Exploring effect of carrier appendage on drag and flow noise of carrier of multi-load AUV

After separation of loads from multi-load AUV (autonomous underwater vehicle), the carrier did not have good hydrodynamic characteristics of the original shape of multi-load AUV. How to reduce the drag and flow noise of carrier has great significance. After carefully studying the ideas in Refs 4 and 5, we came to the idea of adding appendage to carrier, leading to the exploration mentioned in the title. This exploration is explained in section 1, 2 and 3, whose core consists of: "First, the LES (Large Eddy Simulation) with the Smagorinsky model and the FW-H equation based on Lighthill acoustic theory were adopted to simulate the flow field and the sound field of the carrier with different kinds of appendages. Then the drag and flow noise reduction mechanism of the appendages with different shapes and sizes was examined on the basis of the analysis of the flow field." Numerical simulations are performed in section 3. The simulation results, given in Figs.5 through 12 and Tables 2 through 5, and their analysis demonstrate preliminarily that: (1)the match between the length and diameter of the cylindrical appendage has effect on the drag and flow noise reduction; (2) the relationship between hemispherical appendage diameter and its drag and flow noise reduction effect is monotonically positive. Section 4 presents our preliminary main conclusions, which we believe is helpful to the future design of multi-load AUV.