﻿ 机械排烟控制航母机库火灾烟气运动大涡模拟
 舰船科学技术  2016, Vol. 38 Issue (6): 141-146,150 PDF

Large eddy simulation of the control to fire-smoke motion in aircraft garage with a mechanical exhaust
YUAN Shu-sheng, ZHU Xu-cheng, ZOU Qiang, CHEN Zhen-lin
Department of Aircraft Engineering, Naval Aeronautical and Astronautical University, Yantai 264001, China
Abstract: Fires in aircraft garage often pose great hazard to the safety of the aircraft carrier. In order to investigate fire protection and control methods, the control equations of low Mach air flow and the large eddy simulation method of turbulent flows are used to study the spread and the motion of smoke of pool fire in aircraft garage with a mechanical exhaust system. For the researched object, when the exhaust flux is between 300 m3/s and 600 m3/s, the height of heat smoke layer increases, the temperature of cool smoke layer decreases, and the heat flux close to the fire source decreases too. When the exhaust flux is less than 600 m3/s, the mechanical exhaust has little the spread of the pool fire in the garage. The mechanical exhaust elevates markedly the temperature of the exited smoke. Hence the choice of fanner must consider the capabilityof resistanceheat.
Key words: aircraft carrier     aircraft garage     large eddy simulation     pool fire     mechanical exhaust
0 引 言

1 大涡模拟控制方程组

 $\frac{{\partial \bar \rho }}{{\partial t}} + \nabla \cdot \bar \rho \tilde u = 0\text{，}$ (1)
 $\bar \rho \left( {\frac{{\partial \tilde u}}{{\partial t}} + (\tilde u \cdot \nabla \tilde u)} \right) + \nabla \bar p = \bar \rho g + \nabla \cdot {\bar \tau _l} + \nabla \cdot \tau \text{，}$ (2)
 $\begin{array}{l} \displaystyle\frac{\partial }{{\partial t}}(\bar \rho \tilde h) + \nabla \cdot (\bar \rho \tilde u\tilde h) = \displaystyle\frac{{D\bar p}}{{Dt}} \!+\! \dot Q \!+\! \nabla \cdot (\lambda \nabla \tilde T) \!+\! \nabla \cdot q - \\ [10pt] \quad\quad\quad\quad \nabla \cdot {q_r} + \sum\limits_s {\nabla \cdot ({{\tilde h}_s}\bar \rho {D_s}\nabla {{\tilde Y}_s})} \text{，} \end{array}$ (3)
 $\frac{\partial }{{\partial t}}(\bar \rho {\tilde Y_s}) + \nabla \cdot (\bar \rho \tilde u{\tilde Y_s}) = \nabla \cdot (\bar \rho {D_s}\nabla {\tilde Y_s}) + \nabla \cdot {J_s} + {\dot m_s}\text{。}$ (4)

 ${X_f} = \exp \left[{ - \frac{{{h_v}{W_f}}}{R}\left( {\frac{1}{{{T_s}}} - \frac{1}{{{T_b}}}} \right)} \right]\text{。}$ (5)

2 模拟对象与工况参数

 图 1 航母机库分区模型示意图 Fig. 1 Schematic model of aircraft garage zone

3 结果分析与讨论

 图 2 不同工况下机库中心位置处烟气层高度随时间变化 Fig. 2 Height ariations of heat smoke layer at the center point of aircraft garage for simulated cases

 图 3 不同工况下机库油池火灾释热率随时间变化 Fig. 3 Variations of the heat flux of the garage pool fire for simulated cases

 图 4 不同工况下机库中心位置处冷烟气温度随时间变化 Fig. 4 Variations of cooled smoke temperature at the center point of aircraft garage for simulated cases

 图 5 不同工况下机库地面中心上热流密度随时间变化 Fig. 5 Variations of heat flux at center point of the garage floor

 图 6 不同工况下机库首尾中心线距离火源 15 m 地面上热流密度随时间变化 Fig. 6 Variations of heat flux at the point 15 m away from fire source on center line of the garage floor

 图 7 不同工况下机库艏艉垂直对称面上烟气平均温度分布 Fig. 7 Averaged smoke temperature contours in the longitudinal symmetrical plane of the garage

 图 8 不同工况下机库 z = 1.65 m 水平面上烟气平均温度分布 Fig. 8 Averaged smoke temperature contours in the horizontal plane of the garage where z = 1.65 m

 图 9 不同工况下机库门口垂直中心线上烟气温度平均分布 Fig. 9 Averaged smoke temperature distribution on the vertical center line of the garage door
4 结 语

1）采用机械排烟，排烟量介于 300～600 m3/s 不仅会增高热烟气层高度、降低下层烟气温度，还会降低火源附近的热流密度，有利于灭火人员进入火场查找火源并手动快速灭火。

2）当机库门位于首尾方向中间位置时，机械排烟将导致机库门附近区域下层（1.65 m 高度）烟气温度分布趋于对称，不利于采用温度探测器查找火源位置。

3）当机械排烟量不超过 600 m3/s 时，采用机械排烟对油池火蔓延的强化影响不显著。

4）采用机械排烟措施后，机库门口上部热烟气温度有明显增加，设计风机需要满足耐温要求。

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