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Hydrodynamic Performance of Squat Submarine Equipped with Passive Pressure Drag Reductions

Sarraf, Sadyar | 2023

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  1. Type of Document: Ph.D. Dissertation
  2. Language: English
  3. Document No: 56401 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Abbaspour, Madjid; Mohtasham Dolatshahi, Kiarash; Sani, Mahdi
  7. Abstract:
  8. This research empirically examines the hydrodynamic performances of squat submarines under the resistance and wave tests, besides the numerical investigation of pressure drag reduction techniques. Submarines are limited for public use due to military classification issues and being expensive. This research introduces a new squat submarine in order to enable underwater exploration. This squat submarine has a 9- person capacity as a manned midget submersible using specific geometries of length-over-depth ratios (L/D) below four. The cause of such selection is to provide better visibility for the passengers to research and explore the sea. However, the geometrical features considerably change the hydrodynamic performance of the submarine, for example, by causing pressure drag. Despite vast information about the operation of streamlined fluid vessels, there is not much information about the geometries and hydrodynamic behaviors of squat vessels with L/D ratios below four. This study experimentally investigates the impacts of various relative depths and flow inclinations, intending to find drag, heave, and sway forces at the velocities of 0.5, 1.0, 1.5, 2.0, and 2.5-m/s. A one- tenth scaled model of a squat submarine is examined under the resistance and wave train scenarios as the captive model in the towing tank experiments via 110 unique testing scenarios. Then, different pressure drag reduction techniques on the full-scale submarine are evaluated numerically at one-phase fluid by developing stern geometric optimization, nose rod devices, water corridors, and surface patterns at the bow and stern. Results present drag forces increase up to 150% at the 0.5D level for the resistance and wave tests due to the influences of the free surface water. The drag coefficients at the fully submerged depth of 6D differ by up to 13.3% between the numerical and experimental evaluations
  9. Keywords:
  10. Submarine ; Towing Tank ; Drag Reduction ; Hydrodynamic Performance Curve ; Pressure Reduction ; Squat Submarine

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