Dual Pump Fuel Delivery System for Heat Reduction
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Solution Overview
Problem
Fuel delivery systems for gas turbine engines waste energy by raising excess fuel flow to high pressure, leading to undesirable heat input and inefficient operation, especially during varying engine demand conditions.
Innovation Solution
A dual pump, flow-sharing fuel delivery and control system where a main positive displacement pump is sized for cruise burn flow and a supplementary actuation pump with a variable pressure regulator is used to minimize excess fuel pressurization, allowing flow sharing to meet engine demands, thus reducing waste heat energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single high pressure pump is sized to meet maximum fuel demand, then sufficient fuel flow is provided during windmill start and maximum power conditions, but excessive fuel flow is pressurized to high pressure during cruise conditions, wasting energy and generating heat
Solution Approach 1:
The single pump system is segmented into two separate pumps: a main pump sized for cruise conditions and a supplemental pump for peak demand. This allows each pump to be optimized for its specific operating range, preventing the main pump from wasting energy pressurizing excess fuel during cruise while ensuring adequate supply during maximum demand.
Solution Approach 2:
The system dynamically switches between pump configurations based on engine demand. The supplemental pump is activated only when additional fuel flow is needed beyond the main pump's capacity, allowing the system to adapt its pressurization capacity to actual requirements and minimize energy waste during steady-state operation.
2Productivity
If excess high pressure fuel flow is bypassed back to low pressure inlet, then the pump continues to supply required flow, but the energy used to raise the pressure is wasted and heats the fuel
Solution Approach 1:
By segmenting the pump functions, the main pump operates at or near optimal efficiency points without excessive bypass flow. The supplemental pump handles peak demand supplementation, reducing the need for the main pump to recirculate excess flow and thereby minimizing heat generation from pressure-raising operations.
Solution Approach 2:
The system changes the operational parameters of the pumping system by introducing a second pump with different displacement characteristics. This allows the main pump to operate at lower, more efficient pressure differentials during cruise, reducing the thermal energy input to the fuel while maintaining adequate supply through coordinated operation with the supplemental pump.
3Loss of energy
If a smaller main pump is used for cruise conditions, then energy waste is reduced, but additional pump capacity is needed for peak demand conditions
Solution Approach 1:
The total pump flow capacity is segmented between two pumps with different sizing optimizations. The main pump is sized for efficient cruise operation with minimal bypass, while the supplemental pump provides additional capacity for peak demand. This segmentation allows the system to achieve both energy efficiency during steady-state and adequate total capacity during transient peak conditions.
Solution Approach 2:
The supplemental pump serves multiple functions: it supplements the main pump during peak demand, provides standby capacity, and can handle transient surges. This multi-functionality allows the main pump to be sized smaller for cruise efficiency while the supplemental pump ensures adequate total system capacity is available when needed.
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 waste heat generation by minimizing differential pressure across the actuation pump, allowing it to operate at lower discharge pressures, and enables efficient fuel delivery during both steady-state and transient conditions, potentially eliminating the need for a servo heat-exchanger and optimizing pump sizing.
Implementation Method 1
a positive displacement pump is provided and sized to supply fuel at cruise burn flow conditions
Implementation Method 2
The actuation pump is preferably sized to provide sufficient pressure to supply the engine functions and includes a variable pressure regulator to maintain the lowest possible differential pressure (delta P) across the pump
Data Source
Figure 1
AI summary
A fuel delivery and control system is provided including a dual pump fluid circuit configuration comprising a fixed positive displacement pump sized to supply the main engine burn flow ranging from above windmill through cruise, a positive displacement actuation pump including a variable pressure regulator, wherein the actuation pump is sized to supply fluid to engine actuators, valves and other hydraulically operated engine components and a pump flow sharing system interconnecting the two pumps. The combined flow from the two pumps is sufficient to meet the engine flow demand for windmill relight and maximum flow conditions. During cruise or normal operating conditions, the pumps operate in completely isolated flow circuits, minimizing recirculation and therefore heat input into the fuel supply system.