Cryogenic Pump Inducer with Counter-Rotating Vanes
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Solution Overview
Problem
Centrifugal pumps face inefficiencies due to fluid rotation with inducer blades, leading to increased net positive suction head required (NPSHR) and potential cavitation, especially when handling cryogenic fluids, as existing designs fail to effectively manage rotational momentum and prevent fluid vaporization.
Innovation Solution
The implementation of inducer blades with a helicoid plane surface configuration and counter-rotating grooves or vanes that capture and redirect rotational momentum, forming a multi-stage system with alternating rotating and non-rotating stages to enhance fluid flow and reduce NPSHR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inducer blades are used, then the pump can operate, but fluid rotational momentum increases NPSHR and causes cavitation
Solution Approach 1:
The inducer is divided into multiple stages with alternating rotating and non-rotating blade rows. Each stage processes the fluid sequentially, with rotating blades adding pressure and non-rotating blades removing rotational momentum, thereby reducing NPSHR and preventing cavitation through staged pressure increase
Solution Approach 2:
Instead of having all blades rotate in the same direction, the invention uses counter-rotating blade rows where non-rotating blades rotate in the opposite direction to the rotating blades. This counter-rotation removes excess rotational momentum from the fluid, reducing NPSHR while maintaining pressure increase
2Productivity
If fluid rotational momentum is not managed, then pump operation is simple, but NPSHR increases and efficiency decreases
Solution Approach 1:
The inducer system dynamically manages fluid rotational momentum by alternating between rotating and non-rotating blade rows. The rotating blades impart momentum while non-rotating blades remove it, creating a dynamic balance that optimizes pressure increase while minimizing NPSHR and maximizing efficiency
3Reliability
If pressure increase is not smooth, then pump structure is simple, but cavitation occurs and fluid vaporizes
Solution Approach 1:
The pressure increase process is segmented into multiple stages, with each rotating blade row contributing a portion of the pressure increase. This staged approach ensures smooth, gradual pressure rise that prevents sudden vaporization and cavitation, while the modular structure remains manageable in complexity
Solution Approach 2:
The rotating blade rows preliminarily increase pressure before the fluid enters subsequent stages. By progressively building pressure in predetermined stages, the system ensures that pressure always remains above vapor pressure, preventing cavitation before it can occur
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 configuration increases upward fluid flow, minimizes NPSHR, and prevents cavitation, allowing for more efficient pumping of cryogenic fluids by maintaining a lower suction head and ensuring smooth pressure increase, thereby extending pump lifespan and efficiency.
Implementation Method 1
inducer blades with a helicoid plane surface configuration and counter-rotating grooves or vanes that capture and redirect rotational momentum
Implementation Method 2
Noncavitating inducers are used to pressurize the flow of the input fluid sufficient to enable the devices to which the inducer is attached to operate efficiently
Implementation Method 3
counter-rotating grooves or vanes that capture and redirect rotational momentum
Data Source
AI summary
An inducer for vertical flow, cryogenic liquid centrifugal pumps comprising a stationary outer housing portion having an inlet and an outlet, the inlet located at a lower end and the outlet located at an upper end, the housing further having an inner wall portion with one or more spiral vanes projecting outwardly from the inner wall portion, the one or more spiral vanes defining one or more gap regions on the inner wall portion that spiral in a first direction, and an inner rotating impeller mounted on a rotating center shaft, the impeller having at least one curved blade which defines a curved, helicoid plane surface in which the slope of the plane increases as the distance from the center axis increases, the impeller rotating in a second direction which is in counter rotation to the first direction.