高电压点火有效能量的测量及相关问题

Measurement of effective energy from a high-voltage spark discharge and its some related problems

建立了测量高电压点火产生的爆炸波参数装置,利用PCB压力传感器测定了在空气中高压电火花产生的爆炸波压力及其到达时间。改变点火能量和测试距离,得到了爆炸波的变化趋势和传播规律,并探讨了爆炸波各参数的标度尺寸。结果表明,电火花产生的爆炸波符合Hopkinson-Sachs爆炸相似律。把1/4周期放电能量与数值模拟结果进行比较,得知初始1/4周期放电能量(点火能量)与爆炸波能量基本吻合;因此,1/4周期放电能量可被视为作用于直接起爆引起爆轰的有效能量。进一步探讨了高电压点火各能量的分布;结果表明,储存于电容的总能量1/2CU2中约91%消耗于能量损失和欧姆损耗,初始1/4周期放电能量仅约占2%,其余的点火能量只起到加热混合物的作用。

An experimental apparatus was developed for measuring the parameters for the blast waves produced by a high-voltage spark discharge.To investigate the variation and propagation tendency of the blast wave and the scaling law of its parameters,the pressure and arrival time of the blast wave in air were measured at different radii and initial energy using a PCB piezoelectric pressure transducer.The results show that the high-voltage spark-produced blast wave follows the Hopkinson-Sachs scaling law.The comparison between the experimental results and the numerical simulation for a spherical blast wave from a point energy source confirms that the blast wave originated from the high-voltage capacitor spark discharge follows adequately the analytical description and the amount of energy contributed to the direct blast initiation from the spark ignition can be estimated from the first 1/4 cycle current discharge.The composition of the total energy stored in the capacitors,（i.e.,1/2CU2） was further investigated.The results indicate that about 91% of the total energy wastes on the energy loss and ohmic dissipation,and only about 2% contributes to the first 1/4 cycle current discharge energy which is responsible to initiate the detonation.The energy released after the first 1/4 cycle only tends to heat up the surrounding gases.