Gas Turbine Baffles for Uniform Inner Casing Cooling
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Solution Overview
Problem
The existing secondary air systems in gas turbines suffer from nonuniform temperature distribution and thermal expansion due to direct impingement of cooling air on the inner casing, leading to inefficiencies and potential deformation, as well as uneven cooling of turbine vanes and blades.
Innovation Solution
The implementation of baffles within the annular cavity deflects the cooling fluid flow, creating turbulence or rotary flow around the inner casing, preventing direct impingement and ensuring uniform temperature distribution by optimizing the placement, orientation, and shape of the baffles to steer the cooling fluid effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is directed radially inward and directly impinges on the inner casing, then cooling efficiency at the impingement region is improved, but temperature distribution uniformity deteriorates
Solution Approach 1:
The baffle acts as an intermediary element between the cooling air supply and the inner casing. It intercepts the radially inward flowing cooling air and redirects it to flow circumferentially along the inner casing surface, preventing direct impingement while ensuring uniform cooling distribution across the entire casing surface.
2Stability of the object's composition
If direct impingement cooling is used, then local cooling effectiveness is improved, but thermal expansion uniformity deteriorates
Solution Approach 1:
The baffle creates a uniform circumferential flow pattern that distributes cooling效果 evenly across different regions of the inner casing. This ensures that each local region receives appropriate cooling, preventing localized thermal expansion variations and maintaining overall structural stability.
3Productivity
If cooling air flow velocity is increased to improve cooling, then cooling effectiveness is improved, but flow nonuniformity deteriorates
Solution Approach 1:
The baffle transforms the cooling air flow from a purely radial direction to a circumferential direction along the inner casing. This dimensional change in flow direction allows the cooling air to travel along the casing surface, distributing thermal energy more uniformly across the entire circumference while maintaining high cooling effectiveness.
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 solution achieves a more uniform temperature distribution and thermal expansion across the inner casing, enhancing the cooling efficiency and preventing deformation, while ensuring balanced velocity and pressure distribution for improved cooling of turbine components.
Implementation Method 1
baffles deflect the cooling fluid flow and may either create turbulence or a rotary flow around the inner casing
Implementation Method 2
baffles are configured to intercept at least part of the cooling fluid flow fed through the respective cooling inlets and to prevent the intercepted cooling fluid flow from directly impinging on the inner casing
Implementation Method 3
The cooling fluid is steered by the baffle plates by vortices at the edges of the baffles or by deflection
Implementation Method 4
irregular heat exchange with the inner casing is avoided and temperature distribution is made more uniform
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A gas turbine includes: a compressor section (2) and a turbine section (5) extending along an axis (A); an outer casing (10) and an inner casing (11), delimiting an annular cavity (13) between one another in the turbine section (5); a cooling circuit (7), configured to direct a cooling fluid flow (F) from the compressor section (2) to the annular cavity (13) of the turbine section (5) through cooling inlets (17) in the outer casing (10); and baffles (20) arranged in the annular cavity (13) between respective cooling inlets (17) and the inner casing (11) and configured to intercept at least part of the cooling fluid flow (F) fed through the respective cooling inlets (17) and to prevent the intercepted cooling fluid flow (F) from directly impinging on the inner casing (11).