Gas Turbine Vane Baffle Separates Serpentine and Film Cooling
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Solution Overview
Problem
In gas turbine engines, the serpentine cooling passages result in extremely hot cooling air and film temperatures, leading to undesirable metal temperatures near the last serpentine passage due to ineffective heat management.
Innovation Solution
An airfoil design with a baffle and ribs forming a serpentine cooling passage, where the baffle is radially extended through the outer platform, and film cooling holes are oriented to provide cooling fluid to the trailing edge, separating the serpentine cooling passage from the film cooling cavity to reduce heat pickup and maintain lower metal temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a serpentine cooling passage is used in the turbine vane, then the cooling air can convectively cool the vane, but the cooling air becomes extremely hot by the time it reaches the last passage, resulting in high metal temperatures
Solution Approach 1:
The cooling system is divided into two separate cavities: a serpentine cooling cavity and a film cooling cavity. The serpentine passage handles convective cooling of the vane interior, while the film cooling cavity provides a separate pathway for cooler air to reach the exterior surface through film cooling holes, segmenting the cooling functions to prevent heat accumulation in the serpentine passage
Solution Approach 2:
A baffle structure is introduced as an intermediary element that physically separates the serpentine cooling passage from the film cooling cavity. This baffle prevents the extremely hot cooling air from the serpentine passage from directly contacting the film cooling holes, allowing the film cooling system to use cooler air and maintain lower metal temperatures
2Area of stationary object
If the serpentine passage is extended to maximize cooling coverage, then more of the vane can be cooled, but the cooling air temperature increases, reducing cooling effectiveness
Solution Approach 1:
The cooling system is divided into two separate cavities: a serpentine cooling cavity and a film cooling cavity. The serpentine passage handles convective cooling of the vane interior, while the film cooling cavity provides a separate pathway for cooler air to reach the exterior surface through film cooling holes, segmenting the cooling functions to prevent heat accumulation in the serpentine passage
Solution Approach 2:
The cooling system performs multiple cooling functions simultaneously: the serpentine passage provides convective cooling through the vane interior, while the film cooling cavity provides film cooling at the exterior surface. This multi-functionality allows extensive cooling coverage without requiring all cooling air to traverse the entire serpentine path
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 effectively cools the airfoil by maintaining lower metal temperatures and reducing heatup in the serpentine passage, while providing efficient cooling to the exterior surface through film cooling, enhancing the overall cooling efficiency of the gas turbine engine.
Implementation Method 1
As the cooling air travels through the serpentine, it convectively cools the part, picking up heat
Implementation Method 2
providing cooling fluid to a serpentine cooling passage and to film cooling holes that provide film cooling to an exterior airfoil surface
Data Source
AI summary
An airfoil for a gas turbine engine includes pressure and suction side walls joined to one another at leading and trailing edges. The pressure and suction side walls surround an airfoil cavity and provide an exterior airfoil surface. A baffle is arranged in the airfoil cavity and includes a supply hole. Ribs extend between at least one of the pressure and suction side walls into the airfoil cavity to support the baffle relative to the at least one of the pressure and suction side walls. The ribs are configured to provide a serpentine cooling passage between the baffle and at least one of the pressure and suction side walls. The serpentine cooling passage has first and second passes joined by a bend. The ribs form a film cooling cavity between the first and second passes. The supply hole fluidly connects the baffle to the film cooling cavity. Film cooling holes extend through the at least one of the pressure and suction side walls. The film cooling holes are in fluid communication with the film cooling cavity.