The influence of rarefaction wave on die experimental section in blast shock tube with different isolator lengths was simulated. To simulate the incident wave at the entrance of experimental section exactly and efficiently, a new method which couples ID and 3D computational programs was adopted, and small scale explosion was utilized to annulate actual overpressure waveforms in ID computation according to blast similarity rule. The computation results demonstrate the following features: alteration of isolator length L does not affect the peak overpressure; when L is less than or equal to 20m, influence of rarefaction wave will reduce the impact time and impulse of overpressure in experimental section; while L is larger than or equal to 30m, the rarefaction wave doesn' t affect these two parameters in experimental section.%数值模拟了爆炸激波管不同隔离段长度时管口稀疏波对试验段超压的影响.为了准确高效地模拟试验段入口的超压曲线,采用了一种将一维球对称程序和三维程序相结合的计算方法,并在一维计算中利用爆炸相似律,采用小当量爆炸来模拟实际超压波形.计算结果表明,隔离段长度L的变化不影响超压峰值;L小于等于20m时,稀疏波的影响使得试验段超压的作用时间、比冲量减小;L大于等于30m时,稀疏波对试验段超压无影响.
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