Angled Tripped Airfoil Peanut Cavity Cooling
Solution Overview
Problem
The challenge in gas turbine engines is to effectively cool the leading edges of airfoils, which are subjected to extremely high temperatures, while manufacturing constraints limit the optimal positioning of impingement ribs and cooling holes, leading to compromised cooling efficiency and potential erosion or corrosion.
Innovation Solution
The design incorporates a turbine airfoil with a peanut cavity featuring an impingement rib positioned forward of the cooling channel, impingement rib nozzles, turbulators, and leading edge cooling holes, which enhance the flow and heat transfer of cooling air by using trip strips and gill holes to manage the flow and increase the heat transfer coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the impingement rib is positioned closer to the leading edge cooling holes, then the cooling air velocity and heat transfer capacity are improved, but the manufacturing difficulty increases
Solution Approach 1:
The impingement rib is segmented into multiple impingement rib nozzles positioned at different locations within the peanut cavity. This segmentation allows cooling air to be delivered to multiple points along the leading edge, improving overall cooling effectiveness while maintaining manufacturability by distributing the cooling function across multiple smaller features rather than requiring a single precisely positioned rib close to the cooling holes.
Solution Approach 2:
The cooling air flow is enhanced by introducing turbulators that create turbulence in the third dimension within the peanut cavity. This dimensional approach to flow control increases heat transfer capacity without requiring the impingement rib to be positioned closer to the cooling holes, as the turbulence generation occurs in the flow path rather than through geometric positioning.
2Ease of manufacture
If the impingement rib is positioned farther from the leading edge cooling holes, then the manufacturing ease is improved, but the cooling air separation from the interior increases, reducing effective impingement cooling
Solution Approach 1:
The peanut cavity serves as an intermediary chamber that receives cooling air from the cooling channel and delivers it to the leading edge cooling holes. Within this cavity, turbulators are positioned to generate turbulence and maintain effective heat transfer, allowing the impingement rib to be positioned at a manufacturable distance while still achieving effective cooling through the intermediary flow path and turbulence generation.
Solution Approach 2:
The flow parameters of the cooling air are changed by introducing turbulators that increase turbulence intensity and mixing within the peanut cavity. This parameter change in the flow state allows the cooling air to maintain effective heat transfer capacity even when the impingement rib is positioned farther from the leading edge, as the turbulence enhances the heat transfer coefficient independently of the rib position.
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 configuration improves the impingement cooling effectiveness by optimizing the flow and heat transfer of cooling air, reducing recirculation patterns, and increasing the convective heat transfer coefficient, thus enhancing the thermal cooling efficiency of the airfoil leading edge.
Implementation Method 1
The bypass air is passed into the interior of the airfoil to remove heat from the alloy, and subsequently discharged through cooling holes to pass over the outer surface of the airfoil
Implementation Method 2
The impingement rib accelerates the cooling air to a suitable velocity to permit the cooling air to exit the leading edge cooling holes and to increase heat transfer capacity of the cooling air
Implementation Method 3
The plurality of turbulators are positioned within the peanut cavity to locally influence the flow of the cooling air
Data Source
AI summary
A turbine airfoil comprises a wall portion, a cooling channel, an impingement rib, impingement rib nozzles, turbulators and leading edge cooling holes. The wall portion comprises a leading edge, a trailing edge, an outer diameter end, and an inner diameter end. The cooling channel receives cooling air and extends through an interior of the wall portion between the inner diameter end and the outer diameter end. The impingement rib is positioned within the wall portion forward of the cooling channel and between the outer diameter end and the inner diameter end to define a peanut cavity. The impingement rib nozzles extend through the impingement rib for receiving cooling air from the cooling channel. The turbulators are positioned within the peanut cavity to locally influence the flow of the cooling air. The leading edge cooling holes discharge the cooling air from the peanut cavity to an exterior of the wall portion.