Combustion Chamber Cooling via Deflector Airflow Redirection
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Solution Overview
Problem
The cooling efficiency of combustion chambers in turbomachines is compromised by the presence of chimneys and penetrating parts, which obstruct the airflow and reduce the effectiveness of the cooling film formed by microperforations, leading to inadequate cooling of the annular casing downstream of the chimney.
Innovation Solution
A main air collection chamber and a deflector are introduced to capture air from upstream and inject it into the combustion chamber through openings, forming a parietal cooling film that bypasses the chimney, while a secondary air collection chamber ensures air supply to the downstream side of the penetrating part, enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If microperforations are used to form a cooling film on the annular casing, then cooling efficiency is improved, but the presence of a chimney and penetrating parts obstructs the airflow and creates zones devoid of microperforations, degrading cooling efficiency in downstream zones
Solution Approach 1:
A deflector is introduced as an intermediary element to redirect the airflow from the bypass space toward the downstream zone of the annular casing. The deflector mediates between the obstructed airflow and the cooling microperforations, ensuring that cool air reaches the downstream zone despite the presence of the chimney and penetrating parts.
Solution Approach 2:
The cooling system is differentiated into zones: upstream zones use direct bypass airflow, while downstream zones (obstructed by the chimney) receive redirected airflow through the deflector. This local differentiation allows each zone to receive appropriate cooling airflow despite the structural obstructions.
2Adaptability or versatility
If a chimney is provided for the passage of a penetrating part through the annular casing, then functionality is improved, but the chimney and penetrating part interrupt the parietal film of air and create a region devoid of microperforations, degrading cooling efficiency
Solution Approach 1:
The annular casing is segmented into upstream and downstream zones relative to the chimney. The deflector creates a separate airflow path that specifically targets the downstream zone, segmenting the cooling strategy to address the unique obstruction caused by the chimney in that specific region.
Solution Approach 2:
The deflector introduces a new spatial dimension to the airflow pattern by redirecting air at an angle toward the downstream zone. This dimensional change in airflow direction allows the cooling film to form in the shadow zone behind the chimney, where direct airflow would otherwise be blocked.
3Adaptability or versatility
If the chimney obstructs the flow of cool air in the bypass space, then structural functionality is maintained, but microperforations downstream of the chimney are under-supplied with cooling air, reducing cooling effectiveness
Solution Approach 1:
The deflector serves as a mediator that captures cool air in the bypass space upstream of the chimney and redirects it to the downstream zone. This intermediary action bypasses the obstruction created by the chimney, ensuring that microperforations in the downstream zone receive adequate cooling air supply.
Solution Approach 2:
The deflector performs preliminary action by capturing and redirecting cooling air before it reaches the obstructed downstream zone. This preliminary redirection ensures that the cooling airflow is already positioned and directed toward the microperforations downstream, compensating for the chimney's obstruction in advance.
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 improves the cooling efficiency of the annular casing by maintaining a consistent airflow and reducing thermal gradients, thereby extending the service life of the casing and optimizing the cooling of the zone downstream of the chimney.
Implementation Method 1
The main air collection chamber makes it possible to capture air coming from upstream of the chimney and to inject it, via the through-opening, into the inner volume of the combustion chamber, where this air allows for a cooling of the annular casing
Implementation Method 2
The deflector makes it possible to deviate the air injected beforehand into the inner volume of the combustion chamber via the through-opening. The deflector thus favours, in combination with the through-opening, the formation of a parietal cooling film of air circulating along the annular casing
Implementation Method 3
This configuration improves the cooling efficiency of the annular casing by maintaining a consistent airflow and reducing thermal gradients, thereby extending the service life of the casing
Data Source
AI summary
A combustion chamber for a turbomachine including an annular casing delimiting an inner volume of the combustion chamber and provided with a chimney extending to the outside of the inner volume and delimiting a passage for a penetrating part, and a bushing mounted floating on the chimney, further includes: a main air collection chamber open to the upstream arranged facing the downstream portion of the chimney; and a through-opening of the annular casing, connecting the inner volume to the main air collection chamber. The air collected by the main air collection chamber is injected into the inner volume via the through-opening and can cool an annular casing zone downstream of the chimney.