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Slamming Impact Loads on Large High-Speed Naval Craft ASNE 2008

Slamming Impact Loads on Large High-Speed Naval Craft ASNE 2008. Sungeun Kim, Derek Novak (ABS) Hamn-Ching Chen (TAMU). Navy Vessels. Planing Hull High speed vs. length ratio Small high-speed naval craft: PT boats Hydrodynamic lift Displacement Hull Low speed vs. length ratio

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Slamming Impact Loads on Large High-Speed Naval Craft ASNE 2008

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  1. Slamming Impact Loads on Large High-Speed Naval Craft ASNE 2008 Sungeun Kim, Derek Novak (ABS) Hamn-Ching Chen (TAMU)

  2. Navy Vessels • Planing Hull • High speed vs. length ratio • Small high-speed naval craft: PT boats • Hydrodynamic lift • Displacement Hull • Low speed vs. length ratio • Large navy vessels: destroyers, cruisers, battleships • Hydrostatic buoyancy • Semi-Planing/Semi-Displacement Hull • Intermediate speed vs. length ratio • Large high-speed naval craft • Partially dynamic & partially static support

  3. Large High-Speed Naval Craft CAT-2 MONO-1 CAT-1 MONO-2 MONO-3

  4. Design of High-Speed Naval Craft • Consider all intended operating conditions of the craft specified by Naval Administration • Significant wave height: H1/3 • Operating speed: V • Two design conditions in ABS HSNC Guides • Operational Condition: maximum design speed • Survival Condition: 10 knots Note: not to be less than L/12 HSNC 3-2-2/Table 1 Note: to be verified by Naval Administration

  5. Design of High-Speed Naval Craft (cont’d) Design Conditions Design Wave Heights and Speeds Operational Survival

  6. Objectives • Current slamming design pressure in HSNC are originally developed for small planing hulls • Speed vs. length ratio: • Slamming pressure from Heller & Jasper (1960) • Vertical acceleration from Savitsky & Brown (1976) • Refine and expand current rules to cover the bottom slamming design pressure for large semi-planing monohulls • Speed vs. length ratio • Vertical acceleration using LAMP and model test • Update wet-deck slammingdesign pressure for large high-speed multi-hulls • Validate numerical simulation program LAMP

  7. Large Amplitude Motion Program (LAMP) • DARPA 1988 Project • Advanced nonlinear ship motion simulation to complement linear methods • Extreme wave loads • Research sponsors • U.S. Navy (ONR, NSWCCD) • U.S. Coast Guard • American Bureau of Shipping • SAIC/MIT LAMP Development

  8. Bottom Slamming Design Pressure for Semi-Planing Monohulls

  9. Bottom Slamming Design Pressure • Current: 3-2-2/3.1.1 (Heller & Jasper) • Proposed: Pressure distribution factor FL Background: pressure reduction on bow and stern area considering 3D flow effect

  10. Vertical Acceleration • One of the most critical driving design factor for high-speed naval craft • Current: 3-2-2/1.1 (Savitsky & Brown) where • ncg 1/100 highest vertical acceleration • h1/3 1/3 significant wave height • Bw maximum waterline beam • cg deadrise angle at LCG • V design speed (3-2-2/Table 1) •  displacement •  running trim angle • Note: overestimating for smaller vessels and underestimating for larger vessels

  11. Vertical Acceleration (cont’d) • Proposed ncg: • Proposed Kv

  12. Test Vessel: MONO-1 • Design Conditions • Large semi-planing monohull with ship length over 100 m • ABS Class based on HSNC Guides • Loading Conditions

  13. LAMP Geometry Modeling for MONO-1 Nonlinear Geometry Model for Nonlinear Restoring and Froude-Krylov Forces Hydro Panel Model for Linear Radiation-Diffraction Forces

  14. Vertical Acceleration in Operational Condition Bow • Loading Condition: Full Load Departure • Displacement: 3000 tons • Speed: 38 knots • Sea state: SS5 with Hs=4m Mid Stern

  15. Vertical Acceleration in Survival Condition Bow • Loading Condition:Full Load Departure • Displacement: 3000 tons • Speed: 10 knots • Sea state: SS8 with Hs=9m Mid Stern

  16. Statistical Analysis • Peak Counting • Pick a highest peak between zero-crossings • Threshold: 10% of 1/100 highest peak average • Transient: ignore the first 1/5 of time series • 1/100th Highest Peak Average for Vertical Acceleration • Weibull Fitting for Slamming Impact Force

  17. 1/100th Vertical Acceleration • Operational Condition • Full Load Departure: 3000 tons • Speed: 38knots • Sea state: SS5 with Hs=4m • Operational Condition • Full Load Arrival: 2900 tons • Ship Speed: 40 knots • Sea State: SS5 with Hs=4m

  18. 1/100th Vertical Acceleration • Operational Condition • Full Load Minimum: 2800 tons • Ship Speed: 42 knots • Sea State: SS5 with Hs=4m • Survival Condition • Full load departure: 3000 tons • Speed: 10 knots • Sea state: SS8 with Hs=9m

  19. Impact Force in Operational Condition

  20. Impact Force in Survival Condition

  21. Impact Force in Operational Condition

  22. Design Pressure: Operational at Full Load Depart. Bottom Slamming Pressure: Full Load Departure at Hs=4m and V=38 knots Sectional Impact Force: (Heller & Jasper)

  23. Design Pressure: Operational at Full Load Arrival Bottom Slamming Pressure: Full Load Arrival at Hs=4m and V=40 knots Sectional Impact Force: (Heller & Jasper)

  24. Design Pressure: Operational at Full Load Min. Bottom Slamming Pressure: Full Load Minimum at Hs=4m and V=42 knots Sectional Impact Force: (Heller & Jasper)

  25. Design Pressure: Survival at Full Load Depart. Bottom Slamming Pressure: Full Load Departure at Hs=9m and V=10 knots Sectional Impact Force: (Heller & Jasper)

  26. Wet-Deck Slamming Pressure for Multi-Hulls

  27. Wet-Deck Slamming Design Pressure • Current: HSNC 3-2-2/3.5 • Proposed where FI pressure distribution factor VI relative impact velocity ha distance from waterline to deck H1/3 significant wave height

  28. Wet-Deck Design Pressure (cont’d) Current Wet-Deck Design Pressure Proposed Wet-Deck Design Pressure

  29. Test Vessel: CAT-1 • High-speed wave-piercing catamaran • Length: LWL=73m • Speed: 40knots • ABS Class • Hull damage was reported, likely due to wet-deck slamming impact loads

  30. LAMP Simulation for Wet-Deck Slamming • LAMP simulation with wet-deck option • 2D wedge impact theory (Ge, Faltinsen, Moan 2005) on longitudinal cuts • Require smaller time step • Require supplemental pitch damping model • LMPRES to extract wet-deck slamming pressure • PLMPRES to generate nodal pressure time series

  31. Supplemental Pitch Damping in LAMP Based on the model test measurements of CAT-1, additional pitch damping is considered for pitch motion simulation Supplemental pitch damping model in LAMP

  32. Relative Motion in Model Test Condition Relative Vertical Motion Vertical Acceleration

  33. Wet-Deck Slamming Pressure in Model Test Condition P1 P4 P3 P2

  34. Wet-Deck Slamming Pressure in Survival Condition

  35. Wet-Deck Slamming Pressure in Survival Condition x=0.9L from AP x=0.8L from AP

  36. Wet-Deck Slamming Pressure in Survival Condition x=0.6L from AP x=0.2L from AP

  37. Wet-Deck Slamming Pressure in Survival Condition

  38. Wet-Deck Slamming Pressure in Operational Condition

  39. Wet-Deck Slamming Pressure in Operational Condition x=0.9L from AP x=0.8L from AP

  40. Wet-Deck Slamming Pressure in Operational Condition x=0.6L from AP x=0.2L from AP

  41. Wet-Deck Slamming in Operational Condition

  42. FANS (Finite Analytic Navier-Stokes)Code • CFD solver developed by Texas A&M • Unsteady incompressible/compressible two-phase flow solver • Multi-block solver using overset grids • Nonlinear free-surface capturing scheme using level-set method • FANS developments in ABS-TAMU • LNG sloshing impact pressure • Wet-deck slamming impact pressure • Bow/stern slamming and green sea loads

  43. FANS Modeling of CAT-1: Overset Grid 25 blocks, 16 processors, 2.16 million grid points for half-domain

  44. FANS Wet-deck Slamming of CAT-1

  45. Summary • Bottom slamming pressure for monohulls • Vertical acceleration is one of the most driving design factor for high-speed naval craft. • Vertical acceleration has been revised to cover large semi-planing naval craft based on numerical simulation and model test • Slamming design pressure has been validated with existing design of high-speed naval craft • Wet-deck slamming pressure for multi-hulls • Numerical simulation for wet-deck slamming has been performed in time domain using LAMP • Wet-deck design pressure is revised based on numerical simulation. • Survival condition is found to be a governing condition for wet-deck slamming pressure

  46. On-going/Future Projects in ABS-SAIC-TAMU • Guide for direct analysis procedure • Wave-induced design loads • Whipping loads for monohulls • Wet-deck slamming loads for multi-hulls • Guide for slamming model test procedure • Vertical acceleration • Local vs. panel pressure • Statistic analysis for design pressure • Software validation of wet-deck slamming • Numerical simulation using LAMP/FANS code • Model test/Full scale measurements

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