Impeller Shroud Variable Gap for Turbine Leakage Control
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Solution Overview
Problem
Existing rotational equipment, such as gas turbine engines, face challenges with leakage around the impeller rotor, which affects efficiency and requires improved designs to reduce fluid leakage and shear effects.
Innovation Solution
The design incorporates a shroud with varying gap dimensions and protrusions to minimize fluid leakage and shear, featuring a static structure with a cavity surface and an impeller rotor with a vane structure and seal elements, including a base and protrusions that project towards the static structure, and grooves that project into the static structure to manage fluid flow and thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a fixed gap is maintained between the impeller rotor and static structure, then manufacturing and operation are simplified, but fluid leakage increases and efficiency decreases
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed gap to a variable gap configuration. The gap between the impeller rotor shroud and static structure varies along the axial direction, allowing the clearance to adapt to different operational conditions. This dynamic gap design reduces fluid leakage while maintaining manufacturability, as the variable gap is achieved through simple axial positioning rather than complex mechanical adjustments.
Solution Approach 2:
The patent implements local quality by creating different gap dimensions at different locations along the impeller rotor. Specifically, the gap varies axially with different clearance values at different axial positions, optimizing fluid flow control locally rather than using a uniform gap throughout. This localized gap variation reduces overall fluid leakage while keeping the design relatively simple.
2Loss of energy
If seal elements are added to reduce leakage, then fluid leakage decreases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies the extraction principle by removing complex seal elements from the design. Instead of adding seals between the impeller rotor and static structure, the invention extracts the sealing function and achieves it through the variable gap configuration alone. This eliminates the need for additional seal components while maintaining effective leakage control, thereby simplifying manufacturing and assembly.
Solution Approach 2:
The patent uses the variable gap itself as an intermediary mechanism to achieve sealing without physical seal elements. The carefully controlled gap dimensions act as a mediator that manages fluid flow between the rotating impeller rotor and stationary structure, replacing the need for traditional seal components and reducing assembly complexity.
3Loss of energy
If the gap dimension is reduced to minimize leakage, then fluid leakage decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies partial action by implementing gap reduction only in specific critical regions rather than uniformly throughout the entire impeller rotor assembly. The variable gap design reduces clearance where it most impacts leakage, while maintaining larger gaps in non-critical areas. This selective approach minimizes leakage effectiveness while avoiding the need for high precision manufacturing across all surfaces.
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 reduces fluid leakage and shear effects, optimizing the impeller rotor's performance by minimizing fluid flow across control gaps while managing thermal expansion, thus enhancing the turbine engine's efficiency and power output.
Implementation Method 1
The first seal element projects in a first direction out from the base towards the static structure. The first seal element is separated from the static structure by a first gap. The second seal element projects in a second direction out from the base towards the static structure. The second seal element is separated from the static structure by a second gap.
Implementation Method 2
The shroud may include a base and a protrusion. The protrusion may project out from the base towards the static structure. The dimension may have a first value when measured between the base and the static structure. The dimension may have a second value when measured between the protrusion and the static structure that is less than the first value.
Implementation Method 3
A dimension of the gap changes as the gap extends along the shroud
Data Source
AI summary
An assembly is provided for a turbine engine. This assembly includes a static structure and an impeller rotor housed within the static structure. The impeller rotor includes a vane structure and a shroud. The vane structure includes a first sidewall, a second sidewall and a plurality of vanes arranged circumferentially about a rotational axis. The vanes include a first vane. The first vane includes a first portion, a second portion and a third portion. The first portion is axially between the first sidewall and the second sidewall. The second portion is radially between the first sidewall and the shroud. The third portion is radially between the second sidewall and the shroud. The shroud circumscribes the vane structure. A gap is formed by and extends between the shroud and the static structure. A dimension of the gap changes as the gap extends along the shroud.