Variable Speed Electric Motor Drives Gas Turbine Fluid Pumps
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Solution Overview
Problem
Gas turbine engine accessory systems face challenges with oversized pump systems due to direct coupling with turbine shafts, leading to increased weight, cost, and drag, as well as inefficiencies in fluid delivery that are not adequately addressed by existing solutions.
Innovation Solution
A fluid delivery system utilizing an electric motor with variable speed to drive multiple pump systems, including a variable displacement fuel pump and fixed displacement lubrication and scavenge pumps, allowing independent control of fluid flow based on engine demands through an electronic controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pumps are directly coupled to turbine shafts, then pumps are driven at speeds corresponding to engine operational speed, but pump displacements become oversized for expected operating ranges, increasing weight and reducing efficiency
Solution Approach 1:
The patent replaces the traditional mechanical direct-coupling system (turbine shaft to pump) with an electric motor drive system. This substitution allows the pump to be decoupled from the turbine shaft speed constraints, enabling the use of smaller, more efficiently-sized pumps that are not oversized for their operating ranges, thereby reducing pump system weight while maintaining reliable operation.
Solution Approach 2:
The patent introduces variable speed control for the electric motor driving the pump, allowing the pump speed to be dynamically adjusted based on actual operating conditions. This dynamic control enables the pump displacement to be optimized for expected operating ranges rather than being fixed for maximum engine speed, reducing weight while ensuring adequate flow across the operating envelope.
2Ease of operation
If tower shafts and gear boxes are extended from engines, then pumps can be driven, but engine nacelles must be enlarged, increasing frontal area and drag
Solution Approach 1:
The patent replaces the extended mechanical tower shaft and gearbox system with compact electric motor assemblies that can be integrated directly into or near the engine nacelle. This substitution eliminates the need for long mechanical extensions and large gearboxes, allowing the nacelle to maintain a smaller frontal area while still providing adequate pump drive capability through the electric motors.
3Adaptability or versatility
If a single electric motor drives multiple pumps with metering valves, then motor speed can be controlled independent of engine speed, but pumps are still sized for single speed operation, maintaining displacement sizing problems
Solution Approach 1:
The patent applies variable speed control to the electric motor, and couples this with variable displacement mechanisms in the pumps. This combination allows the pump displacement to be dynamically adjusted based on actual flow requirements, solving the sizing problem by enabling the pump to operate efficiently across a range of speeds and flow conditions rather than being optimized for a single speed point.
Solution Approach 2:
The patent changes the operating parameters of the pump system by introducing variable displacement capability in addition to variable speed control. This allows the pump displacement volume to be adjusted as a controllable parameter, enabling precise matching of pump output to actual system requirements across different operating conditions, thereby eliminating the need to oversized pumps for single-speed operation.
4Adaptability or versatility
If multiple electric motors are used for each pump, then independent flow control is achieved, but significant weight and cost are added to the engine
Solution Approach 1:
The patent employs a single electric motor that can drive multiple pumps, with each pump equipped with variable displacement capability. This multi-functional arrangement allows one motor to provide independent flow control to multiple pumps through the variable displacement mechanisms, achieving the same level of independent flow control as multiple motors would provide, but with reduced weight and cost.
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 system enables precise control of fluid flow, reducing excess capacity and weight, improving efficiency, and minimizing frontal area, while maintaining reliable operation of the gas turbine engine.
Implementation Method 1
an electric motor with variable speed to drive multiple pump systems
Implementation Method 2
a variable displacement fuel pump and fixed displacement lubrication and scavenge pumps
Data Source
AI summary
A fluid delivery system in a gas turbine engine includes an electric motor, a first fluid pump system and a second fluid pump system. The electric motor operates at a variable speed. The first pump system includes a first pump driven by the motor to deliver a first fluid to the gas turbine engine. The second pump system includes a second pump driven by the motor to deliver a second fluid to the gas turbine engine, the second pump having a variable displacement.