泄爆口强度对管内天然气爆炸流场的影响仿真

天然气管道处于泄漏燃烧状态时有可能引发管内天然气爆炸,爆炸流场受管道泄爆口强度的直接影响,但目前对于该方面的研究则较为薄弱。为此,选择内边界为80 mm×80 mm×600 mm的小尺寸矩形管道作为仿真研究对象,基于FLACS软件分析了管道在泄爆口承压泄爆、密闭、开口等3种工况下天然气爆炸火焰的传播特性,研究了泄爆口强度对管内爆炸压力、温度、火焰传播速度的影响规律。研究结果表明:①管道内甲烷/空气预混气体燃烧爆炸反应过程中,在泄爆口密闭的条件下,压力和温度上升至峰值后无明显下降趋势,而在泄爆口开口情况下,管道内压力迅速上升至峰值后急剧下降,温度上升至峰值后缓慢下降;②在泄爆口承压泄爆条件下,管道内压力和温度的变化趋势相似,均经过先上升至峰值后下降的过程,随着泄爆口承压能力的增加,管内压力峰值、温度峰值以及到达峰值的时间均增加;③压力峰值由大到小的工况依次为泄爆口密闭、泄爆口承压0.5 MPa、泄爆口承压0.3MPa、泄爆口承压0.1 MPa、泄爆口开口,温度峰值由大到小的工况依次为泄爆口密闭、泄爆口承压0.5 MPa、泄爆口承压0.3 MPa、泄爆口承压0.1 MPa、泄爆口开口,火焰传播速度峰值由大到小的工况依次为泄爆口开口、泄爆口密闭、泄爆口承压0.3 MPa、泄爆口承压0.5 MPa、泄爆口承压0.1 MPa。结论认为,泄爆口强度对管内爆炸压力与火焰传播速度的影响较为显著,而其对管内温度的影响则不明显。

A simulation study on the influence of vent port strength onthe natural gas explosion flow field in line pipes

When a natural gas line pipe is in a leaking combustion state, gas explosion inside the pipe will easily occur, and the flow field of which is directly affected by the strength of the pipe vent port. However, few studies were done in this field. In view of his, we first chose a small-size rectangular pipe (80 mm×80 mm×600 mm) as the simulated object, then based upon the FLAC, analyzed the flame spread properties of methane explosion under such working conditions as vent opening, vent sealing, vent bearing-blast (vent bearing 0.1, 0.3, 0.5 MPa respectively), and obtained the laws of explosion pressure, explosion temperature, and flame spreading-speed varying with time under the above working conditions. The following findings were achieved. (1) In the explosion of the mixed methane and air in the pipe, pressure and temperature show no apparent descending trend after climbing to the peak value under the working condition of vent sealing, but pressure presents a sudden drop and temperature is slowly decreasing after the peak values under the working condition of vent opening. (2) Under the working condition of vent bearing-blast, the trend of pressure and temperature change in the pipe is similar, rising first up to the peak values and then descending afterwards, but along with the rise of bearing-blast pressure, both the peaks and the climbing time of pressure and temperature in the pipe will increase. (3) The pressure peaks under various working conditions are from large to small as follows: pvent sealing> pvent bearing 0.5 MPa> pvent bearing 0.3 MPa> pvent bearing 0.1 MPa> pvent opening, the temperature peaks are: Tvent sealing> Tvent bearing 0.5 MPa> Tvent bearing 0.3 MPa> Tvent bearing 0.1 MPa> Tvent opening, the peaks of the flame propagation speed are: Vvent opening> Vvent sealing > Vvent bearing-blast (Vvent bearing 0.3 MPa> Vvent bearing 0.5 MPa> Vvent bearing 0.1 MPa). This showed that the strength of vent port has an obvious impact on the explosion pressure and flame propagation speed but little effect on the temperature in the pipe. The conclusion fully demonstrates the characteristics of natural gas explosion flow field under different venting strength, and provides a basic reference for strengthening natural gas pipeline accident prevention and control.