Turbine Impeller Cooling Air Channels for Thermal Gradient Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cooling methods for impeller disks in gas turbines, particularly at the inlets of low-pressure turbines, are insufficient in reducing thermal gradients, leading to potential deformation and reduced cooling efficiency due to high gas temperatures and inadequate cooling of the peripheral teeth.
Innovation Solution
An impeller design that includes a disk with cooling air channels covering the crests of the teeth, an annular side plate with axial tongues to direct air flow radially, and a sealing ring to prevent air from circulating at the bottom of recesses, ensuring optimal cooling of the disk crests and reducing thermal gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is directed to circulate in the bottom of recesses using a side plate, then the disk can be cooled, but the side plate deforms under thermal gradient causing reduced gas-tightness and cooling efficiency
Solution Approach 1:
The cooling system is segmented into multiple independent channels: one for cooling the disk through the side plate and another for cooling the tooth crests through axial tongues. This segmentation allows each component to be cooled independently, preventing thermal deformation of the side plate while maintaining cooling effectiveness.
Solution Approach 2:
Axial tongues project from the side plate to serve as intermediaries that direct cooling air flow. These tongues create separate cooling pathways for the tooth crests, acting as mediators between the cooling air source and the hottest parts of the disk, thereby protecting the side plate from excessive thermal gradients.
2Temperature
If cooling air circulates at the bottom of recesses, then the disk is cooled, but the peripheral teeth which are the hottest part remain insufficiently cooled
Solution Approach 1:
The cooling system applies local quality by directing cooling air to specific high-temperature zones. Axial tongues are positioned to create cooling channels that specifically target the crests of the peripheral teeth, ensuring that the hottest parts receive intensified cooling rather than uniform cooling throughout the disk.
Solution Approach 2:
The cooling approach transitions from a single-plane circulation pattern (bottom of recesses) to a multi-dimensional cooling system. Axial tongues extend in the axial dimension to create additional cooling pathways that reach the tooth crests, adding a vertical cooling component to the horizontal radial cooling.
3Temperature
If the thermal gradient in the disk is high, then the disk can handle high gas temperatures, but the thermal gradient between tooth crests and bases becomes more marked causing potential deformation
Solution Approach 1:
The cooling system segments the thermal management into separate zones: the side plate handles disk cooling while axial tongues handle tooth crest cooling. This segmentation creates independent thermal control zones that prevent excessive temperature differences between tooth crests and bases, thereby maintaining structural stability.
Solution Approach 2:
The system changes the cooling parameters by introducing additional cooling air flow paths through axial tongues. This increases the cooling capacity specifically at the tooth crests, altering the temperature distribution parameters to reduce the thermal gradient between crests and bases while maintaining the ability to handle high gas temperatures.
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 design effectively reduces radial thermal gradients, enhances cooling efficiency, and minimizes the risk of side plate deformation and loss of efficiency by directing cooling air to the hottest parts of the disk, thereby extending the service life and performance of the impeller.
Implementation Method 1
a flow of cooling air, said flow being channelled by the axial tongues along the crests of the teeth in the disk
Implementation Method 2
an annular sealing ring pressed against said first side of the disk, inside said annular cavity demarcated by the side plate and opposite the bottom of the recesses formed between the teeth of the disk, so as to prevent circulation of air at the bottom of these recesses
Data Source
AI summary
An impeller for a turbine engine which includes a disk provided with blade retention teeth, wherein associated with each tooth there is a mechanism for channelling a flow of cooling air which covers the crest of the tooth so that the latter is swept by the air flow. A turbine of turbine engine which includes an impeller of this type, and a turbine engine for aircraft which includes a turbine of this type.