Impingement Cooled Wall Flow Diverter for Gas Turbine
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Solution Overview
Problem
Current impingement cooling methods for gas turbine duct walls face efficiency penalties due to increased cross-flow velocity, which diverts jets away from the wall, reducing heat transfer coefficients and leading to non-homogeneous heat loads, particularly in combustion chambers with inclined walls causing 'hot spots'.
Innovation Solution
The impingement cooled wall arrangement incorporates a flow diverter in the cooling flow path to divert cross-flow away from subsequent apertures, maintaining effective impingement cooling by separating the cooling process into impingement-cooled and convectively-cooled sections, with adjustable cross-sections and flow path heights to manage flow velocities and minimize pressure losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the number of impingement rows is increased towards the end of the cooling flow path, then the cooling coverage of the wall is improved, but the cross flow in the cooling channel builds up and diverts the impingement jets away from the wall, lowering the heat transfer coefficients
Solution Approach 1:
The cooling channel is divided into multiple cooling sections with impingement rows, and flow diverters are strategically placed between sections to segment the cross flow. This segmentation allows each impingement row to maintain effective jet impingement on the wall while the flow diverter redirects the cross flow to prevent accumulation and jet diversion in subsequent sections.
Solution Approach 2:
Flow diverters are introduced as intermediary structures in the cooling channel. These diverters act as mediators that redirect the cross flow away from subsequent impingement rows, preventing the cross flow from diverting the impingement jets away from the wall while still allowing the cross flow to provide convective cooling.
2Speed
If the height of the cooling channel is increased to limit the cross flow velocity, then the cross flow is reduced, but the impingement effect of the jet reaching the duct wall is reduced
Solution Approach 1:
Rather than uniformly increasing the cooling channel height, the invention segments the channel into multiple sections with impingement rows. Each section maintains an optimized height for impingement effectiveness, while flow diverters between sections manage the cross flow velocity without compromising the impingement effect in any given section.
Solution Approach 2:
The cooling channel height and cross-section are optimized locally in each cooling section to maintain effective impingement, rather than uniformly increasing the height throughout. Flow diverters are strategically placed at specific locations where cross flow accumulation occurs, allowing local management of cross flow velocity without affecting impingement effectiveness in other sections.
3Area of stationary object
If compressed gas is injected through multiple impingement rows along the wall, then the cooling coverage is improved, but the cross flow builds up and hinders the heat transfer coefficients of subsequent impingement rows
Solution Approach 1:
The impingement cooling system is segmented into multiple independent cooling sections, each with its own impingement row and flow diverter. This segmentation allows each section to maintain high heat transfer coefficients by preventing cross flow accumulation, while the overall system achieves extensive cooling coverage through the series arrangement of multiple sections along the wall.
Solution Approach 2:
Flow diverters are placed between impingement rows as intermediary structures that redirect the cross flow generated by upstream impingement rows. This prevents the cross flow from accumulating and hindering the heat transfer coefficients of downstream impingement rows, allowing multiple rows to operate effectively in sequence.
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 arrangement maintains high cooling efficiency along the wall, enhances heat transfer coefficients, and reduces pressure losses by optimizing flow velocities and mixing, effectively addressing the inefficiencies and hot spots in traditional impingement cooling systems.
Implementation Method 1
compressed gas injected from the plenum through first apertures in the cooling sleeve impinges on the wall
Implementation Method 2
generate an array of air jets which impinge on and cool the outer surface of the wall
Implementation Method 3
After impingement the compressed gas flows as cooling gas in a cooling path delimited by the wall and the impingement sleeve towards an end of cooling flow path
Data Source
AI summary
An impingement cooled wall arrangement includes a flow diverter arranged in the cooling flow path between the cooled wall and a sleeve to divert a cross flow away from a second aperture. The flow diverter extends in downstream direction of the cross flow beyond the second aperture with a first leg extending along one side of the second aperture in downstream direction of the cross flow and a second leg extending along the other side of the second aperture. No impingement cooling aperture is arranged in a first convective cooling section of the wall between the upstream end and downstream end of the flow diverter outside the section shielded by the diverter.