Aircraft Fuel Control System Segmentation for Efficiency
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Solution Overview
Problem
The efficiency of fuel control systems in aircraft engines, which use centrifugal pumps, is dependent on the flow rate of fuel, and existing systems lack durability compared to positive displacement pumps.
Innovation Solution
A fuel control system for aircraft engines is proposed, comprising a main circuit with two centrifugal pumps and a secondary circuit, where the first centrifugal pump supplies a lower pressure and flow rate dedicated to feeding the combustion chamber, while the second centrifugal pump supplies a higher pressure and flow rate for both combustion chamber feeding and actuating variable geometry units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a centrifugal pump is used instead of a positive displacement pump, then durability is improved, but efficiency becomes dependent on flow rate
Solution Approach 1:
The fuel control system is divided into a main circuit with two centrifugal pumps operating in series and a secondary circuit. The first centrifugal pump (411) and second centrifugal pump (412) are segmented to perform different functions: the first pump handles combustion chamber feeding, while the second pump handles both combustion chamber feeding and variable geometry unit actuation. This segmentation allows each pump to operate at optimal efficiency points across different flow rates, resolving the efficiency-flow rate dependency issue while maintaining the durability benefits of centrifugal pumps.
2Device complexity
If a single centrifugal pump is used, then device complexity is reduced, but the pump must be over-dimensioned to handle all flow rate requirements
Solution Approach 1:
Instead of using a single oversized centrifugal pump, the system segments the pumping function into two smaller centrifugal pumps operating in series. The first pump (411) is sized for combustion chamber feeding requirements, while the second pump (412) is sized for combined combustion chamber and variable geometry unit requirements. This eliminates the need for over-dimensioning and reduces overall system mass while maintaining adequate complexity for efficient operation across all flow rate conditions.
Solution Approach 2:
The system transitions from a single-pump configuration to a two-pump series configuration, adding a dimensional aspect to the pump arrangement. This dimensional change allows the system to handle variable flow rate requirements more efficiently by having pumps operate at different points in the flow rate spectrum, rather than relying on a single oversized pump operating inefficiently across all conditions.
3Adaptability or versatility
If pumps are over-dimensioned to handle all engine speeds, then adaptability is improved, but engine mass increases
Solution Approach 1:
The fuel control system segments the pumping function into two centrifugal pumps with different capacity requirements. The first pump (411) handles lower flow rate demands at various engine speeds, while the second pump (412) handles higher flow rate demands. This segmentation allows the system to adapt to the full engine speed range without requiring either pump to be over-dimensioned, thereby reducing overall engine mass while maintaining full adaptability.
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 allows the fuel control system to operate efficiently across a range of engine speeds, maintaining constant efficiency and reducing the need for over-dimensioning pumps, thus minimizing engine mass and optimizing power extraction.
Implementation Method 1
a first centrifugal pump (411) comprising an intake port and a discharge port
Data Source
AI summary
The present invention relates to a fuel control system (4) comprising: a fuel source; a supply conduit; a main circuit comprising: a first centrifugal pump; a connecting conduit; a second centrifugal pump; a discharge conduit; and a secondary circuit.