Dual-Mode Fuel Pump System for Gas Turbine Engine Starting
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Solution Overview
Problem
Large commercial gas turbine engines face challenges with uneven temperature distribution and lack of fine speed control during starting and motoring, particularly at low rotor speeds, in conventional air turbine starting systems.
Innovation Solution
A fuel system that includes a main pump and a start pump connected through a gearbox and pump management valve, allowing for dual-mode operation to drive the engine and generate electrical power, with the ability to motor the engine for cooling and enable slow/variable speed control using fueldraulics instead of pneumatics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional air turbine starting system is used to start the gas turbine engine, then the engine can be started, but fine speed control at low rotor speeds is not achieved and uneven temperature distribution occurs
Solution Approach 1:
The patent replaces the conventional pneumatic air turbine starting system with a hydraulic fuel-based starting system. The main fuel pump delivers pressurized fuel to the air turbine starter, which drives the compressor rotor during engine start-up. This hydraulic approach enables precise flow control through the pump management valve, achieving fine speed control at low rotor speeds and uniform temperature distribution throughout the engine core.
Solution Approach 2:
The system changes the working parameter from pneumatic pressure to hydraulic fuel pressure. By controlling the fuel flow rate and pressure through the main fuel pump and pump management valve, the system can precisely regulate the speed of the air turbine starter and compressor rotor, enabling fine speed control that was not achievable with conventional pneumatic systems.
2Adaptability or versatility
If a dedicated air turbine starting system is used, then engine starting is achieved, but system complexity increases and energy recovery is not possible
Solution Approach 1:
The main fuel pump serves multiple functions: it supplies fuel to the main fuel system during normal engine operation and delivers pressurized fuel to the air turbine starter during engine start-up. The pump management valve similarly controls fuel flow to both the main fuel system and the starting system. This multi-functionality eliminates the need for a separate dedicated starting system, reducing overall system complexity while maintaining full adaptability for both starting and operational modes.
Solution Approach 2:
The patent merges the fuel supply system and the starting system into a single integrated fuel-based starting system. The main fuel pump and its associated control valve manage fuel delivery to both the engine's fuel injection system and the air turbine starter. This consolidation reduces the number of separate components and simplifies the overall system architecture compared to having dedicated separate systems for fuel supply and engine starting.
3Productivity
If the main pump drives the gearbox in run mode, then fuel pumping is achieved, but energy recovery from bypass flow is not possible
Solution Approach 1:
The system converts the previously wasted bypass flow energy into a useful resource for electrical power generation. During normal engine operation, bypass fuel flow that would otherwise be discarded is used to drive the start pump, which is coupled to an electric generator. This generates electrical power that can be used to run engine control systems or other auxiliary equipment, transforming an energy loss into a beneficial power source.
Solution Approach 2:
The main fuel pump's bypass flow automatically serves a dual purpose: it maintains proper fuel system pressure and flow distribution while simultaneously providing mechanical energy to drive the start pump and generator assembly. The system uses its own operational byproducts (bypass flow) to generate additional useful output (electrical power) without requiring external energy input.
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
Enables efficient starting, motoring, and electrical power generation for gas turbine engines with improved temperature management and reduced component wear, replacing traditional pneumatic systems and allowing for energy recovery from waste fuel flow.
Implementation Method 1
drive the main pump with flow pressurized by the start pump
Implementation Method 2
the main pump shaft is connected to drive the gear box in the start mode, and wherein the gear box is connected to drive the engine shaft
Implementation Method 3
the gear box is connected to drive the main pump shaft for fuel pumping in the run mode
Implementation Method 4
driving the start pump with bypass flow from the main pump to motor the gas turbine engine for uniform cooling of the gas turbine engine
Data Source
AI summary
A system includes a main pump having a main pump shaft configured to connect to a gear box for driving the main pump with rotational power from the gear box in a run mode, and for driving the gear box with rotational power from the main pump in a start mode. The system includes a first fuel line with an inlet configured to connect to connected in fluid communication with a fuel source. The first fuel line includes a first branch in fluid communication with the main pump, and a second branch. A start pump is connected in fluid communication with the second branch of the first fuel line. A second fuel line connects the start pump in fluid communication with a pump management valve (PMV). A third fuel line connects the main pump in fluid communication with the pump management valve.