Aircraft Fuel Supply System Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In larger helicopters, the increased fuel head between the fuel tank and the powerplant can lead to suction requirements that result in fuel vapour evolution and air dissolution, potentially causing fuel flow interruptions or engine failure during extreme maneuvers, especially when the absolute pressure at the inlet to the suction pump approaches or falls below the fuel's vapour pressure.
Innovation Solution
A fuel supply system with a downstream pump at the powerplant and an upstream pump in the fuel tank, monitored by a pressure sensor, where a fuel system controller adjusts the upstream pump to maintain the inlet pressure to the downstream pump at or above a predetermined threshold, ensuring sufficient pressure to prevent excessive air and vapour formation, using a control loop that can adapt to changes in fuel temperature and type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fuel tank is located in a lower portion and the powerplant in an upper portion to mitigate fire hazard, then fire safety is improved, but the fuel head increases leading to suction pump inlet pressure dropping below vapour pressure
Solution Approach 1:
A pressurization pump is introduced as an intermediary device between the fuel tank and the powerplant. This pump actively pressurizes the fuel in the supply line, compensating for the pressure drop caused by the vertical head and ensuring the inlet pressure to the suction pump remains above the fuel vapour pressure, thus preventing cavitation and maintaining reliable fuel flow while preserving the fire safety benefits of the lower tank configuration
Solution Approach 2:
The system changes the pressure parameter of the fuel in the supply line by introducing a pressurization pump. This active pressure control ensures that despite the increased vertical head, the absolute pressure at the suction pump inlet remains above the vapour pressure threshold, preventing fuel vaporization and air dissolution that would otherwise occur in larger helicopters
2Quantity of substance
If the helicopter size increases leading to larger fuel head, then payload capacity is improved, but the suction required increases causing fuel vapour evolution and air dissolution
Solution Approach 1:
The pressurization pump serves as a mediator that decouples the relationship between fuel head and suction pump inlet pressure. It actively maintains the pressure above vapour pressure regardless of the vertical distance between tank and powerplant, enabling larger helicopter configurations without compromising fuel flow stability
Solution Approach 2:
The pressurization pump applies preliminary pressurization to the fuel before it reaches the suction pump inlet. This pre-pressurization prevents the formation of vapour bubbles and air dissolution that would occur under high suction conditions, ensuring stable fuel flow delivery to the powerplant
3Adaptability or versatility
If extreme maneuvers are performed to enhance operational capability, then mission performance is improved, but the absolute pressure at pump inlet may fall below vapour pressure causing fuel flow interruption
Solution Approach 1:
The system incorporates a pressure sensor that continuously monitors the absolute pressure at the suction pump inlet and provides feedback to a controller. The controller adjusts the pressurization pump operation in real-time to maintain pressure above the vapour pressure threshold, even during extreme maneuvers that would otherwise cause pressure drops and fuel flow interruptions
Solution Approach 2:
The pressurization pump acts as a buffer that isolates the fuel supply system from the effects of extreme maneuvers. By actively compensating for pressure variations caused by high G-forces and rapid maneuvers, it ensures continuous stable fuel delivery to the powerplant throughout the full envelope of operational capabilities
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 solution maintains stable fuel flow to the powerplant, reducing the risk of engine failure and ensuring survivability by maintaining adequate pressure at the inlet to the downstream pump, even under extreme conditions, while minimizing the risk of fuel leakage and hazards.
Implementation Method 1
A pressure sensor is configured to monitor a pressure at an inlet to the downstream pump
Implementation Method 2
An upstream pump is disposed in or associated with the fuel tank and operable to pump fluid along the fuel flow passage
Implementation Method 3
a downstream pump is associated with the powerplant and configured to draw fluid along the fuel flow path so as to supply it to the powerplant in use
Implementation Method 4
A fuel system controller is responsive to the pressure sensor and configured to control the upstream pump so as to maintain the pressure at the inlet to the downstream pump at or above a predetermined threshold pressure
Data Source
AI summary
A fuel supply system for an aircraft is provided for delivering in use fuel from a fuel tank to an aircraft powerplant. The in use fuel flows along a fuel flow passage from the fuel tank to the powerplant. A downstream pump is associated with the powerplant and configured to draw fluid along the fuel flow path so as to supply it to the powerplant in use. An upstream pump is disposed in or associated with the fuel tank and operable to pump fluid along the fuel flow passage. A pressure sensor is configured to monitor a pressure at an inlet to the downstream pump. A fuel system controller is responsive to the pressure sensor and configured to control the upstream pump so as to maintain the pressure at the inlet to the downstream pump at or above a predetermined threshold pressure.