Method and design for productive quiet abrasive blasting nozzles
AssigneeKennametal Inc.
InventorChristopher Sullivan
Life of this patent
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Abstract
Reduced noise abrasive blasting assemblies and systems are described. The new assemblies and systems are comprised of standard blast hose, accelerator hose, couplings and nozzle. The improved abrasive blasting system maintains abrasive particle velocity while decreasing the exit gas velocity and consequently decreasing sound production. This is accomplished through an acceleration section with reduced inner diameter and sufficient length to provide the necessary abrasive particle velocity. The new system maintains the productivity and efficiency of conventional abrasive blasting systems but with greatly reduced acoustic noise production and reduces operator fatigue due to the lower weight of the carried portion of the system.
Claims29
A productive abrasive blasting nozzle, comprising:
- a converging portion having a converging internal diameter;
- a throat having an internal diameter connected to the converging portion, wherein the throat has a length extending from a beginning of the throat to an end of the throat;
- a diverging portion having an internal diameter connected to the throat;
- and
- a straight portion having an internal diameter connected to and immediately following the diverging portion;
- wherein the straight portion has a length such that a velocity of gas exiting the blasting nozzle is reduced by at least 30% relative to the blasting nozzle with the straight portion removed, when operated with a predetermined gas and particle mix and pressure;
- wherein, in operation, fluid flows through the converging portion, the throat, the diverging portion, and the straight portion, in that order;
- and
- wherein the length, L, of the straight portion is at least L*, as given by the following equation:
- L
- *
- =
- D
- 4
-
- (
- f
- _
- +
- f
- abrasives
- )
-
- [
- 1
- -
- M
- 2
- γ
-
-
- M
- 2
- +
- γ
- +
- 1
- 2
-
- γ
-
- ln
-
- (
- (
- γ
- +
- 1
- )
-
- M
- 2
- 2
- +
- (
- γ
- -
- 1
- )
-
- M
- 2
- )
- ]
- where D is a diameter of the straight section, M is the Mach number of the fluid at an entrance to the straight portion, f is the average friction factor of the straight portion, fabrasives is the friction factor of the particles in the fluid flow, and γ is the specific heat ratio of the fluid flow, for a predetermined gas and abrasive particle mixture.
A productive abrasive blasting nozzle, comprising:
- a converging portion having a converging internal diameter;
- a throat having an internal diameter connected to the converging portion, wherein the throat has a length extending from a beginning of the throat to an end of the throat;
- a diverging portion having an internal diameter connected to the throat;
- and
- a straight portion having an internal diameter connected to and immediately following the diverging portion;
- wherein the straight portion has a length such that a velocity of gas exiting the blasting nozzle is reduced by at least 30% relative to the blasting nozzle with the straight portion removed, when operated with a predetermined gas and particle mix and pressure;
- wherein, in operation, fluid flows through the converging portion, the throat, the diverging portion, and the straight portion, in that order;
- and
- wherein the length, L, of the straight portion is at least L″ adjusted for a ratio of back pressure to exit pressure, where L′ is given by the following equation:
- L
- *
- =
- D
- 4
-
- (
- f
- _
- +
- f
- abrasives
- )
-
- [
- 1
- -
- M
- 2
- γ
-
-
- M
- 2
- +
- γ
- +
- 1
- 2
-
- γ
-
- ln
-
- (
- (
- γ
- +
- 1
- )
-
- M
- 2
- 2
- +
- (
- γ
- -
- 1
- )
-
- M
- 2
- )
- ]
- where D is a diameter of the straight section, M is the Mach number of the fluid at an entrance to the straight portion, f is the average friction factor of the straight portion, fabrasives is the friction factor of the particles in the fluid flow, and γ is the specific heat ratio of the fluid flow, for a predetermined gas and abrasive particle mixture.
Dependencies are inferred from the claim text.