Gas Turbine Starter Generator Cooling via Passive Thermal Convection
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Solution Overview
Problem
Existing starter/generator arrangements for gas turbine engines face challenges in cooling power converters during engine starting, as mechanical power from the engine may be unavailable to drive coolant flow, leading to heat generation issues.
Innovation Solution
The implementation of a coolant circuit with ethoxy-nonafluorobutane and a controller that vaporizes coolant to passively cool the power converter during engine starting, utilizing the heat storage capability of the coolant and positioning the coolant circuit within the fan duct of the gas turbine engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coolant circuit is provided to cool the power converter during engine operation, then the power converter can be effectively cooled during normal operation, but the engine cannot provide mechanical power to drive coolant flow during engine starting
Solution Approach 1:
The coolant circuit is pre-filled with coolant before engine starting. During the starting phase, the coolant is positioned in the circuit ready to absorb heat, and the system is designed so that coolant can be drawn from the circuit without requiring engine-driven pump power. This preliminary preparation allows cooling to occur during starting before the engine generates sufficient mechanical power.
Solution Approach 2:
The system uses the heat generated by the power converter itself to drive coolant circulation during starting. The thermal energy from the power converter's operation creates natural convection currents that circulate coolant through the circuit, eliminating the need for external mechanical pumping during this phase.
2Productivity
If an engine-driven pump is used to circulate coolant during normal operation, then coolant flow can be maintained during engine operation, but coolant circulation cannot occur during engine starting when mechanical power is unavailable
Solution Approach 1:
The coolant circulation system transitions from a static, pump-driven configuration during normal operation to a dynamic, thermally-driven convection system during starting. The system automatically adapts its circulation mechanism based on operational phase, using natural convection during starting and mechanical pumping during normal operation.
Solution Approach 2:
A thermal expansion valve or similar intermediary device is introduced to regulate coolant flow based on temperature differential. This intermediary component enables passive coolant circulation during starting by opening when temperature differential exceeds a threshold, and closing or reducing flow when the engine is running and mechanical pumping is active.
3Device complexity
If the coolant circuit is positioned within the fan duct, then the system utilizes existing engine structure for cooling, but the coolant circuit must be designed to function independently during starting when fan-driven airflow is unavailable
Solution Approach 1:
The coolant circuit is designed to serve multiple functions: during starting, it provides cooling through passive thermal convection; during normal operation, it provides cooling through both convection and mechanical pumping. The circuit's positioning within the fan duct allows it to utilize fan-driven airflow during normal operation while maintaining independent cooling capability during starting through thermal convection alone.
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 enables effective cooling of power converters during engine starting, using the heat storage capability of the coolant to manage heat generated by the power converter, even when mechanical power is not available to circulate the coolant, ensuring efficient operation.
Implementation Method 1
cooling the power converter by storing heat in a coolant disposed within the coolant circuit
Implementation Method 2
cooling the power converter by storing heat in a coolant disposed within the coolant circuit
Implementation Method 3
cooling the power converter by vaporizing the coolant disposed within the power converter
Implementation Method 4
cooling the power converter by vaporizing the coolant disposed within the power converter
Implementation Method 5
a condenser arranged above the power converter relative to gravity
Data Source
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AI summary
A starter/generator arrangement includes a starter/generator (102), a power converter (104) electrically connected to the starter/generator, and coolant circuit (106) with a pump (112) and a condenser (114) in fluid communication with the power converter. The power converter is arranged to flow start mode electrical power in a first direction in a start mode and a second direction in a generate mode. The coolant circuit fluidly couples the pump to the condenser for storing heat in a coolant disposed within the coolant circuit while flowing the start mode electrical power in the first direction. Gas turbine engines and methods of cooling starter/generator arrangements are also described.