Engine Lubricant Bypass Control for Bowed Rotor Startup
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engines experience thermal bowing due to asymmetric heat release after shutdown, leading to rotor assembly eccentricity and unbalance, which can cause damage and increase maintenance costs, with existing dry motoring solutions being time-consuming and inefficient.
Innovation Solution
A lubricant system that selectively bypasses thermal communication with a heat sink based on lubricant temperature and vibratory response, using valves to adjust flow, pressure, and temperature, and incorporating an insulating material to maintain lubricant temperature above a bowed rotor mitigation threshold, reducing dynamic magnification and undesired contact during startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dry motoring is used to alleviate thermal bowing, then rotor eccentricity is reduced, but engine startup time increases
Solution Approach 1:
The patent changes the physical state and temperature parameters of the lubricant by bypassing the heat exchanger during bowed rotor conditions. This maintains the lubricant at higher temperatures that reduce dynamic magnification and allow for shorter dry motoring periods, thereby reducing startup time while still achieving adequate rotor straightening.
Solution Approach 2:
The system dynamically adjusts lubricant flow paths based on real-time sensor feedback regarding rotor condition and lubricant temperature. By making the lubricant system adaptive and controllable, the patent optimizes the balance between thermal management and bowed rotor mitigation, allowing reduced dry motoring time compared to static systems.
2Reliability
If lubricant temperature is maintained high to reduce dynamic magnification, then rotor unbalance is reduced, but lubricant cooling efficiency decreases
Solution Approach 1:
The lubricant cooling system dynamically adjusts its operation based on sensor feedback. The control system monitors rotor condition and lubricant temperature, selectively engaging or disengaging the heat exchanger as needed. This dynamic control allows the system to maintain high lubricant temperatures when bowed rotor conditions exist while providing cooling when conditions normalize, optimizing both rotor unbalance reduction and cooling efficiency.
Solution Approach 2:
The system uses feedback from sensors monitoring rotor and bearing conditions to automatically control lubricant temperature management. The lubricant system essentially self-regulates by using operational data to determine when heating or cooling is needed, eliminating the need for external intervention and optimizing performance automatically.
3Temperature
If thermal communication with heat sink is bypassed, then lubricant temperature is maintained, but thermal management capability is reduced
Solution Approach 1:
The lubricant system incorporates dynamic control capabilities that allow it to switch between different thermal management modes based on real-time conditions. By using sensor feedback and controllable flow paths, the system can selectively bypass or engage the heat sink as needed, providing adaptability across different operating conditions rather than being fixed in one thermal management approach.
Solution Approach 2:
The lubricant system is designed to perform multiple functions: it can maintain high temperatures to reduce dynamic magnification during bowed rotor conditions, and it can provide cooling through the heat exchanger when conditions normalize. This multi-functionality allows a single system to adapt to different operational requirements, enhancing overall system versatility.
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 solution reduces dry motoring time, minimizes rotor-casing contact, and improves engine durability by maintaining lubricant temperature within a desired range, thereby reducing startup time and operational costs.
Implementation Method 1
incorporating an insulating material to maintain lubricant temperature above a bowed rotor mitigation threshold
Implementation Method 2
A lubricant system that selectively bypasses thermal communication with a heat sink based on lubricant temperature
Implementation Method 3
A lubricant system that selectively bypasses thermal communication with a heat sink based on lubricant temperature and vibratory response
Implementation Method 4
selectively bypassing thermal communication of the lubricant with a heat sink is further based on a vibratory response of a rotor assembly of the gas turbine engine
Data Source
AI summary
A gas turbine engine including a lubricant system defining a lubricant circuit through which a lubricant flows in fluid communication with a bearing assembly of the engine. The lubricant system selectively bypasses thermal communication of the lubricant and a heat sink based at least on a temperature of the lubricant within the lubricant circuit.