Gas Turbine Inner Casing Reinforcing Pad for Thermal Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing strut design in gas turbine engine diffuser-combustor assemblies experiences thermal mismatch and torque issues due to uneven temperature distribution of hot, compressed air, leading to ring-strut-ring thermal fighting and inefficiencies in air flow conversion.
Innovation Solution
Incorporating a reinforcing-pad outside the flowpath of hot, compressed air, circumferentially aligned with the strut, to provide additional structural support and distribute torque forces, while maintaining the strut's cross-sectional area to minimize pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a strut is positioned in the flowpath of hot compressed air to create a pre-diffuser, then the air flow conversion efficiency is improved, but thermal mismatch and torque issues occur due to uneven temperature distribution
Solution Approach 1:
A reinforcing pad is introduced as an intermediary component between the strut and the inner ring. This pad acts as a stress-distributing mediator that reduces the thermal mismatch forces transmitted to the strut, thereby improving reliability without compromising the air flow conversion efficiency of the strut itself.
Solution Approach 2:
The reinforcing pad is strategically positioned only at the critical stress concentration point where the strut connects to the inner ring. This localized reinforcement provides thermal stress management precisely where needed, without adding unnecessary weight or complexity to the entire strut assembly.
2Strength
If the strut cross-sectional area is increased to handle thermal stresses, then structural strength is improved, but pressure drop increases
Solution Approach 1:
Instead of increasing the strut's cross-sectional area throughout its entire length, the reinforcing pad provides localized strength enhancement only at the stress-critical connection point. This maintains the strut's original cross-sectional area in the flowpath, preventing pressure drop while still improving structural strength where thermal stresses are highest.
Solution Approach 2:
The reinforcing pad serves as an intermediary that transfers and distributes thermal stresses away from the strut body. This allows the strut to maintain its original dimensions and minimize pressure drop while the pad handles the additional structural strength requirements through stress distribution.
3Reliability
If additional structural support is added to the inner casing, then resilience to thermal and torque stresses is improved, but weight increases
Solution Approach 1:
The reinforcing pad provides targeted structural support only at the specific location where thermal and torque stresses are most severe (the strut connection point). This localized approach significantly improves inner casing resilience without the weight penalty of adding support structures throughout the entire inner casing assembly.
Solution Approach 2:
Rather than providing uniform reinforcement across the entire inner casing, the design applies partial reinforcement only where absolutely necessary. This minimal yet sufficient approach achieves the required resilience improvement while keeping weight additions to an absolute minimum.
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 reinforcing-pad enhances the inner casing's resilience to handle thermal and torque-related stresses, reducing ring-strut-ring thermal fighting and maintaining operational efficiency by ensuring consistent air flow conversion without significant weight addition.
Implementation Method 1
the temperature of the hot, compressed air exiting the compressor may not be equal along an axis extending between the inner and outer-ring of the inner casing, and thus also along a radial axis of the strut that extends between the inner-ring and outer-ring of the inner casing. Thus, the strut may experience a differing expansion or contraction rate than the inner and outer-rings.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An inner casing (66) for a diffuser-combustor assembly (60) of a gas turbine engine (20) is disclosed. The inner casing (66) may include an outer-ring (78), an inner-ring (96) circumscribed by the outer-ring (78), and a strut (100) having a body (108) extending between the inner-ring (96) and the outer-ring (78). In addition, the inner casing (66) may include a reinforcing-pad (110).