Research On Numerical Simulation In Static And Dynamic Aerodynamic Characteristics Of Mars Rover For Ballistic Range Model

Mars exploration is one of the hot spots in space development.The entry-decent-landing stage for Mars rover which is throughout all the Martian atmosphere,is one of the key to the Mars project.Because of the particularity of the Mars atmosphere,the aerodynamic problem in Mars is different from it in Earth.The stability and landing precision are affected by the aerodynamic environment.The research about dynamic stability of the vehicle in Martian atmosphere is still inadequate.There is a little database about it.All of them make a big challenge to our Mars project.Thus,aiming at the requirements of our Mars project,it must solves the aerodynamic problems in Mars of the rover and carries out the stability research about the Mars lander.The thesis analyzes the static and dynamic aerodynamics,researching on the stability about the rover in Mars environment.There are six chapters in the thesis.The first chapter summarizes the research background and significance.Then,it combes detailedly the status of Mars probe at home and abroad and gives the aerodynamic problems and its research progress.In the second chapter,it introduces the governing equation,numerical methods and dynamic derivative parameter identification.It investigates the influence of several parameters about the Earth return capsule.In the third chapter,it makes depth analysis of the Mars atmospheric flow model by retrospective research,giving the applicability analysis of continuous medium hypothesis and analyzing thermal properties as well as transport properties.It conducts CFD numerical simulation verification about the typical Mars rover.Research shows that it should apply continuous medium hypothesis within 60 kilometers of the surface of Mars.Because of the difference about the specific heat ratio,the Martian atmosphere gets more compressible and high Mach number than the air.Approximate specific heat ratio numerical method can simulicates the flow behavior in Mars.In the hypersonic period,when the approximate specific heat ratio is 1.15,it is in good agreement with the experimental.The fourth and fifth chapter are the significant parts.In the forth chapter,it researchs on the static aerodynamic characteristics about the Mars Smart Lander.At first,it gives a brief description of the test facilities and the results.Then,it carefully analysed the influence of the farfield flow parameters.The chapter focuses on the influence of compressibility effect of the structure of convection field and gives the equation of the shock standoff distance by specific heat ratio and Mach number.The results shows that the approximate specific heat ratio is 1.3 in the supersonic period and compressibility effect has a direct influence on the shock standoff distance.Chapter five analyzes the unsteady aerodynamic of the MSL for ballistic range model.It simulates the dynamic flow field of pitching forced oscillation and studies systemically the influence of dynamic stability by compressibility effect during the hypersonic and supersonic period.It investgates influence of dynamic stability by the different afterbody shape and centroidal position.It founds that while the specific heat ratio is less,the stability is stronger.Comparison by changing the shape of afterbody,moving the centroidal position has obvious effect on improving the dynamic stability.The last chapter is the conclusion,summarizing the main work and achievements of this article,and pointing out need of further study.