Takeyoshi Tanaka

Doorway flow induced by a propane fire

A series of full-scale steady-state experiments was conducted to study the high temperature fire-induced flows through doorway openings connecting a burn room to a second room containing a hot gas layer. A propane diffusion burner served as the energy source. Fire strength and doorway width were varied. Measurements included two-dimensional velocity and temperature profiles within the opening and vertical gas temperature profiles within the rooms. Opening mass flows were determined from the opening data. These mass flows are explained in terms of a static pressure model based on actual gas temperature profiles in the two rooms and an orifice coefficient of 0.68. It is also shown that the simple relationship between mass flow rate through the opening, Ma, and ventilation parameter, WH32 (W, opening width; H, opening height) holds even when the opening is in the wall between two rooms. The proportionality constant for this simple relationship may depend on the configuration.

Transport Of Disk-shaped Firebrands In A Turbulent Boundary Layer

A transport model for a disk-shaped firebrand in 3D space has been formulated for the purpose of spotting simulation. In the model, firebrand transport is described by solving the conservation equations of momentum and angular-momentum, simultaneously. The airborne firebrand receives the aerodynamic forces and moment from the surrounding fluid, which varies in time and space due to the change in its location and orientation. An approximate form of the Navier-Stokes equations appropriate for low-Mach number flow was applied for the fluid motion. LES (Large Eddy Simulation) on buoyant flow downstream of a square heat source was carried out, and transport behaviors of various firebrands were investigated. Then, a scaling dimensionless parameter * B for the transport was derived. Numerically obtained mean travel distance to the windward direction, as well as its s.d. (standard deviation), were correlated with * B with reasonable accuracy.

Full Scale Experiments For Determining The Burning Conditions To Be Applied To Toxicity Tests

A series of full scale steady state fire experiments were conducted with a propane burner as the fire source in an attempt to determine the thermal and atmospheric conditions to which building materials are likely to be subjected in the event of a building fire. As a result of the experiments, a close coupling was revealed between the temperature elevation and the oxygen depletion in the room of origin. Based on this finding and the results of other experiments with a crib fire source, some thoughts are presented on the burning conditions to be applied to toxicity test apparatus.

A Physically-Based Model for Urban Fire Spread

An attempt is made to develop a physically-based model for simulating urban fire spread. In the model, urban fire is regarded as an ensemble of multiple building fires. The model consists of two sub-models, i.e. the model to predict the building fire behavior under the exposure of heating from other building fires and the model to predict the thermal environment caused by building fires. The building fire model is based on single zone method, applying control volumes to compartments in a building. When the external heating, whether it is from the same building or from other buildings, exceeds the critical heat flux, the fire load in the compartment ignites and burns. For the thermal environment model, thermal radiation and fire-induced plume are considered as the factors of building-to-building fire spread. The model is applied to a fictitious urban district where 49 multi-room buildings are arrayed in a simple configuration.

Risk-Based Selection of Design Fires to Ensure an Acceptable Level of Evacuation Safety

In a performance-based (P-B) fire safety design, the level of fire safety of a building achieved by the design depends upon the design fire scenarios and acceptable safety criteria used. In other words, their essential role is to keep the fire risk of a building below an acceptable level. However, the relationship of the design fire with the acceptable fire risk is not clearly recognized, which often causes fire performance gaps between a P-B fire safety design and the existing building fire code. It is thought to be vital for a P-B fire safety design method to incorporate fire risk concepts for its sound development. In this paper, consideration for determining acceptable fire risk in the context of fire safety design is made and a methodology for selecting such a design fire as to ensure the risk of evacuation in fire be under the acceptable level is proposed.

A Multi-layer Zone Model For Predicting Fire Behavior In A Single Room

A multi-layer zone fire model for a single compartment was developed to predict the vertical distributions of the temperature and the gas concentrations. The basic concept of this model is to divide the fire room volume into an arbitrary number of horizontal layers, in which the temperature and other physical properties are assumed to be uniform. Considering the mass and the enthalpy flow rates through the layer interfaces and the opening and the heat transfer rates for each layer, the zone equations for the temperature and the species mass fractions are derived. The results of the sample calculations are compared with the experiments conducted by Steckler et al. From the comparison, it is considered that the model can be a practical tool to predict the behavior of fire in a room, although continuing effort may be necessary to improve the prediction.

Integration of Fire Risk Concept into Performance-Based Evacuation Safety Design of Buildings

The integration of the fire risk concept in performance-based fire safety design of buildings is beneficial in many aspects of fire safety. In this paper, a Risk-Based Evacuation Safety Design Method is proposed for rational evacuation safety design as an important area of fire safety design. While the goal of this method is to control the evacuation risk in fire within an acceptable level, the evacuation safety verification in this method can be conducted according to the deterministic procedure in usual performance-based fire safety design. The particular advantage of this method is that design fires and scenarios in the performance-based design of a building are identified in a systematic manner. The practicability of this method in performance-based designs of actual buildings is demonstrated by case studies for realistic buildings.

Statistical Estimations of the Distribution of Fire Growth Factor - Study on Risk-Based Evacuation Safety Design Method

YOSHIKAZU DEGUCHI, HIROAKI NOTAKE, JUN’ICHI YAMAGUCHI, and TAKEYOSHI TANAKA Research & Development Institute Takenaka Corporation 1-5-1 Ohtsuka, Inzai-city, Chiba, 270-1395, Japan Institute of Technology Shimizu Corporation 3-4-17 Etchujima, Koto-ku, Tokyo, 135-8530, Japan Technical Research Institute Obayashi Corporation 4-640, Shimokiyoto, Kiyose-city, Tokyo, 204-8558, Japan Disaster Prevention Research Institute Kyoto University Gokasyo, Uji, Kyoto, 611-0011, Japan

Experimental investigation into penetration of a weak fire plume into a hot upper layer

A hot upper layer pre-established under the ceiling of a room in a house due to a solar load in the summer or room heating in the winter may cause problems for fire detection by ceiling-mounted smoke detectors. A weak plume from a smoldering fire may be pushed back down by the hot layer, and be unable to reach a ceiling-mounted detector. In this study, based on the physics of plume penetration into a hot upper layer, a model for the penetration height was developed as a function of the distance of an upper layer from a fire source and the temperatures of the upper layer and the plume axis. A series of experiments were conducted to validate the model and determine the value of the coefficient involved in the model. Also measurements were made of the heat of combustion of smoldering fire of Test Fire 3 (TF3) prescribed in ISO/TC21/SC3 N301(Draft) using a cone calorimeter to see if a well-established formula for plume temperature is still usable for predicting penetration of a weak plume. Based on these results, it was confirmed that plume penetration height can be estimated even if the plume originates from a small heat source such as smoldering fire.

International Comparison of Fire Safety Provisions for Means of Escape

In this study, the provisions for means of escape in the regulations of several countries are investigated. The provisions for the number, the arrangement and the capacity of means of escape are compared among countries. Then the concept and the engineering basis of these provisions are discussed for developing performance based standards.