nxSERN Nozzle Third Stream Integration
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Solution Overview
Problem
Existing fixed exhaust nozzle systems for jet aircraft face challenges in achieving efficient thrust while minimizing drag penalties and integrating a third stream exhaust without compromising performance, particularly due to steep boat tail angles and complex variable geometry designs.
Innovation Solution
The design of a novel internal/external single expansion ramp nozzle (nxSERN) that reduces the boat tail angle and allows for the integration of a third stream exhaust by using isentropic geometries and the Method of Characteristics to define flow paths, ensuring high Gross Thrust Coefficient performance across a range of pressure ratios without degrading drag performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional single expansion ramp nozzle (SERN) is used to achieve high thrust efficiency, then the Gross Thrust Coefficient is improved, but the boat tail angle becomes steep causing severe drag penalty
Solution Approach 1:
The nozzle flow path is segmented into multiple distinct sections: a convergent section, an expansion section with first and second expansion surfaces, and a boat tail section. This segmentation allows each section to be optimized independently for its specific function while maintaining overall thrust efficiency and reducing drag through a shallower boat tail angle configuration.
2Adaptability or versatility
If a variable geometry nozzle system is used to accommodate different thrust levels, then adaptability is improved, but device complexity and expense increase
Solution Approach 1:
The nozzle is designed with specific geometric parameters including a convergent section with defined area reduction, an expansion section with controlled expansion surfaces, and a boat tail section with optimized angles. These parameter optimizations allow the fixed geometry nozzle to achieve high efficiency across a range of operating conditions without requiring variable geometry mechanisms.
3Adaptability or versatility
If a third stream exhaust is integrated into the nozzle, then propulsion system versatility is improved, but flow path complexity and performance degradation occur
Solution Approach 1:
The nozzle design merges multiple exhaust streams by providing a common flow path that accommodates both the primary exhaust flow and the third stream exhaust. The convergent section, expansion section, and boat tail section are configured to handle combined flows, allowing integration of additional propulsion systems while maintaining efficient thrust generation and avoiding performance degradation.
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 nxSERN nozzle achieves high thrust efficiency with reduced drag and compatible integration of a third stream exhaust, maintaining performance across varying nozzle pressure ratios and flight conditions, thus addressing the limitations of conventional SERN designs.
Implementation Method 1
The design of a novel internal/external single expansion ramp nozzle (nxSERN) that reduces the boat tail angle and allows for the integration of a third stream exhaust by using isentropic geometries and the Method of Characteristics to define flow paths
Implementation Method 2
using isentropic geometries and the Method of Characteristics to define flow paths, ensuring high Gross Thrust Coefficient performance across a range of pressure ratios
Data Source
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AI summary
The construction of an internal/external single expansion ramp nozzle (nxSERN), and method of designing the same, is provided. Initial design parameters for primary stream construction are selected and additional parameters are determined by isentropic relations using the selected design parameters and Prandtl-Meyer function. The nozzle throat input and output angles are determined and used to define an initial portion of the nozzle primary stream lower expansion surface. The nozzle primary stream upper expansion surface and an aft portion of the primary stream lower expansion surface are defined using a method of characteristics. Initial and aft portions of the primary stream lower expansion surface are then connected by a straight line to define the primary stream nozzle.