某850kW水平轴风力发电机机舱火灾模拟与分析

Simulation and analysis of the likely fire disasters in the nacelle of certain 850 kW horizontal axis wind turbine

采用火灾动力学模拟器软件和性能化防火设计理论,基于实际事故案例分析,设计针对某850 kW水平轴风力发电机机舱的典型火灾场景,建立池火灾模型,对额定风速(13 m/s)下机舱内该类型火灾的发生和发展过程进行研究,模拟计算机舱内火灾的热释放速率、温度场和速度场等参数,探讨进气口风速对火灾热释放速率和温度场等的影响。结果表明:封闭条件下,从齿轮箱底部发展起来的油池火灾热释放速率在62.4 s时达到最大值(757 kW),持续燃烧93 s后降至0;齿轮箱附近部件遭受火灾破坏最为严重,喷射油料二次燃烧导致火强度变大并加剧了火灾的破坏程度。额定风速下,齿轮箱附近软管喷射油料未出现二次燃烧现象,但火灾后期热释放速率在335 s内达到4 000 kW;以火源为分界面,火源前方区域温度(406~567℃)明显高于后方区域温度(177~279℃);顶部通风口承受全部热流,机舱罩顶部温度最终达到930℃,并出现轰燃。

The present paper is aimed to make an investigation and exploration of how the fire initiated and developed under the rated wind speed（13 m/s） with a purpose to simulate and acquire the fire-heat release rate,the fire temperature field and the fire velocity spreading in the nacelle.Based on the performancebased fire safety design concept and the typical fire accident cases,we have laid out the fire scene and established a pool fire model and numerically simulated by using a software known as the FDS for a certain type of 850 kW wind turbine with the horizontal axis.At the same time,we have also studied the effects of the air inlet velocity on the heat release rate（HRR） and the temperature field.The results of our simulation and investigation show that under the proper confined ventilation conditions,the heat release rate of the pool fire propagation from the bottom of the gearbox can likely reach as high as 757 kW in 62.4 s and then began to decrease to 0 when the burning temperature can be sustained at least for 93 s.The articles close to the gearbox tend to suffer from the badly damaged situation.As to the secondary induced combustion of the liquid form fuels,an injecting form tends to increase the fire intensity and further aggravates the fire damage.For example,under the rated wind speed,the secondary burning of the fuels in an injection form induced by the broken pipes may not occur near the gearbox,though a much greater HRR value（about 4000 kW） in 335 s do occur.Suppose that the fire source seems to be an interface,the temperature sphere in the nacelle can be divided into two zones,the temperature of the frontal zone（406-567 ℃） can usually obviously higher than those of the rear one（177- 279 ℃）.Whereas all the hot smoke layers with the intense heat emission tend to flow away from the sole ceiling ventilation vent,as a result,the temperature of the nacelle housing ceiling can be made to reach as high as 930 ℃ with a flashover being triggered.