Containment

WP11 looks to eliminate significant containment weaknesses, considering smoke, fire and heat integrity. This will be done through new guidelines etc.

WP11

Containment

Imagine the scenario that a fire ignites in a narrow ro-ro space packed with valuable goods and vehicles. The attempts to detect in time and extinguish failed and now we are facing a full-scale fire. To prevent this fire from spreading to the entire ship, leading to devastating damage as a result, we must stop it. Contain it and perhaps supress it. This containment is the assignment of Work Package number 11.

The WP11 team have the following objectives on the agenda:
Eliminate significant containment weaknesses, considering smoke, fire and heat integrity.

1: Develop and demonstrate artificial and new means for fire integrity sub-division of ro-ro spaces.

2: Develop solutions and recommendations to ensure safe evacuation (in line with purpose of SRtP) and when evacuating at foreign port.

3:Develop ro-ro space openings design guidelines by assessment of the risks of smoke and heat transfer from ro-ro space openings to life-saving appliances, adjacent areas and ventilation inlets.

4: Determine the effects of natural and mechanical ventilation on fire development and evaluate current possibilities and new measures for smoke containment.

The LASH FIRE project examines fire safety from several perspectives. The various RD&D work packages focus on different research topics on how to prevent a fire to ignite, how to early detect and effectively extinguish a fire in order to avoid a scenario with devastating consequences. But if this work has failed and the fire still becomes a fact, or simply in order to help the firefigting step, we need solutions to contain flames, heat and smoke in smart and effective way and, very important, preventing it from spreading to other areas.

The problem today is that when a significant fire is confirmed it might be too late. 15 minutes seams to be the golden limit people in the business is referring to. If it takes more than 15 minutes from observation to extinguishment, the outcome often is severe. But if we now face such a scenario, how can we handle it making consequences are as small as possible?

Different methods of containment and related effects

Fire resistant walls
One way is to improve the walls in the ship, between ro-ro spaces for example, making them more resistant to heat. If they can contain fire (for at least 60 minutes for example) the propagation of fire and smoke would be reduced. This can be obtained by improving the ability for the wall to contain heat in a three-steps study : defining the true heat load to the wall for a realistic fire, improving our understanding of the heat transfer through a multi-component wall, and optimising the right wall design that warrant this 60 minutes protection. This is done through numerical simulations completed by lab tests.

Shielding curtains
In many other applications (tunnels, buildings,…), sort of curtains are effectively used to contain fire and stop the spreading of fire, smoke, and radiation. This method is now investigated and tested for ro-ro spaces by the WP11 team. Two different kinds of curtains are being tested: water curtains and solid curtains, both with their pros and cons.

A reduced scale mock-up has been constructed in one of the labs, simulating a ro-ro space. The team is now in the process of evaluating the solutions and the effects of both curtains. A pool fire is used to generate smoke and fire, checking whether or not curtains can stop their spread. The main objective is to make sure that the fire does not spread to the whole ro-ro space. The second objective is to take care of the smoke that takes new routes due to the curtains.

Simultaneous strategy for escape and evacuation
These technical solutions aimed at protecting the ship and prevent from fire spread should have positive effect on people escape, which must be ensured for a Safe Return to Port (SRtP) even if the fire becomes dramatic. In addition, in case of a return to a foreign port, solutions have to be found for the desembarkment. Egress simulations are conducted to investigate this topic.

Role of the openings and ventilation
This study on possible containment methods has to be connected to the role of openings that are present along the ro-ro space sides. This has been considered through numerical simulations taking account of the wind influence on the smoke flow. These openings must be designed to avoid any smoke exhaust near the Life Saving Appliances (LSA) used as safety areas for crew members and passengers. The ventilation, either natural or mechanical, is also accounted for since the strategy to extract the smoke has to be thought bearing in mind combined effects with containment and firefighting.

Mock-up test in reduced scale of a fire in a ro-ro space with blocs featuring the trailers.

Results
The curtains seam to effectively block the fire and prevent spreading to other areas. Water curtains tends to push the smoke down to the ground. This so-called de-stratification may penalize visibility for firefighters and cause damage on goods or vehicles. Air drag by the spray application may also have unexpected effects on the fire growth by feeding it with oxygen. Solid curtains seem to be able to contain the fire without such negative counterpart, provided they can resist to the fire load. One key point is that the smoke which is blocked within the ro-ro space finds a way out through the openings. This means that a second look needs to be paid to the location of these openings, ensuring that LSA are not impacted by the smoke. Another angle that is now investigated is the ability to close these openings to avoid the smoke exhaust and suffocate the fire by cutting off the oxygen supply to the flames. This is also a recommendation deduced from simulations of fire spread conducted on the whole ship.

Finally, the team must consider the end user, in this case the ship operators that needs to implement the solution. Curtains need a dedicated free space in the ro-ro space. WP11 has to work closely to WP05 who represent the operators, whose first interest is to fill the space with as much cargo as possible. Therefore, new ideas of curtain implementation must be investigated further. A technical solution has also to be found for the closure of the openings if this strategy is retained. Finally second walk-off abandonment solutions are currently investigated for an evacuation after return to port.


Effects of the work in WP11

The most important outcome from WP11 is that they will help people saving their ships with this new containment methods. The difference between a well-functioning containment system could change the whole game. Supplementary benefits are expected on a better understanding of fire spread onboard, or people egress in various conditions. The team also hope that their research can bring light to other applications as well. As an example, the ro-ro space have more or less the same characteristics as a tunnel, meaning if it works in a ro-ro space it might also be applicable in those applications.

 

Current status, May 2021

Action 11-A Division of ro-ro spaces
A lot of simulations in different situations has been conducted. Dimensions (complex geometry) and high heat release rates are difficult to deal with, especially when it comes to a real scale ro-ro space or even a whole ship. Fine description of the fire spread requires several millions of cells and high computational costs. More than hundred experiments were conducted in parallel on a reduced-scale set-up that provide a deep understanding of the curtain effects when used for containment.

Action 11-B Ensuring safe evacuation
A bit late due to corona and to the difficulty to make the simulation on the whole ship, coupling fire spread with evacuation simulations. But escape phase is solved and work on the fire integrity status is in progress. University of Lorraine and RS2N (France) are working hard to tackle the computational difficulties.

Action 11-C Safe design with ro-ro space openings
VTT (in Finland), carried out a lot of simulations in various conditions of wind and fire scenarios. Their impressive work led to the prediction of safety distances between openings and LSA. They are now entering the second test and a large-scale test will soon be conducted together with RISE. The team are also helping WP05 to find practical solutions on how to close some of the openings if possible.

Action 11-D Ro-ro space ventilation and smoke extraction
This action started in March. If you start to close the openings or if you design curtains for ro-ro space subdivision, you need to be sure that the ventilation is working optimal to exhaust the smoke. This will be a challenge for the group involved in this task in RISE

Numerical simulation of smoke propagation from ro-ro space to LSA.

WP Leader Pascal Boulet giving a short presentation about the LASH FIRE project.

Smoke propagation within a ro-ro space with spray activation sequences to study the containment ability of a water curtain.

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