Gas Turbine Fire Wall Actuation via Bowden Cable
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Solution Overview
Problem
In modern gas turbine engines, high temperatures in certain zones render conventional hydraulic and pneumatic actuation mechanisms unreliable, leading to issues like fuel breakdown and air-driven motor inefficiency, and existing cooling mechanisms are complex and limited in effectiveness.
Innovation Solution
A mechanical force transmission system using a flexible elongate element, such as a Bowden cable, actuated by an external mechanism, with a bypass off-take device to supply high-pressure cooling air, ensuring continuous cooling and reliability across fire zones, and a sealing unit to maintain a pressure differential and prevent coolant leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hydraulic motive power (fuel) is used to actuate the device in high-temperature zones, then the actuation mechanism can be compact and integrated, but the fuel heats up, breaks down and cokes, leaving carbon deposits in pipes and valves
Solution Approach 1:
The invention extracts the actuator from the high-temperature zone (second fire zone) and places it in the low-temperature zone (first fire zone), separating the actuation function from the hot environment. This allows hydraulic actuation to work reliably without fuel breakdown, while the mechanical force is transmitted through a fire wall via a flexible elongate element (Bowden cable) to actuate the valve in the hot zone.
Solution Approach 2:
The invention introduces a flexible elongate element (Bowden cable) as an intermediary mechanical force transmission device that crosses the fire wall. This mediator transmits mechanical force from the actuator in the cool zone to the actuatable device in the hot zone, enabling reliable actuation without exposing the hydraulic system to high temperatures.
2Device complexity
If pneumatic motive power (air) is used to actuate the device in high-temperature zones, then the actuation system can be simple and clean, but air driven motors don't work reliably at temperatures of 300°C-400°C or higher
Solution Approach 1:
The invention extracts the pneumatic actuator from the high-temperature zone and places it in the low-temperature zone, where air-driven motors can operate reliably. The mechanical force is then transmitted through the fire wall using a flexible elongate element to actuate the valve in the hot zone, maintaining simplicity while ensuring reliability.
3Temperature
If cooling mechanisms are applied to the actuatable device in high-temperature zones, then the device can operate at higher temperatures, but the cooling mechanisms become complex and lossy
Solution Approach 1:
Instead of cooling the actuatable device in the hot zone, the invention extracts the entire actuator and cooling system to the low-temperature zone. This eliminates the need for complex in-zone cooling mechanisms, as the actuator operates in an inherently cool environment where standard cooling is sufficient and simple.
4Reliability
If a fire wall is installed to separate hot and cool zones, then fire resistance is improved, but it prevents direct actuation across the wall and requires complex force transmission mechanisms
Solution Approach 1:
The invention introduces a flexible elongate element (Bowden cable) as a mediator that transmits mechanical force through the fire wall. This intermediary solution provides a practical and relatively simple method for crossing the fire barrier, avoiding the need for complex sealed penetrations or active cooling of the fire wall itself.
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
Enables reliable actuation of devices in high-temperature zones by maintaining component coolness and preventing fire zone contamination, extending the operational temperature range of actuatable devices beyond conventional limits.
Implementation Method 1
a mechanical force transmitting device (120) that extends from the actuator to the actuatable device... configured to, when the actuator is operated, actuate the actuatable device by transmitting a mechanical force generated by the actuator to the actuatable device
Implementation Method 2
The gas turbine engine includes a device for supplying coolant to be guided into the elongate housing/shell when the gas turbine is in use... an off-take device for extracting cooling air from a bypass airflow (140) in the gas turbine engine
Implementation Method 3
The sealing unit may include one or more seals for inhibiting/preventing coolant from flowing out of (e.g. the cavity in) the sealing unit into the first zone... Preferably, the hole in the fire wall (through which the mechanical force transmitting device extends) is sealed
Data Source
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AI summary
A gas turbine engine (10) having a fire wall (103) that is configured to provide a fire resistant barrier between a first zone (110) and a second zone (112) in the gas turbine engine, the second zone being hotter than the first zone when the gas turbine engine is in use. The gas turbine also has an actuator that is located in the first zone and is configured to generate a mechanical force when operated, an actuatable device that is located in the second zone and is configured to be actuated by a mechanical force and a mechanical force transmitting device (120) that extends from the actuator to the actuatable device via a hole in the fire wall. The mechanical force transmitting device is configured to, when the actuator is operated, actuate the actuatable device by transmitting a mechanical force generated by the actuator to the actuatable device.