Variable Displacement Pump Fuel System for Aircraft Engines
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Solution Overview
Problem
Existing aircraft engine fuel systems suffer from inefficiencies due to the use of fixed displacement pumps, leading to excess fuel flow, increased power consumption, and waste heat, which can cause fuel lacquering and coke formation.
Innovation Solution
The implementation of a variable displacement pump in the fuel system, which allows for independent adjustment of discharge flow rate and pressure relative to the turbo engine speed, reducing excess fuel flow and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fixed displacement pumps are used in the fuel system, then sufficient fuel flow can be ensured, but excess fuel flow and increased power consumption occur
Solution Approach 1:
The patent applies a variable displacement pump instead of a fixed displacement pump, allowing the pump to dynamically adjust its discharge flow rate and pressure according to the actual fuel demands of the combustion section. This dynamic adjustment capability enables the system to match fuel supply with actual consumption needs, reducing excess fuel flow and associated power consumption while ensuring sufficient fuel delivery under all operating conditions
2Quantity of substance
If fixed displacement pumps are used to ensure sufficient fuel flow, then fuel supply is adequate, but waste heat increases causing fuel lacquering and coke formation
Solution Approach 1:
The variable displacement pump dynamically adjusts its operation to match actual fuel demands, reducing excess fuel flow that would otherwise generate waste heat. By controlling the pump displacement based on real-time fuel requirements, the system minimizes unnecessary fuel circulation and the associated heat generation, thereby preventing fuel lacquering and coke formation in the fuel lines and combustion section
3Use of energy by moving object
If variable displacement pump is implemented, then power consumption is reduced, but system complexity increases
Solution Approach 1:
The variable displacement pump system incorporates feedback control mechanisms that monitor fuel pressure and flow conditions, automatically adjusting pump displacement to maintain optimal operation. This feedback-based control enables the system to reduce power consumption by matching fuel supply to actual demands without requiring complex manual intervention or oversimplified control logic
Solution Approach 2:
The system changes the operational parameters of the pump (displacement, flow rate, pressure) based on actual fuel system conditions. By dynamically adjusting these parameters rather than maintaining fixed settings, the system achieves reduced power consumption while managing complexity through parameter optimization rather than structural complexity
4Reliability
If excess fuel flow is produced, then fuel supply adequacy is ensured, but fuel degradation occurs
Solution Approach 1:
The variable displacement pump dynamically adjusts its discharge flow rate to match the actual fuel consumption of the combustion section, avoiding the production of excess fuel flow. This dynamic matching ensures that fuel is supplied at the precise rate needed, maintaining fuel supply adequacy under all operating conditions while preventing the thermal degradation that results from circulating excess fuel through the system
Data Source
AI summary
A turbo engine for an aircraft includes a gas turbine engine having a fuel system to provide fuel to a combustion section. The fuel system includes a variable displacement pump driven by an accessory gearbox that is powered by a shaft of the gas turbine engine. The variable displacement pump has an inlet side and an outlet side. The variable displacement pump includes an actuator configured to adjust a discharge flow rate of the variable displacement pump. The fuel system also includes a fuel metering valve configured to receive pressurized fuel from the variable displacement pump and control a flow rate of the pressurized fuel to the combustion section. The fuel system further includes a bypass valve fluidly coupling the outlet side and the inlet side of the variable displacement pump to direct an excess portion of the pressurized fuel at the outlet side back to the inlet side.