Cowl Door Seal Arrangement for Fire and Burst Duct Containment
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Solution Overview
Problem
Gas turbine engine nacelles face challenges in containing hazardous conditions such as fires and burst ducts, which can affect the sealing capability of cowl door seals and pose risks to sensitive components, necessitating an improved seal arrangement to prevent the spread of hazardous conditions within compartments.
Innovation Solution
A seal arrangement featuring a first outer frame and a seal effect between the cowl door and the frame, which contains hazardous conditions and provides a fire seal, using a configuration that maintains the seal effect even under extreme conditions, such as those caused by fires or burst ducts, by expanding to prevent the ingress or egress of fluids and maintaining the sealing feature despite relative movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cowl door seal is used, then the seal may allow fluid ingress under normal conditions, but under extreme conditions (fire, burst duct) the seal fails to contain hazardous conditions
Solution Approach 1:
The seal assembly is divided into multiple functional components: a rigid outer frame structure and a flexible seal element. This segmentation allows each component to perform its specific function - the frame provides structural support and positioning, while the flexible element provides the actual sealing and expansion capability to contain hazardous conditions during fires or burst duct events.
Solution Approach 2:
The seal element is designed to change its physical parameters (volume, shape, density) in response to temperature changes. During a fire or burst duct event, the seal material expands due to thermal effects, increasing its volume and adjusting its density to maintain effective sealing contact and contain hazardous conditions even under extreme thermal conditions.
2Strength
If the seal is made rigid to maintain structural integrity, then it can resist deformation, but it cannot adapt to relative movement between components
Solution Approach 1:
The seal assembly merges two opposing characteristics by combining a rigid outer frame with a flexible seal element. The rigid frame provides structural integrity, resistance to deformation, and proper positioning, while the flexible seal element provides adaptability to relative movements and maintains sealing contact. This combination allows the overall assembly to simultaneously achieve both strength and flexibility.
Solution Approach 2:
The seal assembly uses composite construction with different material properties - a rigid structural material for the frame and a flexible elastomeric or polymeric material for the seal element. This composite approach allows each material to contribute its optimal properties, creating an assembly that is both structurally sound and adaptable to movement.
3Reliability
If the seal expands to contain hazardous conditions, then it prevents fluid ingress, but it increases the complexity of the seal mechanism
Solution Approach 1:
The seal element is designed to automatically expand and contain hazardous conditions through its own material properties and thermal response, without requiring external actuation systems, sensors, or control mechanisms. The expansion is a passive, self-driven response to the hazardous conditions (such as heat from fire), which simplifies the overall mechanism while maintaining reliable containment capability.
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 seal arrangement effectively contains hazardous conditions within the fan compartment, preventing the spread of fires and burst ducts, and maintains the sealing integrity even under extreme conditions, reducing the risk of fluid ingress or egress and protecting sensitive components.
Implementation Method 1
A seal arrangement featuring a first outer frame and a seal effect between the cowl door and the frame, which contains hazardous conditions and provides a fire seal
Implementation Method 2
by expanding to prevent the ingress or egress of fluids and maintaining the sealing feature despite relative movement
Data Source
Figure 1
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Figure 3
AI summary
A seal arrangement includes a first outer skin (30) and a second outer skin (38) disposed about an axial centerline (20). The second outer skin (38) is adjacent the first outer skin (30) and includes at least one door (38). A bulkhead (32) extends substantially radially at least a portion of a distance between the axial centerline (20) and one of the first outer skin (30) and the second outer skin (38). A first outer frame (44) includes a first portion (46), a second portion (48), and a third portion (50). The first portion (46) of the first outer frame (44) is mounted to the bulkhead (32). A seal (54) is mounted to one of the at least one door (38) and the second portion (48). The at least one door (38) is rotatable between a first position and a second position. In the second position the seal (54) contacts the at least one door (38) and the second portion (48). The third portion (50) is configured to limit a compression of the seal (54).