Turbine Casing Axial Grooves for Cooling Jet Separation
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Solution Overview
Problem
Existing radial clearance control means in turbine engines are inefficient due to interference between cooling air jets from offset openings, which hampers thermal exchange and casing cooling.
Innovation Solution
The use of a casing with axial grooves that alternate between first and second grooves, allowing air jets from annular duct openings to be channeled and preventing interference between jets from different rows, thereby increasing the number of openings on a given surface area while maintaining manufacturing constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the number of openings for injecting cooling air is increased, then the cooling efficiency of the casing is improved, but the manufacturing complexity increases due to minimum centreline distance constraints
Solution Approach 1:
The patent transitions from a single-row arrangement of openings to a multi-row annular configuration, utilizing the circumferential dimension to increase the number of openings without violating the minimum centreline distance constraint. This dimensional change allows more openings to be packed into the available surface area while maintaining adequate spacing between adjacent openings.
Solution Approach 2:
The openings are segmented into multiple annular rows with circumferential offset, where each row contains openings spaced at minimum centreline distance intervals. This segmentation allows the total number of openings to be increased by distributing them across multiple rows rather than concentrating them in a single row, thereby improving cooling efficiency without exceeding manufacturing constraints.
2Quantity of substance
If annular rows of openings are arranged with circumferential offset, then the number of openings per surface area is increased, but jet interference between neighbouring rows increases
Solution Approach 1:
The patent introduces axial grooves as intermediary structures between the cooling air jets originating from different annular rows. These grooves act as physical separators that prevent direct interference between adjacent jets, allowing multiple rows of openings to be arranged with circumferential offset while maintaining effective cooling performance.
Solution Approach 2:
The axial grooves segment the flow paths of cooling air jets from different annular rows, creating distinct flow channels that prevent mutual interference. This segmentation allows the openings to be arranged in multiple circumferentially offset rows without the harmful jet interactions that would otherwise occur.
3Temperature
If axial grooves are added to channel cooling air jets, then jet separation and cooling efficiency are improved, but the device complexity increases
Solution Approach 1:
The axial grooves are implemented as localized features on the casing surface rather than complete structural modifications. By placing grooves only at specific locations where jet interference occurs, the patent improves thermal exchange efficiency while adding minimal structural complexity compared to a complete redesign of the casing geometry.
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 significantly improves the thermal exchange coefficient and casing cooling efficiency by minimizing jet interference, enhancing the overall performance of the turbine engine.
Implementation Method 1
flows cooling air sourced from another part of the turbine engine. Such annular ducts are provided with openings for injecting cooling air onto the outer surface of the casing in order to cool it
Implementation Method 2
cool it and thus limit the thermal expansion thereof
Implementation Method 3
the openings can advantageously have an air ejection axis that is substantially orthogonal to the casing in order to implement a technique commonly called 'impingement cooling'
Data Source
AI summary
An assembly for a turbine of a turbine engine, including a casing and an annular duct surrounding the casing, which can be connected to a device for supplying cooling air, and having a radially inner annular wall provided with openings arranged opposite the casing in order to cool same by the impact of cooling-air jets. The casing has a plurality of axial grooves including first grooves and second grooves arranged in alternation, and the openings are distributed in a plurality of annular rows in which any pair of consecutive annular rows is such that the openings of one of the annular rows of the pair are centered relative to the first grooves while the openings of the other annular row of the pair are centered relative to the second grooves.