Bleed Valve Door Seal Structure for Leak-Resistant Turbomachines
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Solution Overview
Problem
Bleed valves in turbomachines experience significant leaks and control issues due to the flexibility of lip seals, which lead to incorrect repositioning and reduced airtightness, especially under high pressure conditions, causing overconsumption and performance reduction.
Innovation Solution
An airtight seal with a sealing lip and anti-return means, featuring a curved hinge and a thickened heel to prevent deformation and ensure consistent contact, is mounted on the door of the bleed valve, providing enhanced rigidity and maintaining airtightness even under pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lip seal is used to ensure airtightness, then good airtightness is achieved during first closing and pressurisation, but the sealing lip tends to return to opening position causing incorrect repositioning and leaks
Solution Approach 1:
The patent modifies the physical parameters of the seal by adding a thickened heel portion that increases rigidity at the base of the sealing lip. This structural parameter change prevents the lip from过度 flexing and returning to its original position, while the sealing lip itself maintains its flexibility for effective sealing contact.
Solution Approach 2:
The seal combines materials with different properties: a flexible sealing lip for airtight contact and a rigid thickened heel for positional stability. This composite structure integrates the beneficial properties of both flexible and rigid materials to resolve the contradiction between sealing effectiveness and position stability.
2Reliability
If a flexible lip seal is used, then good airtightness is achieved, but the seal requires important contact force loading hydraulic jacks and control mechanisms
Solution Approach 1:
By changing the geometric parameters of the seal structure—specifically adding the thickened heel portion—the patent increases the rigidity at the base of the sealing lip. This allows the seal to maintain effective contact force with the casing while reducing the overall force required from hydraulic jacks and control mechanisms.
3Reliability
If a lip seal is used, then airtightness is ensured, but the lip returns to opening position under bleed flow causing leaks and performance reduction
Solution Approach 1:
The thickened heel portion acts as a preliminary countermeasure against the harmful effect of bleed flow. By providing increased rigidity at the base before the sealing lip is subjected to bleed flow forces, the structure prevents the lip from being pushed back to its opening position, thereby preventing leakage before it occurs.
Data Source
AI summary
An airtight seal configured to be mounted on a first turbomachine member, such as a door of a bleed valve, and to bear against a second member of the turbomachine, such as a hub of an intermediate casing, the airtight seal including a retaining device for mounting the seal on the first member; a sealing lip ensuring airtightness through contact and intended to bear against the second member; an anti-return device for the sealing lip reinforcing the rigidity of the airtight seal at the base of the sealing lip.