Cavitation Peening Nozzle With Constricted Passage
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Solution Overview
Problem
Current cavitation processes for surface treatment in aerospace and allied industries are limited by low cavitation intensity, which affects processing time and efficiency, particularly in enhancing surface integrity and resistance to corrosion and fretting fatigue.
Innovation Solution
A cavitation peening system with a nozzle assembly that includes a cylindrical pipe and an organ pipe cavitator, featuring an inner passage with specific diameter reductions and a converging outlet, enhancing cavitation intensity by altering flow dynamics and increasing the frequency of high-intensity cavitation events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cavitation nozzles with uniform cross-sectional passages are used, then the device complexity is low and ease of manufacture is high, but the cavitation intensity is insufficient leading to longer processing times
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the nozzle passage - specifically creating a non-uniform cross-sectional area along the flow direction with at least one constriction. This geometric parameter change transforms the flow characteristics to generate enhanced cavitation intensity, directly improving processing speed without requiring complex external systems
Solution Approach 2:
The nozzle passage is segmented into distinct zones with different cross-sectional areas - a constriction zone and an expansion zone. This segmentation creates localized flow acceleration and deceleration regions that promote cavitation bubble formation and collapse, enhancing the cavitation effect while maintaining a relatively simple integrated nozzle structure
2Strength
If conventional cavitation nozzles are used, then the equipment requirements are minimal, but the compressive residual stress depth is insufficient for effective surface treatment
Solution Approach 1:
By changing the geometric parameters of the passage - specifically the position, severity, and length of the constriction - the patent optimizes the cavitation intensity and distribution. This controls the depth and magnitude of compressive residual stresses induced in the treated surface, achieving effective surface treatment without complex multi-nozzle configurations
Solution Approach 2:
The constriction and expansion zones create periodic flow acceleration and deceleration, generating repeated cavitation cycles as fluid passes through the nozzle. This periodic cavitation action enhances the penetration depth of compressive residual stresses into the material surface
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 system achieves increased cavitation intensity, deeper compressive residual stresses, and improved surface finishing with reduced processing time and equipment requirements, making it suitable for portable and efficient use in aerospace applications.
Implementation Method 1
Cavitation processes utilize the impact pressures generated by cavitation bubble collapse on metallic surfaces to induce beneficial compressive residual stresses
Implementation Method 2
a cavitation peening system with a nozzle assembly that includes a cylindrical pipe and an organ pipe cavitator, featuring an inner passage with specific diameter reductions and a converging outlet, enhancing cavitation intensity by altering flow dynamics
Data Source
AI summary
An apparatus for cavitation peening is disclosed, including a fluid source, a conduit, and a portable nozzle assembly. The conduit includes a proximal end portion connected to the fluid source and a distal end portion connected to the portable nozzle assembly. The portable nozzle assembly includes an inner nozzle configured to channel a first stream of high-pressure fluid, and an outer nozzle configured to channel a second stream of low-pressure fluid concentrically around the first stream. The inner nozzle includes a cavitation insert having an inner passage with at least two reductions in cross-sectional area.