Filament Winding Technology Based on Stealth Aircraft Jet Engine Nozzle Geometry

 

In modern warfare, stealth technology for fighters, bombers and unmanned combat aircraft (UCAV) is an important factor in determining the outcome of war by ensuring air superiority. Stealth refers to a technology that avoids detection by enemy radar and infrared detectors. In the case of detection by infrared (IR) signature, the heat from the aircraft itself, especially the high-temperature engine and rear fuselage, emits the largest amount of thermal radiation.

 

Since the design of the aircraft engine nozzle must be able to suppress infrared signals, an S-shaped nozzle (double serpentine nozzle) is adopted so that the high-temperature part of the engine cannot be seen. In addition, a large aspect ratio outlet shape is adopted to reduce the infrared signature of the exhaust gas plume temperature (Figure 1). Multilayer composite materials can meet the functional and structural requirements of engine exhaust nozzle manufacturing.

 

 

Figure 1:

(a) UCAV front view and 3D sketch of the inlet (green) and exhaust nozzle (orange)

(b) 3 different exhaust nozzle geometries.

(c) Simulation results after applying infrared signal

 

The innermost layer of the nozzle is made of carbon fiber reinforced silicon carbide (C-SiC) composite material, which has excellent thermal stability and erosion resistance. The outermost layer consists of carbon fiber reinforced plastic (CFRP), a lightweight material that maintains structural strength under axial thrust and internal pressure. Finally, ceramic materials are used between C-SiC and CFR materials for bonding and insulation.

 

Non-Axisymmetric Shapes

 

With Filament Winding Technology

 

For simple axisymmetric nozzle structures (cylindrical, round nozzles), filament winding can be used to manufacture aircraft parts, which is less expensive than other composite preforming processes. On the other hand, there are not many cases where non-cylindrical shapes with sharp bends are manufactured into actual aircraft products using filament winding.

 

 

Winding Pattern sSimulation Results Using a 3D Graphics Viewer (Courtesy of Cadfil)

 

Therefore, in order to uniformly wrap the exterior of a non-axisymmetric shape using conventional filament winding processes, precise fiber positions and winding trajectories must be created in advance by manufacturing (CAD/CAM) design tools.

 

 

Image Of the Winding Pattern Generated by The Experimental Test