Self-Sealing Nozzle Throat Mechanism for Supersonic Flow Control
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Solution Overview
Problem
Current throat area control systems in supersonic vehicles with afterburners face challenges in changing the flow area of nozzle throats without introducing undesirable edges or gaps, which are difficult to seal, especially when the edges need to be angled relative to the airflow, making them infeasible for use.
Innovation Solution
A variable area mechanism that rotates about an off-body axis-of-rotation, utilizing a contoured interface surface to expand and retract within an angle notched nozzle surface, maintaining angular trailing edges without opening asymmetric gaps, thus simplifying sealing and enhancing survivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanism translates or rotates around an axis perpendicular to the flow through the flow area, then the flow area in the throat section can be changed, but edges or hinge lines perpendicular to the exhaust airflow are introduced which are undesirable for survivability
Solution Approach 1:
The patent applies asymmetry by orienting the edges of the movable flow area control surface at an angle to the airflow direction rather than perpendicular to it. This angular orientation eliminates the formation of perpendicular hinge lines that would create vulnerable edges, thereby improving survivability while still enabling flow area adjustment through rotation about an off-body axis
Solution Approach 2:
The patent moves the axis of rotation from a conventional position (within or perpendicular to the nozzle body) to an off-body axis location. This dimensional relocation allows the control surface to rotate and adjust flow area without creating perpendicular edges relative to the exhaust flow, resolving the contradiction between flow control capability and survivability
2Object-affected harmful factors
If the edges of the mechanism are oriented angular to the airflow, then survivability is improved, but gaps are introduced requiring very complicated sealing techniques
Solution Approach 1:
The patent extracts or eliminates the problematic gaps between the movable control surface and nozzle body by carefully designing the rotation geometry. The off-body axis rotation combined with the angular edge orientation ensures that the control surface expands from and retracts into the angle notched nozzle surface without opening asymmetric gaps, thereby removing the need for complicated sealing techniques while maintaining angular edges for survivability
Solution Approach 2:
The geometry of the movable flow area control surface and its rotation path are designed to self-seal against the nozzle body during operation. The contoured interface surface and angle notched nozzle surface work together to maintain contact and prevent gap formation throughout the rotation range, making the system self-sealing without requiring additional sealing components
3Productivity
If a conventional rotation mechanism is used, then flow area control is achieved, but asymmetric gaps open due to rotation about a body axis
Solution Approach 1:
The patent relocates the rotation axis from a conventional body-axis position to an off-body axis position. This dimensional change in the rotation geometry allows the control surface to rotate efficiently for flow area control while simultaneously preventing asymmetric gap formation, as the rotation path is designed to maintain continuous contact between the control surface and nozzle body throughout the motion range
Data Source
AI summary
A flow control panel in an aircraft engine two-dimensional, convergent/divergent nozzle adjusts a throat area of the nozzle and is configured to be self-sealing, thereby requiring fewer parts and providing a more simplified construction of the throat area of the nozzle.