Variable Area Nozzle Assembly for Aircraft Propulsion
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Solution Overview
Problem
Existing exhaust nozzle assemblies for aircraft propulsion systems lack the ability to efficiently control and optimize the flow of exhaust gases, leading to suboptimal performance and efficiency.
Innovation Solution
A variable area nozzle assembly comprising a center plug, an outer nozzle, and an inner nozzle, with the inner nozzle being axially translatable to adjust the cross-sectional area of the primary and secondary ducts, allowing for precise control of gas streams and facilitating cooling through secondary gas stream flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed exhaust nozzle assembly is used, then the structure is simple, but the ability to control and optimize exhaust gas flow is insufficient
Solution Approach 1:
The exhaust nozzle assembly incorporates variable area nozzles that can dynamically adjust their cross-sectional area to optimize exhaust gas flow under different operating conditions. The inner nozzle and outer nozzle can independently vary their areas, transforming the fixed structure into a dynamic one that adapts to changing engine demands, thereby resolving the contradiction between control capability and structural simplicity.
Solution Approach 2:
The nozzle assembly is divided into multiple independent segments: an inner nozzle and an outer nozzle, each capable of independent area adjustment. This segmentation allows each component to be controlled separately, providing fine-grained control over exhaust gas flow paths and enabling optimization of both primary and secondary gas streams without requiring complete redesign of the entire nozzle structure.
2Productivity
If the inner nozzle area is reduced, then the primary gas stream flow is optimized, but the cooling capability is reduced
Solution Approach 1:
The cooling function is separated from the primary exhaust flow control by introducing a distinct secondary gas stream path through the outer nozzle. This allows the inner nozzle to be optimized for primary gas stream efficiency with reduced area, while the outer nozzle independently provides cooling gas flow, eliminating the trade-off between flow optimization and cooling capability.
Solution Approach 2:
A secondary gas stream acts as an intermediary cooling medium that flows through the outer nozzle and around the inner nozzle. This secondary stream provides the necessary cooling function without interfering with the optimized primary gas stream flow through the inner nozzle, allowing both functions to operate simultaneously at optimal levels.
3Productivity
If the nozzle assembly is designed for high efficiency, then propulsion performance is improved, but the device complexity increases
Solution Approach 1:
The variable area nozzle assembly provides multiple functions through a unified structure: it controls primary exhaust gas flow, provides nozzle cooling, and optimizes propulsion performance across different operating conditions. The inner and outer nozzles work together to simultaneously manage flow efficiency and thermal management, reducing the need for separate specialized components and thereby limiting the increase in device complexity.
Data Source
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AI summary
A variable area nozzle assembly (96) includes a fixed center plug (104), a fixed outer nozzle (108), and an inner nozzle (106). The fixed center plug (104) includes a plug body (114) and a protrusion (124). The fixed outer nozzle (108) extends about the fixed center plug (104). The inner nozzle (106) extends about the fixed center plug (104). The inner nozzle (106) is disposed between the fixed center plug (104) and the fixed outer nozzle (108). The inner nozzle (106) forms a primary duct (154) between the inner nozzle (106) and the fixed outer nozzle (108). The primary duct (154) includes an exit plane (158). The inner nozzle body (128) forms a secondary duct (130) and a gap (146). The gap (146) is a nozzle outlet of the secondary duct (130). The gap (146) includes a gap inlet (148) and a gap outlet (150). The gap inlet (148) is disposed upstream of the protrusion (124). The gap outlet (150) is disposed downstream of the protrusion (124). The inner nozzle body (128) is translatable between a first position and a second position. In the first position, the primary duct (154) has a first area at the exit plane (158) and the inner nozzle body (128) is disposed at the protrusion (124). In the second position, the primary duct (154) has a second area at the exit plane and the inner nozzle body is spaced from the protrusion.