Self-Actuating Bleed Valve for Gas Turbine Start-Up
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Solution Overview
Problem
Gas turbine engines face challenges in starting up due to the turbine section not providing full power, making it difficult to drive the compressor section, which is alleviated by using a bleed valve to bleed air away from the compressor section during start-up, but existing solutions lack efficient self-actuation mechanisms.
Innovation Solution
A self-actuated bleed valve with a poppet mechanism biased by a spring to move between open and closed positions based on compressor section pressure, ensuring air is bled into the air plenum to reduce compressor load, featuring a snap action closure to maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bleed valve is used to bleed air away from the compressor section during start-up, then the load on the compressor section is reduced, but the valve requires complex actuation mechanisms to control opening and closing
Solution Approach 1:
The bleed valve utilizes the engine's own operating parameters (compressor inlet pressure and air plenum pressure) to automatically control opening and closing through the poppet mechanism. The valve serves itself by using the pressure differential across the poppet to actuate the bleeding function without external control systems
Solution Approach 2:
The invention replaces complex mechanical actuation systems (motors, solenoids, linkages) with a simple spring-loaded poppet mechanism that responds directly to pressure differential. This mechanical substitution eliminates the need for powered actuation while maintaining reliable control
2Productivity
If the bleed valve remains open during start-up, then air is effectively bled to reduce compressor load, but the valve may open unintentionally during steady-state operation
Solution Approach 1:
The valve operation is controlled by changes in pressure parameters during engine operation. During start-up, low compressor inlet pressure and high air plenum pressure create a differential that opens the valve. During steady-state, the pressure differential reverses, reliably closing the valve and preventing unintended opening
Solution Approach 2:
The poppet mechanism provides inherent feedback control by responding to the real-time pressure differential across it. The spring force and pressure forces continuously balance to maintain the valve in the correct state based on engine operating conditions, automatically adapting to prevent unintended opening
3Speed
If a spring-loaded poppet mechanism is used for self-actuation, then the valve responds quickly to pressure changes, but the snap action closure may cause mechanical stress
Solution Approach 1:
The snap-action closure creates a periodic mechanical action that cycles with engine operation. The rapid closing action is designed to complete within a specific time window, creating controlled periodic stress that the components are engineered to withstand without fatigue failure
Solution Approach 2:
The valve seat and poppet are designed with cushioning features that absorb the impact energy during snap-action closure. The mechanical design incorporates stress distribution and energy absorption mechanisms that protect components from damage during rapid closing
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 self-actuated bleed valve effectively reduces the load on the compressor section during start-up, ensuring reliable engine operation by efficiently venting air and preventing unintended opening, thus facilitating smooth transition from start-up to steady-state conditions.
Implementation Method 1
A spring biases the poppet to the open position and toward the air plenum
Implementation Method 2
moving a poppet within a bleed valve between an open position and a closed position dependent on a pressure within a compressor section
Data Source
AI summary
A bleed valve for an air plenum includes a valve body which defines a valve seat. A poppet is movable relative to the valve seat between an open position and a closed position. A spring biases the poppet to the open position and toward the air plenum.