Hydrodynamic performance of a towed undersea acoustic array
Abstract
A practical, low cost, easily deployable and recoverable acoustic minesweeping device is desired that can be safely towed by a standard 11 meter Rigid Hull Inflatable Boat (RHIB) at an operating speed range of 5 to 20 knots. Hydrodynamic analyses of the drag characteristics for the acoustic device were undertaken to determine whether these requirements could be satisfied. To estimate the drag on the pre-designed acoustic device for the desired range of towing speeds, three analyses were performed: (1) laboratory towing tank experiments on a model, (2) numerical simulations using the commercial CFD package FLUENT, and (3) field-tests on a full-scale (5m long) prototype. Drag force values obtained from these methods are presented as a function of Reynolds number over a range of 105 to 107 and are compared with the expected values for similarly-shaped bodies. To suggest geometric modifications to obtain a low drag configuration of the body, numerical simulations were carried out and a relation between total drag and changing aspect ratios for a constant diameter body is also presented. Results from LES and RANS models in FLUENT are also discussed. Results from interpolation of field-test and experiments and direct results from simulations, predict a drag of less than the threshold value of 400 lbf at 15 knots. The field test results provided the most direct measurements of the force as the flexibility, porosity and impermeability of the proposed acoustic array were taken into account.
Degree
M.S.C.E.
Advisors
Troy, Purdue University.
Subject Area
Naval engineering|Civil engineering
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