Passive Bleed Valve Baffle Tuning for Pressure Threshold Control
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Solution Overview
Problem
Conventional bleed valves in gas turbine engines require active control mechanisms, which add complexity, mass, and size, and do not efficiently manage fluid flow during engine starting and steady-state operations.
Innovation Solution
A passively controlled inline bleed valve design featuring a housing with a duct, guide tube, piston, and baffle, where the piston moves between open and closed positions based on differential pressure, and a set pin mechanism adjusts the baffle to control the flow area, allowing for passive operation without solenoids or pneumatic controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active control mechanisms (solenoids, pneumatic controllers) are used to control bleed valve operation, then the valve can be reliably opened and closed, but the complexity, mass, and size of the system increase
Solution Approach 1:
The bleed valve utilizes the differential pressure between the compressor inlet and outlet to automatically control the piston movement and valve opening/closing. The system serves itself by using the process fluid's own pressure differential as the actuating force, eliminating the need for external solenoids, pneumatic controllers, or other active control mechanisms.
Solution Approach 2:
The patent replaces complex electromechanical or pneumatic control systems with a simple passive mechanical pressure-balance mechanism. The piston responds directly to differential pressure forces, converting pressure differential into mechanical motion that controls the valve state without requiring external control systems.
2Device complexity
If passive control using differential pressure is implemented, then complexity, mass, and size are reduced, but the ability to precisely control opening/closing pressure thresholds is limited
Solution Approach 1:
The baffle position is made adjustable rather than fixed, allowing the pressure threshold at which the valve opens or closes to be dynamically changed. The set pin mechanism enables the baffle to be repositioned along the guide tube, creating different flow areas and thus different pressure thresholds, while the valve remains in passive operation during normal function.
Solution Approach 2:
The control mechanism is divided into separable components: the baffle, guide tube, set pin, and collar. This segmentation allows the baffle to be independently adjusted to different positions along the guide tube, enabling multiple pressure threshold settings while maintaining the simplicity of the overall passive control system.
3Stress or pressure
If the baffle flow area is increased to allow more fluid through the orifice, then the pressure threshold for piston movement decreases, but the differential pressure control precision is reduced
Solution Approach 1:
The baffle is designed with a specific geometry where only a portion of the orifice flow area is blocked at any given position. By adjusting the baffle position along the guide tube, precise local control of the effective flow area is achieved, allowing fine-tuning of the pressure threshold while maintaining control precision through the defined geometric relationship between the baffle and orifice.
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 complexity, mass, and size by enabling passive control of fluid flow, improving reliability and potentially lowering costs, while effectively managing fluid flow during engine operations by using differential pressure to switch between open and closed positions.
Implementation Method 1
the piston is movable between an open and a closed position, the duct fluidly coupling the inlet and outlet in the open position, the duct fluidly separating the inlet and outlet in the closed position. The orifice fluidly couples the inlet and outlet in the open and closed positions to move piston between the open and closed positions according to differential pressure between the bleed valve inlet and outlet.
Implementation Method 2
a guide tube with an orifice fixed in the housing between the inlet and the outlet... The orifice fluidly couples the inlet and outlet in the open and closed positions to move piston between the open and closed positions
Implementation Method 3
a baffle is slideably supported by the guide tube to set the differential pressure at which the piston moves between the open and closed positions. Flow area of orifice can be larger in the second position than in the first position.
Data Source
AI summary
A bleed valve includes a housing with an inlet coupled to an outlet by a duct, a guide tube with an orifice fixed in the housing between the inlet and the outlet, a piston, and baffle. The piston is slideably supported on the guide tube and is movable between an open and a closed position, the duct fluidly coupling the inlet and outlet in the open position, the duct fluidly separating the inlet and outlet in the closed position. The orifice fluidly couples the inlet and outlet in the open and closed positions to move piston between the open and closed positions according to differential pressure between the bleed valve inlet and outlet. The baffle is slideably supported by the guide tube to set the differential pressure at which the piston moves between the open and closed positions. Gas turbines and differential pressure adjustment methods are also described.