Stage separation of recoverable liquid launch vehicle by using moving pulsating ball analogue for propellant sloshing

In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be considered.Considering calculation simplicity and operation practicability,the Moving Pulsating Ball Model(MPBM)of large amplitude liquid sloshing is introduced into the calculation of launch vehicle stage separation.Combining the dynamic equation of the model with the energy relationship during"breathing movement",the formula calculating the force of liquid on the rigid body is derived.Compared with the calculations of commercial CFD calculation software,the accuracy of MPBM model is verified.Then,all the external forces and moments are applied to the rigid body of the stages,so that the translational and rotational dynamic equations of the stages are obtained respectively.According to the relative position of the two stages,the geometric shape of the interstage section and the engine of the second stage,the minimum clearance in the separation process can be decided to guarantee that the separation process is safe.

共底贮箱内液体晃动动力学特性研究及实验验证

本文通过数值方法、实验方法和等效力学模型方法研究了共底贮箱内液体晃动的动力学特性.研究结果表明,一阶晃动频率随着充液比的增加而增大.然而,二阶晃动频率随着充液比的增加而减小.通过两个算例来验证改进的移动脉动球模型,其结果与数值和实验结果非常吻合.此外,通过CFD研究了CBH槽内非线性液体晃动的复杂多模态或高阶模态特征,结果表明,在强迫激励下能明显观察到高阶晃动模态.最后,通过实验揭示了共底贮箱内的旋转晃动和对称旋转晃动现象.发现由于激励振幅和激励频率的数值变化,旋转晃动会变得不稳定,并发展为对称旋转晃动.对称旋转晃动将以特定的节奏间歇性地开始,这取决于激励的频率.