Numerical Simulation Of Fluid-Structure Interaction For Re-entry And Water Entry Of Inflatable Decelerator

Inflatable decelerator is a newly invented re-entry aerodynamic reducer.It has an inverted cone shape after deployment.This pattern is very helpful for starting deceleration.Different with the traditional rigid spacecraft capsule,the flexible material of the inflatable decelerator is prone to change when it is affected by the environment.In order to test the working performance during the re-entry and water entry process,the fluid-structure interaction numerical simulation study of the inflatable decelerator was carried out.First of all,the numerical computation scheme of unidirectional fluid-structure interaction in this paper is established based on ANSYS Workbench platform.The fluid-structure interaction model of flexible structure is established.Numerical simulation of fluid-structure interaction is carried out with the use of inflatable wing model.The numerical results are consistent with the literature results,which verifies the accuracy of the coupled calculation method.The aerodynamic characteristics of the external flow field were studied.In this study the pressure,velocity,and temperature distribution of the flow field under different operating conditions were obtained.It was found that the maximum pressure appeared at the blunt body of the Inflatable decelerator and gradually decreased outward along the meridian。The deformation,stress,and strain of the skin and the inflatable tube in the structure were discussed.It was found that the structural deformation during the reentry of the inflatable decelerator is light and has good shape retention.The maximum stress in the structure is much smaller than the allowable stress of the material,indicating that the process is safe and reliable.Secondly,the modal analysis of inflatable tubes with different thicknesses and internal pressures was carried out.It was found that the natural frequency increased with the increase of the internal pressure of the tube and decreased with the increase of the thickness of the tube.Then,in this paper,the numerical simulation of ALE fluid-structure interaction is carried out on the water entry process of the inflatable decelerator.The accuracy of the ALE method in this paper is verified by comparing the calculation of the hemisphere entry water and the results in the literature.On the base of above,a numerical model of water entry into the inflatable decelerator was established,and the water entry process of the inflatable decelerator was simulated with the ALE method.The attitude,overload,and pressure changes during water entry are obtained.It is found that during the water entry,the maximum overload and pressure occur at the initial water entry time.The influence of entry speed,entry angle and horizontal wind direction on the water entry process was discussed.It was found that the overload increased with the water entry speed and angle,and the horizontal wind direction mainly affected the attitude angle.In this paper,the analysis of the working performance of the inflatable decelerator during the re-entry and water entry process as done by the methods of numerical simulation of fluid-structure interaction,which provides a certain reference for the re-entry and slamming of the inflatable decelerator.