Multiple Stage Gear Pump Thermal Management
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Solution Overview
Problem
Existing fuel delivery systems for gas turbine engines, such as single stage fixed displacement gear pumps, generate excess heat and are costly and heavy due to multiple components, which are critical issues in aerospace applications where low energy consumption and weight are paramount.
Innovation Solution
A thermally efficient multiple stage gear pump is designed with shared mechanical components between stages, including a hydraulically actuated valve and a boost stage impeller assembly, which switches between primary and secondary gear sets based on engine operation regimes to optimize fuel delivery and reduce thermal inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single stage fixed displacement gear pump is used, then the structure is simple and cost is low, but excess heat is generated and thermal efficiency is poor
Solution Approach 1:
The single pumping stage is divided into multiple pumping stages (first stage with first set of gears, second stage with second set of gears), each capable of operating independently or together depending on the operating regime. This segmentation allows the system to reduce heat generation by activating only the necessary number of stages, while the overall structure remains integrated rather than completely separate systems.
2Temperature
If multiple separate gear sets and bearings are used in each stage, then thermal efficiency is improved, but cost and weight increase
Solution Approach 1:
The pump design uses a shared bearing set that supports multiple gear sets (first driving gear, first driven gear, second driving gear, second driven gear). This universal bearing arrangement allows a single bearing set to fulfill the support function for all gear stages, reducing the total number of bearings needed while maintaining the thermal efficiency benefits of multiple stages. The bearing set is positioned to accommodate gears from different stages, making it a multi-functional component.
3Temperature
If multiple separate gear sets and bearings are used in each stage, then thermal efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The pump design uses a shared bearing set that supports multiple gear sets (first driving gear, first driven gear, second driving gear, second driven gear). This universal bearing arrangement allows a single bearing set to fulfill the support function for all gear stages, reducing the total number of bearings needed while maintaining the thermal efficiency benefits of multiple stages. The bearing set is positioned to accommodate gears from different stages, making it a multi-functional component.
Solution Approach 2:
The pump housing integrates multiple functional elements into a unified structure, including the bearing support, gear mounting, and fluid passages. The first and second gear sets are mounted on the same bearing set within a single housing, merging what could have been separate pump units into one integrated assembly, thereby reducing manufacturing cost while maintaining thermal efficiency.
4Temperature
If a hydraulically actuated valve is added to control fuel flow, then thermal efficiency is improved, but device complexity increases
Solution Approach 1:
The hydraulically actuated valve is designed to operate automatically based on pressure differential without requiring external control signals or complex control systems. The valve element responds to pressure changes from the boost stage, automatically switching the first pumping stage between high-pressure delivery and low-pressure recirculating modes. This self-service mechanism reduces thermal efficiency issues while minimizing the addition of complexity, as the valve regulates itself based on operating conditions.
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 reduces thermal inefficiencies and component count, resulting in a lightweight, low-cost fuel delivery system that maintains performance across various engine operations, enhancing the efficiency and reliability of fuel delivery to gas turbine engines.
Implementation Method 1
a spring biased valve element that motively reacts to fluid pressure changes generated at the boost stage
Implementation Method 2
a spring biased valve element that motively reacts to fluid pressure changes
Implementation Method 3
These pumps are used to create pressure through the meshing of gear teeth, which forces fluid around the gears to the outlet side of the pump
Implementation Method 4
a boost stage having an impeller assembly operable at engine start to draw fuel into the pump housing through a fuel inlet at a boost stage pressure
Data Source
AI summary
A multiple stage pump for delivering fuel to an engine is disclosed which includes a pump housing, a boost stage operable at engine start to draw fuel into the pump housing at a boost stage pressure, a first pumping stage operable upon engine start for receiving fuel from the boost stage and delivering the fuel from the pump housing to a fuel metering unit, a second pumping stage operable upon engine start and during engine cruise operation for receiving fuel from the boost stage and delivering the fuel from the pump housing to said fuel metering unit, and a switching valve in fluid communication with the first and second pumping stages, and configured to control fuel flow through the first pumping stage in dependence on changes in boost stage conditions such as pressure or shaft speed.