Gas Turbine Compressor Diffuser Decoupling for Thermal Growth
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Solution Overview
Problem
Gas turbine engines face challenges in managing thermal growth and load transmission in centrifugal compressors, leading to stress on components like the diffuser, which can result in reduced efficiency and increased maintenance costs.
Innovation Solution
The design incorporates a decoupled diffuser and case assembly with struts and reinforcement fins to allow thermal growth of the diffuser while transferring engine loads away from the diffuser, thereby reducing stress and maintaining aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the diffuser is rigidly connected to the case assembly, then structural stability is improved, but thermal growth is constrained causing stress and reduced reliability
Solution Approach 1:
The case assembly is segmented into an outer case and an inner combustor case, with the diffuser decoupled from the outer case. This segmentation allows the diffuser to thermally grow independently while the outer case maintains structural stability, resolving the contradiction between structural stability and thermal growth accommodation.
Solution Approach 2:
A diaphragm acts as an intermediary component between the inner combustor case and the diffuser. The diaphragm blocks exposure of the diffuser to combustion chamber gases while allowing the diffuser to thermally grow, thereby protecting the diffuser from thermal stress and improving reliability without compromising structural stability.
2Temperature
If the diffuser is decoupled from the case assembly, then thermal growth is allowed, but load transmission is compromised
Solution Approach 1:
The case assembly is divided into load-bearing components (outer case, inner combustor case, struts) and a non-load-bearing diffuser. This segmentation enables the diffuser to be decoupled for thermal growth while the struts and inner combustor case maintain load transmission pathways from the impeller to the outer case.
Solution Approach 2:
The diaphragm serves as an intermediary that separates the combustion chamber from the diffuser, blocking hot gases while allowing thermal growth. This intermediary protects the diffuser from thermal stress without interfering with the load transmission function of the struts and inner combustor case.
3Force
If struts are used to transfer loads, then load transmission is improved, but device complexity increases
Solution Approach 1:
The struts serve multiple functions: they transfer loads from the inner combustor case to the outer case, provide structural support for the decoupled diffuser, and maintain the geometric relationship between components. This multi-functionality improves load transmission while minimizing the increase in device complexity.
Solution Approach 2:
The struts are integrated into the nested structure of the case assembly, with the inner combustor case positioned within the outer case and the struts connecting them. This nested arrangement allows efficient load transmission through compact structural elements, improving force transfer without proportionally increasing overall complexity.
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 enhances the durability and efficiency of the compressor by minimizing stress on the diffuser and maintaining aerodynamic performance, while allowing for thermal expansion without compromising load transfer.
Implementation Method 1
Centrifugal compressors use a rotating impeller device to increase kinetic energy in the flow path air and convert the kinetic energy into potential energy in the form of pressure as the air is forced radially outward by the impeller
Implementation Method 2
The diffuser is located downstream and radially outward of the exit of the impeller to decelerate the air delivered from the impeller smoothly and recover static pressure
Implementation Method 3
The deswirler is located downstream of the diffuser and includes vanes that redirect airflow from a circumferential and radial direction to a generally axial direction to be delivered to the combustor
Implementation Method 4
The plurality of struts may allow force loads applied to the inner combustor case during the use of the compressor to be transmitted to the outer case through the plurality of struts to avoid transmitting the force loads through the diffuser
Implementation Method 5
the diffuser may be decoupled from the case assembly and the deswirler such that the diffuser may thermally grow radially and axially relative to the case assembly and the deswirler
Data Source
AI summary
A compressor adapted for use in a gas turbine engine includes an impeller, a diffuser, and a deswirler. The impeller is arranged circumferentially about an axis and configured to rotate about the axis. The diffuser is arranged circumferentially around the impeller to receive the air from the impeller. The deswirler is configured to receive the air from the diffuser and to conduct the air into a combustion chamber.