Stiffening Rib on Gas Turbine Diffuser Pipe
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Solution Overview
Problem
Diffuser pipes in gas turbine engines are prone to vibrations and loads that can lead to undesirable results such as cracks, which existing designs fail to adequately address.
Innovation Solution
The design incorporates a stiffening rib on the diffuser pipe, positioned upstream of the bend portion, to add mass and stiffness, reducing vibratory stresses and reinforcing the pipe structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If diffuser pipes are designed with thin walls to reduce weight, then weight is reduced, but structural strength and resistance to vibratory stresses deteriorate
Solution Approach 1:
The diffuser pipe is segmented into multiple sections along its length, with each section having different wall thicknesses. The upstream portion has thinner walls to reduce weight, while the downstream portion has thicker walls to provide structural strength where needed. This segmentation allows optimization of weight and strength in different locations independently.
Solution Approach 2:
The diffuser pipe features non-uniform wall thickness distribution, with the first portion (upstream) having a first wall thickness and the second portion (downstream) having a second wall thickness that is greater than the first. This local quality variation provides enhanced structural strength at the downstream location where vibratory stresses are highest, while maintaining reduced weight at the upstream portion.
2Ease of manufacture
If diffuser pipes are made with uniform thin walls to simplify manufacturing, then manufacturing complexity is reduced, but resistance to vibratory stresses and structural integrity deteriorate
Solution Approach 1:
The diffuser pipe incorporates variable wall thickness along its length, transitioning from thinner walls in the upstream portion to thicker walls in the downstream portion. This dynamic geometric variation optimizes the structural response to vibratory stresses that vary along the pipe length, improving reliability without significantly complicating manufacturing through the use of standard forming techniques.
3Strength
If diffuser pipes are designed with adequate wall thickness to withstand vibratory stresses, then structural strength is improved, but weight increases
Solution Approach 1:
The diffuser pipe is divided into upstream and downstream portions with different wall thicknesses. The upstream portion has thinner walls where vibratory stresses are lower, reducing weight. The downstream portion has thicker walls where vibratory stresses are highest, ensuring adequate strength. This segmentation enables weight optimization without compromising structural integrity at critical locations.
4Reliability
If diffuser pipes are made with variable wall thickness to optimize strength distribution, then structural integrity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The diffuser pipe features localized variations in wall thickness, with the first portion having a first wall thickness and the second portion having a second wall thickness that is greater than the first. This local quality approach concentrates manufacturing precision requirements at specific transitions rather than requiring uniform precision throughout, making the variable thickness design more manufacturable while maintaining structural integrity.
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 stiffening rib effectively reduces vibratory stresses and enhances the dynamic response of the diffuser pipe, improving its structural integrity and reducing the likelihood of cracks during engine operation.
Implementation Method 1
The design incorporates a stiffening rib on the diffuser pipe, positioned upstream of the bend portion, to add mass and stiffness, reducing vibratory stresses and reinforcing the pipe structure.
Implementation Method 2
The stiffening rib effectively reduces vibratory stresses and enhances the dynamic response of the diffuser pipe, improving its structural integrity and reducing the likelihood of cracks during engine operation.
Data Source
Figure 1~2
Figure 3A~3C
AI summary
A diffuser pipe (20) includes a tubular body (22) defining a pipe center axis (21) extending therethrough. The tubular body (22) includes a first portion (24) extending in a first direction from an inlet (23) of the tubular body (22), a second portion (26) extending in a second direction transverse to the first direction and terminating at a pipe outlet (25), and a bend portion (28) fluidly linking the first portion (24) and the second portion (26). A stiffening rib (30) extends outwardly from an outer surface (22E) of the first portion (24) of the tubular body (22).