Drain Piston Assembly Fuel Management for Gas Turbine Shutdown
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Solution Overview
Problem
Gas turbine engines face ecological issues due to fuel remaining in the fuel manifold draining into the combustion chamber and evaporating or leaking during shutdown, and existing solutions increase system cost, complexity, and weight with additional components.
Innovation Solution
A fuel system incorporating a minimum pressure and shut-off valve (MPSOV) and drain piston assembly that manages fuel flow to store excess fuel during shutdown and return it to the manifold upon startup, using a servo valve and actuator to control pressure and volume within the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If an ecology tank with ejector pump, check valves, vents, and plumbing is used to store fuel after shutdown, then fuel loss and ecological issues are prevented, but system cost, complexity, and weight increase
Solution Approach 1:
The patent combines the ecology tank function with the existing fuel manifold and drain piston assembly, eliminating the need for separate ejector pumps, check valves, and complex plumbing. The drain piston assembly serves dual purposes: draining the fuel manifold during shutdown and storing fuel in the ecology tank, merging multiple functions into a single integrated system that reduces component count and complexity
Solution Approach 2:
The drain piston assembly is designed to perform multiple functions: it acts as a drain mechanism for the fuel manifold during shutdown, serves as a storage chamber (ecology tank) for captured fuel, and provides a return path for fuel to the main tank. This multi-functional design eliminates the need for dedicated single-function components like separate ejector pumps and check valves
2Loss of substance
If a second plumbing line is added from fuel manifold back to fuel tank for draining and pressurization, then fuel loss is prevented and pump performance is improved, but system complexity and weight increase
Solution Approach 1:
The patent uses the existing fuel pump and fuel pressure system to drive fuel through the drain piston assembly and back to the main tank. The fuel pump creates the necessary pressure to move fuel through the integrated drain path without requiring additional pumps or heavy plumbing infrastructure, leveraging the existing hydraulic system for dual purposes
3Loss of substance
If existing drain systems with ejector pumps and check valves are used, then fuel is captured during shutdown, but system weight increases
Solution Approach 1:
The patent extracts the core functionality of fuel capture and storage from the heavy, complex ecology tank system with ejector pumps and check valves, retaining only the essential drain piston assembly and minimal plumbing. By removing unnecessary components (ejector pumps, check valves, extensive vents and plumbing), the system achieves fuel capture capability with significantly reduced weight
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
Effectively prevents fuel loss and ecological issues by storing excess fuel during shutdown and quickly priming the fuel manifold upon restart, reducing system complexity and weight compared to existing solutions.
Implementation Method 1
A drain piston assembly fluidically connected to both the fuel manifold and the actuator. The drain piston assembly includes a housing defining a chamber with a variable volume capable of drawing fuel from the fuel manifold and storing the fuel in the chamber
Implementation Method 2
A servo valve and actuator are provided. The servo valve is fluidically connected to the actuator
Implementation Method 3
When the gas turbine engine is shut down, fuel remaining in the fuel manifold can drain into the combustion chamber, and ultimately evaporate and/or drain out of the gas turbine engine onto the ground
Data Source
Figure 1
Figure 2
AI summary
A fuel system (14) for a gas turbine engine (12) includes an engine fuel manifold (24), a hydraulic actuator (38), and a drain piston assembly (36). The hydraulic actuator (38) actuates in response to a change in pressures within the hydraulic actuator (38). The drain piston assembly (36) is fluidically connected to both the hydraulic actuator (38) and the engine fuel manifold (24). The drain piston assembly (36) receives fuel from the engine fuel manifold (24) and sends fuel to the hydraulic actuator (38) during engine shut down.