Passive Variable Bleed Valve for Turbomachine Hub
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Solution Overview
Problem
Modern bypass turbine engines face head losses and secondary flow separation due to surface irregularities created by discharge valves, particularly when they are in the closed position, which can lead to increased fuel consumption and engine inefficiency during cruise phases.
Innovation Solution
An intermediate casing hub design featuring rotatable discharge fins with a pivot closer to the leading edge, forming a continuous surface in the closed configuration and automatically opening with aerodynamic forces when air flow is present, eliminating the need for servo control systems and reducing mass and fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discharge valves are kept in the closed position to regulate flow rate, then flow regulation capability is improved, but surface irregularities are created causing head losses and secondary flow separation
Solution Approach 1:
The discharge fins are made rotatable around a pivot point, allowing them to dynamically change their position between a first position (flush with outer shroud, forming continuous surface) and a second position (extending into secondary flow space, opening passage). This dynamic capability enables the system to adapt to different operational conditions, eliminating the need to maintain a fixed closed position that creates surface irregularities and head losses.
Solution Approach 2:
The discharge fins are equipped with a spring system that automatically returns them to the first position (closed configuration) when not in use, and they open to the second position automatically when air flow is present, without requiring active servo control. This self-actuating mechanism maintains the continuous surface when needed while allowing automatic opening when flow regulation is required, thereby minimizing head losses during cruise phases.
2Loss of energy
If discharge fins are made fixed to form continuous surface, then surface irregularities are minimized, but flow regulation capability is lost
Solution Approach 1:
The discharge fins are made rotatable around a pivot point, allowing them to dynamically change their position between a first position (flush with outer shroud, forming continuous surface) and a second position (extending into secondary flow space, opening passage). This dynamic capability enables the system to adapt to different operational conditions, eliminating the need to maintain a fixed closed position that creates surface irregularities and head losses.
Solution Approach 2:
The discharge fins are equipped with a spring system that automatically returns them to the first position (closed configuration) when not in use, and they open to the second position automatically when air flow is present, without requiring active servo control. This self-actuating mechanism maintains the continuous surface when needed while allowing automatic opening when flow regulation is required, thereby minimizing head losses during cruise phases.
3Reliability
If active servo control systems are used to control discharge fins, then precise flow regulation is achieved, but device complexity and mass increase
Solution Approach 1:
The discharge fins are equipped with a spring system that automatically returns them to the first position (closed configuration) when not in use, and they open to the second position automatically when air flow is present, without requiring active servo control. This self-actuating mechanism maintains the continuous surface when needed while allowing automatic opening when flow regulation is required, thereby minimizing head losses during cruise phases.
Solution Approach 2:
The system utilizes aerodynamic forces generated by the air flow itself to automatically open the discharge fins when needed. The flow dynamics create the necessary force to overcome the spring tension and rotate the fins to the open position, eliminating the need for external active control systems and reducing both complexity and mass.
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 design minimizes surface irregularities and head losses, enhancing the efficiency of the secondary flow and reducing specific fuel consumption by allowing the discharge fins to adjust passively between open and closed configurations without active control, thereby optimizing engine performance during cruise phases.
Implementation Method 1
automatically opening with aerodynamic forces when air flow is present
Data Source
AI summary
The invention relates to a hub (2) of an intermediate casing (1) for a bypass turbomachine comprising: —a bleed stream duct (18), —a bleed valve, comprising a mobile door at the inlet orifice to the bleed stream duct (18), —a set of bleed vanes (22) which are mounted with the ability to rotate about a pivot (26) in the bleed stream duct (18) between an open configuration in which a flow of air coming from the inlet orifice (4) passes between the bleed vanes (22) and a closed configuration, the pivot (26) for each bleed vane (22) being closer to its leading edge (BA) than to its trailing edge (BF).