Turbine Airfoil Cast Platform Cooling Circuit
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Solution Overview
Problem
Modern gas turbine engines face challenges in cooling the endwalls of turbine airfoils due to increasing inlet temperatures and the limitations of traditional cooling techniques, particularly with advanced aerodynamic features, which restrict the placement and effectiveness of film cooling holes.
Innovation Solution
A turbine airfoil with a cast cooling circuit featuring a forked plenum and constricted flow areas to enhance cooling efficiency, allowing for various patterns of film cooling holes and increased coolant pressure, enabling flexible cooling designs without altering the basic casting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional film cooling holes are drilled through endwalls, then cooling is provided in certain regions, but hole placement is restricted to specific areas where complete drilling is possible or gas path pressure is low enough
Solution Approach 1:
The endwall is segmented into multiple regions with a forked plenum structure that divides the cooling air supply into separate branches. Each branch can independently feed cooling holes in different regions, allowing flexible placement of cooling holes throughout the entire endwall surface rather than being restricted to single continuous drilling paths.
Solution Approach 2:
A plenum chamber acts as an intermediary between the cooling air source and the film cooling holes. The plenum receives cooling air and distributes it to multiple branches, enabling cooling holes to be positioned in regions that would otherwise be inaccessible to direct cooling air injection, thus expanding the effective cooling coverage area.
2Adaptability or versatility
If hollow platforms feed compressor bleed air to film cooling holes, then cooling is provided, but the design is not adaptable to providing different cooling hole patterns based on varying operating conditions
Solution Approach 1:
The forked plenum structure provides dynamic adaptability by allowing different combinations of branches to be activated depending on operating conditions. The modular branch structure enables the cooling system to be reconfigured for different cooling patterns without changing the basic platform casting, achieving operational flexibility through selective branch usage.
3Temperature
If endwalls are cooled with traditional techniques, then some cooling is achieved, but cooling effectiveness deteriorates as turbine inlet temperatures continue to rise
Solution Approach 1:
The forked plenum structure enables localized optimization of cooling by directing cooling air through specific branches to regions with highest thermal loads. Each branch can be designed with appropriate throat dimensions and cooling hole patterns tailored to the specific thermal conditions of its target region, improving overall cooling effectiveness against rising turbine inlet temperatures.
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 allows for improved cooling of turbine airfoils by enabling film cooling holes to be placed anywhere on the endwall, ensuring effective heat transfer and flexibility in cooling patterns, thus addressing the limitations of traditional cooling methods.
Implementation Method 1
each branch having a throat disposed at its upstream end, wherein each throat has a relatively constricted flow area for increasing flow velocity
Implementation Method 2
at least one film cooling hole passing through the outer surface and communicating with the plenum
Implementation Method 3
at least one film cooling hole passing through the outer surface and communicating with the plenum
Data Source
AI summary
A turbine airfoil apparatus includes: an airfoil including a concave pressure sidewall and a convex suction sidewall joined together at a leading edge and at a trailing edge; an endwall that projects laterally outwardly from the airfoil at one spanwise end thereof, the endwall having an outer surface facing the airfoil and an opposing inner surface; a plenum defined within the endwall between the inner and outer surfaces wherein the plenum is forked in plan view, with at least two branches, each branch terminating at a closed end, each branch having a throat disposed at its upstream end, wherein each throat has a relatively constricted flow area for increasing flow velocity; and at least one film cooling hole passing through the outer surface and communicating with the plenum.