The paper described a newly developed high performance compressed air foam system(CAFS). The effective system generates uniform foam w ith greater momentum by injecting compressed air into flowing foam solution. Foa ...The paper described a newly developed high performance compressed air foam system(CAFS). The effective system generates uniform foam w ith greater momentum by injecting compressed air into flowing foam solution. Foa m generated by this system presented superior viscous and wetting properties to water.A pendulum system was designed to measure yield stress of foam. The results pro ved the existence of yield stress of foam. And the increasing tendency of yield stress with gas fraction and bubble size has also been found out.展开更多
In the study a fire and fire environment model is set up and by using PHEONICS software 3 cases of surface fires are studied. The results fit the experimental studies well generally. The simulation reveals that (1) Th...In the study a fire and fire environment model is set up and by using PHEONICS software 3 cases of surface fires are studied. The results fit the experimental studies well generally. The simulation reveals that (1) The wind speed fields in front of fire front generally can be divided into 3 zones and there is always an eddy immediately at the corner between just in front of the fire and the ground. (2) The shape and dimension of the division of the 3 zones is mainly decided by slope angle and ambient wind speed given fire line intensity. (3) There exits an upwind zone in front of fire front. Ambient wind speeds have little effect on the magnitude of the upwind speed when slope angle is 0. But when the slope angle is negative, the upwind is apparently stronger.展开更多
In order to study the convection limits of surface fires and interactions between backfires and main fires,several experiments are conducted in a large space indoor laboratory: in which the effects of ambient wind spe...In order to study the convection limits of surface fires and interactions between backfires and main fires,several experiments are conducted in a large space indoor laboratory: in which the effects of ambient wind speeds and changing temperatures can be avoided.The research shows that:(1) there is a convection field in front of coming fires in which the wind speed direction is toward the fire.In the convection area,the lower part has higher wind speed and when the height is taller than a certain value the convection wind speed is not significant;(2) the backfire and the main fire interact with each other even though they are far apart.When they come near each other to a certain distance,they begin to draw each other.This increases their rates of spread toward each other significantly.For surface fires with a fire line intensity of 160?kW\5m -1 ,their rate of spread increases by 27%.展开更多
文摘The paper described a newly developed high performance compressed air foam system(CAFS). The effective system generates uniform foam w ith greater momentum by injecting compressed air into flowing foam solution. Foa m generated by this system presented superior viscous and wetting properties to water.A pendulum system was designed to measure yield stress of foam. The results pro ved the existence of yield stress of foam. And the increasing tendency of yield stress with gas fraction and bubble size has also been found out.
基金TheresearchissupportedbyFoundationforDoctoralStudiesofMinistryofEducation (No .19980 0 2 2 0 6 )
文摘In the study a fire and fire environment model is set up and by using PHEONICS software 3 cases of surface fires are studied. The results fit the experimental studies well generally. The simulation reveals that (1) The wind speed fields in front of fire front generally can be divided into 3 zones and there is always an eddy immediately at the corner between just in front of the fire and the ground. (2) The shape and dimension of the division of the 3 zones is mainly decided by slope angle and ambient wind speed given fire line intensity. (3) There exits an upwind zone in front of fire front. Ambient wind speeds have little effect on the magnitude of the upwind speed when slope angle is 0. But when the slope angle is negative, the upwind is apparently stronger.
文摘In order to study the convection limits of surface fires and interactions between backfires and main fires,several experiments are conducted in a large space indoor laboratory: in which the effects of ambient wind speeds and changing temperatures can be avoided.The research shows that:(1) there is a convection field in front of coming fires in which the wind speed direction is toward the fire.In the convection area,the lower part has higher wind speed and when the height is taller than a certain value the convection wind speed is not significant;(2) the backfire and the main fire interact with each other even though they are far apart.When they come near each other to a certain distance,they begin to draw each other.This increases their rates of spread toward each other significantly.For surface fires with a fire line intensity of 160?kW\5m -1 ,their rate of spread increases by 27%.
