شناسایی اثر گردابه‌های تشکیل‌شده اطراف تیغه ایزوله بالگرد بر روی واماندگی دینامیکی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی‌هوافضا، دانشگاه صنعتی امیرکبیر، تهران، ایران

2 دانشکده مهندسی‌هوافضا، دانشگاه صنعتی مالک اشتر، تهران، ایران

چکیده

در این‌تحقیق، واماندگی دینامیکی مقاطع نزدیک به نوک تیغه روتور در حداکثر سرعت پروازی بالگرد با نسبت پیشروی 0/35 همراه با تغییرات نوسان پیچشی توسط شبیه‌سازی دینامیک سیالات محاسباتی مورد مطالعه قرار گرفته است. به منظور شبیه‌سازی میدان جریان، معادلات ناپایای متوسط‌‎گیری‌شده ناویر استوکس با استفاده از روش گسسته‌سازی حجم محدود حل شده است. شبکه مورد استفاده از نوع ترکیبی بوده و از مدلK-ω SST    برای مدل‌سازی جریان مغشوش بهره گرفته شده است. جهت اعتبارسنجی شبیه‌سازی عددی از نتایج تست‌ پروازی بالگرد AH1-G استفاده شده که دارای تطابق مناسبی می‌باشد. نتایج نشان‌دهنده این موضوع است که موج ضربه‌ای عامل واماندگی دینامیکی در ناحیه پیش‌رونده تیغه روتور بوده و اثرات موج ضربه‌ای بر روی ضرایب برآ در نواحی نزدیک‌تر به نوک تیغه به دلیل اثرات نفوذ گردابه نوک تضعیف شده و تغییرات ضریب برآ نسبت به نواحی داخلی تیغه کمتر و یکنواخت‌تر گردیده به‌گونه‌ای که نسبت تغییرات ضریب برآ نسبت به بیشینه این ضریب در نواحی نزدیک‌تر به نوک تیغه 2 /10درصد کاهش یافته است. از طرفی نتایج این پژوهش نشان داد که بر خلاف انتظار، با وجود شکل‌گیری گسترده گردابه‌ لبه حمله در قسمت داخلی‌تر تیغه در بیشتر ناحیه پس‌رونده، وجود جریان شعاعی به واسطه چرخش تیغه روتور عامل تضعیف گردابه لبه حمله و محدود شدن واماندگی دینامیکی در این ناحیه شده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Characterization of the Effect of Helicopter Isolated Blade Vortex on Dynamic Stall

نویسندگان [English]

  • Farid Hosseinzadeh Esfahani 1
  • Seyed Mohammad Hossein Karimian 1
  • Hamid Parhizkar 2
1 Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, Iran
2 Department of Aerospace Engineering, Malek Ashtar University of Technology, Tehran, Iran
چکیده [English]

In this research, dynamic stall at sections near the rotor blade tip at a maximum cruise speed of the helicopter with an advanced ratio of 0.35 and cyclic pitching motion, has been studied using computational fluid dynamics simulation. Unsteady Reynolds-averaged Navier–Stokes equations are solved using  model on a domain discretized into a hybrid mesh using finite volume discretization method. Numerical simulation is validated using experimental results of AH1-G helicopter flight tests. Comparison of results indicates that present numerical results match with experimental data well. Dynamic stall occurs as a result of a shock wave in the advancing side which affects the lift coefficient. Interestingly, the effect of the shock wave on the lift coefficient in the regions closer to the blade tip is weakened due to the tip vortex penetration. As a result, few changes are seen in the lift coefficient in these regions in comparison to those of the inner regions of the blade. In addition, the maximum value of lift coefficient in the section closer to the blade tip reduces by 10.2% in comparison to that of the most inner section. Results show that despite the formation of the leading-edge vortex, especially in the inner most sections of the blade, severe dynamic stall does not occur in the retreating side.  In fact, this is due to the weakening of the leading edge vortex by the effect of the radial flow.

کلیدواژه‌ها [English]

  • Dynamic stall
  • Unsteady separation
  • Helicopter aerodynamics
  • Leading edge vortex
  • Trailing edge vortex
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