泡状流中空化与激波相互作用的数值模拟

文章针对定常可压缩泡状流中回转体的空化绕流进行了数值模拟,在给定来流速度和环境压力的条件下,对不同含气率下的空化与激波的相互作用进行了研究。首先,对含气率为0的情形进行计算并同试验数据进行对比,证明所采用的计算模型是可信的。其次,改变流场含气率从0至0.5进行计算,结果表明,随着含气率的增大,流场的可压缩性随之增强,体现为数值模拟得到了回转体绕流流场的3种波系,包括回转体头部处的脱体激波、分离面处的膨胀波和空泡尾端的斜激波。而空化与激波的相互作用则体现为:头激波削弱了空化效应,使得空化区域减小;由于空泡外形的影响,使得空泡尾端出现了斜激波;含气率超过一定值,空泡已经无法闭合在物面上,而是闭合在空泡尾端的激波面上,体现为空泡尾端壁面逆压梯度趋于平缓。计算结果揭示了泡状流中空化与激波相互作用的新的物理现象。

Numerical simulation on interaction between cavitation and shock wave in compressible bubbly flows

The numerical simulation on the cavitating flow around an axis-symmetrical body in the steady compressible bubbly flow was simulated, and the interaction between cavitation and shock wave under dif-ferent air volume fractions with the constant flow velocity and operating pressure was investigated. Firstly, to verify the used calculation model, the case which air volume fraction takes 0 in the incoming flow was cal-culated and shows a good agreement with the experimental result. Secondly, more cases with air volume frac-tions varying from 0 to 0.5 were calculated. The results show that with the increase of air volume fractions, flow field becomes more compressible. This result was confirmed by the appearance of three kinds of wave systems, including detached shock wave before the head, expansion wave at separation surface and oblique shock wave after cavity tail. The interaction between cavitation and shock wave is reflected as follows: bow shock before caviting region weakens cavitation effects, making caviting region decrease; cavity generated by cavitation results in occurrence of oblique shock;cavity closure point cannot locate on the body surface but on the shock surface, which can be confirmed by the adverse pressure gradient at the end of cavity. These results revealed a new physical phenomenon which existed in the interaction process between the cavity and the shock wave in compressible bubbly flows.