shown in Fig.2.The sharp tip occurs at=/+1,which is the critical moment that the direction of smoke motion is changing. 107 -28r9 4 810 12 Fig.2.Rising rate of smoke temperature in an adiabatic compartment under wind effect(r0.2.=10) When y=0,the temperature rising rate firstly increases then decreases to zero at = When the rate always decreases.In the cases of the curve of the rate firstly drops to zero at =0/0+1 and then climbs,finally also dropping to zero at =o.This indicates that the ambient wind has great influence on the smoke temperature rising If the walls are not adiabatic,it can be extrapolated from Fig.2 that the sharp tip of d/dr profile will intersect with zero line possibly.Fig.3 gives two examples with different B values. V+rP0+1)+-+1o--=0 2 a12 b 10 2 10 ure I ment under wind effect (r=.2 cordingly the re is a critical va alue of ambient wind speed.N we obtain two critica wind speeds, one of wl h determines the direction of smoke motion and the other the number of the stea states of smoke temperat ntilation-controlled conditio the ormalized smoke tem nally reac h nearly 3.4 when there is no ambient wind (=0).If the ambient wind begins to blow and the speed increases very slowly so that the quasi-steady stateshown in Fig. 2. The sharp tip occurs at    / 1 , which is the critical moment that the direction of smoke motion is changing. Fig. 2. Rising rate of smoke temperature in an adiabatic compartment under wind effect (r = 0.2,  10 ) When   0, the temperature rising rate firstly increases then decreases to zero at    . When  1, the rate always decreases. In the cases of 0   1, the curve of the rate firstly drops to zero at    / 1 and then climbs, finally also dropping to zero at    . This indicates that the ambient wind has great influence on the smoke temperature rising. If the walls are not adiabatic, it can be extrapolated from Fig. 2 that the sharp tip of d / d   profile will intersect with zero line possibly. Fig. 3 gives two examples with different  values. Fig. 3. Rising rate of smoke temperature in a non-adiabatic compartment under wind effect (r =0.2,  10 ).   0.3 (a) and   0.9 (b). Accordingly, there is a critical value of ambient wind speed. Now we obtain two critical wind speeds, one of which determines the direction of smoke motion and the other the number of the steady states of smoke temperature equation. Considering a compartment fire in ventilation-controlled conditions, the normalized smoke temperature will finally reach nearly 3.4 when there is no ambient wind (  0). If the ambient wind begins to blow and the speed increases very slowly so that the quasi-steady state