Serrated Air Cap Nozzle for Spray Gun Noise Reduction
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Solution Overview
Problem
Existing paint spray guns generate high velocity atomizing air jets that cause noise and fluctuations, leading to reduced transfer efficiency due to turbulence and instability in the air jet, resulting in uneven paint distribution.
Innovation Solution
An air cap nozzle with a serrated rim region featuring protrusions that introduce stream-wise vortices, reducing turbulence and enhancing mixing between the atomizing air jet and ambient air, thereby stabilizing the air jet and improving paint distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high pressure air source is used to generate high velocity atomising air jet, then atomisation quality is improved, but noise level increases and jet stability deteriorates
Solution Approach 1:
The invention introduces protrusions into the air cap nozzle that generate stream-wise vortices, converting the harmful high-velocity turbulent flow into controlled rotational structures. These vortices enhance mixing between the atomising air jet and ambient air, reducing peak velocities and turbulence intensity, thereby converting the harmful high-speed jet into a beneficial controlled flow structure that reduces noise while maintaining atomisation quality
2Speed
If high pressure air source is used to generate high velocity atomising air jet, then atomisation quality is improved, but jet stability deteriorates causing flapping
Solution Approach 1:
The protrusions in the air cap nozzle generate stream-wise vortices that stabilize the high-velocity atomising air jet. These vortices create a more uniform and controlled flow structure, reducing instabilities and flapping while maintaining the high velocity needed for effective atomisation. The harmful jet instability is thus converted into a beneficial stabilized flow pattern
3Ease of operation
If mixing layer is created at interface between discharged air and ambient air, then atomisation is achieved, but turbulence intensity increases causing noise
Solution Approach 1:
The invention uses protrusions to generate stream-wise vortices that enhance the mixing between discharged atomising air and ambient air. This controlled vortex-induced mixing achieves effective atomisation while reducing peak velocity differences and turbulence intensity, thereby converting the harmful turbulent mixing layer into a beneficial controlled mixing zone that reduces noise
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces noise and fluctuations, enhancing the stability and transfer efficiency of the paint spray, resulting in improved paint distribution and reduced operational noise.
Implementation Method 1
The plurality of protrusions are found to reduce turbulence in the mixing layer by introducing stream-wise vortices that enhance mixing between the discharging airjet and the ambient air
Implementation Method 2
The protrusions are separated by valleys configured to permit entrainment of ambient air by the atomising air jet, the entrained ambient air being drawn through the valleys
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
An air-cap nozzle (103b) for discharging an atomising air jet (101b) for atomising paint from a spray gun, the air cap nozzle comprising a tip surface having an atomizing air outlet (100b) and a rim region (102b) surrounding the outlet. The rim region (102b) comprises a continuous serrated portion formed by a plurality of protrusions (104) that protrude axially outward from the rim region (100b) of the tip surface. The protrusions (104) are separated by valleys (105) configured to permit entrainment of ambient air by the atomising air jet (101b), the entrained ambient air being drawn through the valleys. The permitted entrainment provides mixing between the entrained ambient air and the atomising air jet (101b).