Confined Laser Drilling for Airfoil Cooling Hole Breakthrough Control
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Solution Overview
Problem
The challenge in drilling holes in gas turbine airfoils is the risk of damaging the thermal barrier coating and the complexity of maintaining cooling passages, especially as temperatures and performance standards increase, requiring precise control and labor-intensive processes.
Innovation Solution
A method and system using a confined laser drill with sensors to direct a confined laser beam and monitor light characteristics, allowing for precise drilling through the airfoil near wall while preventing damage to the opposite cavity surface by using a backstrike protection mechanism and sensors to determine drilling progress and breakthrough.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a water jet is used to create cooling passages, then cooling passages can be formed through the thermal barrier coating, but portions of the thermal barrier coating may chip off
Solution Approach 1:
The patent replaces the mechanical water jet drilling method with a laser-based drilling system. The laser beam drills cooling passages through the thermal barrier coating and airfoil material without mechanical contact, eliminating the chipping problem caused by water jet impact while maintaining the ability to create effective cooling passages.
Solution Approach 2:
The patent changes the drilling mechanism from mechanical (water jet) to optical (laser). By using laser energy with controlled parameters (power, pulse duration, wavelength), the system can precisely ablate material through the thermal barrier coating without the mechanical forces that cause chipping, thus improving coating integrity while maintaining manufacturability.
2Ease of manufacture
If an electron discharge machine (EDM) is used to create cooling passages, then cooling passages can be formed, but additional processing is required to remove thermal barrier coating from the newly formed passages
Solution Approach 1:
The patent combines the functions of cooling passage creation and thermal barrier coating removal into a single laser drilling operation. The laser beam simultaneously drills through the coating and creates the cooling passage in one continuous process, eliminating the need for separate EDM operation and subsequent coating removal steps, thus reducing overall process complexity.
Solution Approach 2:
The laser drilling process performs the coating removal action preliminarily and simultaneously with the cooling passage creation. By removing the thermal barrier coating as the passage is being drilled, the system eliminates the need for subsequent separate processing steps to clear coating from completed passages, simplifying the overall manufacturing workflow.
3Reliability
If conventional laser drilling methods are used, then cooling passages can be created with reduced chipping risk, but precise control is required to prevent damage to the opposite side of the cavity
Solution Approach 1:
The patent implements a feedback control system using optical sensors that monitor the drilling process in real-time. Sensors detect changes in light transmission or reflection as the laser drills through the airfoil, providing feedback to the control system to automatically adjust laser parameters or stop drilling when the opposite side is approached, preventing damage while maintaining automated precise control.
Solution Approach 2:
The patent employs dynamic control of the laser drilling process, where drilling parameters (power, speed, pulse frequency) are continuously adjusted based on real-time sensor feedback. This dynamic adaptation allows the system to maintain precise control without requiring overly complex static control mechanisms, as the system automatically responds to changing drilling conditions.
4Reliability
If the number of cooling holes increases and size decreases, then cooling performance improves, but the drilling process becomes increasingly difficult and requires more labor hours and skill
Solution Approach 1:
The patent replaces manual or mechanically-controlled drilling with an automated laser drilling system. The laser can precisely create multiple small cooling holes with consistent dimensions and spacing without the diminishing returns that affect mechanical drilling at small scales. This automation eliminates the increasing labor hours and skill requirements while maintaining the ability to create high-density cooling hole patterns for improved thermal management.
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 approach enables accurate and efficient drilling of holes in gas turbine airfoils, reducing the risk of damaging the thermal barrier coating and improving the manufacturing process by allowing for real-time monitoring and control of the drilling process.
Implementation Method 1
A laser drill utilizing a focused laser beam may also be used to create the cooling passages through the airfoil
Implementation Method 2
sensing a first characteristic of light from the hole in the near wall of the component with a first sensor positioned outside the component
Data Source
AI summary
A method for drilling a hole in a component is provided. The method includes directing a confined laser beam of a confined laser drill towards a near wall of the component and sensing a first characteristic of light from the hole in the near wall of the component with a first sensor positioned outside the component. The method also includes sensing a second characteristic of light from the hole in the near wall the component with a second sensor. The second characteristic of light is different from the first characteristic of light. Additionally, the method includes determining a hole progress based on the sensed first characteristic of light and the sensed second characteristic of light.