Multiphase Pump Swirl Brake Rotor Stability
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Solution Overview
Problem
Multiphase pumps face challenges in maintaining rotor stability and hydraulic efficiency, particularly at high gas volume fraction (GVF) operating conditions, where rotor vibrations and pressure drop issues arise due to limited damping and increased swirl in the fluid flow, leading to destabilizing hydrodynamic effects.
Innovation Solution
Incorporating swirl brakes at the entrance and along the passage between the rotating impeller ring and the stationary part to reduce inlet swirl and swirl build-up, allowing for a narrower passage clearance without compromising rotordynamic stability, thereby enhancing hydraulic efficiency and damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the passage clearance between the rotating impeller ring and stationary part is reduced to improve hydraulic efficiency, then hydraulic efficiency is improved, but rotor vibrations increase and rotordynamic stability deteriorates at high GVF conditions
Solution Approach 1:
Swirl brakes are introduced as intermediary elements within the passage to actively control and reduce swirl flow. These brakes act as mediators between the rotating impeller ring and stationary part, dissipating harmful swirl energy while allowing the passage clearance to remain narrow for high hydraulic efficiency. The swirl brakes convert excessive kinetic energy from swirl into useful pressure head, enabling both high efficiency and rotor stability at high GVF conditions.
2Stability of the object's composition
If the passage clearance is widened to improve rotordynamic stability and reduce rotor vibrations, then rotor stability is improved, but hydraulic efficiency decreases
Solution Approach 1:
Swirl brakes serve as active intermediaries that allow the passage clearance to be optimized for hydraulic efficiency without compromising rotor stability. By introducing these controlled dissipation elements, the system can maintain narrow clearances for high efficiency while the swirl brakes actively manage the hydrodynamic forces that would otherwise cause rotor vibrations at high GVF conditions.
3Device complexity
If conventional multiphase pump design is used without swirl brakes, then device complexity is low, but at high GVF values the pressure rise is significantly smaller and rotor damping is insufficient
Solution Approach 1:
Swirl brakes are introduced as relatively simple intermediary components that significantly enhance pressure rise capability at high GVF conditions. These brakes convert harmful swirl kinetic energy into useful pressure head, enabling the pump to maintain high pressure rise even when conveying fluids with high gas volume fractions where conventional designs would experience significant performance degradation.
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 implementation of swirl brakes effectively reduces rotor vibrations and maintains rotordynamic stability across the entire operating range, from low to high GVF values, while improving the hydraulic efficiency of the multiphase pump.
Implementation Method 1
at least one swirl brake is provided at the passage, and the swirl brake is configured and arranged to brake a swirl of the process fluid passing through the passage
Implementation Method 2
The physical phenomenon, on which this damping is based, is the Lomakin effect. The Lomakin effect is a force created at small gaps, e.g. at wear rings, throttling bushes or balancing devices in centrifugal pumps. The force is a result of an unequal pressure distribution around the circumference of the pump shaft during periods of rotor eccentricity or pump shaft deflection.
Implementation Method 3
The leakage flow of the process fluid through these seals or gaps counteracts vibrations and generates rotor damping. The physical phenomenon, on which this damping is based, is the Lomakin effect.
Implementation Method 4
The force is a result of an unequal pressure distribution around the circumference of the pump shaft during periods of rotor eccentricity or pump shaft deflection.
Implementation Method 5
The rotor comprises a pump shaft and at least one impeller fixedly mounted on the pump shaft
Data Source
AI summary
A multiphase pump for conveying a multiphase process fluid includes a pump housing, a stationary diffuser, a rotor and swirl brake. The rotor is arranged in the pump housing and is rotatable about an axial direction, the rotor including a pump shaft and an impeller fixedly mounted on the pump shaft. The stationary diffuser is arranged adjacent to and downstream of the impeller. The impeller includes a blade with the blade having a radially outer tip, and a ring surrounding the impeller and arranged at the radially outer tip of the blade. A passage is between the ring and a stationary part configured to be stationary with respect to the pump housing, the passage extending in the axial direction from an entrance to a discharge. The swirl brake is disposed at the passage, and configured and arranged to brake swirling of the process fluid passing through the passage.