Conclusiones Parciales

The objectives of this thesis are addressed by providing a platform that promotes shared understanding, transfer of knowledge and expertise advancing the development of Subway Climatology. Of extreme importance is the presentation of information in a format that can be understood by non-experts as it is the subway system operatives that will have to make operational decisions in the event of an incident. It is important then that any information that is produced in this research is presented in a comprehensible format that will allow quick and accurate responses to be made. This is a natural extension of the OrgGaMIR (Pflitsch, 2010) project that showed the existence of the variable back ground air flow in a subway system but was not able to develop a method of enabling operatives to make decisions based on real time events. Also it could not be applied to additional stations without a great deal of extra work nor could it be used to predict the airflow in a station in real time or as a design tool for architects and station designers.

It can be appreciated from the above that this is a complicated and ambitious task. To put this into perspective the flow chart in Figure 11 has been produced to show how the different parts of this project are inter related.

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Figure 11: Research Method flow chart

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This research has been divide to three parts which are brought together to produce an integrated design tool that will be useful to the key stakeholders in station design and subway operation improving the safety of the travelling public. The first part is the experimental measurements, shown in the left hand column of Figure 11. These physical experiments include an assessment of Newcastle city weather data collected from a nearby weather station (the top item in the column), the taking of measurements inside the station and at locations just outside the station exits using portable instruments (the second item in the column) and finally a series of experiments in which a tracer gas was released in the station, in a train passing through the station and at different locations in the subway system (the third item in the column). The tracer gas experiments were done in collaboration with the Cave and Subway Research Group of the Ruhr University at Bochum who provided the equipment and technical support for the correct running of the experiments. The main outcomes from this physical experimental part of the thesis are shown in Figure 11 underneath the boxes in the column appropriate to the activity and they are used as inputs to the next phase of the work as indicated by the labels on the connecting arrows. These experimental parts of the project furnished a preliminary understanding of the air flow in and around the station and provide data for use in the CFD simulation.

The second part was the virtual model development which is shown as the middle column in Figure 11. A modelling environment was created from the Newcastle Gateshead City Model to enable a CFD model of the local microclimate in the vicinity of the station. This was intended to investigate the impact of the buildings surrounding the station on air flow strength and direction at the station exits and provide data to inform a CFD model of the station created to examine the internal airflow. The development of the CFD model is shown in the right hand column. In the absence of and computer aided drawings of the station (which will be the same for the vast majority of existing subway station elsewhere) an efficient and straightforward means of generating a model environment was required. This was achieved by laser scanning the station and converting the point cloud thus created into a three dimensional model using the package 3ds Max and then into a CFD mesh that could be used in a CFD package. These steps are shown as the yellow boxes in Figure 11. The main elements of the three columns were then brought together to create a CFD model of the station using the CFD package ANSYS-Fluent. Information from the experimental measurements provided the input data for the CFD boundary conditions and enabled

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the CFD output to be validated. An important part of this work was the creation of the CFD mesh in a quick and efficient manner and the establishment that the CFD results were not mesh sensitive. The output of this part which integrated all the aspects mentioned previously was the modelling of the air flow in the station to understand the nature of the airflow and the impact the outside climate has upon it. A sensitivity analysis was performed that established ways of controlling the airflow in the station.

Finally, a Virtual model of the station was created which formed the link between the highly technical features developed so far and the subway operators and the Fire and Rescue personnel. This is shown as the main output of this project in Figure 11 as the horizontal box at the bottom of the figure from which are emerging boxes indicating additional tasks such as pedestrian evacuation, Fire and Safety training and the development of evacuation strategies which will all be of use to the Subway operating companies, station designers and architects and the Fire and Rescue personnel.