Axial Balancing System for Pump Impeller
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Solution Overview
Problem
Current axial balancing systems for pumps and compressors, particularly in aerospace turbomachines, require precise calculations and tests to define the dimensions and geometry of the fluid flow restricting passage, making the calibration process time-consuming and costly, and difficult to control radial play while avoiding contact between the casing and rotor.
Innovation Solution
The system includes a centrifugal wheel with a second balancing portion that moves from a rest position to an operating position under centrifugal force, overlapping with a first balancing portion to form a controlled axial clearance, allowing for better calibration of the fluid flow rate in the restricting passage, and features an expansion portion with a lattice structure or anisotropic material for simplified assembly and enhanced axial balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dimensions and geometry of the restrictive passage are precisely defined to optimize axial balancing, then the axial balancing performance is improved, but the time and cost for calculations and tests increase significantly
Solution Approach 1:
The invention changes the geometric parameters of the balancing portions, specifically defining the axial length and radial thickness relationships. By setting the axial length of the first balancing portion to be between 0.5-2 times the radial thickness of the second balancing portion, the system achieves optimal axial balancing performance through standardized parameter ranges rather than requiring exhaustive calculations for each specific case
Solution Approach 2:
The invention performs preliminary action by pre-defining the geometric relationships and dimensional ratios of the balancing portions before actual pump assembly. The standardized design criteria for the balancing portions allow manufacturers to prepare optimized geometries in advance, eliminating the need for time-consuming tests during the assembly or operation phase
2Reliability
If the restrictive passage dimensions are precisely controlled to limit contact risk between casing and rotor, then the reliability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The invention segments the axial balancing function into two separate balancing portions: a first balancing portion on the casing and a second balancing portion on the rotor. This segmentation allows each portion to be manufactured independently with standard tolerances, and their combined geometric relationship (axial length and radial thickness ratios) ensures proper clearance control without requiring ultra-precise manufacturing of the restrictive passage itself
Solution Approach 2:
The balancing portions act as intermediary elements between the casing and rotor. By introducing these intermediate balancing structures with defined geometric relationships, the system mediates the clearance control function, preventing direct contact between the casing and rotor while avoiding the need for extremely precise manufacturing of the restrictive passage dimensions
3Measurement precision
If the second balancing portion is positioned close to the first balancing portion to form the restrictive passage, then the flow rate calibration is improved, but the risk of contact between casing and rotor increases
Solution Approach 1:
The invention resolves the spatial conflict by utilizing multiple dimensions: the first balancing portion extends in the axial direction while the second balancing portion extends in the radial direction. The restrictive passage is formed at the intersection of these two dimensional extensions, allowing precise flow rate calibration through the axial length of the first portion and radial thickness of the second portion, while the perpendicular dimensional arrangements maintain adequate clearance to prevent contact
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 simplifies the mounting process, reduces the risk of contact, and effectively calibrates the fluid flow rate, ensuring better axial balancing of the pump or compressor while maintaining control over axial clearance and minimizing the complexity of the assembly process.
Implementation Method 1
the second balancing portion of the centrifugal wheel being configured to pass from a rest position, in which the first and second balancing portions are at a distance, to an operating position in which the first and second balancing portions overlap in the axial direction, under the effect of the force exerted on the rotating centrifugal wheel
Data Source
Figure 1~2
Figure 3~5
AI summary
The present description relates to a pump (11) or compressor for the flow of a fluid, comprising a casing (13), a centrifugal impeller (15), configured to be rotationally driven with respect to the casing (13) about a main axis defining an axial direction (DA), a restrictive fluid-flow passage formed between the casing (13) and the centrifugal impeller (15) defining an axial balancing system (19), the casing (13) comprising a first balancing portion (23) and the centrifugal impeller (15) comprising a second balancing portion (29), the first and second balancing portions (23, 29) defining the inlet of the restrictive flow passage, the second balancing portion (29) of the centrifugal impeller (15) being configured to pass from a rest position, in which the external diameter of the second balancing portion (29) is less than the internal diameter of the first balancing portion (23), to an operating position in which the first and second balancing portions (23, 29) overlap in the axial direction (DA), under the effect of the centrifugal force applied to the rotating centrifugal impeller (15).