Chevron Nozzle for Thermal Spray Gun Mixing
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Solution Overview
Problem
Existing thermal spray process guns using axial injection face limitations in mixing particulate-bearing carrier streams with effluent streams, leading to energy loss and turbulence, which hampers efficient energy transfer and coating quality, especially when using liquids.
Innovation Solution
The implementation of a chevron nozzle at the axial injection port to promote mixing between the particulate-bearing carrier stream and the heated/accelerated effluent stream, reducing turbulence and enhancing energy transfer by increasing the shared boundary area between the streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If axial injection is used to control particle trajectory linearity and direction, then particle trajectory control is improved, but mixing efficiency deteriorates due to limited boundary layer breakdown
Solution Approach 1:
The axial injection port is segmented into multiple annular regions with different injection velocities. The inner annular region injects at a higher velocity than the outer annular region, creating velocity differences that promote boundary layer instability and enhanced mixing while preserving the axial trajectory control that makes axial injection attractive.
Solution Approach 2:
The invention changes the velocity parameter across different radial positions of the axial injection port. By varying the injection velocity from the center outward (or vice versa), the system creates controlled instabilities that accelerate mixing without sacrificing the directional control inherent in axial injection geometry.
2Productivity
If sufficient travel distance is provided for boundary layer breakdown and mixing, then mixing efficiency is improved, but device length increases leading to energy loss
Solution Approach 1:
By segmenting the injection port into annular regions with different velocities, the mixing process is accelerated and can be completed in a shorter device length. The velocity differential creates immediate boundary layer instabilities that promote rapid mixing, eliminating the need for long travel distances.
Solution Approach 2:
The invention converts what would normally be a harmful effect (boundary layer stability preventing mixing) into a beneficial one by introducing controlled velocity differences. The velocity differential creates controlled instabilities that accelerate the boundary layer breakdown process, enabling efficient mixing in a compact device.
3Productivity
If radial injection is used for rapid mixing and energy transfer, then mixing efficiency is improved, but particle trajectory control deteriorates
Solution Approach 1:
The injection port is divided into annular regions that can be independently controlled. This segmentation allows the system to use axial injection geometry (which provides good trajectory control) while creating velocity differentials across the annular regions that produce mixing effects similar to radial injection, combining the advantages of both approaches.
4Stability of the object's composition
If liquid feedstock is injected axially, then trajectory control is improved, but mixing efficiency deteriorates due to limited boundary layer breakdown
Solution Approach 1:
The axial injection port is segmented into annular regions with different injection velocities. This segmentation creates velocity differentials that promote boundary layer instability and enhance mixing of liquid feedstock, while maintaining the axial injection geometry that provides superior trajectory control compared to radial injection methods.
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
This approach enables more efficient energy transfer and improved coating quality by minimizing turbulence and energy loss, allowing for higher mass flow rates and better energy utilization without introducing significant turbulence, thus enhancing the thermal spray process efficiency.
Implementation Method 1
the boundary layer between the two flows to break down and thus permit mixing to occur
Implementation Method 2
promote mixing between the particulate-bearing carrier stream and the heated/accelerated effluent stream by increasing the shared boundary area between the streams
Implementation Method 3
Energy is transferred from the effluent to the particles in the carrier gas stream
Implementation Method 4
a stream of energized gas that is heated, accelerated, or both
Data Source
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Figure 6~7
AI summary
An improved thermal spray apparatus (100) and method of promotes mixing of axially fed particles in a earner stream with a heated effluent stream without introducing significant turbulence into either the effluent or carrier streams. An axial injection port (114) includes a plurality of chevrons (120) at the distal end of the port. The chevrons (120) are located radially around the circumference of the distal end of the axial injection port to increase the shared area between the two flow streams at the outlet of the port.