| Citation: | FEI Zhongyang, JIANG Xiangwen, ZHAO Qijun, et al. Analyses of radar stealth characteristics of morphing rotor based on dynamic time-varying mesh method[J]. Journal of Aerospace Power, 2025, 40（4）：20230397 doi: 10.13224/j.cnki.jasp.20230397
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Morphing techniques such as varying diameter, active twist and varying speed were proposed for significant improvement of rotor aerodynamic performance. However, rotor echo may be potentially interfered after morphing, which in turn affected its radar stealth characteristics. In order to explore the influence mechanism and select appropriate morphing parameters for better stealth characteristics, firstly, a whole helicopter trim model was established to obtain actual state of the rotor, and a time-varying electromagnetic computing mesh method was proposed to characterize the dynamic responses of rotor morphing, cyclic pitch, flapping and rotating. Then, under the constraint of rotor aerodynamic performance, the dynamic electromagnetic scattering characteristics of three morphing rotors were calculated and compared based on the shooting and bouncing rays method and the uniform theory of diffraction, and the influence mechanism of the morphing on rotor radar stealth was revealed by inverse synthetic aperture radar imaging. The results showed that the change of rotor diameter shall be coupled with pitch adjustment to maintain the aerodynamic performance, and the combined effects of rotor attitude and area caused fluctuation of radar cross section (RCS). When the diameter was reduced by 8%—10%, the RCS could be significantly reduced. When active twist was performed on rotor, the ray reflection direction may change, but RCS reduction was obvious only at a few frequencies. The effect of varying speed on RCS reduction was not prominent, but varying speed rotor could make a significant change in micro-Doppler features and had the best anti-identification stealth characteristics among the three morphing rotors. Therefore, optimization of the morphing scheme according to the electromagnetic environment can also effectively improve the rotor radar stealth while ensuring the rotor aerodynamic performance.
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