CAJ | 학술논문

采用非线性自治动力系统分叉理论，耦合求解非定常 Navier—Stokes 方程和俯仰运动方程，研究了再入飞行器单自由度俯仰运动失稳问题。研究表明，航天飞行器再入时，如果仅有一个配平攻角，随马赫数降低，其配平攻角处的俯仰动态失稳一般对应于 Hopf 分叉，并存在亚临界 Hopf 分叉和超临界 Hopf 分叉两种失稳形态。作为验证实例，数值模拟了飞船返回舱外形和平头有翼双锥外形的俯仰动态失稳现象。结果表明，返回舱再入时，随马赫数降低将发生超临界 Hopf 分叉，俯仰运动由点吸引子演化为周期吸引子，临界 Hopf 分叉点发生在马赫数2．2处；而平头再入体随马赫数降低，发生亚临界 Hopf 分叉，俯仰运动则是由周期吸引子演化为点吸引子，马赫数6．8为临界 Hopf 分叉点。
채용비선성자치동력계통분차이론，우합구해비정상 Navier—Stokes 방정화부앙운동방정，연구료재입비행기단자유도부앙운동실은문제。연구표명，항천비행기재입시，여과부유일개배평공각，수마혁수강저，기배평공각처적부앙동태실은일반대응우 Hopf 분차，병존재아림계 Hopf 분차화초림계 Hopf 분차량충실은형태。작위험증실례，수치모의료비선반회창외형화평두유익쌍추외형적부앙동태실은현상。결과표명，반회창재입시，수마혁수강저장발생초림계 Hopf 분차，부앙운동유점흡인자연화위주기흡인자，림계 Hopf 분차점발생재마혁수2．2처；이평두재입체수마혁수강저，발생아림계 Hopf 분차，부앙운동칙시유주기흡인자연화위점흡인자，마혁수6．8위림계 Hopf 분차점。
To study the problem about dynamic destabilization of the reentry vehicles,the bifurcation theory of nonlinear autonomous dynamic system is used together with the unsteady Navier—Stokes equations simulating the pitching process.The investigations shown that,the astronautic vehicles reentering into the atmosphere would generally occur a dynamic destabiliza—tion of pitching motion as their flight Mach number decreased,and the phenomenon of dynamic destabilization befallens at the point of the Hopf bifurcation,furthermore,there are two types of Hopf bifurcation named subcritical Hopf bifurcation and supercritical Hopf bifurcation.To vali—date the theory of the Hopf bifurcation,two reentry configurations are numerically studied.One is the Japanese capsule OREX,composed of a spherical cap facing forward and a reversed cone fa—cing backward.With Mach number decreases in the reentry process for the capsule,the pitching motion would evolve from a point attractor to a periodic attractor,and the critical Mach number is about 2.2 when the subcritical Hopf bifurcation occurs,the theory analysis and simulation re—sult is in good agreement with the experiment and flight test results.The other configuration is a flat—nose winged double—cone body,with the decrease of Mach number,its pitching motion would evolve from a periodic attractor to a point attractor,and the critical Mach number at which the supercritical Hopf bifurcation occurs is about 6.8.