Active Turbine Tip Clearance Control Using Ejector Pressure Amplification
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Solution Overview
Problem
Conventional active tip clearance control (ATCC) systems in gas turbine engines face inefficiencies due to low pressure differentials, which can compromise their operation and efficiency, especially in engines with low pressure differentials between the inlet scoop and downstream bypass duct locations.
Innovation Solution
The proposed ATCC system incorporates an ATCC manifold, an inlet passage, a vent passage, a solenoid valve, and an ejector to selectively control and amplify the high-pressure air flow, increasing the energy level of the cooling air flow and creating a higher pressure differential for effective impingement cooling, thereby enhancing the system's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional ATCC systems use fan driven bypass air through a diffusion duct to maintain tip clearance, then the system can operate with simple structure, but the pressure differential becomes very low which compromises system efficiency and operation
Solution Approach 1:
The patent introduces a high pressure air source as an intermediary element that provides a controlled high pressure air flow to the ejector. This intermediary high pressure air flow is specifically designed to create a stronger pressure differential than the conventional bypass air alone, thereby resolving the contradiction between simple structure and system operation efficiency.
Solution Approach 2:
The patent employs pneumatic principles by using a controllable valve to regulate high pressure air flow and an ejector to convert this high pressure air flow into a controlled cooling air flow. The ejector creates a pressure differential that forces cooling air through the ATCC manifold, significantly improving the pressure differential and system efficiency while maintaining relatively simple structure.
2Device complexity
If the pressure differential between inlet scoop and downstream bypass duct is low, then the engine design is simpler, but the ATCC system operation and efficiency are at risk
Solution Approach 1:
The patent changes the pressure parameter by introducing a high pressure air source that provides a controlled high pressure air flow. This high pressure air flow is regulated by a controllable valve and directed through an ejector to create a significantly higher pressure differential than the conventional system, thereby improving ATCC system efficiency without substantially increasing overall engine design complexity.
Solution Approach 2:
The patent uses pneumatic mechanisms including a controllable valve to regulate high pressure air flow and an ejector to convert this flow into controlled cooling air flow. The ejector creates a pressure differential that effectively increases the cooling air flow through the ATCC manifold, improving productivity while maintaining manageable design complexity.
3Reliability
If a controllable valve and ejector are added to increase high pressure air flow control, then the pressure differential and cooling effectiveness are improved, but the device complexity increases
Solution Approach 1:
The patent introduces a high pressure air source as an intermediary that provides controlled high pressure air flow to the ejector. This intermediary element, along with the controllable valve, enables precise control of the cooling air flow and pressure differential, significantly improving tip clearance control effectiveness while adding only necessary components to achieve this control.
Solution Approach 2:
The patent employs pneumatic components including a controllable valve to regulate high pressure air flow and an ejector to convert this flow into controlled cooling air flow. These pneumatic mechanisms work together to create the necessary pressure differential for effective tip clearance control, with the added complexity being justified by the significant improvement in control effectiveness.
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 solution ensures the effective maintenance of tip clearance between turbine blades and shroud by increasing the pressure differential, improving the efficiency and reliability of the ATCC system, even in engines with low pressure differentials.
Implementation Method 1
an ejector configured to use the controlled high pressure air flow to selectively drive said air through the ATCC manifold
Implementation Method 2
The proposed ATCC system incorporates an ATCC manifold, an inlet passage, a vent passage, a solenoid valve, and an ejector to selectively control and amplify the high-pressure air flow, increasing the energy level of the cooling air flow and creating a higher pressure differential for effective impingement cooling
Implementation Method 3
This portion of bypass air is directed to flow over the high pressure turbine case through a series of impingement holes... the appropriate tip clearance between the turbine blades and the turbine shroud is maintained... creating a higher pressure differential for effective impingement cooling
Data Source
AI summary
An active tip clearance control (ATCC) system of a gas turbine engine includes an ejector to selectively drive an air flow passing through the ATCC system. A high pressure air flow as a motive flow of the ejector is controlled by a valve according to engine operation requirements.