Aircraft Fuel System Weight and Heat Reduction
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Solution Overview
Problem
Conventional fuel systems for aircraft face challenges in reducing weight and heat rejection, limiting the amount of fuel that can be carried and increasing heat rejection, necessitating improvements for more efficient fuel management.
Innovation Solution
A fuel system incorporating a main fuel pump, an augmentor fuel pump, and a variable displacement pump assembly, along with a main fuel throttle valve assembly and actuation assembly, which allows for fluid communication and flow redirection between different lines and modes to optimize fuel flow and pressure distribution, ensuring efficient operation and backup in various failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional fuel systems are used, then the system structure is simple, but the weight is high and heat rejection is excessive
Solution Approach 1:
The fuel system is divided into multiple independent pump assemblies: a main fuel pump assembly with a main fuel pump and a first variable displacement pump assembly, and an augmentor fuel pump assembly with an augmentor pump and a second variable displacement pump assembly. This segmentation allows each pump to be optimized for specific functions, reducing overall system weight while distributing thermal loads across multiple components.
Solution Approach 2:
The variable displacement pump assemblies are designed to perform multiple functions: they can operate independently to provide fuel flow, work in combination with the main pump to increase capacity, and serve as backup systems. The pumps can also redirect fuel flow for thermal management, allowing a single component type to address multiple system requirements simultaneously.
2Quantity of substance
If conventional fuel systems are used, then the system design is straightforward, but the fuel capacity is limited due to heat rejection constraints
Solution Approach 1:
The variable displacement pump assemblies act as intermediaries between the fuel tanks and the engine, providing precise control over fuel flow rates and pressures. They can redirect fuel flow through heat exchangers or thermal management pathways, decoupling the fuel delivery function from the thermal management function and allowing increased fuel capacity without proportional increases in heat rejection issues.
Solution Approach 2:
The variable displacement pumps dynamically adjust their output based on real-time system requirements, including thermal conditions and fuel demand. This dynamic control allows the system to optimize the balance between fuel delivery and heat rejection, enabling higher fuel capacities by actively managing thermal loads rather than being constrained by static design parameters.
3Reliability
If conventional fuel systems are used, then the system has fewer components, but the reliability in failure modes is reduced
Solution Approach 1:
The system incorporates redundant pump assemblies that can be activated in advance or automatically upon detection of failures in primary components. The variable displacement pumps are designed with inherent backup capabilities, and the system includes pre-configured flow paths that can be activated to maintain fuel delivery even when individual pumps fail, providing cushioning against reliability issues before they occur.
Solution Approach 2:
The variable displacement pumps can change their operational parameters (flow rate, pressure, displacement) in response to system conditions and failures. This parameter flexibility allows the system to maintain reliable operation across a wide range of scenarios, from normal operation to various failure modes, by adapting pump characteristics rather than requiring complete system redundancy.
Data Source
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AI summary
A fuel system can include a main fuel pump (MFP) (104) configured to output main flow to a main line, an augmentor fuel pump (AFP) (106) configured to output an augmenter flow to an augmenter line, and a variable displacement pump assembly (VDPP) in fluid communication with the AFP via the augmentor line to receive the augmentor flow. The VDPP can include a variable displacement pump (VDP) configured to output a VDP flow to a VDP output line. The system can include a main fuel throttle valve assembly (MFTV) in fluid communication with the main fuel pump via the main line to receive the main flow and in fluid communication with the VDPP via a backup line. The MFTV can be in fluid communication with an engine line, an actuation assembly in fluid communication with the VDPP via an actuation line to receive an actuation flow.