Hydrodynamic Model Testing
Resistance & propulsion testing
Resistance and propulsion testing provides information about the resistance of the ship hullform at a range of speeds, the power requirements and can include understanding the nominal wake of the ship. Propulsion tests are required to specify the propeller design for the ship. QinetiQ has also a range of tests to help with appendage alignment such as streamline tests. Used in conjunction with numerical (computational) analysis they can improve the total propulsive efficiency of the vessel by aligning particular components like appendages, rudders and ducts with the flow to minimise hydrodynamic drag.
We conduct these tests in our 270m long Towing Tank. Testing in a large tank such as QinetiQ’s allows large models to be tested without wall effects, meaning highly accurate results are obtained.
Resistance and propulsion tests are required as part of the set of model tests conducted to demonstrate compliance with the IMO EEDI legislation. Further information on the tests required for EEDI certification can be found here.
Seakeeping & manoeuvring testing
Seakeeping and manoeuvring tests enable an understanding of the performance of a vessel in the environment and role in which it will be utilised. We use free running models in our large Ocean Basin to produce the key indicators for seakeeping performance including Response Amplitude Operators, Motion Induced Interruptions and Motion Sickness Incidence. Our wavemakers can produce long or short crested irregular seas and our large basin size allows us to test the response of the vessel to waves from any angle.
Our autopilot control systems not only control the speed and heading of the vessel, but can also control stabilising fins, hence we are able to report on the likely effectiveness of these devices in damping the roll motion of the vessel. For manoeuvring performance our tests report against the requirements of IMO manoeuvring criteria (MSC 137(76)), or against role-specific manoeuvring requirements.
Our large basin means we can test large or high speed models.
We also investigate seakeeping and manoeuvring performance using computational simulations on our high performance computing cluster.
Alongside our propeller design and analysis capability, we use our ship tank and cavitation tunnel to assess propeller designs and their interaction with the proposed vessel hullform.
Cavitation Tunnels replicate the conditions which a full scale propeller would operate by changing the pressure within the tunnel. A suite of instrumentation and photographic techniques are used to capture the data for the propeller tested.
The Cavitation Tunnel is also routinely used for more unconventional tests, such as hull coating analysis, testing small boat propellers and investigating the flow induced vibration of cables.
The IMO Energy Efficiency Design Index legislation requires for all new ships demonstration of compliance at the design stage. This demonstration is required through calculation of the EEDI and verification of this through model testing. QinetiQ are able to conduct the required calculations, and/or model testing. EEDI testing comprises resistance, propulsion and propeller open water tests as necessary to characterise the ship and propeller.
QinetiQ’s test report provides the required speed power curves for the EEDI and sea trial loading conditions.
IMO allow CFD analysis to be submitted as evidence for modifications to classes of ships, for example, the addition of a bulbous bow or energy efficiency device, where the baseline class has already been model tested. QinetiQ is also able to provide this CFD analysis using Star CCM+ on our large computing cluster.