Ship Simulation for Military and Civil Works

Transcription

1 Ship Simulation for Military and Civil Works S. Keith Martin Research Physicist Navigation Branch David J. Mark Research Hydraulic Engineer River Engineering Branch 2 November 2017

2 Bringing the real world into a laboratory environment.

3 Man In The Loop Computer Display Vessel Response Software Pilot Commands

4 Six Degrees of Freedom

5 Forces Modeled

6 Pilot Response Response to the forces on the ship are important in training, channel design testing, operational guideline development The pilot must account for these forces when ordering his vessel Training mariners are being trained how to respond to these forces Channel Design the pilot response is essentially being measured. Does the pilot s maneuvering fit within the existing/proposed channel for a given ship(s) How should the design be modified to incorporate pilot response while maintaining a margin of safety (e.g. extra rudder, throttle) Operational Planning An expert pilot transits a given reach under a variety conditions in order to develop guidelines. Where is the deep/shallow water Is there adverse current Is there an optimum angle of approach on flood/ebb

7 Simulators that can be configured for ships, tows, assist tugs, small craft, etc. Multiple simulators can be operated independently or interact with each other. 240 horizontal degree field of view 40 degree vertical field of view Calculate & reproduce vessel response to forces. Wind Currents Bank Effects Under keel forces Vessel to vessel interaction Six degrees of freedom Real-Time: Movements require the same amount of time as real life Provide same information as would be onboard ship Ship/Tow Simulator Capabilities Steering systems, throttles (3), azimuth controls, and thrusters Speed, rudder angle, engine speed, rate of turn, heading, water depth, etc Displays include radar, ECDIS, doppler log, binocular view, and many more

8 Ship Simulation at ERDC ERDC has been engaged in ship simulation exercises since the late 1980s Simulation is used at the Engineer Research and Development Center (ERDC) to test U.S. Army Corps of Engineers (USACE) channel designs and recently as an operational support tool for the U.S. Military ERDC Ship Simulation uses input from a variety of sources output from validated numerical, hydrodynamic models Uses wind data based on pilot input and/or gage data uses pilots from actual study area

9 Steps for Conducting a Simulator- Based Navigation Study Reconnaissance Trip Database Preparation Validation Pretesting & Design Testing Result Analysis and Reporting

10 Environmental Databases Channel Definition. Obtained from COE District Office Bathymetric Surveys Currents Usually a separate model study Can model existing and proposed conditions Waves Usually hindcasting study determines appropriate height/period/direction to be used during simulations Wind Wind Roses and Pilot Experience

11 Result Analysis Compare Simulation Runs Existing Proposed Vessel Track Plots Navigation Parameter Plots Rudder Engine Speed Pilot Evaluations

12 Lake Borgne Surge Barrier Project Lake Pontchartrain Seabrook Sector Gate Michoud Slip / Canal IHNC Bayou Bienvenue Sector Gate Lake Borgne

13 GIWW Gate Structure

14 Flood Current Conditions ~ 1.7 m/s ~ 5.4 fps ~ 3.7 mph

15 Conditions Simulated Lake Borgne ship simulation testing was conducted over a six month period including validation, preliminary sensitivity simulations, and final design testing Eighteen tow captains with experience ranging from <5 years to more than 35 years were used for the testing Current databases were developed using the AdH hydrodynamic modeling code Average and severe conditions are both simulated: Average/Severe Wind: 13/22 knots Average/Severe Current: 1.6/3.4 mph Developed with input from towing industry and U.S. Coast Guard

16 8 Different Tow Configurations Description LOA Width Barge Size Draft Configuration Power % Tested Typical East End liquid x inline 1200 HP 6 Typical East End dry cargo x x HP 8 Large East End liquid x inline 1800 HP 10 Liquid Empty Tow x Doubled up 1200 HP 20 Loaded 4 barge tow varies x inline 1800 HP 8 Six pack 3 wide x x HP 18 Large East End dry cargo x pack 1350 HP 7 Dry Cargo Empty Tow x pack 1350 HP 23 * Highlighted Tows are empty with a 1.5 draft

17 Loaded 4 Barge Tow (longest allowed)

18 Loaded 4 Barge Tow (longest allowed)

19 Loaded 4 Barge Tow (longest allowed) Comments from pilots No problem except depending on how much current is running thru gate. Rated 4 for average conditions, 6 for severe conditions As far as handling this tow is doing good, with the length of the tow it will tend to shear across the structure when running into the current, this could cause contact. Rated 7 for both average and severe conditions This tow handled very well in all conditions. Loaded barges are no problem for 150 ft wide gate. Rated 1 for both average and severe conditions It was very easy getting through structure safely in all weather conditions. Rated 0 for both average and severe conditions Easy Average Difficult Unsafe

20 Empty 8-pack (most difficult, max wind)

21 Empty 8-pack (most difficult, avg wind)

22 Empty 8-pack (most difficult) Comments from pilots This tow steers as expected, it is difficult though to transit the structure without contact. If the pilot is distracted in any way, given the proposed width of this structure, there will most probably be contact with damage. Rated 7 for average conditions, 10 for severe conditions Very difficult to line up & get in & out of gate in high winds. I did it but it was not easy, would not try in real world, wait till wind dies down. Light winds had no problems. Rated 4 for average conditions, 10 for severe conditions This tow is very difficult because of the length plus it is empty. Rated 7 for average conditions, 10 for severe conditions Light winds had no problems getting through structure safely, high winds I would not try till winds die down. Rated 4 for average conditions, 9 for severe conditions Easy Average Difficult Unsafe

23 Simulation Results Pilots ran 460 simulation run during 3 weeks of formal testing: 260 exercises for empty barges and 200 loaded tow runs 315 successful (68%) were conducted with severe currents and severe wind 90% of total runs with max current, 81% of total runs with max wind Fourteen failed runs were all empty tows: 12 had an allision with the structure and 2 grounded before reaching the structure. (Simulation failure is an impact to the structure > 2 knots) The allisions all occurred under extreme wind conditions and several captains stated they would normally wait for conditions to improve before transiting the structure Results from the simulation were in the form of data recorded during each exercise and from questionnaires. Data Recorded Position and heading processed to give track plots All data was provided to the US Coast Guard for a Risk Analysis Study.

24 Questionnaires Simulation Results Scenario questionnaires were given after each exercise is completed. Final questionnaires were filled out by each captain at the end of each week. Tow Captain comments which resulted in changes to the final design Treat the structure as a "touch" instead of a "no touch" system Longer & angled guidewalls with possible flow curtains Stronger dolphins Additional moorings Ranges would be extremely useful in determining structure centerline

25 Amphibious Operations Improve realistic planning of an amphibious operation by Providing a tool to assess operational risk by testing the feasibility of the navigability of an area Determining the capacity and timing of the amphibious operations Defining the optimal axes-of-approach that best ensures navigational safety Enable the development of a training venue for executing a particular operation. Provide analytic rigor of operations in the littoral zone using state-of-the-art tidal circulation models for estimating tides and current for planning amphibious operations. Amphibious planning has historically been developed in the same manner as during World War II, using a high tide elevation at the beachhead and a crudely estimated peak current along the axis-of-approach. Factors addressed by using tidal circulation models to improve planning are the following: o Estimating tidal range and current at a proposed beach landing site o Determining whether a site is appropriate for amphibious ship-to-shore operations o Determining the time during which tidal conditions are favorable for conducting operations The modeling and simulation can incorporate and help assess two critical factors, in particular in areas of extreme tidal range, strong current and shear zones, and in areas having limited maneuverability : The navigability of waters from the sea echelon area to the beachhead by the landing craft The capacity and timing of the ship-to-shore operation. A proof-of-concept study has been conducted and demonstrates that the combined use of a high-resolution tidal circulation model and a ship simulator can be practically applied.

26 Operational Applicability This modeling and simulation will provide Ship s Masters and Craftmasters who are unfamiliar with the operating area the ability to test the craft s response and validate the amphibious operations plan. The end state is the ability to conduct an analysis of the proposed amphibious operations (from ship-to-shore for Assault Amphibious Vehicles (AAV7A1), Landing Craft Utility Class 1646 (LCU), and Landing Craft Air Cushion (LCAC) Commanders are then able to conduct a risk assessment regarding the feasibility of the operation.

27 Amphibious Operations Summary Able to provide analytic rigor to the amphibious planning process incorporating tidal and wave form modeling Ideally suited for operational planning, can be adapted for crisis response with sufficient lead time (minimum of 3 weeks) Has applicability to a wide variety of amphibious operations, from ship-to-shore operations for landing craft to other logistics over the shore craft. Only limit is vessel model availability.

28 Conclusions Each pilot is different (training received, apprenticeship, years experience, comfort level, etc). Computer will respond the same way to the same set of conditions Interaction between mariners, design engineers, and simulation engineers Design modifications/improvements for safety, efficiency and cost savings Significantly improved amphibious operational guidelines which improve mission success and safety

29 Questions?