Pump Sharing Valve Control for Dual Fuel Pump Shutdown Flow
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Solution Overview
Problem
Conventional fuel systems for gas turbine engines require large main fuel pumps to accommodate varying engine conditions and actuator demands, leading to inefficiencies and challenges in controlling fuel flow, especially during engine shutdowns.
Innovation Solution
A dual-pump system with a pump sharing valve that regulates fuel flow between a main fuel pump and a servo fuel pump, allowing them to share fuel flows in various concentrations to optimize operation under different conditions, ensuring adequate fuel supply to nozzles and actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large main fuel pump is used to accommodate the entire engine operating envelope, then fuel flow requirements are met across all conditions, but pump size and energy consumption increase
Solution Approach 1:
The fuel pumping function is segmented into two separate pumps: a main fuel pump for combustion fuel delivery and a dedicated servo pump for actuator operation. This segmentation allows each pump to be optimized for its specific function and operating conditions, eliminating the need for an oversized main pump that must accommodate all engine conditions including shutdown scenarios.
Solution Approach 2:
A pump sharing valve is introduced as an intermediary device that selectively directs fuel flow from either the main fuel pump or the servo pump to the actuators based on engine operating conditions. During normal operation, the valve directs servo pump output to actuators; during shutdown, it redirects main pump flow to supplement servo pump output, ensuring continuous actuator operation without requiring the main pump to be oversized.
2Reliability
If a dedicated servo pump is used to service actuators, then actuator operation is improved, but system complexity increases
Solution Approach 1:
The pump sharing valve serves multiple functions: it normally directs servo pump flow to actuators, but during shutdown conditions automatically redirects main pump flow to supplement the servo pump. This multi-functionality allows the system to maintain simple two-pump architecture while achieving complex flow management capabilities that would otherwise require additional control systems.
Solution Approach 2:
The pump sharing valve is designed to automatically respond to engine shutdown conditions and redirect fuel flow without requiring external control signals or complex electronic systems. The valve self-regulates based on system state, reducing control complexity while maintaining reliable actuator operation during shutdown.
3Reliability
If the main fuel pump is sized for maximum transient conditions, then fuel availability during take-off is ensured, but pump efficiency decreases during idle operation
Solution Approach 1:
By segmenting the fuel pumping function into main pump and servo pump, the main pump can be sized appropriately for combustion fuel delivery without needing to accommodate actuator flow requirements. The servo pump handles actuator flow independently, allowing the main pump to operate at optimal efficiency across all engine conditions without the penalty of oversized design.
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 configuration reduces the size and operational demands of the main pump, enhances fuel efficiency, and ensures sufficient fuel flow to actuators even during low engine output conditions, facilitating efficient engine operation and restart.
Implementation Method 1
a pump sharing valve that regulates fuel flow between a main fuel pump and a servo fuel pump
Data Source
Figure 1A
Figure 1B
AI summary
A fuel system (10), such as for use in an aircraft, comprises a main pump (14), a servo pump (16), a metering valve (24), a shut-off valve (26), an actuator (20) and a pump sharing valve (12). The main pump (14) and the servo pump (16) receive fuel from a source (30). The metering valve (24) receives main flow (31) from the main pump (14). The shut-off valve (26) receives fuel flow from the metering valve (24). The actuator (20) receives fuel flow from the servo pump (16). The pump sharing valve (12) receives circulating flow from the servo pump (16) and alternatively directs shared flow to the main flow (31) or an inlet of the servo pump (16). The pump sharing valve (12) also sends main pump flow to supplement the servo pump during shutdown conditions.