بررسی اثر صدمه بر مشخصات ائرودینامیکی بال با در نظر گرفتن آثار جریان سه‌بعدی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 عضو هیات علمی / پژوهشگاه هوافضا، وزارت علوم، تحقیقات و فناوری

2 عضو هیات علمی / دانشکده مهندسی هوافضا، دانشگاه صنعتی امیرکبیر

چکیده

در این مقاله، یک نمونه بال محدود که در اثر برخورد یک جسمی مانند گلولة جنگی، دچار صدمه می‌شود، با استفاده از آزمایش تونل باد و روش عددی مطالعه و آثار صدمه روی مشخصات ائرودینامیکی بال بررسی شده است. در مقایسه با تحقیقات پیشین که صدمة دایروی روی بال نامحدود با مشخصات جریان دوبعدی انجام شده است، در این مقاله، شبیه‌سازی با استفاده از یک بال محدود در نظر گرفته شده تا آثار جریان سه‌بعدی روی بال مطالعه شود. از اینرو، برای بررسی اثر موقعیت صدمه در راستای دهانة بال سه‌بعدی، صدمه در سه نقطة سر، میانه و ریشة بال مدلسازی شده است. برای بررسی اثر گوشه‌های تیز صدمة واقعی، از هندسة مثلث برای شبیه‌سازی شکل صدمه استفاده شده است. مقطع بال مورد مطالعه، ایرفویل‌ نامتقارن ناکا با شمارة NACA 641-412 در نظر گرفته شده که ابعاد وتر بال 200 میلی‌متر و نیم‌دهانة آن به‌طول 800 میلی‌متر است. در این مقاله مشخصات جریان عبوری از روی بال و صدمه آشکارسازی شده و آثار آن بر ضرایب ائرودینامیکی نیرو و ممان ‌پیچشی ارائه شده است. نتایج نشان می‌دهد صدمه‌ای که مساحت آن حدود 1 درصد مساحت سطح مؤثر بال است می‌تواند در مقایسه با بال سالم ضریب بـرآی بال را حدود 5 درصد کاهش و ضریب پسا را حدود 14 درصد نسبت به بال سالم افزایش دهد. همچنین صدمه سبب می‌شود بال ضریب ممان ‌پیچشی منفی‌تری را تجربه کند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The effect of the damage on the aerodynamic characteristics of wing with respect to the three-dimensional effects

نویسندگان [English]

  • Soheila Abdolahi Poor 1
  • Mahmoud Mani 2
چکیده [English]

In this paper the flow on a finite wing with triangular damage is numerically and experimentally investigated to understand the influences of damage on the aerodynamic characteristics of wing. To study the effects of different span positions, the damage was considered in tip, middle and root position of the wing span. The aerodynamic coefficients and their increments due to damage were extracted and the results were compared to each other and also to the experimental results. Then flow visualizations were practiced to make evident the flow structure on the model and to help to understand the influences of each position of damage on the aerodynamic coefficients. There was the flow through the damage which was driven by the pressure difference between the upper and lower wing surfaces. The flow could take two forms dependent on the angle of attack. The first form was a "weak-jet" which formed an attached wake and resulted in small changes in force and moment coefficients. The second form resulted from increased incidence. This was the "strong-jet" where through flow penetrated into the free stream flow with large separated wake and reverse flow. The effect on the force and moment coefficients was significant in this case. Generally comparing to an undamaged model, increasing incidence for a damaged model resulted increase loss of lift coefficient, increased drag coefficient and more negative pitching moment coefficient.

کلیدواژه‌ها [English]

  • damaged wing
  • aerodynamic characteristics
  • Numerical method
  • wind tunnel test
  • flow visualization

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