Stepped Turbomachinery Seal Face for Adaptive Balance Ratio
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Solution Overview
Problem
Conventional turbopump seals in rocket engines have fixed balance ratios that do not adapt to manufacturing tolerances or operational variations, leading to undesirably short lifespan and/or excessive leakage.
Innovation Solution
A self-optimizing seal system with a ring element featuring a stepped surface that passively adjusts its balance ratio by wearing away steps with different surface areas to maintain an optimal sealing performance under varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher balance ratio is used to reduce leakage, then sealing performance is improved, but seal wear increases
Solution Approach 1:
The seal face is designed with a stepped topology that allows the balance ratio to dynamically change during operation. As the seal operates, wear progresses through the steps, automatically adjusting the balance ratio to maintain optimal sealing performance throughout the seal's lifespan, rather than being fixed at a single ratio.
Solution Approach 2:
The invention changes the balance ratio parameter over time through the stepped face design. Each step represents a different balance ratio, and as wear progresses from one step to the next, the balance ratio parameter automatically adjusts to compensate for wear and maintain sealing effectiveness.
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 stepped face design enables the balance ratio to dynamically adapt as wear progresses. Starting with a higher balance ratio for immediate sealing performance, the system automatically transitions through intermediate steps to lower balance ratios that extend lifespan, maintaining the optimal balance between sealing and wear throughout operation.
Solution Approach 2:
The stepped face is pre-configured with multiple balance ratio levels that anticipate future wear conditions. Before wear occurs, the design already incorporates the sequence of balance ratio adjustments needed to maintain optimal performance throughout the seal's operational life.
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 operational variations
Solution Approach 1:
Different zones of the seal face (represented by different steps) have different balance ratio properties. This local differentiation allows each zone to be optimized for specific operating conditions, with the system automatically selecting the appropriate zone based on wear progression and operational requirements.
Solution Approach 2:
The seal face is segmented into multiple steps, each with a different balance ratio. This segmentation allows the seal to function as multiple seals in sequence, with each step handling specific wear and operational conditions, thereby adapting to variations without requiring complex active control systems.
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 seal system automatically balances wear and leakage by adapting its balance ratio, extending lifespan and reducing debris production by a factor of two compared to conventional seals.
Implementation Method 1
The first sealing surface is positioned and configured to wear away to expose a second sealing surface of a second step. The second sealing surface has a second surface area that is different from the first surface area.
Implementation Method 2
A front side of the ring element contacts a revolving surface of a rotor to form a seal with the rotor surface
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.