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بررسی تجربی میدان جریان القائی درون ریز و فرو وزش در زیر ملخ‌های کوچک پشت سرهم | ||
| نشریه مهندسی مکانیک امیرکبیر | ||
| مقاله 8، دوره 52، شماره 11، بهمن 1399، صفحه 3071-3090 اصل مقاله (2.72 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22060/mej.2019.16497.6374 | ||
| نویسندگان | ||
| علی مهرابی؛ علیرضا داوری* | ||
| دانشگاه آزاد اسلامی، واحد علوم و تحقیقات، گروه مهندسی هوافضا، تهران، ایران | ||
| چکیده | ||
| در این مطالعه تعدادی از آزمایش‌ها به منظور درک دقیق رفتار جریان درون ریز و فرو وزش ملخ‌های پشت سرهم با استفاده از یک دستگاه آزمایشگاهی چند منظوره انجام شدند. نتایج نشان دادند که برای یک ملخ تنها، جریان درون‌ریز در نواحی نوک و سه پنجم میانی طول ملخ، به سمت بالاست. الگوی ارائه شده برای جریان درون‌ریز و فرو وزش ملخ مورد آزمایش با متوسط میزان عدم قطعیت 6/ 5± درصد شبیه به الگوی ملخ بالگردهای مرسوم در حالت نزول همراه با قدرت تشخیص داده شد. تأثیر نوسانات و اغتشاشات ناشی از جریان‌های حلقوی لبه فرار پره‌های ملخ جلویی بر جریان درون‌ریز ملخ عقبی باعث تغییر رفتار آن نسبت به یک ملخ تنها می‌شود. با توجه به اثرات بدنه، نوسانات و پدیده‌های غیر دائم روی داده در آزمایش‌ها، نتایج به دست آمده واقعی‌تر بودند. نتایج نشان دادند که مقادیر سرعت فرو وزش در زیر نواحی غیر مرکزی ملخ بیشتر از مقدار سرعت درون‌ریز آ نها هستند ولی تقریبا در تمام نقاط طول ملخ، این مقادیر کمتر از 2 برابر هستند. بنابراین, رابطه مستخرج از تئوری اندازه حرکت در مورد ارتباط جریان درون‌ریز و فرو وزش ملخ‌های کوچک صدق نکرد و نیاز است تا در پیش بینی عملکرد و طراحی این نوع وسایل پرنده، به این تفاوت‌ها و تغییرات توجه شود. | ||
| کلیدواژه‌ها | ||
| جریان درون‌ریز؛ فرو وزش؛ ملخ های پشت سرهم؛ اندرکنش آیرودینامیکی ملخ ها؛ پهپاد عمودپرواز | ||
| عنوان مقاله [English] | ||
| Experimental Study of Inflow and Downwash Flow Fields under the Small Tandem Rotors | ||
| نویسندگان [English] | ||
| ali mehrabi؛ Ali R. Davari | ||
| Department of Aerospace Engineering, Science & Research Branch, Islamic Azad University, Tehran, Iran | ||
| چکیده [English] | ||
| In this study, a number of experiments were conducted to understand the inflow and downwash behaviors of tandem rotors by using multipurpose testing equipment. The results showed that for single rotor, inflow is descending except in tip and the 3/5 length of the rotor central areas. An estimated pattern of inflow and downwash of rotor with 94.6% confidence levels, was found to be similar to the pattern for conventional helicopters rotors under settling with power condition. The fluctuations and turbulences caused by trailing edge vortices of the forward rotor blades have an effect on the behavior of the rear rotor inflow and changes its behavior in comparison with single rotor. By considering the effects of the body, actual flow fluctuations, and unsteady phenomenon’s occurrences, the results were more realistic. Downwash velocity mean values below the non-central areas of the rotor were more than inflow values but almost in all parts of the rotor, the downwash to inflow velocity ratios are less than 2 times. Therefore, the downwash to inflow equation derived from the momentum theory was not value for the small rotors. It is necessary to pay enough attention to these differences and behaviors in predicting the aerodynamic performance and design of this type of unmanned aerial vehicles. | ||
| کلیدواژه‌ها [English] | ||
| Inflow, down wash, Tandem rotors, Aerodynamic interaction, Unmanned aerial vehicles | ||
| مراجع | ||
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