Variable Displacement Fuel System Bypass Valve for Thermal Management
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Solution Overview
Problem
Conventional aircraft fuel systems require thermal recirculation systems due to over-temperature heat loads at low burn flow conditions, necessitating additional components and space, which is undesirable.
Innovation Solution
A fuel system design that includes a bypass valve in parallel with the fuel oil cooler, allowing fuel to bypass the cooler when temperature exceeds a predetermined limit, eliminating the need for thermal recirculation and combining main and augmentor pumps for efficient fuel flow modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If thermal recirculation system is eliminated, then device complexity and weight are reduced, but over-temperature heat loads at low burn flow conditions cannot be managed
Solution Approach 1:
The system dynamically switches between thermal recirculation mode and bypass mode based on operating conditions. The bypass valve opens when burn flow exceeds cooling demand, allowing the system to adapt to varying temperature requirements without a fixed thermal recirculation path.
Solution Approach 2:
The thermal recirculation function is extracted as an optional mode rather than a required continuous function. The bypass valve enables the system to operate without thermal recirculation when conditions permit, removing the necessity for permanent thermal recirculation infrastructure.
2Weight of moving object
If thermal recirculation system is eliminated, then weight and fuel capacity are improved, but heat load management capability is reduced
Solution Approach 1:
The system changes the flow path parameter by opening the bypass valve when thermal recirculation is not needed. This parameter change allows the system to operate in a lightweight configuration while maintaining heat load management capability through controlled bypass flow.
3Adaptability or versatility
If bypass valve is added to allow FOC bypass, then heat load management flexibility is improved, but device complexity increases
Solution Approach 1:
The bypass valve serves multiple functions: it allows FOC bypass when conditions permit, enables thermal recirculation mode when needed, and provides a simple mechanism for heat load management flexibility without requiring complex control systems.
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
The system reduces weight and complexity by eliminating thermal recirculation, modulates fuel flow to prevent overcooling, and allows for increased fuel capacity in aircraft.
Implementation Method 1
A fuel oil cooler (FOC) is included in a first branch of the supply line. The FOC is in fluid communication to receive flow from the second outlet.
Implementation Method 2
The APS includes a bypass valve (BPV) in a second branch of the supply line, in parallel with the FOC and in fluid communication to allow flow from the third outlet into the supply line bypassing the FOC.
Data Source
Figure 1
AI summary
A system (100) includes an actuation pump sub-system (APS) (102). A fuel oil cooler (FOC) (124) is included in a first branch (120) of a supply line (116). The FOC (124) is in fluid communication to receive flow from a second outlet (114) of the APS (102). The APS (102) includes a bypass valve (BPV) (126) in a second branch (122) of the supply line (116), in parallel with the FOC (124) and in fluid communication to allow flow from the third outlet (118) into the supply line (116) bypassing the FOC (124). A combined main and augmentor pump sub-system (CMAPS) (129) has a main inlet (130) connected in fluid communication with the supply line (116) downstream of the BPV (126) and FOC (124), a gas generator (GG) outlet (134) for supplying fuel to a downstream gas generator, and an augmentor outlet (135) for supplying fuel to a downstream augmentor (150).