Turbomachine Oil Circuit Control for Long-Pipe Temperature Delay
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Solution Overview
Problem
The existing lubricating oil circuits in turbomachines face challenges in controlling oil flow rate and temperature, particularly due to the long pipes causing pure delay in temperature regulation, which affects the performance, accuracy, and robustness of the system.
Innovation Solution
A lubricating oil circuit with a distribution valve, heat exchangers, and a regulation device comprising local and global loops to servo-control oil temperatures, minimizing delay by measuring a homogeneous mixture temperature and adjusting setpoints dynamically to manage thermal exchanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If long pipes are used to connect the heat exchanger to the gearbox, then the system layout flexibility is improved, but the temperature regulation accuracy deteriorates due to pure delay
Solution Approach 1:
The temperature regulation system is segmented into two independent control loops: a local loop that regulates temperature at the heat exchanger outlet (Teq) and a global loop that regulates the gearbox temperature (Trgb). This segmentation allows each loop to operate independently, with the local loop compensating for the delay introduced by long pipes, thereby maintaining temperature regulation accuracy while preserving layout flexibility.
Solution Approach 2:
The first oil duct (CEq) acts as an intermediary between the heat exchanger and the gearbox. By measuring the temperature at this intermediate point and regulating it through the local loop, the system creates a controlled intermediate stage that compensates for the thermal delay caused by long pipes, ensuring accurate temperature regulation at the gearbox while maintaining system layout flexibility.
2Device complexity
If a single temperature measurement point is used at the gearbox inlet, then the measurement system complexity is reduced, but the response time to thermal disturbances deteriorates
Solution Approach 1:
The system performs preliminary temperature measurement and regulation at the heat exchanger outlet (Teq) before the oil reaches the gearbox. By detecting and correcting thermal disturbances at this earlier stage through the local loop, the system responds to changes before they affect the gearbox, significantly reducing the effective response time without requiring complex multi-point measurement at the gearbox itself.
3Temperature
If the oil flow rate is increased to improve cooling capacity, then the thermal management performance is improved, but the system energy consumption increases
Solution Approach 1:
The oil flow rate is made dynamic rather than fixed, being continuously adjusted by the two-stage control system based on real-time temperature measurements and thermal conditions. The local loop optimizes flow distribution between bypass and heat exchanger, while the global loop adjusts the overall flow rate to match actual cooling demands, ensuring optimal cooling capacity while minimizing energy consumption by avoiding excessive flow rates.
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 regulates oil temperatures in turbomachines, ensuring targeted performance without modifying the thermo-hydraulic architecture, achieving accuracy and rapid response to thermal disturbances while maintaining system robustness.
Implementation Method 1
a first heat exchanger positioned in contact with a secondary gas flow of the turbomachine to cool the oil therein
Implementation Method 2
a second heat exchanger positioned against a turbomachine fuel passage duct to cool the oil therein
Data Source
AI summary
A lubricating oil circuit of a turbomachine includes a distribution valve that distributes an oil flow rate among a first heat exchanger and a bypass duct, connected to an oil duct, which is connected to an heat exchanger positioned against a turbomachine fuel passage duct, and includes a gearbox of a rotation speed reducer that lowers a rotational speed of a first rotary fan shaft of the turbomachine relative to a rotational speed of a second low-pressure compressor rotary shaft of the turbomachine or of a second low-pressure turbine rotary shaft of the turbomachine, and a regulation device. The regulation device includes a local regulation loop that generates an oil flow rate distribution control signal and regulates an oil temperature of the oil duct on a temperature setpoint, and a global regulation loop that generates the temperature setpoint as a function of the temperature and of the temperature setpoint.