Objectives To investigate the acoustic target strength (TS) characteristics of extra-large unmanned underwater vehicles (XLUUVs), a systematic analysis is conducted on the TS characteristics of the “Orca” XLUUV in the 1k-10kHz frequency band.

Methods Based on the Orca model, the finite element method is employed to calculate the TS of the Orca model in the 1k-3kHz frequency band, while the planar element method is used for the 3k-10kHz band. The results are compared with those of the Benchmark model. The angular detection probability is proposed as a more comprehensive indicator for evaluating the stealth performance of unmanned underwater vehicles (UUVs). Additionally, a scaled model experiment is conducted in a water tank, and a correction method is proposed for the experimental TS measurements.

Results The TS characteristics of the Orca model are studied at first. Compared with the Benchmark model, the Orca model exhibits better stealth performance in the azimuthal direction, with additional advantages in the circumferential direction at higher frequencies, which becomes more pronounced as frequency increases. For cases where the distance between the hydrophone and transducer fails to satisfy the far-field condition, the experimental target strength measurements are corrected, resulting in improved agreement with simulation values. This validates the accuracy of the numerical simulation results.

Conclusions The research findings provide a theoretical basis for optimizing underwater detection systems and the stealth design of UUVs.