پیوندهای مفید
آمار
| تعداد نشریات | 7 |
| تعداد شماره‌ها | 399 |
| تعداد مقالات | 5,389 |
| تعداد مشاهده مقاله | 5,288,038 |
| تعداد دریافت فایل اصل مقاله | 4,882,776 |
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 (1.76 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 | ||
|
سایر فایل های مرتبط با مقاله
|
||
| مراجع | ||
|
[1] D. Schrage, M. Costello, D. Mittleider, Design concepts for an advanced cargo rotorcraft, Journal of the American Helicopter Society, 34(4) (1989) 56-65. [2] A. Antoniadis, D. Drikakis, B. Zhong, G. Barakos, R. Steijl, M. Biava, L. Vigevano, A. Brocklehurst, O. Boelens, M. Dietz, Assessment of CFD methods against experimental flow measurements for helicopter flows, Aerospace Science and Technology, 19(1) (2012) 86-100. [3]J.Y. Hwang, O.J. Kwon, Assessment of S-76 rotor hover performance in ground effect using an unstructured mixed mesh method, Aerospace Science and Technology, 84 (2019) 223-236. [4] M. Ramasamy, M. Potsdam, G.K. Yamauchi, Measurements to Understand the Flow Mechanisms Contributing to Tandem-Rotor Outwash, (2018). [5] J. Leishman, Principles of Helicopter Aerodynamics, CambridgeUniv, Press, New, (2000). [6] D. Shukla, N. Komerath, Multirotor Drone Aerodynamic Interaction Investigation, Drones, 2(4) (2018) 43. [7] D.A. Peters, S.Y. Chen, Momentum Theory, Dynamic Inflow, and the Vortex‐Ring State, Journal of the American Helicopter Society, 27(3) (1982) 18-24. [8] W. Stepniewski, A simplified approach to the aerodynamic rotor interference of tandem helicopters, in: Proc Annu Western Forum, 1955, pp. 71-90. [9] W.Z. Stepniewski, C. Keys, Rotary-wing aerodynamics, Courier Corporation, 1984. [10] 24-ft Wind Tunnel Tests of Model Multi-Rotor Helicopters, RAE Report No. Aero 2207, 1947. [11] G.E. Sweet, Hovering measurements for twin-rotor configurations with and without overlap, (1960). [12] R.C. Dingeldein, Wind-tunnel studies of the performance of multirotor configurations, (1954). [13] F.D. Harris, Twin rotor hover performance, Journal of the American helicopter society, 44(1) (1999) 34- 37. [14] M. Knight, R.A. Hefner, Static thrust analysis of the lifting airscrew, (1937). [10] M.K. Taylor, A balsa-dust technique for air-flow visualization and its application to flow through model helicopter rotors in static thrust, (1950). [16] E.A. Fradenburgh, Flow Field Measurements for a Hovering Rotor Near the Ground, in: Fifth Annual Western Forum, Los Angeles, CA, 1958. [17] W. Schane, Effects of Downwash Upon Man, ARMY AEROMEDICAL RESEARCH UNIT FORT RUCKER AL, 1967. [18] J.R. Preston, S. Troutman, E. Keen, M. Silva, N.Whitman, M. Calvert, M. Cardamone, M. Moulton, S.W. Ferguson, Rotorwash Operational Footprint Modeling, MISSILE RESEARCH DEVELOPMENT AND ENGINEERING CENTER REDSTONE ARSENAL AL …, 2014. [19] W. Brady, G.R. Ludwig, TheoreticalAnd Experimental Studies Of Impinging Uniform And Nonuniform Jets, Cornell Aeronautical Lab Inc Buffalo Ny, 1964. [20] R.E. Kuhn, An investigation to determine conditions under which downwash from VTOL aircraft will start surface erosion from various types of terrain, National Aeronautics and Space Administration, 1959. [21] P. Hrycak, Experimental flow characteristics of a single turbulent jet impinging on a flat plate, National Aeronautics and Space Administration, 1970. [22] M. Glauert, The wall jet, Journal of Fluid Mechanics, 1(6) (1956) 625-643. [23] P.R. Spalart, On the flow field induced by a hovering rotor or a static jet, Journal of Fluid Mechanics, 701 (2012) 473-481. [24] A.J. Wadcock, L.A. Ewing, E. Solis, M. Potsdam, G. Rajagopalan, Rotorcraft downwash flow field study to understand the aerodynamics of helicopter brownout, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH …, 2008. [25] A. Radhakrishnan, F. Schmitz, An experimental investigation of a quad tilt rotor in ground effect, in: 21st AIAA Applied Aerodynamics Conference, 2003, pp. 3517. [26] F.F. Felker, J.S. Light, Aerodynamic interactions between a rotor and wing in hover, Journal of the American Helicopter Society, 33(2) (1988) 53-61. [27] C. Phillips, H.W. Kim, R.E. Brown, The flow physics of helicopter brownout, in: 66th American Helicopter Society Forum: Rising to New Heights in Vertical Lift Technology, 2010. [28] C. Phillips, R.E. Brown, Eulerian simulation of the fluid dynamics of helicopter brownout, Journal of Aircraft, 46(4) (2009) 1416-1429. [29] D.P. Garrick, R.G. Rajagopalan, K. Guntupalli, Simulation of Landing Maneuvers of Rotorcraft in Brownout Conditions, in: 2013 International Powered Lift Conference, 2013, pp. 4266. [30] J.F. Tan, T.Y. Zhou, Y.M. Sun, G.N. Barakos, Numerical investigation of the aerodynamic interaction between a tiltrotor and a tandem rotor during shipboard operations, Aerospace Science and Technology, 87 (2019) 62-72. [31] M. Derby, G. Yamauchi, Design of 1/48th-scale models for ship/rotorcraft interaction studies, in: 21st AIAA Applied Aerodynamics Conference, 2003, pp. 3952. [32] B. Johnson, J.G. Leishman, A. Sydney, Investigation of Sediment Entrainment Using Dual‐Phase, High‐ Speed Particle Image Velocimetry, Journal of the American Helicopter Society, 55(4) (2010) 42003- 42003. [33] M. George, E. Kisielowski, D. Douglas, Investigation of the Downwash Environment generated by V/STOL Aircraft operating in Ground Effect, DYNASCIENCES CORP BLUE BELL PA, 1968. [34] J. Milluzzo, J.G. Leishman, Assessment of rotorcraft brownout severity in terms of rotor design parameters, Journal of the American Helicopter Society, 55(3) (2010) 32009-32009. [35] D.J. Hohler, An Analytical Method of Determining General Downwash Flow Field Parameters for V/ STOL Aircraft, AIR FORCE AERO PROPULSION LAB WRIGHT-PATTERSON AFB OH, 1966. [36] M. Silva, R. Riser, CH-47D tandem rotor outwash survey, in: AHS 67th Annual Forum, 2011. [37] J.-f. Tan, H.-w. Wang, Simulating unsteady aerodynamics of helicopter rotor with panel/viscous vortex particle method, Aerospace Science and Technology, 30(1) (2013) 255-268. [38] F. Shahmiri, " Experimental investigation of the hovering performance of a twin-rotor test model," Journal of Aerospace Science and Technology (JAST), vol.10, no. 2, pp.1-7, 2013. [39] A. Halliday, D. Cox, Wind Tunnel Experiments on a Model of a Tandem Rotor Helicopter, HM Stationery Office, 1961. [40] F. Handbook, 8083-21, Rotorcraft Flying Handbook, (2000). [41] J. Seddon, S. Newman, Basic helicopter aerodynamics, American Institute of Aeronautics and Astronautics, 2001. [42] J.G. Leishman, A. Baker, A. Coyne, Measurements of rotor tip vortices using three‐component laser Doppler velocimetry, Journal of the American Helicopter Society, 41(4) (1996) 342-353. [43] W. Johnson, Helicopter theory, Courier Corporation, 2012. [44] T.E. Lee, J.G. Leishman, M. Ramasamy, Fluid dynamics of interacting blade tip vortices with a ground plane, Journal of the American Helicopter Society, 55(2) (2010) 22005-22005. [45] J. Wolkovitch, Analytical Prediction of Vortex‐Ring Boundaries for Helicopters in Steep Descents, Journal of the American Helicopter Society, 17(3) (1972) 13- 19. [46] A. AZUMA, Induced flow variation of the helicopter rotor operating in the vortex ring state, Journal of Aircraft, 5(4) (1968) 381-386. [47] J. Stack, F.X. Caradonna, Ö. Savaş, Flow visualizations and extended thrust time histories of rotor vortex wakes in descent, Journal of the American Helicopter Society, 50(3) (2005) 279-288. [48] M.D. Betzina, Tiltrotor descent aerodynamics: A small-scale experimental investigation of Vortex Ring State, in: American Helicopter Society 57th Annual Forum, Washington, DC, 2001. [49] M.J. Bhagwat, J.G. Leishman, Stability analysis of helicopter rotor wakes in axial flight, Journal of the American Helicopter Society, 45(3) (2000) 165-178. [50] J.R. Spreiter, The rolling up of the trailing vortex sheet and its effect on the downwash behind wings, Journal of the Aeronautical Sciences, 18(1) (1951) 21- 32. [51] R. Brown, J. Leishman, S. Newman, F. Perry, Blade twis effects on rotor behaviour in the vortex ring state, (2002). [52] A. Azuma, J. Koo, T. Oka, K. Washizu, Experiments on a model helicopter rotor operating in the vortex ringstate, Journal of Aircraft, 3(3) (1966) 225-230. | ||
|
آمار تعداد مشاهده مقاله: 485 تعداد دریافت فایل اصل مقاله: 1,163 |
||
