Differential Valve Assembly for Gas Turbine Clearance Cooling
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Solution Overview
Problem
Conventional active clearance control systems for gas turbine engines are complex, require frequent maintenance, and are not adaptable for controlling complex cooling flow relationships without adding weight and complexity, making them inefficient in achieving optimal turbine efficiency due to differential expansion rates of turbine case and blades.
Innovation Solution
A valve assembly with a housing, annular inlet and outlet ducts, and coupled valve discs rotated by a shaft, featuring a flow control member in the second outlet duct to restrict fluid flow differentially, allowing for fewer parts, reduced weight, and improved control over complex flow relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate ACC systems or complex valve assemblies with multiple independent valve elements are used to control differential cooling airflows to different turbine case sections, then the desired clearance control can be achieved, but the device complexity increases and maintenance requirements increase
Solution Approach 1:
The patent combines multiple valve elements into a single integrated valve assembly with a common body and shared actuation mechanism. The valve assembly includes a first valve element for controlling airflow to a first turbine case section and a second valve element for controlling airflow to a second turbine case section, both integrated within one assembly rather than using separate independent systems.
Solution Approach 2:
The valve assembly is designed to perform multiple functions through its differential valve elements. The first and second valve elements can independently control cooling airflow to different turbine case sections, allowing a single assembly to replace multiple separate ACC systems while maintaining the ability to provide differential cooling control.
2Reliability
If conventional valve assemblies with multiple actuators, gears and cam mechanisms are used to drive multiple valve elements at differential rates, then the correct differential cooling airflow can be supplied, but the weight increases and the assembly becomes less adaptable
Solution Approach 1:
The patent extracts and eliminates unnecessary mechanical components from conventional valve assemblies. By using a simplified valve design with elements that can be directly actuated or controlled through a streamlined mechanism, the patent removes heavy components such as multiple actuators, gears, and cam mechanisms while maintaining the capability to supply correct differential cooling airflow.
Solution Approach 2:
The valve assembly incorporates dynamic control capabilities through its differential valve elements that can respond to varying engine operating conditions. The design allows the valve elements to adjust their positions and opening rates dynamically based on real-time cooling requirements, enabling adaptability without adding heavy mechanical transmission components.
3Reliability
If conventional ACC systems are used, then cooling airflow can be directed to turbine case sections, but the systems require frequent maintenance and are not readily adaptable for controlling complex cooling flow relationships
Solution Approach 1:
By integrating multiple valve elements into a single valve assembly with a common body and shared components, the patent reduces the total number of parts that require maintenance. The unified design allows for easier inspection, troubleshooting, and repair compared to multiple separate ACC systems, directly addressing the high maintenance frequency issue.
Solution Approach 2:
The valve assembly is designed with adjustable and configurable parameters that allow it to be adapted for different cooling flow relationships. The differential valve elements can be configured to provide various opening rates and flow control characteristics, enabling the system to handle complex cooling requirements without requiring hardware modifications or frequent maintenance interventions.
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
The valve assembly effectively varies fluid flow through the outlet ducts, enabling precise control of cooling airflow to different turbine sections, enhancing turbine efficiency and reducing maintenance needs by simplifying the design and reducing potential leakage.
Implementation Method 1
Rotation of the shaft rotates both the first and second valve discs within the first and second outlet ducts, respectively
Implementation Method 2
a flow control member in the second outlet duct surrounding the second valve disc, which is configured to restrict fluid flow passing through the second outlet duct to a greater extent than the fluid flow passing through the first outlet duct
Data Source
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AI summary
The present disclosure provides a valve assembly (200) for an active clearance control (ACC) system in a gas turbine engine. The assembly (200) comprises a first valve disc (216) positioned within a first outlet duct (206), a second valve disc (218) positioned within the second outlet duct (208), and a shaft (224) coupled to the first and second valve discs (216, 218) such that rotation of the shaft (224) rotates both the first and second valve discs (216, 218) within the first and second outlet ducts (206, 208), respectively. A flow control member (226) in the second outlet duct (208) surrounds the second valve disc (218), and is configured to restrict fluid flow passing through the second outlet duct (208) to a greater extent than the fluid flow passing through the first outlet duct (206) for a given degree of rotation of the first and second valve discs (216, 218). A corresponding ACC system, gas turbine and method is also provided.