Axial Flow Conditioning Device Mitigating Cavitation
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Solution Overview
Problem
Existing flow conditioning devices, such as single-hole orifices, suffer from instabilities like vortex shedding and cavitation when reducing pressure in axial flows, leading to vibrations and erosion in piping systems, especially with cryogenic and volatile liquids, and fail to minimize pressure fluctuations effectively.
Innovation Solution
A flow conditioning device with concentrically disposed annular elements and undulated surfaces that separate axial flows into multiple paths, directing them radially to reduce pressure while maintaining it above vapor pressure, thereby minimizing instabilities and viscous drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a single-hole orifice is used to reduce pressure in axial flow, then pressure drop is achieved, but vortex shedding and cavitation occur causing instabilities
Solution Approach 1:
The single-hole orifice is segmented into multiple axial flow paths by introducing intermediate annular elements with multiple holes arranged axially. This segmentation distributes the flow through multiple channels, reducing the intensity of vortex shedding and cavitation in each individual path while achieving the required pressure drop, thereby improving flow stability
Solution Approach 2:
The invention transitions from a single-plane orifice to a multi-axial flow path structure by arranging holes along the axial dimension. This dimensional change allows the flow to be conditioned through multiple stages, with each stage contributing to pressure reduction while maintaining stability through the distributed flow paths
2Stress or pressure
If pressure is reduced through an orifice, then pressure drop is achieved, but cavitation occurs when pressure falls below vapor pressure
Solution Approach 1:
The pressure reduction process is segmented into multiple stages across different axial levels. Each annular element creates a separate flow path that reduces pressure incrementally, preventing the pressure from dropping below vapor pressure in any single location, thereby eliminating cavitation while achieving the overall pressure reduction goal
Solution Approach 2:
Instead of achieving the full pressure drop in a single orifice, the invention applies partial pressure reduction at each axial stage. The cumulative effect of multiple partial reductions achieves the desired total pressure drop while keeping the pressure at each intermediate stage above the vapor pressure threshold, preventing cavitation
3Stress or pressure
If flow velocity is increased through orifice constriction, then pressure drop is achieved, but shear stresses increase causing vortex shedding
Solution Approach 1:
The flow velocity increase and associated shear stress generation are segmented across multiple axial levels. Each annular element creates a milder velocity gradient compared to a single orifice, reducing the intensity of vortex shedding. The cumulative velocity increase across stages achieves the pressure drop without generating excessive shear stresses in any single location
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 device effectively suppresses vortex shedding and cavitation, reduces pressure fluctuations, and minimizes vibrations, ensuring stable flow and preventing phase changes in downstream fluids, while being modular for customizable solutions.
Implementation Method 1
The invention employs viscous dissipation to step down pressure within an axial flow
Implementation Method 2
straightens an axial flow, and damps out free-stream instabilities within an axial flow
Implementation Method 3
damps out free-stream instabilities within an axial flow
Implementation Method 4
The pressure within the axial flow along each axial flow path is greater than a vapor pressure for the axial flow
Data Source
AI summary
A flow conditioning device for incrementally stepping down pressure within a piping system is presented. The invention includes an outer annular housing, a center element, and at least one intermediate annular element. The outer annular housing includes an inlet end attachable to an inlet pipe and an outlet end attachable to an outlet pipe. The outer annular housing and the intermediate annular element(s) are concentrically disposed about the center element. The intermediate annular element(s) separates an axial flow within the outer annular housing into at least two axial flow paths. Each axial flow path includes at least two annular extensions that alternately and locally direct the axial flow radially outward and inward or radially inward and outward thereby inducing a pressure loss or a pressure gradient within the axial flow. The pressure within the axial flow paths is lower than the pressure at the inlet end and greater than the vapor pressure for the axial flow. The invention minimizes fluidic instabilities, pressure pulses, vortex formation and shedding, and/or cavitation during pressure step down to yield a stabilized flow within a piping system.