مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

مقایسه عملکرد چند نمونه پرتابه تفنگ بادی به‌همراه اصلاح شکل دماغه

نویسندگان
سید عرفان سلیمی پور 1
علیرضا تیمورتاش 2
مجتبی ماموریان 3
1 دانشگاه فردوسی مشهد
2 استاد-دانشگاه فردوسی مشهد
3 دانشیار-دانشگاه فردوسی مشهد
چکیده
یکی از مسائل مهم در تیراندازی با تفنگ‌های بادی، انتخاب پرتابه مناسب برای فواصل مختلف هدف می‌باشد. در این مقاله به شبیه‌سازی عددی و مقایسه عملکرد چهار نمونه مختلف از پرتابه‌های تفنگ بادی پرداخته شده که حرکت این پرتابه‌ها به‌صورت 4 درجه آزادی، شامل سه حرکت انتقالی و یک حرکت چرخشی در کد تدوین شده منظور شده است. پرتابه‌‌های مورد بررسی دارای سه اندازه کالیبر 4.5، 5.5 و 6.35 میلی‌متر و چهار نوع مختلف با نام‌های سرتخت، نوک‌تیز، گنبدی و کروی هستند. به‌منظور تحلیل عددی این مسأله، پس از مدل‌سازی هندسی پرتابه‌ها، معادلات ناویر- استوکس سه‌بعدی تحت شرایط ناپایای تراکم پذیر آشفته به همراه معادلات دینامیکی حرکت پرتابه به‌صورت کوپل و در یک شبکه محاسباتی متحرک حل شده‌اند. شبیه‌سازی عددی، بر پایه طرح "رو" با دقت مرتبه دو مکانی و به لحاظ اهمیت زمان با مرتبه دو زمانی به شیوه حجم محدود می‌باشد. برای اعتبارسنجی برنامه کامپیوتری، پاسخ‌های حاصل با نتایج تجربی معتبر مقایسه شده‌اند. مقایسه نتایج حاصل از بررسی عملکرد پرتابه‌ها شامل مسیر حرکت، تغییرات سرعت و افت ارتفاع نشان می‌دهند که پرتابه گنبدی، بهترین عملکرد را تقریباً در تمامی فواصل هدف داشته و پرتابه سرتخت در فواصل کم، عملکرد بسیار خوب و در فواصل زیاد عملکرد بسیار ضعیفی در مقایسه با سایر نمونه‌ها دارد. درادامه، اثر شکل دماغه بر عملکرد پرتابه‌‌های نوک‌تیز و گنبدی بررسی و شکل‌های بهینه به‌دست آمده‌اند.
کلیدواژه‌ها
پرتابه تفنگ بادی
مقایسه عملکرد
اصلاح شکل دماغه
شبیه سازی عددی سه بعدی
حل ناپایا

عنوان مقاله English

Performance Comparison of Several Air Gun Projectiles with Nose Shape Modification

نویسندگان English

Seyed Erfan Salimipour 1
Ali Reza Teymourtash 2
Mojtaba Mamourian 3
1 Ferdowsi university of mashhad
3 Ferdowsi university of mashhad
چکیده English

One of the important issues in shooting by air guns is to select the appropriate projectile for different distances of the target. In this paper, the performance of four samples of air gun projectiles (pellets) is studied. The motion of these projectiles is assumed in four degrees of freedom including three translational motions and one rotational motion. The considered projectiles have three calibers of 4.5, 5.5 and 6.35 mm, and four different types, namely flat nose, sharp nose, round nose and spherical. In order to numerical simulation of the problem, after these projectiles have been modeled geometrically, the 3-D compressible turbulent Navier-Stokes equations and dynamic equations of the projectiles motion are solved in a coupled form and in a moving computational grid. The numerical simulation is based on “Roe” scheme with second-order accuracy in space and time using a finite volume method. To validate the computer program operation, the results are compared to valid experimental data. Computed results describe the trajectory, velocity variations and altitude loss of the projectiles with time and location. Comparison of the projectiles performance including the trajectory, velocity variations and altitude loss indicate that the round nose projectile has the best performance in long distances compared to the other samples and the flat nose projectile has a great performance in short distances, while it has a weak behavior in long distances. Additionally, effect of nose shape on the performance of the sharp and round nose projectiles is investigated and the optimum nose shapes are obtained.

کلیدواژه‌ها English

Air gun projectiles
Performance comparison
Nose shape modification
3-D numerical simulation
Non-stationary solution
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مهندسی مکانیک مدرس
دوره 18، شماره 3
خرداد 1397
صفحه 395-405