Annular Turbine Casing Cooling via Segmented Ducts
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Solution Overview
Problem
Existing cooling devices for annular outer turbine casings in turbomachines, such as those in aeronautical engines, face inefficiencies in uniform cooling due to varying air temperatures along the circumference, leading to inconsistent performance and reduced effectiveness.
Innovation Solution
A device comprising circumferentially extending tubes with an air inlet manifold and radially inner and outer walls, featuring an intermediate wall that forms two air ducts, where cooling air is conveyed through both ducts before being discharged, with the inner duct providing thermal insulation to maintain a consistent temperature and ensure homogeneous cooling across the circumference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cooling air is conveyed through a single tube extending circumferentially around the outer casing, then the device structure is simple, but the cooling air temperature varies along the circumference leading to non-uniform cooling
Solution Approach 1:
The single tube is segmented into two separate air ducts (first air duct and second air duct) that are circumferentially offset. Each duct conveys cooling air through a different path, with the first duct positioned radially inside the second duct. This segmentation allows independent temperature control and prevents the cooling air from being overheated by the casing in any single zone, thereby achieving uniform cooling across the entire circumference.
Solution Approach 2:
The first air duct is nested radially inside the second air duct, creating a concentric arrangement. The first duct extends from the air inlet to a first circumferential position, while the second duct extends beyond it. This nested configuration allows the inner duct to provide thermal insulation to the outer duct in certain zones, preventing overheating and maintaining consistent cooling air temperature throughout the circumferential path.
2Area of stationary object
If the tube radial extension is increased to improve cooling coverage, then more areas are cooled, but the air temperature increases due to prolonged exposure to casing heat radiation
Solution Approach 1:
The cooling path is segmented into two circumferentially offset ducts, allowing the cooling air to traverse the entire circumference through distributed discharge openings rather than a single long path. This reduces the continuous exposure time to casing heat radiation while still achieving comprehensive cooling coverage.
Solution Approach 2:
The solution transitions from a single radial dimension to a multi-dimensional approach by creating circumferential offset between the two ducts. The first duct operates in an inner radial dimension while the second duct operates in an outer radial dimension, allowing simultaneous cooling of different circumferential zones with air at different thermal states.
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
The solution ensures uniform cooling of the annular outer turbine casing by maintaining a consistent temperature of the cooling air, enhancing the cooling efficiency and performance of the turbomachine by preventing overheating of the air in specific zones, thus improving the overall operational efficiency.
Implementation Method 1
the inner duct providing thermal insulation to maintain a consistent temperature
Data Source
AI summary
A device (26) for cooling an annular outer turbine casing (17) includes at least one circumferentially extending tube (27) having an air inlet intended for conveying cooling air, the tube having a radially inner wall provided with cooling air discharge openings and a radially outer wall arranged radially opposite each other, an air inlet manifold (28), the inlet of the tube opening into the manifold, the tube (27) including at least one intermediate wall extending over a circumferential portion of the tube from the air inlet, the intermediate wall being located radially between the radially inner wall and the radially outer wall, the radially inner wall and the intermediate wall forming a first air conveying duct, the radially outer wall and the intermediate wall forming a second air conveying duct extending circumferentially beyond the first air conveying duct, relative to the air inlet.