Hemi-elliptical Check Valve for Aircraft Engine Bleed Air
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Solution Overview
Problem
High-stress levels and increased pressure drop occur in existing check valves used in gas turbine engine bleed systems due to high backflow velocities during compressor stalls, which affect surge recovery and environmental control system performance.
Innovation Solution
A check valve design featuring first and second valve portions arranged in different planes with a non-perpendicular seat orientation, allowing for reduced travel and stress when transitioning from an open to a closed position, utilizing a hemi-elliptical shape and acute angles to minimize velocity and restriction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the discs are reduced to less open position (30-40 degrees) to reduce angular travel and stress, then the stress levels on discs and seat are reduced, but the pressure drop across the valve increases
Solution Approach 1:
The single disc is segmented into two separate valve portions that can move independently. This segmentation allows each portion to travel a shorter angular distance (30-40 degrees) while collectively providing effective sealing, thereby reducing stress on individual components without significantly increasing pressure drop.
Solution Approach 2:
The valve portions are arranged in different planes rather than being coplanar. This spatial arrangement in multiple dimensions allows the valve to achieve closure with reduced angular travel in each plane, reducing the velocity at impact and stress levels while maintaining effective sealing against the seat.
2Stress or pressure
If the disc travel is reduced to reduce angular velocity at impact, then the stress levels and backflow are reduced, but the valve closure time may be insufficient for fast acting requirements
Solution Approach 1:
By dividing the valve into two separate portions that close simultaneously, the system achieves effective sealing with reduced individual travel distances. This segmentation enables faster closure response while reducing the angular velocity and stress at impact compared to a single disc traveling a longer arc.
Solution Approach 2:
The valve portions are designed to be dynamically responsive to flow conditions, utilizing the kinetic energy of the backflow itself to drive the closure action. This dynamic design allows the valve to achieve rapid closure with minimal travel, reducing impact velocity while maintaining fast response times under 100 ms.
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 solution reduces stress and response time while maintaining minimal restriction, effectively preventing backflow and ensuring efficient air supply during normal operating conditions.
Implementation Method 1
a fast acting pneumatic check valve to prevent engine core bleed flow from returning to the engine during a compressor stall
Data Source
Figure 1~4
AI summary
An engine air supply system includes an air source, which is a gas turbine engine in one example. A component, such as an environmental control system component, is interconnected to the air source by a conduit (24) that includes a supply flow direction (B). A check valve (20) is arranged in the conduit. The check valve includes first and second hemi-elliptical valve portions (32, 34) moveable in the supply flow direction from a closed position (C) to an open position (O). The closed position is arranged at an acute angle (A) relative to the supply flow direction. The first and second valve portions are non-planar and arranged approximately 90 degrees apart when in the closed position (C). The first and second valve portions move toward one another from the closed position to the open position (O). Each of the first and second valve portions moves approximately 30-40 degrees from the open position to the closed position in response to a stall condition, which significantly reduces the response time and forces generated by the first and second valve portions when closing.