KI50X特高压变压器油火灾特性参数分析

On the oil fire feature parameter analysis of the fire disaster initiated by the UHV KI50X typical UHV transformer

为了获得KI50X特高压变压器油火灾特性参数,在大空间试验厅中,通过在不同尺寸油盘中燃烧KI50X型特高压换流变压器油,测量了燃烧速率、火焰平均高度、羽流轴向温度等燃烧特性参数。详细讨论了燃料初始温度、燃料厚度、油池直径等对燃烧速率、火焰平均高度、羽流轴向温度的影响。燃料厚度对质量损失速率有较大影响,燃料厚度为20mm时,可以观察到包括:(Ⅰ)初始增长、(Ⅱ)准稳态燃烧和(Ⅲ)衰减至熄灭3个典型燃烧阶段,因此燃料厚度都设为20 mm。当初始燃料温度从25℃升高到90℃时,会出现整体沸腾现象,导致质量损失率出现第二个峰值。此外,分别提出了在常温(25℃)和高温(90℃)下,油池直径与稳定阶段燃烧速率的关联式参数。通过对试验数据的拟合,在过渡火焰和总湍流火焰条件下,KI50X型特高压换流变压器油的燃烧速率符合液体燃料燃烧速率与油池直径的一般关系。火源上方无量纲高度处的轴向无量纲温度分布与Z/D成正比。拟合得到的轴向平均温度分布关系式表明,随轴向高度与KI50X变压器油池直径之比的增大,轴向无量纲温度升高比生物柴油和正庚烷油池快。最后系统地给出了25℃及90℃下KI50X型特高压变压器油燃烧特性拟合公式的一系列参数。

The paper is inclined to trace and determine the combustion features and the parameters of KI50 X UHV transformer oil by burning it in the oil pans of different sizes in a large space laboratory.To achieve the purpose,we have discussed in detail the effects of the fuel initial temperature,its thickness and fuel pool diameter on the combustion rate,the average flame height and the plume axial temperature,for the fuel thickness tends to have a great impact on the mass losing rate.To be accurate,when the fuel thickness is 20 mm,it can be observed that it may experience 3 typical combustion stages:the first stage:the initial growth;the second stage:the quasi steady combustion.And,the third stage is actually to transform the fuel from the turning decay to extinction,so that the fuel thickness is getting to 20 mm.And,then,when the initial fuel temperature rises from 25℃to 90℃,it would come to the total boiling stage,that is,it may turn to come to and result in the second peak of the mass losing rate.In addition,the correlation parameters between the diameters of the oil pool and the combustion rates in the stable stage can be supposed to reach a range between 25℃and 90℃,so that the combustion rate of the KI50 X UHV transformer oil may turn to be in accord with the general transferring relationship between the combustion rate of the liquid fuel and the diameter of the oil pool by fitting the experimental data under the condition of transition flame and the total turbulent flame.And,then,the axial dimensionless temperature distribution at the dimensionless height above the fire source may turn to become proportional to Z/D.And,so,it would be possible to find that the relation among the axial average temperature distributions tends to show that the axial dimensionless temperature rise can be made much faster than that of the biodiesel and n-heptane oil pool with the increase of the ratio of the axial height to the diameter of KI50 X transformer oil pool.Thus,it can be found that the paper has given a series of parameters of fitting formula for the combustion features of KI50 X UHV oil transformer at the temperatures from 25℃to 90℃,systematically.