Stepped Turbomachinery Seal for Adaptive Balance Ratio Control
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Solution Overview
Problem
Conventional seals in turbomachinery, such as turbopumps for rocket engines, face challenges with fixed balance ratios that do not adapt to manufacturing tolerances or operational changes, leading to short lifespan and excessive leakage.
Innovation Solution
A self-optimizing seal system featuring a ring element with a stepped surface that wears away during operation, adjusting the balance ratio by exposing underlying sealing surfaces with different areas, automatically balancing wear and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher balance ratio is used to reduce leakage, then sealing performance is improved, but wear on the seal increases
Solution Approach 1:
The seal face area is designed to change dynamically during operation through controlled wear of sacrificial material. The seal transitions from an initial state with higher wear resistance to a later state with optimized sealing performance as the face area decreases, allowing the system to adapt its characteristics over time rather than remaining fixed.
Solution Approach 2:
The invention changes the physical parameter of seal face area over time through controlled material removal. By designing the seal with a sacrificial layer that wears away at a controlled rate, the effective face area decreases, thereby changing the balance ratio from an initial value to a target value that optimizes sealing performance while managing wear.
2Duration of action of moving object
If a lower balance ratio is used to reduce wear, then seal lifespan is extended, but leakage increases
Solution Approach 1:
The seal begins operation with a larger face area providing lower balance ratio and reduced wear, then transitions as the sacrificial layer wears away to reveal a smaller effective face area with higher balance ratio and improved sealing, creating a dynamic adaptation to operating conditions.
Solution Approach 2:
The seal is pre-configured with a sacrificial layer of controlled thickness and composition that will wear away to expose the underlying sealing surface at the desired target face area. This preliminary structuring ensures that the wear process leads to the optimal sealing configuration without requiring active control.
3Ease of manufacture
If a fixed balance ratio is used in conventional seals, then design and manufacturing are simplified, but the seal cannot adapt to manufacturing tolerances or changing conditions
Solution Approach 1:
The seal automatically adjusts its own face area through controlled wear of the sacrificial layer, eliminating the need for external control systems or complex adjustment mechanisms. The seal self-regulates its balance ratio by wearing away material until the target face area is reached, then maintains that configuration through the low-friction coating.
Solution Approach 2:
The invention introduces a controlled parameter change in the seal face area through the wear of sacrificial material, allowing the balance ratio to evolve from an initial design value to a target operating value. This parameter evolution enables adaptation to manufacturing tolerances and changing operating conditions while maintaining manufacturing simplicity.
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 self-optimizing seal system extends the lifespan of turbomachinery seals by automatically adjusting the balance ratio, reducing wear and leakage, and maintaining performance across varying conditions.
Implementation Method 1
A biasing element can be positioned behind the ring element and configured to elastically bias the sealing surface toward the rotor surface.
Implementation Method 2
Each step is positioned and configured to wear away during operation of the machine to expose an underlying step and surface to change the sealing area and the balance ratio of the seal.
Data Source
AI summary
A representative seal system (such as a seal system for a turbopump of a rocket engine) automatically adjusts a balance ratio of a seal. The system can include a ring element encircling an axis. A front side of the ring element contacts a revolving surface to form a seal with the revolving surface. The front side can include a stepped surface having two or more steps. Each step includes a sealing surface configured to contact the revolving surface to form a sealing area that is different from a sealing area of each other sealing surface. Each step is positioned and configured to wear away during operation of the machine to expose an underlying surface to the revolving surface, to change the sealing area and the balance ratio of the seal. A representative method of operating a turbomachinery system includes changing the balance ratio of a seal while rotating a rotor.