Offset Herringbone Cooling Hole Pattern for Airfoil Transition Regions
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Solution Overview
Problem
In gas turbine engines, areas of airfoils may not receive adequate cooling due to cooling holes pointing in different directions, leading to insufficient cooling and potential early wear or failure.
Innovation Solution
The airfoil features an offset herringbone cooling hole pattern with multiple filmrows, each having radially outward and inward facing portions and transition boundaries positioned at specific radial distances to ensure non-contiguous alignment, allowing cooling air to effectively cool transition regions between adjacent filmrows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling holes are arranged in groups pointing in different directions, then the airfoil can be cooled from multiple directions, but some areas of the airfoil do not receive cooling air leading to insufficient cooling
Solution Approach 1:
The cooling holes are segmented into multiple filmrows with distinct functions. Each filmrow contains radially outward facing portions, radially inward facing portions, and transition regions. This segmentation allows different portions to target specific areas needing cooling, ensuring comprehensive coverage without leaving uncovered zones.
Solution Approach 2:
Different portions of the cooling hole pattern are designed with different orientations to address local cooling needs. The radially outward facing portions cool outer surfaces, while radially inward facing portions cool inner surfaces. Transition regions with angled orientations specifically address the cooling needs of transition areas between these zones.
2Temperature
If transition regions between filmrows are aligned contiguously, then the structure is simpler, but cooling air from adjacent filmrows cannot effectively cool each other's transition areas
Solution Approach 1:
The transition boundaries of adjacent filmrows are deliberately positioned at different radial distances from the engine central longitudinal axis, creating an asymmetric, staggered pattern. This asymmetry ensures that transition regions are offset rather than aligned, allowing cooling air from one filmrow to effectively reach and cool the transition regions of adjacent filmrows.
Solution Approach 2:
The solution moves from a simple radial arrangement to a three-dimensional staggered configuration. By offsetting transition boundaries in the radial dimension across multiple filmrows, the design creates overlapping cooling zones that enhance cooling effectiveness in transition regions without requiring additional complexity in the hole orientation patterns.
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 enhances convective cooling by staggering transition regions, ensuring that cooling air from adjacent filmrows can cool each other's transition areas, thereby improving temperature management and reducing wear.
Implementation Method 1
cooling air to pass from cavities inside the airfoil and out through the cooling holes, cooling the airfoil
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
An airfoil (100) having a cooling hole pattern (52) is disclosed. The cooling hole pattern (52) may be an offset herringbone pattern. For instance, the airfoil (100) may have rows of cooling holes arranged in filmrows (55-1, 55-2, 55-3, 55-4), each filmrow 955-1...55-4) divided into groups of cooling holes. A first group may be oriented to direct cooling air generally radially outward over a surface of the airfoil (100) and a second group may be oriented to direct cooling air generally radially inward over a surface of the airfoil (100). Between the first group and the second group of cooling holes in each filmrow (55-1...55-4), a transition region exists. The adjacent filmrows (55-1...55-4) are staggered to enhance the effectiveness of the convective cooling proximate to the transition regions by causing each filmrow (55-1...55-4) to direct cooling air over the transition region of an adjacent filmrow (55-1...55-4).