Motive Pump Fuel Actuation System for Gas Turbine Engines
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Solution Overview
Problem
Conventional fuel systems for gas turbine engines require large main fuel pumps to accommodate varying engine conditions, leading to inefficiencies such as excessive horsepower consumption and waste heat generation, as well as fatigue stress on servo valve-controlled actuators due to the wide operating envelope.
Innovation Solution
A fuel and actuation system utilizing a main fuel pump and a motive fuel pump, where the motive pump provides fuel to actuators, allowing the main fuel pump to be sized only for the required distribution system flow, thereby reducing its capacity and eliminating the need for excessive fuel flow to actuators, which are powered by the motive pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the main fuel pump is sized to provide fuel to both the distribution system and actuators across the entire engine operating envelope, then the system can accommodate all engine conditions, but the pump capacity becomes excessively large, consuming more horsepower and generating waste heat
Solution Approach 1:
The fuel delivery system is divided into two separate pumps: a main fuel pump dedicated to the distribution system and a motive fuel pump dedicated to the actuators. This segmentation allows each pump to be sized for its specific function rather than requiring one oversized pump to handle all functions across the entire operating envelope.
Solution Approach 2:
The motive fuel pump serves multiple functions by providing fuel to both the actuator system and, through the ejector, to the distribution system. This multi-functionality eliminates the need for the main fuel pump to be oversized for actuator requirements while still ensuring adequate fuel delivery to all system components.
2Reliability
If the main fuel pump is sized to provide sufficient fuel flow to actuators during transient conditions, then actuator performance is maintained, but the pump generates excessive waste heat
Solution Approach 1:
By separating the actuator fuel supply function into a dedicated motive fuel pump, the main fuel pump no longer needs to be oversized for transient actuator demands. This eliminates the waste heat generation associated with pumping excess fuel that is not actually consumed by the distribution system during normal operation.
3Adaptability or versatility
If the actuators are sized to withstand elevated pressures during transient conditions, then they can handle the wide operating envelope, but the actuators become heavier and more expensive
Solution Approach 1:
The ejector utilizes the motive fuel pump's output to provide fuel to the distribution system, eliminating the need for a separate high-capacity main fuel pump. This allows actuators to be sized for their actual requirements rather than being oversized to handle the full range of transient conditions, reducing their weight and cost.
4Ease of operation
If the main fuel pump is sized to provide fuel to the distribution system at idle engine speed, then idle operation is maintained, but the pump cannot efficiently handle transient conditions without excessive capacity
Solution Approach 1:
The fuel system is segmented into two independent delivery paths: one for the distribution system (maintaining idle operation) and one for actuators (handling transient demands). This allows the main fuel pump to be optimized for idle operation while the motive fuel pump handles transient conditions, improving overall system productivity without requiring excessive pump capacity.
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 configuration results in a more efficient fuel system with reduced horsepower consumption, lower system heat generation, lighter and less expensive actuators, and lower cycle fatigue, as the main fuel pump is 20-30% smaller and lighter, and actuators operate at lower pressures.
Implementation Method 1
The motive pump provides a motive fuel flow to an ejector that distributes fuel within the fuel tank and delivers fuel to the actuators
Data Source
Figure 1
AI summary
A fuel system (10) for an aircraft comprises a boost pump (22), a main fuel pump (12) and a motive pump (14). The boost pump (22) receives fuel from a storage unit (20). The main fuel pump (12) receives fuel from the boost pump (22) and delivers fuel to a distribution system (16). The motive fuel pump (14) receives fuel from the boost pump (22), routes fuel through the storage unit (20), and delivers fuel to an actuator (18A, 18B). A method for delivering fuel in an aircraft comprises pumping fuel from a fuel tank (20) to a distribution system (16) using a main pump (12), pumping fuel from a fuel tank (20) to an actuator using a motive pump (14), and routing fuel from the actuator (18A, 18B) to the main pump (12).