Gas Turbine Diffuser Circumferential Gap Design
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Solution Overview
Problem
In gas turbine engines, increasing the axial dimension of the diffuser to reduce pressure loss results in a corresponding increase in the entire engine's dimension, which is undesirable.
Innovation Solution
The design incorporates a diffuser with a concentric inner and outer tube configuration and a transition duct with a gradually decreasing circumferential dimension, forming a circumferential gap between combustors, along with auxiliary elements and a concave chamber surface to ensure efficient gas flow and reduce pressure loss without increasing the engine's axial dimension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the axial dimension of the diffuser is increased to reduce pressure loss, then the pressure loss reduction is achieved, but the axial dimension of the entire gas turbine engine increases
Solution Approach 1:
The patent redirects the compressed gas flow from the diffuser outlet in the axial direction to the radial direction. This dimensional change allows the gas to flow through circumferential gaps between transition duct portions rather than requiring extended axial space, thereby reducing pressure loss without increasing the engine's axial dimension
Solution Approach 2:
The patent creates localized circumferential gaps between adjacent transition duct portions at specific locations where flow redirection is needed. These localized flow paths enable efficient gas distribution to multiple combustors without requiring a uniformly extended diffuser structure along the axial direction
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 effectively reduces pressure loss while maintaining a compact engine size by ensuring a sufficient flow path and uniform gas distribution, minimizing collisions and rotational vibrations.
Implementation Method 1
a diffuser is provided at an outlet of an axial-flow compressor, whereby static pressure of a compressed gas is recovered
Implementation Method 2
static pressure of a compressed gas is recovered, and pressure loss (mainly, dynamic pressure loss) which occurs until the compressed gas flows into a combustor is reduced
Data Source
AI summary
A gas turbine engine includes: a plurality of combustors disposed so as to incline radially outward from a turbine side toward a compressor side; and a diffuser inner tube and outer tube forming a diffuser as an upstream portion of a path that introduces a compressed gas from the compressor to the combustors. A transition duct portion of each combustor has such a shape that a circumferential dimension thereof gradually decreases from the turbine side to the compressor side so that a circumferential gap is formed between the transition duct portions. Downstream-side portions of the diffuser inner tube and outer tube each have a shape gradually increasing in diameter toward the downstream side. A turbine-side end of the circumferential gap at an inner diameter side of the transition duct portion is positioned radially inward of an imaginary extension conical surface continuous from the diffuser inner tube.