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<p>The design of an underwater vehicle is a complex process and involves numerous design variables. The dynamic stability is the most significant of these variables. This research is focused on the dynamically unstable model, DARPA Sub-Off. For which new stern control surfaces are to be designed to make it stable in straight-line motion at a constant depth. This study is based on the steady-state numerical CFD method which incorporates Menter’s SST two-equation turbulence modeling technique. Menter’s SST modeling is a hybrid of <i>k</i> − ω and <i>k</i> − ε, wherein <i>k</i> − ω is used to estimate the flow characteristics in the boundary layer and <i>k</i> − ε for external shear flow regions. Two types of hydrodynamic tests are conducted which are straight-line towing tests and rotating arm tests for both horizontal and vertical planes. All tests were conducted at a speed of 6.5knots. The simulation for the towing tank was carried out at three angles (1, 3, and 5) and the rotating arm test at three radii (14, 21, and 42). The forces and moments estimated through these tests were plotted to take required gradients for each and then compared with experimental results. The hydrodynamic coefficients derived from gradients of plotted curves had an error of less than 12%. Based on these validations’ stern appendages of Sub-Off were modified span-wise. Design 1 had a good effect on horizontal plane stability but a negative effect on the vertical plane. Further increase in span was done for Design 2 which resulted in a stable model for both horizontal and vertical planes. The stability indexes were both positive and within the permitted range for good operational maneuverability and seakeeping. Optimization of the model with Design 2 control surfaces can be done in future. In addition, other configurations of control surfaces can also be modified and studied with the current simulation method or by virtual Planar Motion Mechanism.</p>

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CFD-based study of appendages design for dynamic stability of underwater vehicle

  • 期刊论文

  • 发表日期：

    2025年7月12日

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  • Muhammad Ali Tariq,
  • Zulqarnain Mukhtar Mahmood,
  • Muhammad Aasil Qureshi,
  • Nimra Khan,
  • Muhammad Junaid Javaid,
  • Balaj Hussain

摘要

The design of an underwater vehicle is a complex process and involves numerous design variables. The dynamic stability is the most significant of these variables. This research is focused on the dynamically unstable model, DARPA Sub-Off. For which new stern control surfaces are to be designed to make it stable in straight-line motion at a constant depth. This study is based on the steady-state numerical CFD method which incorporates Menter’s SST two-equation turbulence modeling technique. Menter’s SST modeling is a hybrid of k − ω and k − ε, wherein k − ω is used to estimate the flow characteristics in the boundary layer and k − ε for external shear flow regions. Two types of hydrodynamic tests are conducted which are straight-line towing tests and rotating arm tests for both horizontal and vertical planes. All tests were conducted at a speed of 6.5knots. The simulation for the towing tank was carried out at three angles (1, 3, and 5) and the rotating arm test at three radii (14, 21, and 42). The forces and moments estimated through these tests were plotted to take required gradients for each and then compared with experimental results. The hydrodynamic coefficients derived from gradients of plotted curves had an error of less than 12%. Based on these validations’ stern appendages of Sub-Off were modified span-wise. Design 1 had a good effect on horizontal plane stability but a negative effect on the vertical plane. Further increase in span was done for Design 2 which resulted in a stable model for both horizontal and vertical planes. The stability indexes were both positive and within the permitted range for good operational maneuverability and seakeeping. Optimization of the model with Design 2 control surfaces can be done in future. In addition, other configurations of control surfaces can also be modified and studied with the current simulation method or by virtual Planar Motion Mechanism.