Multiphase Pump Wear Ring for Rotor Dynamic Stability
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Solution Overview
Problem
Multiphase pumps face fluid-induced rotor dynamic instability and vibration issues due to increased differential pressures, which are exacerbated by the Thomas-Alford effect, and existing solutions that eliminate blade tip clearance for stability compromise fluid mixing.
Innovation Solution
A multiphase axial pump with impeller blades and a wear ring positioned along the blade tips to provide rotor dynamic stability while allowing limited leakage for active phase mixing, using a wear ring with a reduced axial length relative to the blade tips to suppress fluid-induced instability and enhance stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a shroud is placed over the blade tips to eliminate blade tip clearance, then rotor dynamic stability is improved, but fluid mixing capability deteriorates
Solution Approach 1:
The wear ring is applied locally only to the blade tip region rather than covering the entire impeller. This localized application provides stability where needed at the blade tips while leaving the rest of the impeller structure unchanged to maintain fluid mixing capability. The wear ring extends axially for only a portion of the blade tip length, creating a local modification that addresses the stability issue without globally affecting fluid dynamics.
2Stability of the object's composition
If blade tip clearance is eliminated using a shroud, then fluid induced instability is reduced, but viscosity-related instability increases
Solution Approach 1:
The invention changes the physical parameters of the blade tip region by adding a wear ring with specific dimensional characteristics. The wear ring has a reduced axial length compared to the full blade tip axial length, creating a partial clearance configuration. This parameter modification allows the system to achieve reduced fluid induced instability while maintaining enough clearance to handle high viscosity fluids without becoming unstable.
3Power
If increased differential pressure is generated, then pumping performance is improved, but vibration levels increase
Solution Approach 1:
The wear ring converts the potentially harmful fluid induced instability into a beneficial stabilizing effect. By providing a controlled interaction surface at the blade tips, the wear ring transforms the unstable fluid forces into useful rotor dynamic stiffness. This allows the pump to operate at higher differential pressures with reduced vibration, as the wear ring effectively converts the harmful Thomas-Alford effect into a stabilizing mechanism.
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 effectively reduces undesirable vibrations and maintains active phase mixing, enabling operation at higher differential pressures and increased head without instability, even with high viscosity fluids.
Implementation Method 1
A wear ring is positioned along the blade tips to suppress fluid induced Alford effects and to add annular seal direct stiffness to the impeller
Implementation Method 2
add annular seal direct stiffness to the impeller and to thus provide rotor dynamic stability
Implementation Method 3
the axial length of the ring is limited relative to the axial length of the impeller blade tips to enable flow, e.g. leakage, across the blade tips in a manner which causes active phase mixing
Data Source
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AI summary
A technique facilitates operation of a pump such as a multiphase pump. The pump may be provided with an impeller having a plurality of impeller blades. The impeller blades have blade tips which extend over an axial length. A ring is positioned along the blade tips to stiffen the impeller and to thus provide stability. However, the axial length of the ring is limited relative to the axial length of the impeller to enable flow, e.g. leakage, across the blade tips in a manner which causes active phase mixing during pumping of a fluid, e.g. a multiphase fluid.