G. W. Zou

Evaluation of the Field Model, Fire Dynamics Simulator, for a Specific Experimental Scenario

The new version of the fire dynamics simulator, FDS version 3.01, is verified by a series of full-scale fire tests. Experiments are carried out in a compartment similar in size to the ISO-9705 room calorimeter. Gasoline pool fires of different diameters are used to give different heat release rates. The ventilation factors of the compartment are adjusted to produce flashover. Fire-induced flow, temperature, and pressure fields in these different physical scenarios are calculated using the FDS software. The predictions for temperature and radiative heat flux of a post-flashover fire in the specific configuration tested are in reasonably good agreement with experimental results even when the flame occupies most of the room volume.

Experimental Studies on Minimum Heat Release Rates for Flashover with Oxygen Consumption Calorimetry

Studies on minimum beat release rates for flashover in a compartment fire will be reported in this paper. Experiments were carried out in a chamber with dimensions similar to that in the standard ISO9705 Room-Corner Fire test. This chamber is located inside a new full-scale burning facility, the PolyU/HEU Assembly Calorimeter, at the remote areas of Northern China. This is a joint project between Department of Building Services Engineering, The Hong Kong Polytechnic University (PolyU) and the Harbin Engineering University (HEU) in Heilongjiang, China. Heat release rates were measured by the oxygen consumption method. Correlation equations on estimating the minimum heat release rates for flashover will be reviewed and compared with the experimental results. Results are useful in fire hazard assessment while implementing engineering performance-based codes.

Will Water Mist Extinguish a Liquid Fire Rapidly

Local professionals are quite worrying about whether a water mist fire suppression system (WMFSS) can extinguish afire rapidly. It was also suggested in the literature that discharging water mist, even under the design operating conditions, might not always control afire rapidly. To explore more on that, a series of experiments on discharging water mist from low/moderate-pressure system on gasoline fires were carried out at the new full-scale burning facility, Poly U/USTC Assembly Calorimeter at Lanxi, Harbin, Heilongjiang China. An interesting point identified for quick communication is that for some designs of fuel container, the liquid fire cannot be extinguished even when all the fuels were consumed.

Effects of varying Smagorinsky constant on simulating post-flashover fires

Air flow post-flashover room fire is weakly compressible. In this paper, Navier–Stokes equations in an appropriate form will be applied to simulate such motion. Large eddy simulation (LES) is used with the Smagorinsky sub-grid scale model. A pool fire was described by the combustion model based on simple and fast chemical reaction. Three-dimensional simulations were carried out by using different values of Smagorinsky sub-grid scale constant. Predicted results on air temperatures and radiative heat fluxes were compared with the experimental values. Results illustrated that the value of the Smagorinsky constant would affect the simulations for strong buoyant plume. Value of the Smagorinsky constant from 0.20 to 0.21 appears to be reasonable in simulating flashover with a filter width of 0.1 m.

Generation of an internal fire whirl in an open roof vertical shaft model with a single corner gap

An internal fire whirl can be generated by burning a pool fire in a vertical shaft with appropriate sidewall ventilation provision. Earlier experimental results show that the flame swirling motion depends on the corner gap width providing ventilation. In this article, experiments on generating an internal fire whirl in a 9 m tall vertical shaft model will be reported. Flame shapes in burning a gasoline pool fire inside the shaft model with different corner wall gap widths and tray diameters were observed. Fuel mass of the pool fire, flame height of the internal fire whirl, and transient air temperatures were measured. From the results, it is further confirmed that an internal fire whirl cannot be generated when the gap width is too wide or too narrow. An internal fire whirl is developed in five stages. The pool fire is burning in a way similar to burning in open air at stage I. The burning rate of pool fire increases at stage II. Swirling flame motion starts to develop at stage III. An internal fire whirl develops fully at stage IV. Stage V is the decay stage. Furthermore, the created internal fire whirl can be divided into three zones. Zone I is at the lower part with the flame rotating violently. Zone II is in the middle part with a slower swirling rate. The upper part zone III has no flame rotation.

Atrium hot smoke tests in a big shopping complex

Hot smoke tests were carried out in the site of four atriums of heights over 32 m in a big shopping complex. The objective was to evaluate the performance of the mechanical smoke exhaust systems installed. This is required while inspecting the fire service installations as specified in the local codes. Testing procedures followed those in Australian Standard with slight modifications. A 2 MW methanol pool fire was agreed in the tests. It was set up with six trays in a test chamber for reducing the radiation effect to adjacent combustibles. The main testing criterion is to demonstrate that the smoke layer can be kept above 8 m upon operating the smoke exhaust system. Other testing criteria listed in the code such as that on roof air temperature were also assessed. Elevation of the smoke layer interface was observed visually through indication marks placed at height 8 m above the floor. Vertical temperature profile was also measured by a thermocouple tree placed a distance away from the fire source. Results of the hot smoke tests confirmed that operating the mechanical smoke exhaust system installed in the four atriums would keep space below 8 m free of smoke. Language: en

Assessment of fire hazard in timber karaoke music boxes with real-scale burning tests

Karaokes are very popular places for entertainment in the Far East. Special features are having small karaoke music boxes and narrow corridors partitioned by timber products. Consequent to an arson fire in a karaoke in Hong Kong, the general public is quite concerned about fire safety in karaokes. There had been numerous studies on assessing the fire hazard through fire models, evacuation, and fire safety management; however, there are not yet real-scale burning tests on karaoke fire. A karaoke arrangement with three boxes and a corridor was set up by chipboards at a remote site in China. Two sets of real burning tests on these small karaoke boxes were carried out for studying flame spreading under flashover fires. Chipboards with and without treatment of fire retardant were compared. The heat release rate, upper layer gas temperature, surface temperature of materials, heat flux imposed to the floor, and the temperature profile at the doorway were measured. Results showed that the selected fire retardant passing a bench-scale test on surface spread of flame might not provide sufficient protection to the chipboard partitions in the real-scale arson fire. The heat given out and the burnt areas of the partitions were comparative to the untreated chipboard. Language: en

Preliminary full-scale burning tests of electric cables

Full-scale burning tests on PVC electric cables at post-flashover stage were carried out. Real-scale room fires were considered and the heat release rates were measured. The results on the total heat release were compared with those measured from a cone calorimeter with different heat fluxes. Language: en

Some Experimental Results on Internal Fire Whirls in a Vertical Shaft

Earlier studies on burning a pool fire in a vertical shaft model indicated that appropriate sidewall ventilation provision is a key factor for the onset of an internal fire whirl. Experiments on burning a pool fire inside a real-scale shaft model of 9 m tall were performed to further investigate the swirling motion. The full-scale modeling burning tests were carried out at a remote site in China. Four different ventilation openings were arranged. Results of onsetting of internal fire whirls for the four tests will be reported.Copyright