نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشکده ی مهندسی مکانیک، دانشگاه تربیت دبیر شهید رجایی
2 دانشکده ی مهندسی مکانیک- دانشگاه تربیت دبیر شهید رجایی
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In the present study, a novel method has been introduced to estimate the hydrodynamic coefficients of an axisymmetric submersible prolate spheroid. In
this heuristic procedure which is based on combination of the nonlinear Hybrid
Extended Kalman Filter (HEKF) observer and Computational Fluid Dynamics (CFD), all of the hydrodynamic derivatives of a prolate spheroid in horizontal plane
are estimated to simulate the Three Degrees of Freedom (3DoF) equations of
motion. For this purpose, first, a CFD-based numerical model has been developed
for an axisymmetric prolate spheroid by the commercial code ANSYS CFX software using the remeshing algorithm in dynamic mesh method. In this algorithm, the grid around objects deform locally using the Arbitrary Lagrangian-Eulerian (ALE) form of the governing fluid equations. When this deformation reduces the mesh resolution, significantly, the grid is re-meshes and improved. By
performing the corresponding calculations along with the simulation, some
hydrodynamic derivatives were obtained. Then, utilizing the hybrid kalman
filter simulation code based on the parameter identification, other unknown
derivatives were estimated in the MATLAB software environment by applying the
equations of motion governing an ellipsoidal body shape. It should be noted
that, for deriving the remaining hydrodynamic coefficients of the mentioned
prolate spheroid using HEKF, positions and velocities of the object in each
time step are needed. So, the dynamic motion of the vehicle in the fluid is
simulated using the transient tool of the ANSYS CFX software while benefiting
from the remeshing algorithm. Furthermore, the hybrid form of the Extended
Kalman Filter (EKF) is chosen as the equations governing the 3DoF motion of the
ellipsoid is continuous and the measurements are discrete. Results obtained
from the proposed method indicate a good agreement for estimated added mass
derivatives in comparison with the available analytical ones. The following
study is an effort made to introduce an innovative strategy to investigate the
hydrodynamic coefficients of submersible platforms like submarines, torpedoes
and AUVs.
کلیدواژهها [English]
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