Electro-pneumatic Starter for Bowed Rotor Prevention
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Solution Overview
Problem
Gas turbine engines face issues with bowed rotor conditions due to uneven thermal cooling, leading to blade tip clearance problems during engine start-ups, which existing methods like motoring at specific speeds or using pneumatic starters are inefficient and prone to wear.
Innovation Solution
An engine starting system utilizing an electro-pneumatic starter connected to an electric drive motor, controlled by a motor controller, to rotate the rotor components at a selected angular velocity for a specified period, preventing bowed rotor conditions through continuous low-speed motoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pneumatic starters are used for engine starting, then the engine can be started, but the starters are duty cycle limited due to lubrication issues and heat dissipation
Solution Approach 1:
The patent replaces the traditional pneumatic starter system with an electric motor-driven starter system. The electric motor eliminates the lubrication and heat dissipation limitations of pneumatic systems, allowing for extended duty cycles and continuous operation during engine cool-down periods without the reliability issues associated with pneumatic lubrication.
Solution Approach 2:
The invention changes the operating parameters of the starter system by using an electric motor that can operate at controlled speeds for extended periods. This allows the starter to motor the engine at low speeds continuously after shutdown to prevent bowed rotor conditions, a function that was previously limited by pneumatic starter duty cycle constraints.
2Ease of operation
If butterfly type start valves are used to control starter speed, then the starter speed can be modulated, but the valve and start life decreases significantly due to wear
Solution Approach 1:
The patent replaces the mechanical butterfly valve system with an electric motor control system. The electric motor can be precisely controlled through electrical signals to rotate the engine at selected speeds without the mechanical wear associated with butterfly valves. This eliminates diaphragms and linkage in the actuator piston assembly that are prone to wear, significantly extending system life.
Solution Approach 2:
The invention introduces an electric motor as an intermediary between the control system and the engine starter mechanism. This intermediary allows for precise speed modulation through electrical control rather than mechanical valve adjustment, reducing wear on critical components while maintaining ease of operation.
3Stability of the object's composition
If the engine is motored at low speed for extended periods to prevent bowed rotor, then uniform thermal conditions are achieved, but traditional starters cannot sustain this operation due to duty cycle limitations
Solution Approach 1:
The patent replaces the pneumatic starter with an electric motor system that can sustain extended low-speed operation. The electric motor eliminates the duty cycle limitations of pneumatic systems, enabling continuous motoring during engine cool-down to achieve uniform thermal conditions and prevent bowed rotor without time constraints.
Solution Approach 2:
The invention enables continuous useful action by allowing the electric motor to motor the engine continuously after shutdown for extended periods. This continuous low-speed rotation prevents bowed rotor conditions by maintaining uniform thermal distribution throughout the engine components, a function that cannot be achieved with duty-cycle-limited pneumatic starters.
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 effectively prevents bowed rotor conditions by maintaining uniform thermal conditions and reducing wear on starter components, enhancing the reliability and efficiency of gas turbine engine start-ups.
Implementation Method 1
an electric drive motor operably connected to the electro-pneumatic starter, the electric drive motor being configured to rotate the rotational components through the electro-pneumatic starter
Implementation Method 2
an electro-pneumatic starter operably connected to at least one of the rotational components, the electro-pneumatic starter being configured to rotate the rotational components
Data Source
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AI summary
A method of cooling a gas turbine engine 250 is provided. The method comprises rotating, using an electric drive motor 500, rotational components 260 of a gas turbine engine 250, the rotational components 260 comprising an engine compressor 256, an engine turbine 258, and a rotor shaft 259 operably connecting the engine turbine 258 to the engine compressor 256. Each rotational component 260 is configured to rotate when any one of the rotational components 260 is rotated; wherein the electric drive motor 500 is operably connected to at least one of the rotational components 260 through an electro-pneumatic starter 120.