Numerical simulation of air flow in short metro ventilation shafts caused by a piston effect

Protecting the infrastructure of the metro from unauthorized actions with the help of ventilation openings of the systems is one of the main security problems of this type of transport. This article discusses the problem of the dynamics of distribution of the mass flow rate of ventilation air in a two-component system “tunnel vertical ventilation shaft”, due to the piston effect of a moving train. The dependence of the mass flow rate of ventilation air passing in both directions in short ventilation shafts (up to 10 m), on the speed, location of the rolling stock and cross-sectional area of the ventilation shaft is investigated. It is shown, that at speeds of 10–20 m / s of rolling stock and sections of the ventilation shaft of more than 4 m2, the mass flow rate of air passing through the ventilation shaft must be taken into account with the mass flow rate of ventilation air in the transport tunnel for assessing the safety of the harmful aerosols. These processes can have a significant impact on the air quality of the underground infrastructure of the metro.

Study of the Fire Service Training Environment: Safety, Fidelity, and Exposure -- Acquired Structures

Previous FSRI led research projects have focused on examining the fire environment with regards to current building construction methods, synthetic fuel loading, and best-practices in firefighting strategies and tactics. More than 50 experiments have been previously conducted utilizing furniture to produce vent-limited fire conditions, replicating the residential fire environment, and studying the methods of horizontal ventilation, vertical ventilation, and positive pressure attack. Tactical considerations generated from the research are intended to provide fire departments with information to evaluate their standard operating procedures and make improvements, if necessary, to increase the safety and effectiveness of firefighting crews. Unfortunately, there still exists a long standing disconnect between live-fire training and the fireground as evident by continued line of duty injury and death investigations that point directly to a lack of realistic yet safe training, which highlights a continued misunderstanding of fire dynamics within structures. The main objective of the Study of the Fire Service Training Environment: Safety, Fidelity, and Exposure is to evaluate training methods and fuel packages in several different structures commonly used across the fire service to provide and highlight considerations to increase both safety and fidelity. This report is focused on the evaluation of live-fire training in acquired structures. A full scale structure was constructed using a similar floor plan as in the research projects for horizontal ventilation, vertical ventilation, and positive pressure attack to provide a comparison between the modern fire environment and the training ground. The structure was instrumented which allowed for the quantification of fire behavior, the impact of various ventilation tactics, and provided the ability to directly compare these experiments with the previous research. Twelve full scale fire experiments were conducted within the test structure using two common training fuel packages: 1) pallets, and 2) pallets and oriented strand board (OSB). To compare the training fuels to modern furnishings, the experiments conducted were designed to replicate both fire and ventilation location as well as event timing to the previous research. Horizontal ventilation, vertical ventilation, and positive pressure attack methods were tested, examining the proximity of the vent location to the fire (near vs. far). Each ventilation configuration in this series was tested twice with one of the two training fuel loads. The quantification of the differences between modern furnishings and wood-based training fuel loads and the impact of different ventilation tactics is documented through a detailed comparison to the tactical fireground considerations from the previous research studies. The experiments were compared to identify how the type of fuel used in acquired structures impacts the safety and fidelity of live-fire training. The comparisons in this report characterized initial fire growth, the propensity for the fire to become ventilation limited, the fires response to ventilation, and peak thermal exposure to students and instructors. Comparisons examined components of both functional and physical fidelity. Video footage was used to assess the visual cues, a component of the fire environment that is often difficult to replicate in training due to fuel load restrictions. The thermal environment within the structure was compared between fuel packages with regards to the potential tenability for both students and instructors.

ANALYSIS OF RESILIENT DESIGN BY THERMOACOUSTIC ADAPTATION OF TROPICAL URBAN MODEL

Climate and urban environment changes lead to tropical building adaptation and resilient strategy. They focus especially on thermal comfort and noise propagation variation as the result of global warming and urban growth. This study analyzes a conceptual design of tropical urban model on integrated design of thermal and acoustic (thermoacoustic) issues. By experimental measurement and simulation method using Computational Fluid Dynamics, the findings are directed to meet the standards and to recommend the new guidelines for sustainable urban building. The research location is in Surabaya as the urban tropical lowland area and Eco-House of ITS, a tropical building model in an urban environment, was built as experiment model. The results highlighted that the noise barrier should consider 5.24% of the maximum window to wall ratio (WWR) in tree dimensionally analysis, horizontally and vertically. Providing vertical ventilation is the best solution for urban density, but the orientation and its flanking noise affect the passive cooling. In general, there are some factors having a high contribution in addition to WWR, such as wind acceleration, the distance, and building material.

Natural Convection of Air through an Asymmetrically Heated Vertical Channel with a Baffle

The buoyancy-induced air flow through a two-dimensional vertical ventilation channel is calculated. One of the channel walls is heated uniformly, and the other wall is adiabatic. A thin baffle is placed on the heated wall to manipulate the air flow through the channel. Numerical results are obtained for baffles of different lengths and placed at various heights along the heated wall. It is found that the baffle is effective in weakening a reverse flow at the exit of the channel, and significant enhancement of ventilation performance may be achieved with the presence of the baffle.