Scalloped Diffuser Pipe Outlet for Vibration Mitigation
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Solution Overview
Problem
Diffuser pipes in gas turbine engines face damage from vibrations, leading to undesirable effects such as cracking, due to their exposure to vibrations and loads during operation, which existing designs fail to adequately mitigate.
Innovation Solution
The diffuser pipes are modified with a tubular body having a radial, an axial portion, and a bend portion fluidly linking them, with a scalloped pipe outlet that reduces mass and shifts the center of mass, thereby reducing bending and strain energy, and incorporating scalloped openings to further enhance vibratory response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diffuser pipes are designed with conventional smooth outlets, then manufacturing is simpler, but vibrations cause cracking and damage
Solution Approach 1:
The diffuser pipe outlet incorporates scalloped openings that create localized variations in the outlet geometry. These scallops are strategically positioned to modify the stress distribution pattern at the outlet, creating areas of reduced stress concentration that prevent crack initiation and propagation while maintaining the overall structural integrity of the pipe
Solution Approach 2:
The continuous outlet edge is segmented into multiple scalloped openings rather than maintaining a smooth continuous edge. This segmentation divides the stress distribution into multiple zones, preventing the formation of continuous stress paths that would lead to cracking, while each individual scallop maintains sufficient structural strength
2Force
If diffuser pipes operate under high vibration loads, then they can handle operational demands, but they suffer from cracking and damage
Solution Approach 1:
The outlet geometry parameters are changed by introducing scalloped openings with specific dimensions, spacing, and patterns. This modification alters the natural frequency and mode shapes of the diffuser pipe, changing its vibratory response characteristics to avoid resonance with operational excitation frequencies, thereby reducing vibration-induced stress and preventing cracking
3Stability of the object's composition
If diffuser pipes have uniform exit flow, then flame stability and combustor performance improve, but vibration-induced damage occurs
Solution Approach 1:
The scalloped openings are strategically positioned and dimensioned to create localized flow modifications that collectively achieve uniform overall flow distribution. Each scallop is designed to correct specific flow non-uniformities in its local region, and the combined effect of all scallops produces a uniformly distributed exit flow that satisfies combustor requirements while the scalloped geometry simultaneously provides vibration resistance
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 solution effectively reduces the likelihood of pipe cracking and improves fluid flow quality by minimizing bending and strain energy, raising the natural frequency of the diffuser pipes and preventing problematic vibrational modes.
Implementation Method 1
a scalloped pipe outlet that reduces mass and shifts the center of mass, thereby reducing bending and strain energy
Implementation Method 2
raising the natural frequency of the diffuser pipes and preventing problematic vibrational modes
Data Source
AI summary
A diffuser pipe is disclosed having a tubular body including a first portion extending in a generally radial direction, a second portion extending in a generally axial direction and terminating at a pipe outlet, and a bend portion fluidly linking the first portion and the second portion. The pipe outlet is scalloped.