Ecology Valve Fuel Return System for Gas Turbine Engine Start-Up
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Solution Overview
Problem
Existing ecology valve fuel return systems disrupt the predetermined flow schedule of gas turbine engines during start-up by directly returning withdrawn fuel to the manifolds, and they may become inoperable when fluidly isolated from the fuel tank due to shut-off valves or high return pressures.
Innovation Solution
The ecology valve fuel return system includes a housing assembly with a piston and a fuel routing assembly that routes fuel from the storage chamber to the supply system during start-up and from the control chamber to the storage chamber during shut-down, avoiding direct return to the manifolds and allowing operation even when isolated from the fuel tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If withdrawn burn fuel is returned directly to the fuel manifolds during GTE start-up, then the fuel is reused efficiently, but the predetermined flow schedule is disrupted and ideal engine light-off conditions are compromised
Solution Approach 1:
The fuel return system is segmented into two distinct operational modes: during start-up, fuel is routed to the supply system to preserve flow schedules, while during shut-down, fuel is returned to manifolds to prevent vaporization and coking. This segmentation allows the system to optimize for different priorities at different times.
Solution Approach 2:
The system performs preliminary routing of withdrawn fuel to the supply system during start-up mode before the engine reaches operating conditions, ensuring that the predetermined flow schedule is maintained and ideal light-off conditions are achieved. This preliminary action prevents fuel disruption at the critical start-up phase.
2Object-affected harmful factors
If a shut-off valve closes between the EV fuel return system and the fuel tank, then fuel tank contamination is prevented, but the EV fuel return system becomes fluidly isolated and inoperable
Solution Approach 1:
The EV fuel return system introduces an intermediary pathway through the supply system that allows fuel to circulate between the manifolds and supply system even when the tank is isolated by a shut-off valve. This intermediary route maintains system operability without compromising fuel tank protection.
Solution Approach 2:
The fuel routing assembly is designed to perform multiple functions: it can return fuel to the tank when open, and it can route fuel through the supply system when the tank is isolated. This multi-functionality ensures the system remains operational under different valve configurations.
3Stress or pressure
If a relatively strong fuel boost pump is included within the fuel supply system, then fuel delivery pressure is improved, but high return pressures result in hydraulic lock and prevent EV fuel return system operation
Solution Approach 1:
Instead of trying to overcome the high pressure from the boost pump directly, the system inverts the approach by routing fuel through the supply system in the opposite direction, from manifolds back through the supply system to the storage chamber. This inversion allows the system to utilize the existing pressure dynamics rather than fighting against them.
Solution Approach 2:
The supply system acts as an intermediary medium that facilitates fuel return despite high boost pump pressures. By using the supply system as the return pathway, the EV fuel return system can operate without directly opposing the high delivery pressures generated by the boost pump.
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 design prevents disruption of the engine's flow schedule during start-up and ensures the ecology valve can function properly even when isolated from the fuel tank, maintaining optimal engine light-off conditions and preventing hydraulic lock issues.
Implementation Method 1
The fuel within the EV control chamber acts on the EV piston in opposition to the fuel within the fuel storage chamber
Data Source
AI summary
An ecology valve (EV) fuel return system includes a housing assembly, an ecology valve, and a fuel routing assembly. The ecology valve includes an EV piston slidably disposed within the housing assembly for movement between a fuel storage position and a fuel return position, a fuel storage chamber defined by the EV piston and the housing assembly, and an EV control chamber defined by the EV piston and the housing assembly. The fuel routing assembly, which is fluidly coupled to the EV control chamber and to the fuel storage chamber, is configured to route fuel: (i) from the fuel storage chamber to a fuel supply system when a gas turbine engine (GTE) is in a start-up mode, and (ii) from the first fuel manifold and from the EV control chamber to the fuel storage chamber when the GTE is in a shut-down mode.