The high maneuverability for the next generation of fighter aircraft is important to survive attacks. Studies1 have shown that a fighter aircraft equipping with thrust-vectoring nozzles can increase its survivability by enhancing its maneuverability and turn rate. Therefore, modern-day aircraft designers are turning to the vectorable nozzles, which turn or vector the exhaust flow and thrust of the gas turbine engine powering the aircraft, such as the two-dimensional convergent-divergent vectoring nozzle invented by Thayer. In the two-dimensional vectoring nozzle, the flat flaps are employed relatively to direct the pitch or yaw direction of the engine's thrust. However, these designs are heavy and require a conversion section to change the axisymmetric flow to a two-dimensional flow and still only provide thrust vectoring in one plane, pitch, or yaw. The singularity is the inherent characteristics of parallel manipulators. At near-singular configurations, the parallel manipulator cannot resist externally applied force/torque along certain directions. The axisymmetric vectoring exhaust nozzle is driven by the 3-SPS + 3-PRS parallel manipulator to change its exit area A9 and make the universal vector of its divergent section. Preventing the 3-SPS + 3-PRS parallel manipulator from falling into the singular configuration is very important for the maneuverability and safety of the jet-thrust aircraft equipping with the axisymmetric vectoring exhaust nozzle. In this paper, a methodology to eliminate the singularity of the 3-SPS + 3-PRS parallel manipulator is presented. At first, with the aid of the configuration homotopy-tracing algorithm, the configuration curves relative to the input parameters are figured out. It is found that the singularity-free zone corresponding to the input parameter exists between the left and the right extreme singular positions. Based on the extended equation algorithm, the curves of singular points going with the input parameters are drawn. By selecting the suitable initial working point and letting the input parameters locate within the singularity-free zones of input parameters determined by these curves, the singularity can be eliminated in the design stage. The method to eliminate the singularity presented in this paper is simple, efficient, and easy to be implemented directly through inspecting the lengths of the input parameters.
Eliminating singularity of a parallel driving mechanism of axisymmetric vectoring exhaust nozzle
2014
10 Seiten, Bilder, 28 Quellen
Article (Journal)
English
Eliminating singularity of a parallel driving mechanism of axisymmetric vectoring exhaust nozzle
Online Contents | 2014
|Eliminating singularity of a parallel driving mechanism of axisymmetric vectoring exhaust nozzle
SAGE Publications | 2014
|Vectoring exhaust nozzle technology
AIAA | 1984
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