Abstract: An investigation was conducted on flow fields in deflected center-line isolator by using steady and unsteady numerical simulation methods. The shock train structure was studied under different back-pressure. The hysteresis characteristics of shock train were analyzed with simulating the pressurized and depressurized process of isolator. The difference of hysteresis characteristics among isolators with 0，10% and 37% expanded ratio were compared. Results show that there are two different hysteresis phenomena in analyzed isolator at coming Mach 2.0. The position of shock train is nearer to isolator inlet in the depressurized process under the same back-pressure. The hysteresis phenomenon disappears when back-pressure approaches the limit pressure of isolator. To the isolator with larger expanded ratio (e.g. 37%)，the hysteresis phenomenon of leading-edge positon appears in a wider back-pressure range with smaller hysteresis value. In the end，an explaination for hysteresis phenomenon in viscous isolator was made by equaling the flux to an inviscid flow passage.

Key words: Isolator；Shock train hysteresis；Numerical simulation；Deflected center-line；Expanded ratio

摘要： 采用定常与非定常数值计算相结合的方法研究了一种中心线偏置的隔离段流场，分析了不同反压作用下的激波串特征。通过模拟隔离段反压升高和降低的过程，研究了隔离段内激波串的迟滞特性，并比较了扩张比为0，10%，37%隔离段内迟滞特性的差异。结果表明，在来流马赫数2.0条件下，所研究隔离段内存在两种类型的迟滞现象；在同一反压条件下，降压路径对应的激波串更靠近管道入口。当反压接近隔离段所能承受的最大反压时，流场迟滞现象消失。隔离段扩张比越大(如37%)，激波串位置出现迟滞的反压范围越宽，迟滞量越小。最后利用流量匹配的观点从无粘角度解释了有粘流道内的激波串迟滞现象。

关键词: 隔离段；激波串迟滞；数值计算；中心线偏置；扩张比