Apertured Leaf Seal for Symmetric Pressure Distribution
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Solution Overview
Problem
Existing leaf seals in gas or steam turbines face challenges in achieving symmetric pressure distribution, leading to unbalanced lifting forces and poor sealing performance due to asymmetric pressure distribution, which is difficult to maintain accurately, especially in production environments.
Innovation Solution
The design incorporates apertured front and back plates in an annular carrier to ensure a symmetric pressure drop across the leaves, reducing sensitivity to precise plate and leaf location, with axial gas flow and optional in-turned lips to enhance even pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If equal gaps between leaves and front/back plates are used to achieve symmetric pressure distribution, then sealing performance is improved, but manufacturing precision and location accuracy become extremely difficult to maintain
Solution Approach 1:
The patent changes the geometric parameters of the plates by introducing apertures with specific area ratios. The front plate aperture area is designed to be 0.5-2.0 times the back plate aperture area, creating asymmetric aperture geometry that compensates for gap variations and maintains symmetric pressure distribution without requiring precise gap equality
Solution Approach 2:
The apertures in the front and back plates act as intermediary flow control elements. By regulating fluid flow through these apertures, the patent mediates the pressure distribution across the leaves, ensuring symmetric pressure even when the physical gaps between leaves and plates vary due to manufacturing tolerances
2Force
If asymmetric pressure distribution occurs in the leaf seal, then the lifting force becomes unbalanced, but achieving symmetric pressure distribution through equal gaps is difficult to maintain in production
Solution Approach 1:
The patent modifies the plate structure by adding apertures with controlled area ratios. This parameter change allows the system to achieve balanced lifting forces through flow regulation rather than relying on difficult-to-maintain equal gaps, making the solution feasible for mass production
Solution Approach 2:
The patent deliberately introduces asymmetric aperture areas in the front and back plates (front aperture area = 0.5-2.0 times back aperture area) to compensate for asymmetric gap variations. This controlled asymmetry in aperture design creates symmetric pressure distribution and balanced lifting forces, resolving the contradiction between force balance and manufacturability
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 solution achieves a symmetric pressure distribution across the leaves, reducing the impact of variations in gap sizes and improving sealing performance by stabilizing the lifting force, thus enhancing the sealing efficiency between the stator and rotor.
Implementation Method 1
the apertures dimensioned for providing a substantially symmetric pressure drop across the leaves
Implementation Method 2
when the rotor rotates the free tips of the leaves experience hydro-dynamic lift so that the leaves are held just off the surface of the rotor
Data Source
AI summary
This invention relates to a seal for sealing between a stator and rotor, including a generally annular carrier, an array of adjacent leaves mounted in the annular carrier for sealing between the stator and the rotor with their panes lying parallel to the axis of the carrier and front and back plates disposed on respective axial sides of the leaves, characterized in the front and back plates have one or more apertures dimensioned for providing a substantially symmetric pressure drop across the leaves.