The objective of this experimental study is to characterize the flow behaviours and to estimate the coefficients of head loss (F ) and heat loss (ΔQ ) when the fire products flow were divided at the branching part in the T-shaped full scale corridor.
The wood crib pile as a model fire source was set at 4m apart from the closed end of the main corridor. The vertical (Y-axis) profiles of velocity (V ), temperature (T ), optical smoke density (C_s ) and gas concentration (C_g ), were measured along the corridor (X-axis). The ignition system, measuring system of aforesaid quantities were the same as the ones in the previous report.¹⁾
Following results were obtained;
(1) Main flow from the starting line to branching part (expressed suffix i =1) was divided into two flows, i.e. maintained flow (i =2) and branched flow (i =3) at the branching part. The ratio of the flow thickness (δ_vi ) and width (B_i ), δ_vi /B_i ≈0.1«1 were estimated and so those value implied that the flow can be taken as a shallow flow. δ_v1 ≅δ_v2 ≅0.3m and δ_v3 ≅0.2m were observed, and the ratio of δ_v3 /δ_v1 ≅0.7 was observed as independent of time.
(2) Rankin's and Taylor's relations were also estimated tobe equally conserved in both corridor as V_avi /√θ_i ·δ_vi ≈0.14 and as V_i /Q_i^1/3 ≅0.2 independent of time.
(3) As for the flow in the early stage of the penetration, its Reynolds number Re is less than 3000, Richardson number R_i ≈0 and Archimedes number A_r ≈1. This means that in the estuary stage the situation of the penetrated flow is critical with large C_f , very unstable free surface and considerable heat loss. However, when the flow is developed, Re exceeds 3000, R_i > 0 and A_r > 1.
(4) The estimation on the head loss (F ) and heat loss (ΔQ ) of branching have been pursued on the basis of Bernoulli's equation and the heat balance. The attenuation coefficient Ω and χ for the head loss and heat loss can beexpressed by equation (1)
Ω = F⁄ 1⁄2V_av ²·(1+A_r ) ≡ K_v· L_v ⁄δ_v ,   χ = ΔQ ⁄ρ·C_p·T_av·V_av ≡ K_T ·L_T ⁄δ_v ,     (1)
where L_v and L_T are the equivalent length for the head loss and heat loss regarding the penetrated flow.

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Upward flame spread over paper in an air stream flowing vertically downward has been studied. The experiments were conducted in a vertical duct of 10 cm × 10 cm cross section and 22 cm long, which was placed underneath a converging nozzle of a wind tunnel. The paper used for the experiments was a sheet of filter paper of 10 cm × 23 cm surface area and 0.026 cm thick.
Following detailed observations of the behavior of flame spread, the effects of the air stream on gas-temperature profiles near the preheat zone and streams passing through the preheat zone were examined using particle tracer techniques, fine-wire thermocouples, and schlieren photography.
Three different types of flame spread were observed. In Region I, representing the range of air-stream velocities from 0 to 85 cm/sec, flame spread was accelerative, although the acceleration decreased with the increase of the air-stream velocity. In Region II, representing the range of air-stream velocities from 85 cm/sec to 125 cm/sec, local flame spread rate fluctuated greatly, and flame spread had intermediate characteristics between those of accelerative flame spread and steady flame spread. In Region III, representing the range of air-stream velocities from 125 cm/sec to 190 cm/sec, the behavior of flame spread was almost steady and resembled that of downward flame spread.
In Region I, the unburned material far preceding the pyrolysis front was preheated by a hot gas stream. In Region II, the unburned material preceding the pyrolysis front was preheated periodically. In this case, the heat transfer from one side of the paper was different from that from the other side. In Region III, the preheating of the unburned material was confined in a narrow region ahead of the pyrolysis front.
The most noticeable difference between the flow fields near the leading edges of spreading flames observed in Region I and Region III was the difference of gas-stream directions. In Region I, the gas near the leading flame edge flowed upward, while in Region III it flowed downward. In Region II, it flowed upward and downward alternately.
It was inferred that the flame spread phenomena in different directions resembled each other if the external air streams canceled the difference of the buoyancy effects caused by the density difference between the gas near the flame front and ambient air and caused similar flow fields near the leading flame edges.
The difference of the momentums of the external air streams for the cases when similar stable flames spread vertically upward and downward was estimated to be about 0.2 kg · sec/(m² · sec).

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This paper deals with the experimental studies on the effect of the ambient condition (the air and CO₂ atmosphere) upon oxidizing behaviour of wooden boards heated continuously for 600 hours and the experimental results are analyzed by means of statistics.
As a heating source of the wooden boards an electric pipe heater, 1500 mm in length and 25.5 mm in outside diameter, was used. Two wooden boards, each 100 mm × 100 mm × 25 mm, were penetrated by the electric pipe heater and covered by vinyl chloride sheet. Air was sent to one of the wooden boards and carbon dioxide was sent to the other, and both were heated by an electric pipe heater kept automatically at a constant temperature of 150 °C. Five pairs of wooden boards were similarly examined.
The results are summarized as follows;
(1) The temperatures of wooden board in the carbon dioxide atmosphere, at the point of 0 mm and 5 mm from the surface of the electric pipe heater, are not different from the temperatures in the air.
(2) The temperature rise of wooden board is not so much influenced by the heat of oxidization in case of heating wooden board at 150 °C.
(3) The temperature of wooden board decreases slowly with the elapse of time and this effect is the more conspicuous as the measuring point is nearer to the heat source.

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