Abstract:

To investigate the effect of obstacle position and oil-gas concentration on characteristics of gasoline-air mixture explosion, a series of contrast experiments were conducted under the condition of three different initial gasoline vapor concentrations (1.3%, 1.7% and 2.1%) and different obstacle positions. The main observed results are:(1) Three typical peak values are observed in gasoline-air mixture explosion. The peak value of pressure relief p_v is independent of obstacle position, while the maximum absolute value of negative pressure peak p_neg is obtained when the dimensionless distance between the obstacle and the igniter head L_i/L=0.4. In the condition of 2.1% concentration, the peak value of maximum overpressure p_max is obtained at L_i/L=0.4, while under the condition of 1.3% concentration, it is obtained at L_i/L=0.6. (2) The maximum values of average pressure boost rate (dp/dt)_ave, index of explosive power E_max, maximum pressure boost rate (dp/dt)_max and maximum explosion index K_max are all obtained at L_i/L=0.4 under the condition of three initial concentrations. (3) During the initial flame propagation process, it presents a “finger-like” shape, while after disturbance by obstacles, the flame fronts produce irregular deformations, a mushroom like flame is formed outside the pipe. When L_i/L=0.2, mushroom like flames are most pronounced. (4) The maximum flame propagation velocity S_fmax is obtained at L_i/L=0.2 which monotonously decreases with the increase of L_i/L from 0.2 to 0.8. Above observation results show that both location of obstacles and initial oil gas concentration have an influence on the characteristic parameters of the gas explosion in the pipeline with built-in obstacles.

Key words: vented gasoline-air mixture explosions, obstacle position, explosion overpressures, flame speeds

摘要：

为研究障碍物位置和油气浓度对油气爆炸特性影响，选取1.3%（低）、1.7%（危险浓度）和2.1%（高）三种初始浓度，进行了多工况油气泄压爆炸对比实验，主要结果为：（1）泄压爆炸超压曲线存在三个典型峰值，其中，泄压峰值p_v大小与障碍物位置无关，负压峰值p_neg的最大绝对值在障碍物与点火头的无量纲距离L_i/L=0.4取得；最大超压峰值p_max最大值在L_i/L=0.4取得（1.7%和2.1%工况），而1.3%工况在L_i/L=0.6取得；（2）平均升压速率（dp/dt）_ave、爆炸威力指数E_max、最大升压速率（dp/dt）_max和最大爆炸指数K_max的最大值均在L_i/L=0.4取得；（3）在传播初期，火焰呈现较规则的“指尖形”形状，受障碍物扰动后，火焰锋面产生不规则变形，并在管道外部形成“蘑菇状”火焰，当L_i/L=0.2时，“蘑菇状”火焰最明显；（4）最大火焰传播速度S_fmax在L_i/L=0.2取得，并随着L_i/L从0.2升至0.8时，单调递减。上述观测结果表明，障碍物位置和油气浓度对内置障碍物管道中油气爆炸特征参数均具有影响。

关键词: 油气泄压爆炸, 障碍物位置, 爆炸超压, 火焰速度