Turbine Engine Oil Circuit Control During Fire and Autorotation
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Solution Overview
Problem
Current oil systems for turbomachines are over-dimensioned to maintain sufficient oil flow during autorotation, leading to increased mass, space requirements, and costs, and existing solutions like heat shields also incur similar drawbacks, necessitating a more efficient and cost-effective method to ensure lubrication and cooling, especially in fire scenarios.
Innovation Solution
An oil system featuring an electrically driven pump piloted by an electronic control unit with separate logic modes, allowing decoupling of pump speed from turbomachine speed, enabling continuous oil supply during fires without over-dimensioning, and incorporating a fire detector to manage oil flow according to needs, potentially reducing the need for heat shields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pumps are over-dimensioned to ensure sufficient oil flow rate during autorotation, then oil supply reliability is improved, but mass and space requirements increase
Solution Approach 1:
The patent applies dynamics by replacing the fixed-speed mechanically driven pump with a variable-speed electrically driven pump. The pump speed can be dynamically adjusted based on operational conditions: running at higher speeds during normal operation to ensure adequate oil flow, and being controllable during autorotation to maintain sufficient flow without requiring the pump to be permanently over-dimensioned. This resolves the contradiction by making the pump capacity adaptive rather than static.
Solution Approach 2:
The patent changes the operating parameters of the pump by controlling its rotational speed through an electronic control unit. During fire conditions or autorotation, the control unit adjusts the pump speed to maintain adequate oil flow rate. This parameter adjustment allows the use of a smaller, more compact pump that can operate effectively across different conditions without needing to be over-dimensioned for the worst-case scenario, thereby reducing mass while maintaining reliability.
2Object-affected harmful factors
If heat screens or fire-resistant shields are added to protect equipment, then protection against heat radiation is improved, but mass and cost increase
Solution Approach 1:
The patent replaces the mechanical/physical protection system (heat screens and fire-resistant shields) with an active thermal management system using variable-speed oil pumping. By dynamically controlling the oil flow rate through the lubrication circuit, the system actively removes heat from critical components during fire conditions, substituting passive thermal barriers with an active cooling mechanism that uses the existing oil system infrastructure.
3Device complexity
If pump speed is mechanically coupled to turbomachine speed, then system simplicity is maintained, but oil flow rate cannot be maintained during autorotation
Solution Approach 1:
The patent replaces the mechanical drive system (pump driven by AGB which is driven by turbomachine) with an electrical drive system. The electric motor driving the pump can be independently controlled and is not mechanically coupled to the turbomachine speed. This substitution allows the pump speed to be decoupled from turbomachine speed, enabling the pump to maintain adequate oil flow rate during autorotation even when the turbomachine is rotating at low speeds, while the overall system complexity remains manageable through electronic control.
Data Source
AI summary
Oil system for a turbomachine, making it possible to continue the supply of oil to the pieces of equipment of the turbomachine in case of occurrence of a fire within the turbomachine, including an oil circuit, at least one oil-consuming piece of equipment, supplied by the oil circuit, a pumping unit, including at least one speed-pilotable electrically driven pump, supplying the oil circuit, and an electronic control unit, configured to pilot the electrically driven pump, wherein the electronic control unit includes two separate logics of piloting the electrically driven pump, and wherein the electronic control unit is configured to pilot the electrically driven pump according to the first logic by default and to switch to the second logic in case of receipt of a signal representative of the presence of a fire or of an overheating.