Abstract: To address the direct exposure of internal equipment to incoming flow and the additional drag induced by the external structure of a multi-acoustic-buoy carrier-release platform during underwater navigation, this study designs external fairing configurations and numerically investigates their drag characteristics. Based on a prescribed installation envelope, nine fairing models were constructed by combining three types of forebody expansion curves with three types of afterbody contraction curves. CFD (computational fluid dynamics) simulations were then conducted to evaluate their hydrodynamic performance. The results show that the total mean drag differs markedly among the different curve combinations. The Q1-H2 configuration exhibits the lowest total mean drag, at 1652.41 N, whereas the Q3-H1 configuration shows the highest value, at 2481.72 N. When grouped by forebody curve, the total mean drag values of Q1, Q2 and Q3 are 1711.09, 1898.61 and 2282.31 N, respectively, indicating that the forebody expansion curve is the dominant factor affecting drag variation. Flow-field analysis further shows that Q1-H2 has a smaller upstream high-pressure region, a narrower low-velocity wake region and faster wake recovery. Therefore, Q1-H2 can be recommended as the preferred configuration under the given geometric and installation constraints.

Key words: marine acoustic detection, acoustic buoy, fairing, drag characteristics, computational fluid dynamics