Cooling-Air Injection Casing for High-Tangential Turbomachine Flow
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Solution Overview
Problem
Existing turbomachine ventilation circuits extract cooling air from both radially below the combustion chamber and downstream of the compressor disk, resulting in reduced performance due to mixing of air with low tangential speed, which diminishes cooling effectiveness.
Innovation Solution
An annular cooling-air injection casing with separate air intake, mixing, and bleeding cavities, utilizing sealing gaskets and fluid communication paths to route high-tangential-speed air for efficient cooling, bypassing low-speed air extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air is extracted downstream of the last stage of the compressor disk for cooling, then the cooling circuit can operate, but the tangential speed of the cooling air is low which reduces cooling effectiveness
Solution Approach 1:
The invention segments the cooling air extraction into two separate circuits: one extracting air radially below the combustion chamber (high tangential speed) and another extracting air downstream of the compressor disk (low tangential speed). By separating these extraction points and using independent passage cavities, the system maintains the necessary cooling air flow while preserving the high tangential speed characteristics of the primary cooling air.
Solution Approach 2:
The air passage cavity acts as an intermediary element that selectively routes cooling air from the air mixing cavity to the air bleeding cavity. This intermediary structure enables the system to maintain fluid communication between cavities while controlling the tangential speed characteristics of the cooling air through strategic aperture placement in the radial and axial walls.
2Reliability
If air from two different sources is mixed for cooling, then the cooling cycle can be maintained, but the mixing diminishes the overall cooling effectiveness
Solution Approach 1:
The invention segments the air flow paths into distinct cavities (air intake cavity, air mixing cavity, air passage cavity, air bleeding cavity) with controlled fluid communication. This segmentation allows the system to maintain separate high-tangential-speed and low-tangential-speed air streams while ensuring minimal mixing, thereby preserving cooling effectiveness.
Solution Approach 2:
Different regions of the cooling system are assigned different air sources with different tangential speed characteristics. The air intake cavity receives high-tangential-speed air radially below the combustion chamber, while the air bleeding cavity receives low-tangential-speed air downstream of the compressor disk. This local differentiation optimizes cooling effectiveness in critical areas.
3Productivity
If air extraction downstream of the compressor disk is reduced, then cooling effectiveness improves, but the risk of pumping phenomenon increases
Solution Approach 1:
The invention segments the air extraction system into two independent circuits, allowing the downstream compressor disk extraction to be minimized for pumping prevention while the radial below combustion chamber extraction provides the primary cooling air flow. This segmentation enables the system to maintain adequate cooling effectiveness without excessive reliance on the low-tangential-speed air source.
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
Enhances cooling efficiency by maintaining high-tangential-speed air for effective cooling without mixing with low-speed air, reducing pressure loss and improving turbomachine performance.
Implementation Method 1
the air passage cavity being in fluid communication with the air mixing cavity via apertures made in the substantially axial wall, and in that the air passage cavity is in fluid communication with the air bleeding cavity by means of apertures made in the substantially radial wall
Implementation Method 2
the presence of the first sealing gasket, also called the upstream sealing gasket, and of the second sealing gasket, also called the downstream sealing gasket, will allow ensuring that the air intake cavity retains a higher pressure than that of the air bleeding, air passage and air mixing cavities
Implementation Method 3
during operation, the air bleeding cavity is under reduced pressure due to its proximity with the trailing edge of the high-pressure guide nozzle
Implementation Method 4
the air extracted downstream of the last stage of the compressor disk has a low tangential speed. Yet the cooling of the rotor blades is all the better when the tangential speed of the cooling air is high
Data Source
AI summary
The invention relates to a cooling-air injection casing (100) comprising a casing upstream end (30a), a casing downstream end (30b), and a casing main wall (30) and further comprising:an air mixing cavity (41);an air intake cavity (42);an air bleeding cavity (44);a first sealing gasket (51);a second sealing gasket (52);the injection casing having further an air passage cavity (43) bounded by a substantially radial wall (33), the casing main wall (30) and the substantially axial wall (32), the air passage cavity (43) being in fluid communication with the air mixing cavity (41) via apertures (62) made in the substantially axial wall (32), and in that the air passage cavity (43) is in fluid communication with the air bleeding cavity (44) by means of apertures made in the substantially radial wall (63).