Aircraft Fuel System Backup Pump Selection
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Solution Overview
Problem
In gas turbine engine fuel delivery systems, the boost pump is often oversized and not optimized for most of its operating range, leading to inefficiencies, wasted power, and excess heat at normal cruise/low power conditions.
Innovation Solution
A fuel system with a boost pump, one or more selector valves, a first component pump, and a second component pump, where the selector valves allow for the redirection of fuel flow between the pumps and components, enabling optimized fuel delivery based on operational requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the boost pump is oversized to meet peak fuel flow requirements, then the fuel delivery system can handle maximum power conditions, but the boost pump operates inefficiently at normal cruise/low power conditions, wasting power and generating excess heat
Solution Approach 1:
The fuel delivery system is segmented into multiple boost pumps, each optimized for specific operating conditions. A first boost pump handles high-power conditions while a second boost pump handles cruise/low-power conditions, allowing each pump to operate at optimal efficiency in its designated range.
Solution Approach 2:
The system dynamically selects which boost pump to operate based on current power conditions. The controller activates the appropriate pump (first or second) depending on whether the engine is in high-power or cruise/low-power mode, ensuring optimal efficiency across all operating conditions.
2Device complexity
If a single boost pump is used for all operating conditions, then the system is simpler, but the pump cannot be optimized for different phases of flight, resulting in operational inefficiencies
Solution Approach 1:
The second boost pump is designed with multi-functionality to serve dual purposes: it can deliver fuel to the combustor during cruise conditions and also provide backup fuel delivery if the first boost pump fails. This universal design allows one pump to cover multiple operational scenarios.
Solution Approach 2:
The system changes operational parameters by switching between different pump configurations based on flight phase. During cruise, the second pump operates at optimized parameters for efficiency, while during high-power conditions, the first pump operates at parameters optimized for maximum flow capacity.
3Reliability
If the second component pump is selectively coupled to either the input or output of the boost pump, then backup fuel flow capability is provided, but the valve configuration becomes more complex
Solution Approach 1:
The selector valve acts as an intermediary component that manages the complex routing between the boost pump and component pumps. It provides a controlled interface that enables the second component pump to be selectively coupled to either the input or output of the boost pump, simplifying the overall system architecture while maintaining backup capability.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A fuel system (100) of an aircraft engine, having: a boost pump (130) having an input (1301) and an output (1302); one or more selector valves (171); a first component pump (141) having an input (1411) fluidly coupled to the output (1302) of the boost pump and an output (1412) of the first component pump is configured to direct fuel to a first component (151) via the one or more selector valves (171); and a second component pump (142) having an input (1421) that is selectively coupled to either the input (1301) or the output (1302) of the boost pump by the one or more selector valves (171), and an output (1422) of the second component pump is fluidly coupled to a second component (152) and selectively coupled to the first component (151) by the one or more selector valves (171).