Turbine Casing Cooling Device With Integral Tubular Sleeves
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Solution Overview
Problem
Existing cooling devices for turbine casings using air jets suffer from non-uniform air gaps between cooling lines and the casing surface, leading to incomplete cooling and potential brazing issues, resulting in reduced cooling effectiveness and increased maintenance risks.
Innovation Solution
The cooling device features a pressurized air supply housing with integral tubular sleeves that match the bottom level of the housing, ensuring a constant air gap and structural reinforcement, with air injection orifices aligned across the housing, pipes, and sleeves to maintain uniform cooling and reduce brazing stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pipe end is made rectilinear to ensure correct brazing in the socket, then the brazing quality is improved, but the air gap between the pipe and the casing skin increases and becomes non-constant, reducing cooling effectiveness
Solution Approach 1:
The cooling line is divided into multiple segments: the housing with its bottom surface, the curved pipe section, and the rectilinear end section. Each segment serves a specific function - the curved section maintains constant air gap for effective cooling, while the rectilinear end section ensures proper brazing alignment in the socket, thus resolving the contradiction between cooling effectiveness and brazing quality.
Solution Approach 2:
Different sections of the cooling line have different geometries optimized for their specific functions. The curved section follows the casing contour to maintain constant air gap, while the end section is rectilinear for brazing. This local differentiation allows each part to optimize its performance without compromising the other.
2Device complexity
If the housing does not have orifices at its ends and sockets do not have orifices, then the structural integrity and simplicity of the housing is improved, but areas Z1 appear where no air injection occurs, creating cooling gaps on the casing skin
Solution Approach 1:
The cooling function is nested across multiple components: the housing bottom, the curved pipe section, and the rectilinear end section all contribute cooling orifices. This nested arrangement ensures continuous cooling coverage across the entire casing surface, including areas that would otherwise be missed by a single-component design.
Solution Approach 2:
The cooling action is made continuous across the entire casing surface by distributing orifices along the full length of the cooling line, from the housing bottom through the curved section to the rectilinear end. This eliminates dead zones and ensures uninterrupted cooling coverage, maintaining reliable thermal protection.
3Reliability
If multiple cooling lines are arranged around the casing to provide comprehensive cooling, then the cooling coverage is improved, but the number of housings and brazing joints increases, raising the risk of premature damage
Solution Approach 1:
Multiple cooling functions are merged into a single integrated housing structure that contains multiple cooling lines. The housing serves as a common support for all cooling lines, consolidating what would otherwise be separate assemblies. This reduces the total number of external joints and connections, lowering the risk of premature failure while maintaining comprehensive cooling coverage.
4Reliability
If the air gap between the pipe and the casing is reduced to improve cooling effectiveness, then the cooling performance is improved, but the pipe must be positioned closer to the casing, increasing stress on the brazing joints during fitting and maintenance
Solution Approach 1:
The cooling line is segmented into a curved section that positions the cooling orifices close to the casing for effective cooling, and a separate rectilinear end section that provides a robust connection point for brazing. This segmentation allows the cooling section to optimize for minimal air gap while the connection section can be designed for mechanical strength and ease of assembly.
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 provides uniform cooling, increases the cooled surface area, enhances mechanical strength, and simplifies manufacturing by reducing brazing operations, thereby extending the service life of the turbine casing.
Implementation Method 1
The casing C is cooled using impact cooling technology. The pressurized air flowing through these orifices O thus provides impact ventilation of the casing C.
Data Source
AI summary
The invention relates to a device (2) for cooling a turbine casing, preferably of a low-pressure turbine of a turbomachine, with air jets, the device comprising a pressurised air supply housing (3) and at least two curved cooling pipes (40) arranged on either side of the housing (3), around and spaced apart from a part of the casing and provided with air injection holes (41), the housing comprising, in particular, a bottom (31) and two longitudinal side walls (32, 33), and the bottom being pierced by air injection holes. The device is characterised in that each of the side walls extends outwards as at least one single-piece tubular sleeve, to which a cooling pipe is joined, the bottom of the sleeve being located at the same level as the bottom of the housing at the point where they are joined together.