Pump Sharing Valve Flow Distribution for Gas Turbine Fuel Systems
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Solution Overview
Problem
In gas turbine engines, the existing fuel systems face challenges in efficiently managing the flow of fuel between servo gear pumps and main gear pumps, particularly during start-up and steady-state operations, leading to increased complexity and size requirements as the number of accessories increases.
Innovation Solution
A pump sharing valve with a spool movable between positions to regulate flow between the servo gear pump and the main gear pump, allowing supplemental fuel flow from one pump to the other until pressure downstream increases, optimizing fuel distribution based on system conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the servo gear pump is sized to supply adequate fuel to all accessory actuators, then the fuel supply to actuators is sufficient, but the pump size and complexity increase
Solution Approach 1:
The patent combines the fuel supply functions of the servo gear pump and main gear pump through a pump sharing valve. The valve allows the servo gear pump to receive supplemental fuel flow from the main gear pump, merging their capabilities to ensure adequate fuel supply to accessory actuators without requiring the servo gear pump to be oversized for all conditions
Solution Approach 2:
The pump sharing valve dynamically adjusts fuel flow distribution between the servo gear pump and main gear pump based on system operating conditions. During start-up, the valve directs maximum flow to the servo gear pump; during steady-state, it supplements flow from the main gear pump, allowing the servo gear pump to be smaller while maintaining reliability across varying conditions
2Productivity
If the servo gear pump provides high flow at start conditions, then fuel supply during startup is adequate, but the pump is oversized for steady-state operation
Solution Approach 1:
The pump sharing valve implements partial action by directing fuel flow selectively to the servo gear pump based on operational needs. During start-up, full flow is directed to the servo pump; during steady-state, only supplemental flow is provided from the main pump, allowing the servo pump to be sized for partial rather than excessive capacity
Solution Approach 2:
The main gear pump serves multiple functions: it supplies fuel to the combustion chamber and, through the pump sharing valve, supplements fuel flow to the servo gear pump during specific operating conditions. This multi-functionality allows the servo pump to be smaller since it doesn't need to handle all flow requirements alone
3Reliability
If fuel flow is supplemented from the main gear pump to the servo gear pump, then fuel supply adequacy is maintained, but system complexity increases
Solution Approach 1:
The pump sharing valve acts as an intermediary device that automatically manages fuel flow distribution between the main gear pump and servo gear pump. It mediates the complex flow requirements by using pressure differential operation to automatically direct or supplement flow based on system conditions, maintaining reliability while managing complexity through a single integrated valve mechanism
Data Source
AI summary
A pump sharing valve for a gas turbine engine fuel system includes a housing having multiple ports. A sleeve is arranged in the housing and includes an inlet window and first, second and third windows axially spaced apart from one another. A spool is slidably received in the sleeve and includes a diameter and first and second cylindrical portions. The first cylindrical portion selectively connects the inlet window to the second and third windows. The second cylindrical portion selectively connects the inlet window to the first window. The spool is movable between first and second positions relative to the first, second and third windows to regulate flow. The first and second cylindrical portions respectively includes first and second widths. A first ratio corresponds to the first width to the spool diameter and a second ratio corresponds to the second width to the spool diameters. The first ratio is between 1.83 and 1.93 and the second ratio is between 1.22 and 1.32.