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Numerical simulations of the influence of the propeller race on the interference drag of twin prolate spheroids at various longitudinal offsets and transverse separations

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Title Numerical simulations of the influence of the propeller race on the interference drag of twin prolate spheroids at various longitudinal offsets and transverse separations
 
Creator Rattanasiri, Pareecha
Wilson, Philip A.
Phillips, Alexander B.
 
Subject AUV
Spacing
Drafting
CFD
Fleet configuration
 
Description 964-970
Present study investigates the combined drag
of a pair of propelled prolate spheroids compared to the towed models for a
length Reynolds Number of 3.2×106. Each spheroid has a
length-diameter ratio of 6:1. A series of fleet configurations is simulated at
various longitudinal offsets and transverse separations. Three-dimensional
simulations are performed using a commercial Reynolds Averaged Navier-Stokes
(RANS) Computational Fluid Dynamics code ANSYS CFX 12.1 with the SST turbulence
closure model. In each case, the fluid domain has a mesh size of approximately
nine million cells including inflated prism layers to capture the boundary
layer. Mesh convergence is tested and then validated with wind tunnel test
results. Drag of each spheroid is compared against the benchmark drag of a
single hull. Three-dimensional cylinder is modelled to simulate the thrust
distribution of propeller. The drag of the propelled model is compared against
the single bare hull model. Results show that the transverse separations and
longitudinal offsets determine the interaction drag between both hulls, increasing
of separation results in lower interference drag, decreasing of offset results
in higher drag reduction.
By implementing the body force propeller, the combined drag and drag of the
follower is modified by the accelerated flow due to the propeller. Based on the
numerical information, operators can determine the optimal configurations in
transvers separation and longitudinal offset based on energy considerations.
 
Date 2014-01-10T11:56:44Z
2014-01-10T11:56:44Z
2013-12
 
Type Article
 
Identifier 0975-1033 (Online); 0379-5136 (Print)
http://hdl.handle.net/123456789/25474
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJMS Vol.42(8) [December 2013]