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Proceedings ArticleDOI

Experimental and Numerical Studies on an Underwater Towed Body

TL;DR: In this article, a streamlined form of underwater towed body is considered for the experimental and CFD studies to verify its stability when towed in submerged condition, and the main variants associated with the body, and which affect the tow characteristics, are identified as basic body shape, tow point location, fin size for stable tow and dynamic trim due to forward speed.
Abstract: A streamlined form of underwater towed body is considered here for the experimental and CFD studies to verify its stability when towed in submerged condition. Its physical characteristics lead to different behavior in the hydrodynamic tow conditions. Influence of lifting fins and tow arrangements on the operational depth and stability of the tow body are studied. The main variants associated with the body, and which affect the tow characteristics, are identified as basic body shape, tow point location, fin size for stable tow and dynamic trim due to forward speed. In order not to disturb the flow around the sensor location, the fin is placed further away towards the lower aft end. Additionally, the stable tow is validated and demonstrated in the towing tank at IIT Madras using the scaled model. The drag and lift force values obtained from model tests are extrapolated to the prototype and compared with CFD results.Copyright © 2014 by ASME
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Journal ArticleDOI
TL;DR: In this paper, a new computational fluid dynamics approach is suggested to calculate translational longitudinal and transverse added mass coefficients of an underwater vehicle, which can be used as a reliable and inexpensive method to extract translational added mass coefficient of underwater vehicles instead of expensive experimental methods or other CFD methods simulating oscillatory motions.

21 citations

Journal ArticleDOI
TL;DR: In this paper, the accuracy of experimental procedure used to calculate the drag coefficient of an AUV in a towing tank is investigated using computational fluid dynamics, and the effects of struts used to connect the AUV model to towing carriage, at various relative submergence depths, at AUV speeds of 1.5 and 2.5 m/s are numerically simulated.
Abstract: The accuracy of experimental procedure used to calculate the drag coefficient of an Autonomous underwater vehicle (AUV) in a towing tank is investigated using computational fluid dynamics. Effects of struts, used to connect the AUV model to towing carriage, on the hydrodynamics coefficient of the AUV at various relative submergence depths, at AUV speeds of 1.5 and 2.5 m/s are numerically simulated. Various numerical modeling are performed to investigate the effects of free surface with and without presence of struts on the drag coefficient of the AUV. Volume of fluid (VOF) model is used to solve the two phase flow RANS equations. The drag coefficients obtained from two phase flow simulations are compared with those obtained from single phase flow at corresponding velocities. The results obtained from experiments conducted in the towing tank of the Subsea Science and Technology centre, on a full-scale model of the AUV developed in this Centre, agreed well with those obtained by numerical simulations.

8 citations

Journal ArticleDOI
TL;DR: In this paper, the hydrodynamic coefficients of a research AUV were determined using Computational and Experimental Fluid Dynamics (CFD) methods, at AUV speed of 1.5 m s-1 for two general cases: I. AUV without control surfaces (Hull) at various angles of attack in order to calculate Hull related hydrodynamynamics, and II. AUVM with control surfaces at zero angle of attack but in different stern angles to calculate hydroglobal coefficients related to control surfaces.
Abstract: Determination of hydrodynamic coefficients is a vital part of predicting the dynamic behavior of an Autonomous Underwater Vehicle (AUV). The aim of the present study was to determine the drag and lift related hydrodynamic coefficients of a research AUV, using Computational and Experimental Fluid Dynamics methods. Experimental tests were carried out at AUV speed of 1.5 m s-1 for two general cases: I. AUV without control surfaces (Hull) at various angles of attack in order to calculate Hull related hydrodynamic coefficients and II. AUV with control surfaces at zero angle of attack but in different stern angles to calculate hydrodynamic coefficients related to control surfaces. All the experiments carried out in a towing tank were also simulated by a commercial computational fluid dynamics (CFD) code. The hydrodynamic coefficients obtained from the numerical simulations were in close agreement with those obtained from the experiments.

2 citations