Aircraft Engine Fuel Supply Centrifugal Pump Segmentation
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Solution Overview
Problem
Existing fuel supply systems for aircraft engines are inefficient in terms of weight and power consumption, with electrically-controlled vane pumps requiring large capacity for metering, leading to accuracy issues at slow speeds and potential fuel metering failure.
Innovation Solution
A fuel supply circuit utilizing a centrifugal pump driven mechanically by the engine, combined with an electrically-controlled assistance pump unit, which includes a positive-displacement pump or regenerative pump, to optimize fuel delivery and minimize weight and power consumption, with a regulator circuit for precise flow rate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an electrically-controlled vane pump is used for fuel metering, then fuel pressure can be raised to the needed value, but the pump requires large capacity which leads to poor metering accuracy at slow speeds and potential metering failure
Solution Approach 1:
The fuel supply system is segmented into two distinct pump units: a first pump unit (centrifugal pump) for main fuel supply and a second pump unit (positive-displacement pump) for precise metering. This segmentation allows each pump to be optimized for its specific function, resolving the contradiction between pressure generation and metering accuracy
Solution Approach 2:
A check valve is introduced as an intermediary component between the two pump units. The check valve selectively directs fuel flow from either the first or second pump unit to the fuel injector based on operating conditions, enabling the system to achieve both high pressure and precise metering accuracy without compromise
2Power
If an electrically-controlled vane pump operates continuously for metering, then fuel can be delivered at needed pressure, but weight and power consumption increase
Solution Approach 1:
The second pump unit (positive-displacement pump) operates periodically or selectively based on engine speed conditions rather than continuously. The control system activates this pump only when precise metering is required at lower speeds, reducing overall power consumption while maintaining necessary fuel delivery pressure
Solution Approach 2:
The system uses the engine's own mechanical power to drive the first centrifugal pump unit, eliminating the need for an separate electric motor for the main fuel supply. This self-service approach reduces external power consumption and system weight
3Productivity
If a large-capacity vane pump is used to accept maximum fuel flow rate, then fuel pressure can be maintained, but metering accuracy at slow speeds deteriorates
Solution Approach 1:
The fuel supply function is divided between two specialized pump units: the first centrifugal pump unit handles high flow rate requirements at maximum power, while the second positive-displacement pump unit provides precise metering at lower speeds. This segmentation resolves the contradiction between productivity and measurement precision
Solution Approach 2:
Each pump unit is designed with local quality optimized for its specific operating range. The first pump unit has large capacity for high flow rates, while the second pump unit has precision metering capabilities for slow speeds. The check valve enables selective engagement of the appropriate pump quality for each operating condition
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 solution achieves better weight and power efficiency by leveraging mechanical engine power, ensuring reliable fuel delivery at minimum pressure, and precise flow rate regulation, while avoiding the limitations of electrically-controlled vane pumps.
Implementation Method 1
a centrifugal pump (100) driven by mechanical coupling with the engine (14), having a low pressure inlet receiving fuel from a fuel circuit (11) of the aircraft and a high pressure outlet connected to the fuel flow rate regulator circuit (120)
Implementation Method 2
an electrically-controlled assistance pump unit (110) having an inlet connected to the fuel circuit (11) of the aircraft and an outlet connected to the flow rate regulator circuit (120), to deliver at its outlet, fuel at a predetermined minimum pressure
Data Source
AI summary
A centrifugal pump driven by mechanical coupling with an engine has a low pressure inlet receiving fuel from a fuel circuit of an aircraft, a high pressure outlet connected to a regulator circuit for regulating the flow rate of fuel supplied to the engine, and an assistance pump unit that is electrically controlled, having an inlet connected to the aircraft fuel circuit and an outlet connected to the flow rate regulator circuit so as to deliver, via its outlet, fuel that is at a predetermined minimum pressure, the pressure of the fuel supplied to the regulator circuit being the higher of the pressures delivered by the centrifugal pump and the assistance pump unit.