【作者】 李权威；

【导师】 廖光煊； 秦俊；

【作者基本信息】 中国科学技术大学 ， 安全技术及工程， 2010， 博士

【摘要】 隧道类狭长空间建筑的日益发展在给日常生活带来便利的同时也给火灾防治带来了许多新的问题。同时,随着科技的进步,社会对狭长空间火灾的防治提出了更高的要求。细水雾灭火技术由于清洁、高效、对人员和设备安全、用水量少等诸多优点而备受青睐,并且近年来在交通隧道及电缆隧道等狭长空间中逐步得到推广应用,而狭长空间通风条件下细水雾灭火的相关研究相对滞后。为此,本文选取纵向通风这一狭长空间的典型通风方式,通过实验模拟和理论分析,就狭长空间纵向通风条件下细水雾抑制油池火的机理开展较为系统的研究。为方便实验研究工作的开展,首先建立了小尺度狭长空间模拟实验台,并对实验台的气流分布特性进行了测量校正。通过三维LDV/APV系统对静止无风条件下的细水雾雾场进行测量,并利用DPIV技术对纵向通风条件下的细水雾雾场特性进行了实验测量,基于以上实验数据对狭长空间内纵向通风对细水雾雾场的影响进行了理论分析。参考前人的工作,对现有小型燃烧风洞进行了改造,并在风洞内较为细致地开展了纵向通风条件下油池火燃烧特性的实验研究。从能量守恒的角度出发,对纵向通风条件下典型液体燃料池火的燃烧过程进行对比研究,给出了各燃料池火燃烧速率随纵向通风风速的变化规律,并对通风加速各燃料池火燃烧速率的加速效应进行了分析。在风洞内开展了不同辐射强度下酒精的蒸发速率受纵向通风风速影响的实验研究,对不同纵向通风风速条件下酒精池火的热反馈特性进行了实验测量,并在此基础上探讨纵向通风对酒精池火燃烧速率的影响机理。在无细水雾作用条件下临界纵向抑制风速预测模型的基础上,从火灾区能量守恒出发,建立了细水雾作用下临界纵向抑制风速的预测模型。在狭长空间模拟实验台上分别开展了细水雾施加前后临界纵向抑制风速的实验研究。将未施加细水雾时的测量结果与前人预测模型的预测值进行了对比,并根据测量结果对未施加时临界纵向抑制风速预测模型中的系数进行了拟合,在此基础上结合细水雾作用下临界纵向抑制风速的测量结果及纵向通风条件下细水雾雾场在烟气层内吸热的计算结果对本文细水雾作用下临界纵向抑制风速预测模型的准确性进行了验证。开展了不同位置施加细水雾时临界纵向抑制风速的实验研究,根据实验结果分析了细水雾施加位置对临界纵向抑制风速的影响,并对细水雾影响临界纵向抑制风速的机理进行了探讨。利用狭长空间模拟实验台,较为细致地开展了纵向通风条件下细水雾抑制正庚烷池火的模拟实验。通过改变油池火预燃时间、细水雾工作压力、细水雾施加位置以及纵向通风风速,研究了细水雾在不同纵向通风风速下的灭火有效性,分析了纵向通风对细水雾灭火性能的影响。结合纵向通风条件下油池周围细水雾雾场的测量结果、不同风速条件下灭火时燃油温度、火源周围烟气浓度的测量结果以及灭火过程中火焰的形态,对纵向通风条件下细水雾抑制熄灭正庚烷池火的因素进行了探讨,揭示了纵向通风条件下细水雾抑制正庚烷池火的机理。更多还原

【Abstract】 The increasing development of the buildings of long and narrow space, like tunnels, brings lots of new problems to the fire protection with the convenience brought to daily life. Meanwhile, with the development of science and technology, the higher requirement for protecting the long and narrow space from fire is put forward by society. Water mist is used widely for suppressing fires in the long and narrow space like traffic tunnels and cable tunnels, due to no pollution, high fire extinguishing effectiveness, safety to human and equipment, less water consumption, etc. However, the study on fire suppression with water mist on the condition of ventilation in long and narrow space is lagging behind. Therefore, the longitudinal ventilation, a typical ventilation mode of long and narrow space, is chosen in the paper. And the mechanism of liquid pool fire suppression with water mist on the condition of longitudinal ventilation in the long and narrow space is investigated systematically.A small-scale experimental bench of long and narrow space, whose dimension is 5.5m X 0.9m X 0.6m, was established. And the airflow distribution characteristics was measured and then corrected. The water mist field measurement was performed through three-dimensional LDV/APV system and DPIV technology on the windless and longitudinal ventilation condition, respectively. Then longitudinal ventilation’s influence on the water mist field was analyzed theoretically based on the above experimental results.Available small wind tunnel for combustion was modified, and the experimental study on the combustible characteristics of liquid pool fire on the condition of longitudinal ventilation was closely performed in the wind tunnel. According to the conservation of energy, the combustion processes of different typical liquid pool fires on the condition of longitudinal ventilation were compared and the rule of their burning rates’changes with longitudinal wind velocities was proposed and the ventilation’s acceleration effect on their burning rates was analyzed. The experimental study on longitudinal wind velocities’influence on the ethanol evaporation rates on the different conditions of radiation intensity in the wind tunnel was performed, and the experimental measurement of thermal feedback characteristics on the different conditions of ventilation velocities was carried out, and based on which, the mechanism of longitudinal wind velocities’influence on the burning rates of ethanol pool fires was discussed.Based on the model for predicting the critical ventilation velocity on the condition of no water mist and the conservation of energy in the field of fire, the critical prediction model on the condition of water mist was established. The experimental study on critical ventilation velocities with or without applying water mist in the long and narrow space was carried out. And the results without water mist was compared with the value predicted based on the previous predict models, and the coefficient in the model for predicting the critical ventilation velocity without water mist was fitted according to the measurement results. On this basis, the accuracy of the model for predicting the critical ventilation velocity with water mist was verified by combining the measured critital longitudinal ventilation velocity and the heat-absorbing calculated value by water mist. We still performed the experimental study on critical ventilation velocities on the condition of different positions where water mist was sprayed, and analyzed the positions’ influence on the critical longitudinal ventilation velocity according to the experimental results, and discussed the mechanism of the water mist’s influence on the critical longitudinal ventilation velocity.Experiments of n-heptanes pool fire suppression with water mist on the condition of longitudinal ventilation was performed closely using the simulated test bench of long and narrow space. The extinguishing effectiveness with water mist on the different conditions of longitudinal ventilation velocity was studied by way of changes of oil pool fire’s pre-ignition time, working pressure for water mist, the position where the water mist was sprayed and longitudinal ventilation velocity. And the longitudinal ventilation velocity’s influence on the extinguishing performance with water mist was discussed. Then,the factors of fire suppression with water mist on the condition of longitudinal ventilation were studied by combining the results of the water mist field measurement on the condition of longitudinal ventilation, the fuels’ temperature on the different condition of wind speed, the results of smoke concentration around the fire and the fire morphology in the extinguishing process, thereby the mechanism of wate mist suppressing n-heptane pool fire was revealed.更多还原