Turbine Blade Platform Groove for Cooling Airflow Guidance
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Solution Overview
Problem
High-temperature blades in turbomachines, particularly in high-pressure turbojet engines, face challenges in cooling the critical trailing edge area due to inefficient air flow distribution, leading to increased operating temperatures, mechanical stresses, and reduced service life.
Innovation Solution
Incorporating a groove along the lower surface of the blade's platform near the trailing edge, where air injection passages guide cooling air along the intrados, preventing flow separation and enhancing cooling efficiency of the critical connection part between the trailing edge and platform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air injection passages are used to cool the critical part of the blade, then cooling effect is provided, but the air flow separates from the lower surface and fails to reach the trailing edge connection area effectively
Solution Approach 1:
The groove is positioned upstream of the critical trailing edge area, allowing the cooling air flow to be pre-directed and pre-positioned along the lower surface before reaching the critical zone. This preliminary positioning ensures the flow remains attached and effectively cools the trailing edge connection area when it arrives.
Solution Approach 2:
The groove acts as an intermediary structure that mediates between the air injection passages and the critical trailing edge area. It provides a guided pathway that prevents flow separation and ensures the cooling air reaches its destination effectively, solving the problem of flow detachment.
2Reliability
If multiple air injection passages are provided to ensure adequate cooling, then cooling coverage is improved, but the number of passages increases manufacturing complexity and cost
Solution Approach 1:
The invention transitions from a purely longitudinal arrangement of cooling passages to a two-dimensional configuration by introducing the groove as a lateral guiding structure. This dimensional addition allows a single or few injection passages to effectively cover the critical area by directing flow along the groove, reducing the need for multiple passages.
Solution Approach 2:
The groove utilizes fluid dynamic principles to guide and attach the cooling air flow along the lower surface of the blade. By creating a controlled flow path, the groove ensures the air remains attached to the surface through aerodynamic attachment, maximizing cooling efficiency with minimal passages.
3Reliability
If the groove is formed in depression with respect to the platform surface, then flow guidance is improved, but manufacturing complexity increases
Solution Approach 1:
The groove formation process is merged with the existing blade manufacturing process, allowing the groove to be created as an integrated feature during blade fabrication. This integration eliminates the need for separate post-processing steps, reducing overall manufacturing complexity despite the added geometric feature.
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 design effectively lowers the operating temperature of the critical blade area, extending its service life while potentially reducing the number or flow rate of air injection passages, thus maintaining low production costs.
Implementation Method 1
the phenomenon of separation of the flow from the pressure side wall is avoided
Implementation Method 2
the cooling of the aerodynamic profiles and of the platforms of the blades thus stressed is carried out by means of air passages arranged in the volume of the blades themselves
Data Source
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AI summary
A turbine blade (10) for a turbine wheel (100) of a turbomachine, comprising an aerodynamic profile (12) and a platform (60) with at least one air injection passage (16), the platform (60) having a groove (40, 140, 240) running along the lower surface (56) in the vicinity of at least one downstream portion (57) thereof, at least one air injection passage being provided in this groove. Thanks to the presence of this groove, the airflow injected by the air injection passage(s) is confined to the vicinity of the lower surface, and thus ensures efficient cooling of its downstream portion.