports," which just refers to the number of inlets through which the vortex-inducing/enhancing air is introduced (shown as 60, 62) in Figure 1. Two inlets 60, 62 are shown in Figure 1.
  • the 'Vortex Taper Included Angle refers to the angle at which the inside diameter of the second stage 14 converges. More specifically, it refers to the angle formed by lines tracing a cross-section of the interior wall of the second stage, measured from the beginning of the second stage 14 to D 2 .
  • the 'Vortex Air Inlet Skew Angle refers to the positioning of the air inlets 60, 62.
  • the angle at which air enters the interior of the device relative to a plane parallel with the page on which the drawing is inscribed is the 'Vortex Air Inlet Skew Angle.”
  • the next parameter is the "UHP Waterjets Trajectory Intersect," shown in Figure 1 as L v
  • L is the distance from the point where the individual jets of ultra-high pressure water (delivered from the injection ports 52, 52) converge, to the end of the second stage (coterminus with L_).
  • a UHP Waterjets Trajectory Intersect value of "@D 2 " means that the jets converge at the point D 2 (shown in Figure 1).
  • the parameter values are based on multiples of D 2 ; hence a value of +10 x D 2 means that the jets converge downstream from the point where D 2 is measured, by a distance of ten times the value of D 2 .
  • the next parameter refers to the number of ultra-high pressure water injection ports 52, 54. Two such ports are shown in Figure 1.
  • the next parameter listed in Table 1 is the "UHP Water Jet Injection Port Diamater,” which is merely the inside diameter of the injection ports 52, 54.
  • the next parameter is the "UHP Waterjet Included Angle" which is the angle formed by the two jets exiting the ports 52, 54.
  • the final parameter in Table 1 is the "UHP Water Jet Skew Angle.” This parameter partially defines the position of the individual ports 52, 54 along a plane perpendicular to the page upon which Figure 1 appears. Table 1
  • the conventional device comprised a 3/16" diameter (or #3) converging/diverging dry abrasive blasting nozzle, which is common in the industry.
  • the nozzle was driven by 100 psi air at a flow-rate of 50 ft 3 /min to propel 260 lbs/hr of 16-40 mesh size abrasives onto the test surface.
  • the present invention apparatus comprised the conventional device described above, serving as its first acceleration stage, driven by the same air pressure, same air-flow rate and delivering the same abrasives mass-flow at identical particle size to the second acceleration stage.
  • the second acceleration stage is water jet driven with a jet velocity of about 2200 ft/sec.
  • Vortex action was not externally promoted, i.e. no additional fluid was injected from the side into the mixing chamber to amplify vortex action in the mixing chamber.
  • vortex motion was not deliberately induced, such motion may occur anyway as an inherent consequence of the internal geometry of the chamber. The results are summarized below:
  • the conventional device comprised a 4/16" diameter (or #4) converging/diverging dry abrasive blasting nozzle, which is common in the industry.
  • the nozzle was driven by 100 psi air at a flow-rate of 90 ft 3 /min to propel 500 lbs/hr of 16-40 mesh size abrasives on to the test surface.
  • the present invention apparatus comprised the conventional device described above, serving as its first acceleration stage, driven by the same air pressure, same air-flow rate and delivering the same abrasives mass-flow at identical particle size to the second acceleration stage.
  • the second acceleration stage is water jet driven with a jet velocity of about 2,200 ft/sec. Vortex action was not externally promoted, i.e. no additional fluid was injected from the side into the mixing chamber to amplify vortex action in the mixing chamber.
  • the conventional device comprised a 4/16" diameter (or #4) converging/diverging dry abrasive blasting nozzle, which is common in the industry.
  • the nozzle was driven by 100 psi air at a flow-rate of 90 ft 3 /min to propel 500 lbs/hr of 16-40 mesh size abrasives onto the test surface.
  • the present invention apparatus comprised the conventional device described above, serving as its first acceleration stage, driven by the same air pressure, same air-flow rate and delivering the same abrasives mass-flow at identical particle size to the second acceleration stage.
  • the second acceleration stage is water jet driven with a jet velocity of about 2,200 ft/sec. Vortex action was not externally promoted, i.e., no additional fluid was injected from the side into the mixing chamber to amplify vortex action in the mixing chamber. The results are summarized below:
  • the conventional device comprised a 3/16" diameter (or #3) converging/diverging dry abrasive blasting nozzle, which is common in the industry.
  • the nozzle was driven by 100 psi air at a flow-rate of 50 ft 3 /min to propel 260 lbs/hr of 16-40 mesh size abrasives onto the test surface.
  • the present invention apparatus comprised the conventional device described above, serving as its first acceleration stage, driven by the same air pressure, same air-flow rate and delivering the same abrasives mass-flow at identical particle size to the second acceleration stage.
  • the second acceleration stage is water jet driven with a jet velocity of about 2,200 ft/sec. Vortex action was promoted, through the injection of additional compressed air producing a rotation effect amounting to 0.17 inch-pound per pound of air entering the first acceleration stage. The results are summarized below:
  • the conventional device comprised a 4/16" diameter (or #4) converging/diverging dry abrasive blasting nozzle, which is common in the industry.
  • the nozzle was driven by 100 psi air at a flow-rate of 90 ft 3 /min to propel 500 lbs/hr of 16-40 mesh size abrasives onto the test surface.
  • the present invention apparatus comprised the conventional device described above, serving as its first acceleration stage, driven by the same air pressure, same air-flow rate and delivering the same abrasives mass-flow at identical particle size to the second acceleration stage.
  • the second acceleration stage is water jet driven with a jet velocity of about 2,200 ft/sec. Vortex action was promoted, through the injection of additional compressed air producing a rotation effect amounting to 0.17 inch-pound per pound of air entering the first acceleration stage. The results are summarized below:
  • the conventional device comprised a waterblast nozzle, delivering 25 hydraulic horsepower (HHP) driven by a pressure of 35,000 psi.
  • Abrasives size 40-
  • the present invention apparatus comprised the identical conventional device described above, plus vortex enhancing air injection amounting to an additional 7 HHP taking total system power to 32
  • F D C D x p v 2 A/2
  • F D the drag force
  • C D the particle's drag coefficient
  • p the density of the fluid
  • v the relative velocity of the particle with respect to the surrounding fluid
  • A the particle's cross-sectional area or, in the event of an irregular shaped particle, its projected area.
  • C D is an experimentally determined function of the particle's Reynolds number (N R ).
  • the Reynolds number is defined as:
  • N R pvd/ ⁇
  • p the fluid density
  • v the relative particle velocity
  • d the particle diameter
  • ⁇ the fluid's dynamic viscosity
  • a high-pressure water pump capable of producing a pressure of about 5,400 psi at a delivery rate of 1 ft 3 /min (7.5 GPM), would be required to accelerate the particles to a velocity of about 600 ft/sec (or to about 70% of the fluid velocity) with a capital cost of about $6,000, driven by about a 25 HP engine.
  • the comparison of capital cost and required energy demonstrates that air can accelerate particles to a velocity of about 600 ft/sec at 1/lOOth of the capital cost and at about 1/lOOth of the energy input than what can be accomplished with water as a driving fluid.
  • a secondary consideration for utilizing air for first stage acceleration is that the particles are readily conveyed and transported in a turbulent air stream, within a hose or pipe, to extended distances and heights.
  • the abrasive particle reservoir can be large, resulting in fewer interruptions to replenish the reservoir, and does not have to be near the nozzle ejecting the particles onto a surface to be abraded or cut.
  • the benefit of accelerating particles with an ultra-high velocity water jet or jets is further exacerbated by inducing vortex, or swirling motion, into the fluid stream and subjecting the particles to such vortex or swirling motion.
  • Trials conducted with such a configuration have produced superior results (measured by surface removal) which is evidence of superior momentum transfer onto and entrainment of the particles by the driving ultra-high velocity water jet.
  • the particles are contacted with a fluid having a vortex motion, the particles are propelled outward radially by centrifugal force. This force, and the resultant particle motion, is exploited in one embodiment of the present invention in the following way.
  • the particles As the particles are propelled outward by centrifugal force, they concentrate in a region where they are preferentially contacted with ultra-high velocity water jets, deliberately directed at such region. The result is a dramatically enhanced exit velocity of the particles being ejected from the chamber, a more energy efficient acceleration process, and the ability to introduce a greater concentration of particles relative into the driving, ultra-high velocity, water jet stream.
  • Experiments conducted in support of the present application indicate that currently available technology is limited to introduction of about 12% of particles into the propelling fluid.
  • the present invention through the introduction of vortex or swirling motion, allows for particle concentrations of up to 50% (relative to the driving water media) to be accelerated effectively to ultra-high velocities.
  • the present invention overcomes that limitation-though still achieves maximum particle acceleration-by concentrating the particles into the water jet's path by centrifugal force, with a low resultant force in the direction perpendicular to the direction of the water jets.
  • the vortex motion can be induced by a variety of means well known to the skilled artisan.
  • a variable radius chamber could be used-i.e., a chamber whose radius increases downstream.
  • grooves can be machined into the interior of the chamber or vanes can be added; alternatively, a fluid can be injected, inducted or aspired into the chamber at oblique angles or tangentially relative to the longitudinal axis formed by the chamber.
  • the imposition of vortex or swirl motion onto the particles dramatically enhances the acceleration process and ability to introduce more particles per unit of ultra-high velocity water (referred to as particle concentration) from about 12% for currently available technology to 50%, a four-fold increase.
  • the vortex action also assists in focusing the particle jet to a smaller area D 0 hence the particle concentration per impacting area on a material is increased.
  • achieving a focusing diameter D c the particle concentration per area increases with the square of the diameter ratio (D,/D 0 ) 2 .
  • the focusing diameter can be reduced by about 25% of that of conventional abrasive particle stream cutters, resulting in a two-fold increase in cutting performance.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Disintegrating Or Milling (AREA)

Abstract

L'invention porte sur un procédé et un appareil permettant de produire à faible coût des courants de particules à grande vitesse accélérées en plusieurs étapes (12, 14) recourant chacune à plusieurs moyens. Les particules sont tout d'abord portées à une vitesse subsonique (relativement à la vitesse du son dans l'air) par un ou plusieurs jets de gaz, puis à une vitesse supersonique par un ou plusieurs jets d'eau. Pour produire une accélération supplémentaire, on crée un mouvement tourbillonnaire, et on introduit les particules dans un fluide en mouvement tourbillonnaire ce qui renforce la projection des particules sur une cible.
PCT/US1997/012055 1997-07-11 1997-07-11 Procede et appareil permettant de produire des courants de particules a grande vitesse WO1999002302A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU36574/97A AU3657497A (en) 1997-07-11 1997-07-11 Method and apparatus for producing a high-velocity particle stream
PCT/US1997/012055 WO1999002302A1 (fr) 1997-07-11 1997-07-11 Procede et appareil permettant de produire des courants de particules a grande vitesse

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1997/012055 WO1999002302A1 (fr) 1997-07-11 1997-07-11 Procede et appareil permettant de produire des courants de particules a grande vitesse

Publications (1)

Publication Number Publication Date
WO1999002302A1 true WO1999002302A1 (fr) 1999-01-21

Family

ID=22261237

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/012055 WO1999002302A1 (fr) 1997-07-11 1997-07-11 Procede et appareil permettant de produire des courants de particules a grande vitesse

Country Status (2)

Country Link
AU (1) AU3657497A (fr)
WO (1) WO1999002302A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1422026A2 (fr) * 1999-03-18 2004-05-26 Shibuya Kogyo Co., Ltd Procédé de nettoyage/raclage et dispositif approprié
WO2005037489A1 (fr) * 2003-10-17 2005-04-28 Szuecs Johan Dispositif de production d'un jet fluidique rotatif
EP1820604A1 (fr) * 2006-02-17 2007-08-22 ANT Applied New Technologies AG Tête de buse
CN101885274A (zh) * 2009-05-14 2010-11-17 Bsh博施及西门子家用器具有限公司 制造灶面的方法
EP3061567A4 (fr) * 2013-10-21 2017-05-24 Fuji Manufacturing Co., Ltd. Méthode d'usinage par sablage et dispositif d'usinage par sablage
WO2022170697A1 (fr) * 2021-02-09 2022-08-18 华东理工大学 Appareil et procédé intégrés de renforcement et de polissage par jet

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4080762A (en) * 1976-08-26 1978-03-28 Watson John D Fluid-abrasive nozzle device
US4389820A (en) * 1980-12-29 1983-06-28 Lockheed Corporation Blasting machine utilizing sublimable particles
US4540121A (en) * 1981-07-28 1985-09-10 Browning James A Highly concentrated supersonic material flame spray method and apparatus
US4545317A (en) * 1981-04-01 1985-10-08 Gkss-Forschungszentrum Geesthacht Gmbh Device for treating the surfaces of structures and ships
US5184427A (en) * 1990-09-27 1993-02-09 James R. Becker Blast cleaning system
US5365699A (en) * 1990-09-27 1994-11-22 Jay Armstrong Blast cleaning system
US5390450A (en) * 1993-11-08 1995-02-21 Ford Motor Company Supersonic exhaust nozzle having reduced noise levels for CO2 cleaning system
US5405283A (en) * 1993-11-08 1995-04-11 Ford Motor Company CO2 cleaning system and method
US5514024A (en) * 1993-11-08 1996-05-07 Ford Motor Company Nozzle for enhanced mixing in CO2 cleaning system
US5545073A (en) * 1993-04-05 1996-08-13 Ford Motor Company Silicon micromachined CO2 cleaning nozzle and method
US5601478A (en) * 1994-03-01 1997-02-11 Job Industries Ltd. Fluidized stream accelerator and pressuiser apparatus
US5616067A (en) * 1996-01-16 1997-04-01 Ford Motor Company CO2 nozzle and method for cleaning pressure-sensitive surfaces

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4080762A (en) * 1976-08-26 1978-03-28 Watson John D Fluid-abrasive nozzle device
US4389820A (en) * 1980-12-29 1983-06-28 Lockheed Corporation Blasting machine utilizing sublimable particles
US4545317A (en) * 1981-04-01 1985-10-08 Gkss-Forschungszentrum Geesthacht Gmbh Device for treating the surfaces of structures and ships
US4540121A (en) * 1981-07-28 1985-09-10 Browning James A Highly concentrated supersonic material flame spray method and apparatus
US5184427A (en) * 1990-09-27 1993-02-09 James R. Becker Blast cleaning system
US5365699A (en) * 1990-09-27 1994-11-22 Jay Armstrong Blast cleaning system
US5545073A (en) * 1993-04-05 1996-08-13 Ford Motor Company Silicon micromachined CO2 cleaning nozzle and method
US5405283A (en) * 1993-11-08 1995-04-11 Ford Motor Company CO2 cleaning system and method
US5514024A (en) * 1993-11-08 1996-05-07 Ford Motor Company Nozzle for enhanced mixing in CO2 cleaning system
US5390450A (en) * 1993-11-08 1995-02-21 Ford Motor Company Supersonic exhaust nozzle having reduced noise levels for CO2 cleaning system
US5601478A (en) * 1994-03-01 1997-02-11 Job Industries Ltd. Fluidized stream accelerator and pressuiser apparatus
US5681206A (en) * 1994-03-01 1997-10-28 Mesher; Terry Method of accelerating fluidized particulate matter
US5616067A (en) * 1996-01-16 1997-04-01 Ford Motor Company CO2 nozzle and method for cleaning pressure-sensitive surfaces

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1422026A2 (fr) * 1999-03-18 2004-05-26 Shibuya Kogyo Co., Ltd Procédé de nettoyage/raclage et dispositif approprié
EP1422026A3 (fr) * 1999-03-18 2004-06-02 Shibuya Kogyo Co., Ltd Procédé de nettoyage/raclage et dispositif approprié
WO2005037489A1 (fr) * 2003-10-17 2005-04-28 Szuecs Johan Dispositif de production d'un jet fluidique rotatif
EP1820604A1 (fr) * 2006-02-17 2007-08-22 ANT Applied New Technologies AG Tête de buse
WO2007093154A1 (fr) * 2006-02-17 2007-08-23 Ant Applied New Technologies Ag Tête de buse
CN101885274A (zh) * 2009-05-14 2010-11-17 Bsh博施及西门子家用器具有限公司 制造灶面的方法
EP3061567A4 (fr) * 2013-10-21 2017-05-24 Fuji Manufacturing Co., Ltd. Méthode d'usinage par sablage et dispositif d'usinage par sablage
WO2022170697A1 (fr) * 2021-02-09 2022-08-18 华东理工大学 Appareil et procédé intégrés de renforcement et de polissage par jet

Also Published As

Publication number Publication date
AU3657497A (en) 1999-02-08

Similar Documents

Publication Publication Date Title
AU747679B2 (en) Method and apparatus for producing a high-velocity particle stream
US6168503B1 (en) Method and apparatus for producing a high-velocity particle stream
US3852409A (en) Process for the removal of particulate matter and acidic gases from carrier gases
EP1893305B1 (fr) Distributeur basse pression a haute vitesse
JP2601031B2 (ja) 扇形ノズル
US8691014B2 (en) System and nozzle for prepping a surface using a coating particle entrained in a pulsed fluid jet
US5283990A (en) Blast nozzle with inlet flow straightener
US5918817A (en) Two-fluid cleaning jet nozzle and cleaning apparatus, and method utilizing the same
JP5184347B2 (ja) ガスダイナミックコーティング装置およびコーティング方法
US4765540A (en) Process and apparatus for generating multiple fluid jets
EP2542384B1 (fr) Systèmes à jet abrasif, y compris systèmes à jet abrasif utilisant des matériaux repoussant les fluides, et procédés associés
US7380918B2 (en) Method and apparatus for forming high-speed liquid
US6626738B1 (en) Performance fan nozzle
US8006961B1 (en) Apparatus and method for treating process fluid
EP0110529B1 (fr) Jet abrasif liquide à haute vitesse
WO1999002302A1 (fr) Procede et appareil permettant de produire des courants de particules a grande vitesse
US5857900A (en) Blast nozzle containing water atomizer
MXPA00000434A (en) Method and apparatus for producing a high-velocity particle stream
CA2010083C (fr) Appareil de coupe et methode connexe
JP2010137341A (ja) 噴射加工装置
RU2223167C2 (ru) Способ гидрогазоабразивной обработки и устройство для абразивной обработки поверхности
EP0153942A1 (fr) Appareil de coupe du beton
RU2175599C2 (ru) Бустерное пескоструйное устройство
CA2116709A1 (fr) Methode et dispositif pour l'acceleration de particules fluidisees
Goenka Supersonic exhaust nozzle having reduced noise levels for CO2 cleaning system

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AL AM AT AU AZ BB BG BR BY CA CH CN CZ DE DK EE ES FI GB GE HU IL IS JP KE KG KP KR KZ LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK TJ TM TR TT UA UG UZ VN

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 1999508579

Format of ref document f/p: F

NENP Non-entry into the national phase

Ref country code: CA

122 Ep: pct application non-entry in european phase