Jet Pump Recirculation for Fuel Manifold Cooling
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Solution Overview
Problem
Existing fuel systems for gas turbine engines face challenges in preventing coke formation in non-flowing fuel circuits during main flow off operations, as previous solutions either add significant weight, compromise engine envelope, or disrupt fuel dynamics, making it difficult to maintain efficient main fuel circuit flow at low metered flows.
Innovation Solution
A jet pump driven recirculation circuit is used to provide cooling flow through the main manifold, utilizing a flow split valve and jet pump to create a low static pressure area, allowing for weight-effective and dynamic response that enables robust fuel delivery at all flow rates while preventing coke formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If recirculation back to pump inlet is used to cool non-flowing fuel manifold, then cooling is provided, but weight increases and engine envelope is compromised
Solution Approach 1:
The patent merges the cooling flow recirculation with the existing fuel manifold structure by integrating a recirculation orifice directly into the manifold body. This eliminates the need for separate cooling circuits and additional fittings, thereby providing effective cooling while minimizing weight increase and avoiding engine envelope compromise.
Solution Approach 2:
The patent introduces a recirculation orifice as an intermediary element that enables cooling flow to bypass the fuel nozzle and return to the pump inlet. This simple orifice structure provides the necessary cooling function without requiring complex additional components, thus achieving weight effectiveness while maintaining proper cooling of the non-flowing fuel manifold.
2Temperature
If recirculation back to pump inlet is used, then cooling flow is provided, but fuel flow dynamic response deteriorates
Solution Approach 1:
The patent applies local quality by positioning the recirculation orifice at a specific location within the fuel manifold where it can provide cooling flow without interfering with the main fuel flow path to the nozzle. This localized approach ensures that cooling is achieved while maintaining proper fuel flow dynamic response to engine operability changes.
3Object-affected harmful factors
If cooling flow is added to non-flowing circuit, then coke formation is prevented, but fuel system complexity increases
Solution Approach 1:
The patent extracts the cooling function from the main fuel flow path by creating a separate recirculation pathway through a dedicated orifice. This allows cooling flow to be provided to the non-flowing manifold circuit independently, preventing coke formation without adding significant complexity to the overall fuel system architecture.
Solution Approach 2:
The recirculation orifice serves multiple functions: it provides cooling flow to prevent coke formation in the non-flowing manifold, maintains fuel system pressure balance, and enables simple implementation without requiring additional active components. This multi-functionality achieves coke prevention while minimizing system complexity.
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 effectively prevents coke formation, maintains weight efficiency, and ensures superior cooling performance and fuel system dynamics, addressing the limitations of previous approaches by enabling main fuel circuit flow at low total metered flows.
Implementation Method 1
a jet pump operatively disposed in fluid communication with the pilot manifold such that a pilot flow stream from the flow split valve to the fuel nozzle through the pilot manifold flows through the jet pump and creates a low static pressure area therein
Data Source
AI summary
Cooling flow recirculation in fuel manifolds, such as fuel manifolds associated with gas turbine engines is disclosed. An example system for jet pump driven recirculation of manifold cooling flow according to at least some aspects of the present disclosure may include a flow split valve having a spool valve disposed therein, the flow split valve having a pilot manifold and a main manifold attached thereto; a jet pump fluidically coupled to the pilot manifold, the jet pump being arranged to drive recirculation of a cooling flow through the main manifold via a cooling flow circuit in a pilot only mode of operation; and/or a fuel nozzle in fluid communication with the pilot manifold and the main manifold.