Compressor Back-Disk Seal with Calibrated Vent
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rotary machines face issues with axial loads due to gas leakage between rotor blades and the bearing housing, leading to increased rotational drag, wear, and reduced performance, as existing solutions like gas vents and speed bumps are either ineffective or limited by clearance requirements.
Innovation Solution
A rotary machine design featuring a bearing housing with a calibrated vent and a soft seal member that allows for precise control of pressure in the back-disk chamber, using an orifice to vent gas and a soft seal material to maintain tight clearances without significant wear, reducing axial loads and operational drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a speed bump is used to minimize gas flow into the back-disk chamber, then axial loads are reduced, but the clearance between the speed bump and the wall must be significant to avoid contact, which limits the effectiveness of the speed bump
Solution Approach 1:
A soft seal member is introduced as an intermediary element between the speed bump and the back-disk. This soft seal member can deform to maintain sealing contact while accommodating clearance variations, preventing gas leakage without requiring significant clearance like rigid speed bumps. The soft material acts as a mediator that resolves the conflict between achieving low gas flow (for reduced axial loads) and maintaining mechanical reliability.
Solution Approach 2:
The invention changes the material parameter of the seal from rigid (metal speed bump) to soft (elastomeric or polymeric material). This parameter change allows the seal to deform and maintain effective sealing with minimal clearance, thereby improving the effectiveness of axial load reduction while maintaining mechanical reliability through the compliant nature of the soft material.
2Force
If tight clearances are used to minimize gas leakage, then axial loads are reduced, but wear increases significantly
Solution Approach 1:
The seal material parameter is changed from hard/rigid to soft/compliant. This allows tight clearances to be maintained for minimizing gas leakage while the soft material's compliance prevents excessive wear by deforming under load rather than experiencing rigid contact wear. The soft seal member can be periodically replaced at lower cost than hard seals.
Solution Approach 2:
The soft seal member is designed as a consumable component that can be easily replaced. Rather than designing for long life with hard materials, the invention accepts that the soft seal will wear and needs periodic replacement, but this is economically acceptable given the low cost of the soft seal member compared to the overall system and the benefits of maintained sealing performance.
3Reliability
If axial-load features are tuned to minimize axial forces, then performance and functional lifetime are improved, but the complexity of the device increases
Solution Approach 1:
The axial-load management function is segmented into two independent components: the speed bump for primary gas flow control and the soft seal member for clearance sealing. This segmentation allows each component to be optimized independently and simplifies the overall design by dividing the complex axial-load control function into manageable, modular elements that can be tuned separately.
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 minimizes axial loads and maintains mechanical reliability by allowing for smaller clearances and controlled pressure drops, enhancing the performance, weight, and cost-effectiveness of rotary machines.
Implementation Method 1
The chamber wall forms one or more calibrated vents that are not impeded by moving parts. The effective size of the one or more calibrated vents is selected to limit the pressure change of the back-disk chamber through the one or more calibrated vents during normal operational conditions.
Implementation Method 2
The back-disk seal member is composed of a material significantly softer than the materials of the hub and the chamber wall.
Data Source
Figure 1
AI summary
A turbine or compressor wheel mounted in a housing. The wheel is carried on two radial bearings both mounted in a wall of the housing. The wall has a venting orifice that is not impeded by moving parts such as bearings. The wall also has a circular seal member extending toward a back-disk of the wheel with only a very small clearance.