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1 COMUNICAÇÃO TÉCNICA Nº The use of CFD on the Naval Engineering Research at IPT João Lucas Dozzi Dantas Palestra apresentada no SIMCETER USERS MEETING SOUTH AMERICA, 2018, São Paulo A série Comunicação Técnica compreende trabalhos elaborados por técnicos do IPT, apresentados em eventos, publicados em revistas especializadas ou quando seu conteúdo apresentar relevância pública. Instituto de Pesquisas Tecnológicas do Estado de São Paulo S/A - IPT Av. Prof. Almeida Prado, 532 Cidade Universitária ou Caixa Postal 0141 CEP São Paulo SP Brasil CEP Tel /4000 Fax

2 The use of CFD on the Naval Engineering Research at IPT IPT Institute for Technological Research João Lucas Dozzi Dantas

3 Agenda: About IPT Institute for Technological Research Vessel Resistance and Motion Geometry simplification using porous approach Propeller blockage and hydrophobic investigation Laminar-turbulent transition model

4 IPT Institute for Technological Research Page 3

5 IPT Institute for Technological Research Page 4

6 IPT-NAVAL: Towing Tank Large Section: 200 x 6.6 x 4.5 m Narrow Section: 60 x 3.7 x 2.0 m Maximum test speed: 3.5 m/s Model length: up to 6.0 m Page 5

7 IPT-NAVAL: Cavitation Tunnel IPT s Cavitation Tunnel, model Kempf & Remmers K18, was inaugurated in 1963 in a partnership with Brazilian navy Section test: 0.5 x 0.5 m² Range of pressure: 0.2 ~ 1.6 atm Propeller rotation: up to 3000 rpm Advance velocity: up to 5.0 m/s Page 6

8 IPT-NAVAL: Cavitation Tunnel: Instrumentation Capabilities Force, torque and vibration measurement Strain gauges and load cells Strobe light Velocity measurements Pitot Acoustic (ADV) Laser (PIV and LDV) Measurement of dissolved oxygen Underwater acoustic sensors Page 7

9 Vessel Resistance and Motion Some results published in: PELICIA, R.S.; DANTAS, J.L.D. Model Calm Water Resistance and Motion Simulation, Experiments and Verification.The 30th American Towing Tank Conference. SNAME

10 Vessel Resistance and Motion Objectives Calm water resistance test are common test in towing tanks, being used to verify a hull performance or calibrate a numerical model. Verify the numerical model through mesh sensitiveness analysis Validate the numerical model by comparison of towing tank results Page 9

11 Case study Two platform supply vessel model Prototype planform: Page 10

12 Results: Resistance Page 11

13 Results: Wave incidence Only M536 (Prototype I) Draft of 6.6 m Vp =1.048 m/s (15 knot) Page 12

14 Simplification of a floating line using porous approach Some results published in: KATSUNO, E.T.; CASTRO, F.S.; DANTAS, J.L.D. Debris Containment Grid CFD validation with Towing Tank Tests.The 30th American Towing Tank Conference. SNAME KATSUNO, E.T.; CASTRO, F.S.; DANTAS, J.L.D. Hydrodynamic Analysis of Debris Containment Grid in Hydropower Plant Using Porous Media.24th International Congress of Mechanical Engineering. ABCM KATSUNO, E.T.; GOMES, G.G.; CASTRO, F.S.; DANTAS, J.L.D. Numerical Analysis of Debris Containment Grid Fluid-Body Interaction.37th International Conference on Ocean, Offshore and Artic Engineering. ASME

15 Objectives Develop a simplified numerical model of a truncated version (with fewer modules) of a debris containment grid line Dynamic Fluid Body Interaction - DFBI Several conditions: Advance velocity and side-slip angle Hydrodynamic Investigation is conducted using CFD software Page 14

16 Methodology Complete representation Simplified representation using porous media approach Line with simplified representation Page 15

17 Complete representation setup Two DoF: sinkage of the module and rotation of the chassis Two regions: domain region (include the grid) and chassis region Boundary conditions of domain region Log boom module: Grid + chassis Boundary conditions of chassis region Page 16

18 Simplified representation setup Dimensions are the same as complete representation. Grid are simplified by a porous region Boundary Conditions of Domain (I), Grid (II), Chassis (III) and Frontal part of Chassis (IV) regions (figures are not in the same scale) Fewer elements Page 17

19 Porous formulation Comparative of complete and porous model in grid force magnitude (x and y directions) (left); and in moment (right) Page 18

20 Log Boom line Float-Grid Six simplified representation 13 regions with overset interfaces Grid-Grid Edges Page 19

21 Next steps Modeling porous region using Momentum source Increase number os lof boom modules Compare results with experimental values obtained in IPT s Towing Tank Page 20

22 Propeller blockage and hydrophobic investigation Some results published in: KATSUNO, E.T.; DANTAS, J.L.D. Investigação da metodologia para simulações de propulsores utilizando fluidodinâmica computacional. 26º Congresso Nacional de Transporte Aquaviário, Construção Naval e Offshore. SOBENA KATSUNO, E.T.; DANTAS, J.L.D. Analysis of the Blockage Effect on a Cavitation Tunnel using CFD Tools. 36th International Conference on Ocean, Offshore and Artic Engineering. ASME KATSUNO, E.T.; DANTAS, J.L.D.; SILVA, E.C.N. Analysis of Hydrophobic Painting in Model-Scale propeller. 37th International Conference on Ocean, Offshore and Artic Engineering. ASME

23 Number of elements CFD model study Domain size study V&V study Mesh topology study Turbulence model Model KT KQ η Experimental 0,330 0,0433 0,231 SA 0,317 0,0419 0,256 SST 0,316 0,0417 0,256 SST LowRe 0,316 0,0418 0,256 Realizable k ε 0,317 0,0419 0,256 Trimmed Polyhedral Page 22

24 Open Water results Periodic condition with cavitation model Experimental comparatives Page 23

25 Cavitation and Blockage results Results Results with blockage correction Page 24

26 Next steps Analysis for lower cavitation number Noted a high influence of blockage ratio in the cavitation area Comparative between two blockage ratio for the same advance ratio of Not contemplated in Glauert mode Page 25

27 Research at superhydrophobic painting Perform a numerical analysis of superhydrophobic surface on propeller Boundary condition not implemented Trade-off between gain in performance and suction pressure Using Field Functions and storing previous results in Monitors Page 26

28 Laminar-Turbulent transition model Some results published in: GOMES, G.G.; ESTEVES, F.R.; KATSUNO, E.T.; DANTAS, J.L.D. Simulations of Laminar Turbulent Transition in foils using CFD. 27º Congresso Internacional de Transporte Aquaviário, Construção Naval e Offshore. SOBENA

29 Laminar to turbulent transition simulations using Gamma- ReTheta turbulence model Transition for the S9000 airfoil, α = 5.21 degrees. Intermittency field (upper figure), alongside the wall shear stress for the upper side of the airfoil, transition occurs between Rex = 9*10⁴ and 1.1*10⁵ Page 28

30 Bubble comparative Comparison between the separation bubble in the upper side of the airfoil obtained with the SST low- Reynolds Turbulence model (top) and with γ-reθ (bottom) Page 29

31 Turbulence Intensity Use of ambient turbulent source to counteract turbulence decay Page 30

32 Comparison with experimental values Comparison with other turbulence models for simulations with low-reynolds number over airfoils NACA43012A airfoil using different turbulence models with experimental data Re = 6e4 Page 31

33 Conclusions CFD has demonstrated great potential in assisting NAVAL-IPT experiments, allowing new types of analysis and results to be incorporated into the laboratory portfolio. NAVAL-IPT will continue to improve its researchers to use this tool to offer more specialized services to their clients Page 32

34 João Lucas Dozzi Dantas Head of Laboratory Naval Architecture and Ocean Engineering Laboratory Center for Mechanical, Electrical and Naval Technologies