Turbomachine Combustion Chamber Perforated End Wall Cooling
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Solution Overview
Problem
Existing cooling solutions for combustion chambers in turbomachines with centrifugal compressors are inefficient, as they require sectorized deflectors that consume excessive cooling air and lead to uneven wall temperatures, and previous perforation-based solutions fail to adequately cool the inner wall without increasing airflow, which can result in inefficiencies and unburnt species production.
Innovation Solution
An annular combustion chamber design with a chamber end wall featuring cooling-air supply perforations inclined at angles greater than 60°, with a higher density of perforations directed away from the diffuser outlet to ensure uniform cooling of both inner and outer walls, eliminating the need for deflectors and optimizing airflow for efficient cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If sectorized deflectors are used to protect the chamber end wall from thermal radiation, then the wall is protected from intense heat, but the cooling air consumption increases excessively and the device complexity increases
Solution Approach 1:
The patent removes the deflector component entirely from the combustion chamber design. Instead of using deflectors to protect the end wall from thermal radiation, the invention uses a perforated end wall with optimized cooling air injection to directly cool the wall surface, eliminating the need for separate protective deflectors and reducing cooling air consumption.
Solution Approach 2:
The chamber end wall is designed with multiple perforations that allow cooling air to pass through and directly cool the wall surface. This porous-like structure enables efficient heat transfer from the combustion zone to the cooling air, replacing the solid deflector approach and reducing the cooling air flow rate required.
2Temperature
If deflectors are used to cool the chamber end wall, then the wall is protected from thermal radiation, but the device complexity and mass of metal increase
Solution Approach 1:
The patent eliminates the deflector component from the combustion chamber design. The end wall is cooled directly through perforations without requiring separate deflectors, simplifying the overall structure and reducing the mass of metal components while maintaining effective cooling.
Solution Approach 2:
The perforated end wall serves multiple functions simultaneously: it provides structural closure for the combustion chamber, enables cooling air injection, and facilitates heat transfer to the cooling air. This multi-functionality replaces the separate deflector component, reducing device complexity.
3Quantity of substance
If multiple perforations are used to cool the chamber end wall without deflectors, then the cooling air flow rate is reduced, but the inner wall may be insufficiently cooled and could become burnt
Solution Approach 1:
The patent implements non-uniform perforation distribution in the end wall, with different numbers of perforations in different radial zones. The outer zone has more perforations to cool the outer wall effectively, while the inner zone has fewer perforations. This localized optimization ensures adequate cooling of the inner wall without requiring excessive overall cooling air flow.
Solution Approach 2:
The perforation pattern in the end wall is asymmetric, with varying densities in different radial positions. This asymmetric distribution is optimized to match the thermal and flow conditions at different locations, ensuring effective cooling of both inner and outer walls with reduced total cooling air consumption.
4Volume of moving object
If the diffuser outlet is positioned at the periphery of the combustion chamber, then the engine size is reduced, but the outer wall is adequately cooled while the inner wall becomes insufficiently cooled
Solution Approach 1:
The patent uses non-uniform perforation distribution to address the asymmetric cooling requirements created by the peripheral diffuser outlet position. The inner zone of the end wall has optimized perforation density to ensure adequate cooling of the inner wall, while the outer zone has higher perforation density for outer wall cooling, balancing the thermal management across the entire end wall.
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 achieves uniform temperature distribution across the chamber walls with reduced cooling airflow, halving the cooling air flow rate and improving chamber efficiency by ensuring effective cooling without deflectors, while maintaining combustion mixture integrity.
Implementation Method 1
cool the chamber end wall using multiple perforations and to orient the air stream that passes through these perforations so that it sweeps over the inside of the chamber end wall
Implementation Method 2
Air is therefore introduced via orifices made in the chamber end wall behind deflectors in order to cool them. This air flows along the rear face of the deflectors and is then guided to form a film along the interior face of the outer and inner walls of the chamber
Data Source
AI summary
An annular combustion chamber for a turbomachine, including an external wall and an internal wall which are oriented substantially axially relative to the rotation axis of the turbomachine, the combustion chamber being closed upstream by a chamber end wall oriented substantially radially, the chamber being supplied with compressed air coming from a compressor via a nozzle, the output direction of which is offset radially relative to the mid-axis of the combustion chamber, the chamber end wall including cooling air supply holes inclined to the direction normal to the chamber end wall. The number of holes oriented radially in the direction opposite to that where the outlet of the nozzle is located is greater than the number of holes oriented radially in the direction of the outlet of the nozzle.