Gas Turbine Blade Shroud Cooling Protrusion
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Solution Overview
Problem
Existing gas turbine cooling arrangements for blade shrouds and heat shields are inefficient in separating cooling airflow from hot gas flow, leading to reduced cooling effectiveness and increased operating temperatures, which can shorten the operational lifetime and reduce efficiency.
Innovation Solution
A cooling arrangement featuring a protrusion on the blade shroud that divides the circumferential cavity into two spaces, with openings for the cooling flow in the radially outer space, allowing the cooling fluid to follow a vortex path and minimizing the mixing of hot gas and cooling flows, thereby maintaining a lower temperature and improving cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is directed to the blade shroud and heat shields, then the cooling effectiveness is improved, but the mixing of cooling flow with hot gas flow increases, reducing cooling efficiency
Solution Approach 1:
The circumferential cavity is divided into two separate spaces by a protrusion extending from the blade shroud: a first space for cooling flow and a second space for hot gas flow. This segmentation prevents mixing between the two flows while maintaining effective cooling of the blade shroud and heat shields.
Solution Approach 2:
The protrusion acts as an intermediary structure that physically separates the cooling flow path from the hot gas flow path. It serves as a barrier that directs cooling flow through the first space while allowing hot gas to flow through the second space, preventing direct contact and mixing between the two flows.
2Temperature
If cooling flow pressure is increased to reach the leading edge of the shroud, then cooling effectiveness is improved, but the complexity of the cooling arrangement increases
Solution Approach 1:
The protrusion is pre-positioned in the circumferential cavity to create the first space that directly receives cooling flow through openings in the cavity wall. This preliminary structural arrangement guides the cooling flow along a vortex path to the leading edge of the blade shroud, eliminating the need for high pressure requirements and complex cooling system design.
3Productivity
If the blade shroud is fully shrouded to minimize hot gas leakage, then turbine efficiency is improved, but the operating lifetime is reduced due to high temperatures
Solution Approach 1:
The cavity space is segmented into two distinct flow paths: one for cooling air and one for hot turbine gas. This allows the blade shroud to maintain its fully shrouded configuration for maximum turbine efficiency while simultaneously receiving effective cooling protection, thereby extending operating lifetime.
Solution Approach 2:
Different regions of the circumferential cavity are assigned different functions: the first space (radially outer) is dedicated to cooling flow with openings in the cavity wall, while the second space (radially inner) handles hot gas flow. This local differentiation enables simultaneous optimization of cooling effectiveness and turbine efficiency.
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 enhances the cooling effectiveness of the shroud and heat shields, extends the operating lifetime of the blade, and reduces the necessary cooling fluid usage, improving the overall efficiency of the gas turbine.
Implementation Method 1
the cooling fluid flow is separated from the hot gas flow in the turbine flow channel and is led into a vortex flow within the first space
Implementation Method 2
cooling arrangement for the cooling of the blade shrouds
Data Source
Figure 1
Figure 2~3
AI summary
A gas turbine comprises an inner casing (3) and a rotor (1) having rotating blades (5) with a shroud (7) and a fin (8), and a cooling arrangement arranged in a cavity (9) in the casing (3) and about the rotating blade (5). According to the invention, the blade shroud (7) comprises a protrusion (12) extending away from the blade leading edge (te5) into the cavity (9) and openings (11') in the cavity wall (9a) for a cooling fluid. The protrusion (12) is defined by angles in relation to the flow channel wall (4'). The protrusion (12) effects a vortex flow of cooling fluid entering through the openings (11') and a vortex flow of hot gas entering from the flow channel (4) into the cavity (9). The double-vortex formation reduces a mixing of the cooling flow with the hot gas flow and increases the efficiency of the cooling arrangement of the blade shroud and cavity walls.