Active Clearance Control Manifold Impingement Heat Transfer
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Solution Overview
Problem
Existing active clearance control systems for gas turbine engines are ineffective due to limited heat transfer capacity and often require large amounts of thermal control air, which can adversely affect engine performance.
Innovation Solution
A circumferentially mounted spray tube with impingement holes is used to direct thermal control air onto clearance control components, optimizing the stand-off distance and arc spacing to enhance heat transfer efficiency while minimizing the amount of thermal control air required, employing a rigid or sliding mounting assembly for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional active clearance control systems are used, then blade tip clearance control is achieved, but heat transfer capacity is limited and large amounts of thermal control air are required
Solution Approach 1:
The patent applies local quality by directing thermal control air through impingement holes in spray tubes to create localized high-velocity jets that concentrate heat transfer at specific locations on the turbine case. This localized approach maximizes heat transfer efficiency where needed most, reducing the overall amount of thermal control air required while maintaining effective blade tip clearance control.
Solution Approach 2:
The system employs periodic action by using multiple spray tubes arranged circumferentially around the turbine case, which are activated in a sequenced manner. This periodic activation pattern ensures continuous thermal control while allowing each spray tube to operate at optimal intensity, improving heat transfer capacity and reducing total thermal control air consumption.
2Reliability
If traditional active clearance control systems are used, then blade tip clearance control is achieved, but heat transfer capacity is limited
Solution Approach 1:
The patent utilizes mechanical vibration principles by creating high-velocity impingement jets that generate turbulent flow patterns and enhanced mixing at the spray-turbine case interface. This turbulent interaction significantly increases heat transfer coefficients and overall heat transfer capacity, enabling more effective blade tip clearance control with reduced air consumption.
Solution Approach 2:
The system applies pneumatic principles by using compressed thermal control air delivered through impingement holes in spray tubes. The high-pressure air jets create forced convection and impingement heat transfer, which are highly effective thermal management mechanisms. This pneumatic approach dramatically enhances heat transfer capacity compared to traditional diffusion-based systems.
3Power
If spray tube is mounted closer to clearance control component, then heat transfer efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies dynamics by designing the spray tube mounting system to accommodate thermal expansion and manufacturing variations. The mounting structure allows for controlled movement and adjustment, maintaining optimal stand-off distance despite temperature changes and manufacturing tolerances. This dynamic approach preserves heat transfer efficiency while reducing sensitivity to manufacturing precision requirements.
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 allows for precise control of turbine blade tip clearances with reduced thermal control air usage, improving engine performance, fuel efficiency, and reducing manufacturing costs and weight.
Implementation Method 1
a plurality of impingement holes arranged to impinge thermal control air on a clearance control component of a case
Implementation Method 2
direct relatively cool or relatively hot air, which may be generally referred to as thermal control air, onto high or low pressure turbine casings to cause the casings to thermally expand away from the blade tips (increasing the tip clearances) or contract (reducing the tip clearances)
Data Source
AI summary
Active clearance control systems for gas turbine engines are disclosed. An example active clearance control system may include a generally circumferentially mounted spray tube comprising a plurality of impingement holes arranged to impinge thermal control air on a clearance control component of a case; a rigid mounting assembly substantially rigidly coupling the spray tube to the case; and/or a sliding mounting assembly coupling the spray tube to the case while permitting limited relative movement between the spray tube and the case in a direction generally parallel with an engine axis. The sliding mount may be coupled to the case generally axially forward of the rigid mount. A ratio of the stand-off distance to the impingement hole diameter may be less than about 8. A ratio of the arc spacing to the impingement hole diameter may be less than about 15.