نویسندگان

دانشکده مهندسی مکانیک، دانشگاه علم و صنعت ایران

چکیده

یکی از پارامترهای تعیین‌کنندة پیشرانش در یک موتور سوخت جامد، هندسة گرین در هر لحظه است. در این مقاله شبیه‌سازی پس‌روی سطح سوزش گرین‌های سه بعدی سوخت جامد توسط روش لِوِل‌سِت انجام شده است. برای این منظور هندسة اولیة گرین‌ در یک نرم‌افزار CADتولید می‌شود. سپس سطح سوزش اولیة گرین توسط تابع فاصلة علامت‌دار به صورت ضمنی تعریف شده، و به عنوان شرط اولیة معادله مرز متحرک در روش لِوِل‌سِت استفاده می‌شود. برای تعیین مشخصه‌های بالستیکی گرین (مانند مساحت سطح سوزش، مساحت عبور گاز، حجم گرین) در هر گام پس‌روی، از خواص توابع ضمنی بهره گرفته شده است. برای ارزیابی دقت تحلیل پس‌روی و محاسبه مشخصه‌های بالستیکی گرین، از چند نمونه‌ تحلیلی استفاده شده، و توافق بسیار خوبی مشاهده شده است. تحلیل پس‌روی برای چند گرین سه‌بعدی کاربردی سوخت جامد توسط این روش انجام شده، و قسمتی از نتایج با داده‌های تجربی موجود مقایسه شده‌ است.سوزش غیریکنواخت و شرط مرزی اتمام سوزش نیز در مثال‌هایی مورد بررسی قرار گرفته‌اند.

کلیدواژه‌ها

عنوان مقاله [English]

Numerical Simulation of Complicated Grain Burnback in Three Dimensions

نویسندگان [English]

  • H. Ghasemmi
  • A. Barkhordar

چکیده [English]

Instantaneous grain geometry is one of the most affecting parameters on the performance of the solid rocket motors (SRMs). This paper presents the simulation of geometrically complicated solid propellant grain burnback using the level set method. The initial form of the grain is assumed in this method. Propagation of the grain boundaries in a velocity field is described using the Hamilton-Jacobi type equation. The solution of this equation in successive time steps gives the new burning boundaries of the grain. For this purpose, the initial geometry of grain is modeled in any CAD software. Then, the initial burning surfaces of grain are implicitly defined by the sign distance function and are used as the initial conditions of the level set equation. The geometrical characteristics of grain, such as burning surface area, port area, burning perimeter, and port volume are determined by Heaviside and Delta Dirac functions. The result of simulation is validated by an analytically predictable case, which shows excellent agreement. Burnback analysis is done for some practical grains including two cases that the test data were available. Using an unsteady zero dimension interior ballistic analysis, the resulting motor pressure curves are compared with the experimental data showing good agreement. The capability of the approach to handle the analyzing of problems, including non uniform burning velocity and arbitrary burnout configurations of grain are shown in examples.

کلیدواژه‌ها [English]

  • Level set
  • Complicatedgrain
  • Burnback
  • Sign distance function
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