Turbine Blade Tip Plenum Cooling Against Trailing-Edge Backflow
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Solution Overview
Problem
Turbine blade tips, particularly near the trailing edge, experience inadequate cooling and thermal-induced degradation due to backflow of hot combustion gases, leading to reduced operational durability.
Innovation Solution
A turbine blade design featuring a root with supply channels, a blade tip with tip cooling apertures, and serpentine interior cooling passages that exhaust pressurized gas to the exterior, including a plenum connected to tip cooling apertures to enhance cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing cooling configurations are used for turbine blade tips, then the structure is simple, but cooling effectiveness is inadequate particularly near the trailing edge
Solution Approach 1:
The cooling system is divided into multiple independent cooling passages (first cooling passage, second cooling passage, third cooling passage) that can be configured separately. Each passage serves specific regions of the blade tip, allowing optimized cooling coverage without requiring a single complex passage design.
Solution Approach 2:
The cooling passages extend in multiple spatial dimensions including axial, radial, and circumferential directions. The passages can extend axially beyond the trailing edge and radially to reach different tip regions, providing three-dimensional cooling coverage that addresses the inadequate cooling near the trailing edge.
2Reliability
If cooling air flow is provided to turbine blade tip, then operational durability is improved, but back flow of hot combustion gas can occur due to inadequate feed pressure
Solution Approach 1:
A plenum chamber is introduced as an intermediary component between the cooling air supply and the cooling passages. The plenum receives cooling air at higher pressure and distributes it to multiple passages, ensuring adequate feed pressure is maintained throughout the system to prevent hot gas backflow while improving operational durability.
Solution Approach 2:
The system utilizes pressurized cooling air flow through strategically designed passages to create a protective gas barrier at the blade tip. The pneumatic flow is directed to exit regions where hot combustion gases might backflow, using the high-velocity cooling air jet to prevent hot gas intrusion and protect the blade tip.
3Reliability
If tip cooling apertures are positioned radially outward of cooling passages, then cooling coverage is improved, but pressure loss in passages increases
Solution Approach 1:
The plenum chamber is positioned to receive and pressurize cooling air before it enters the cooling passages. This preliminary pressurization action ensures that sufficient pressure is available to drive cooling air through the passages to the radially outward apertures, maintaining adequate cooling coverage while minimizing pressure loss during passage flow.
Solution Approach 2:
Different cooling passages are configured with different characteristics suited to their specific functions. Passages leading to radially outward apertures are designed with appropriate dimensions and lengths to balance cooling coverage requirements with pressure loss constraints, allowing each region to receive optimized cooling.
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 design provides improved cooling to the turbine blade tip, reducing thermal degradation and increasing operational durability by effectively exhausting pressurized gas and preventing backflow of hot gases.
Implementation Method 1
The first leg is configured to receive pressurized gas from at least one supply channel of the plurality of supply channels
Implementation Method 2
providing cooling air flow to the turbine blade tip can improve the operational durability of the turbine blade
Implementation Method 3
exhausting pressurized gas and preventing backflow of hot gases
Data Source
AI summary
A turbine blade includes a blade tip defining pressure side cooling apertures. The turbine blade defines a serpentine cooling passage having a first, second, and third legs, and first and second junction portions. The first leg extends radially and is connected to the second leg by the first junction portion proximate the blade tip. The second leg extends radially between the first and second junction portions. The second junction portion connects the second leg to the third leg which extends radially toward the blade tip and is connected to a trailing edge cooling aperture to exhaust the gas to an exterior of the turbine blade. The turbine blade defines a plenum connected to the first junction portion. At least one tip cooling aperture connects to the plenum and is radially outward of the third leg and axially aftward of at least a portion of the third leg.