مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

بررسی عددی پدیده کاویتاسیون در انژکتور روی رفتار اسپری سوخت دیزل

نویسندگان
1 عضوهیات علمی
2 دانشگاه تبریز،تبریز،ایران
چکیده
در موتورهای دیزل تزریق مستقیم، هندسه نازل به علت تاثیر گذاری روی جریان داخلی، پدیده کاویتاسیون، مشخصات اسپری سوخت و رفتار اتمیزاسیون به عنوان یک موضوع مهم برای تحقق کنترل انتشار گاز است. که برای عمکرد موتورها و تشکیل آلاینده بسیار مهم است. هدف این مقاله بررسی عددی تاثیر پدیده کاویتاسیون روی رفتار اسپری دیزل از قبیل طول نفوذ افشانه و قطر متوسط ساتر است. برای ایجاد پدیده کاویتاسیون و بررسی تاثیر آن روی مشخصات اسپری سوخت از دو انژکتور مشابه با سطح مقطع ورودی نازل متفاوت استفاده شده است و جریان مایع درون آن ها و رفتار اسپری حاصل از آن ها بررسی شده است( این کار با جابجایی نازل روی بدنه انژکتور انجام شده است). برای مش زنی و شبیه سازی و حل معادلات بقا از نرم افزارAVL-FIRE استفاده شده است. نتایج نشان می‌دهد که با قرار دادن نازل در قسمت پایین‌تر کیسه‌ انژکتور میزان کسر حجمی فاز بخار افزایش یافته و رشد پدیده کاویتاسیون زیادتر می‌شود. همچنین نتایج اسپری نشان می‌دهد که طول نفوذ افشانه برای سوراخ نازل پایین تر افزایش پیدا می‌کند . نکته قابل توجه این است که تغییر قابل توجهی در اندازه قطرات اسپری برای هر دو انژکتور دیده نمی شود. و مهم تر از همه، طول نفوذ افشانه سوخت با تغییر محل سوراخ نازل انژکتور می تواند کنترل شود.
کلیدواژه‌ها

عنوان مقاله English

Numerical investigation of the cavitation phenomenon on spray behavior of diesel fuel in injector

نویسنده English

saeid azizi hasanakloo 2
2 department of mechanical engineering, Tabriz university,Tabriz, Iran
چکیده English

In direct injection diesel engines, diesel nozzle geometry is a major issue in order to fulfill control of emission due to the influence on internal flow, cavitation phenomenon, spray characteristics and therefore atomization behavior, which are very important for engines performance and

pollutant formation. The aim of this article is to study the effect of cavitation on Diesel spray behavior such as spray penetration lengths and sauter mean diameter. In this study To create a cavitation phenomenon and to investigate its effect on the fuel spray characteristics two similar injector different in the inlet cross section nozzle have been considered and their internal liquid flow and the behavior of their resulted sprays have been investigated( this has been done by moving nozzle on the injector body). AVL-Fire CFD code has been used for meshing and simulating and solving the conservation equations. The results show that by placing the nozzle hole in lower part of the injector sac, the volume fraction of the vapor phase increases. So the growth of the cavitation phenomenon increases. Also the results of the spray show that the spray penetration length for lower nozzle hole increases. An interesting point is that there is no significant change in the size of the spray droplet for two injectors. Most importantly, the spray penetration length can be controlled by place of nozzle hole.

کلیدواژه‌ها English

Injector geometry
cavitation phenomenon
fuel spray
[1] F. J. Salvador, J. Martínez-López, M. Caballer, C. De Alfonso, Study of the influence of the needle lift on the internal flow and cavitation phenomenon in diesel injector nozzles by CFD using RANS methods, Energy Conversion and Management, Vol. 66, No. 2, pp. 246-256, 2013.
[2] C. Yao, C. Cheung, C. Cheng, Y. Wang, Reduction of smoke and NO x from diesel engines using a diesel/methanol compound combustion system, Energy & fuels, Vol. 21, No. 2, pp. 686-691, 2007.
[3] C. Yao, P. Geng, Z. Yin, J. Hu, D. Chen, Y. Ju, Impacts of nozzle geometry on spray combustion of high pressure common rail injectors in a constant volume combustion chamber, Fuel, Vol. 179, No. 1, pp. 235-245, 2016.
[4] W. Huang, Z. Wu, H. Gong, Y. Gao, J. Deng, Z. Hu, L. Li, Effect of nozzle geometry on macroscopic behavior of diesel spray in the near-nozzle field, SAE Technical Paper, Vol. 12, No. 2, pp. 1236-1246, 2013.
[5] K. Sato, J. Kanzaki, M. Yamakawa, K. Nishida, Effects of hole geometry and its internal flow on spray and mixture properties of hole-type injectors for a DISI engine, Proceedings of the International Conference on Liquid atomization and spray systems, Koyoto, Japan , Vol. 27, No. 4, pp. 06-16, 2006.
[6] M. A. Shost, M. C. Lai, B. Befrui, P. Spiekermann, D. L. Varble, GDi nozzle parameter studies using LES and spray imaging methods, SAE Technical Paper, Vol. 17, No. 20, pp. 650-661, 2014.
[7] P. Bergstrand, The effects of orifice shape on diesel combustion, SAE Technical Paper, Vol. 13, No. 3, pp. 106-116, 2004.
[8] P. K. Karra, S. C. Kong, Experimental study on effects of nozzle hole geometry on achieving low diesel engine emissions, Journal of Engineering for Gas Turbines and Power, Vol. 132, No. 2, pp. 22-35, 2010.
[9] S. Som, A. I. Ramirez, D. E. Longman, S. K. Aggarwal, Effect of nozzle orifice geometry on spray, combustion, and emission characteristics under diesel engine conditions, Fuel, Vol. 90, No. 3, pp. 1267-1276, 2011.
[10] M. T. Shervani-Tabar, S. Parsa, M. Ghorbani, Numerical study on the effect of the cavitation phenomenon on the characteristics of fuel spray, Mathematical and Computer Modelling, Vol. 56, No. 5, pp. 105-117, 2012.
[11] H. Mohammadi, P. Jabbarzadeh, M. Jabbarzadeh, M. T. Shrevani-Tabar, Numerical investigation on the hydrodynamics of the internal flow and spray behavior of diesel fuel in a conical nozzle orifice with the spiral rifling like guides, Fuel, Vol. 196, No. 5, pp. 419-430, 2017.
[12] F. Payri, V. Bermúdez, R. Payri, F. J. Salvador, The influence of cavitation on the internal flow and the spray characteristics in diesel injection nozzles, Fuel, Vol. 83, No. 4, pp. 419-431, 2004.
[13] R. Payri, F. J. Salvador, J. Gimeno, J. de la Morena, Study of cavitation phenomena based on a technique for visualizing bubbles in a liquid pressurized chamber, International Journal of Heat and Fluid Flow, Vol. 30, No. 4, pp. 768-777, 2009.
[14] H. K. Suh, C. S. Lee, Effect of cavitation in nozzle orifice on the diesel fuel atomization characteristics, International Journal of Heat and Fluid Flow, Vol. 29, No. 4, pp. 1001-1009, 2008.
[15] Z. Y. Sun, G. X. Li, C. Chen, Y. S. Yu, G. X. Gao, Numerical investigation on effects of nozzle’s geometric parameters on the flow and the cavitation characteristics within injector’s nozzle for a high-pressure common-rail DI diesel engine, Energy Conversion and Management, Vol. 89, No. 1, pp. 843- 861, 2015.
[16] S. H. Park, H. K. Suh, C. S. Lee, Effect of cavitating flow on the flow and fuel atomization characteristics of biodiesel and diesel fuels, Energy & Fuels, Vol. 22, No. 1, pp. 605-613, 2007.
[17] S. Khosravi, M. Aansari, The effect of various parameters on breakup length of the outflow from nozzle, Modares Mechanical Engineering, Vol. 12, No. 4, pp. 125-133, 2012. (in persion فارسی(
[18] S. Sohrabi, A. Zandi, M. Shams, Numerical investigation of the effect of the number of injector holes on the flow inside the nozzle, 8th International Conference on Internal Combustion Engines & Oil, Tehran, Iran, 2013. (in (فارسی persion
[19] P. Jabbarzadeh, M. Jabbarzadeh, M. T. Shervanitabar, Numerical study on the diesel fuel penetration length in the cylindrical and conical nozzles, 8th International Conference on Internal Combustion Engines & Oil, Tehran, Iran, 2013. (in persion فارسی(
[20] F. Salvador, J. Martínez-López, J. V. Romero, M. D. Roselló, Computational study of the cavitation phenomenon and its interaction with the turbulence developed in diesel injector nozzles by Large Eddy Simulation (LES), Mathematical and Computer Modelling, Vol. 57, No. 7, pp. 1656-1662, 2013.
[21] Fire Software help, AVL, Version. 2013
[22] S. Som, S. Aggarwal, Effects of primary breakup modeling on spray and combustion characteristics of compression ignition engines, Combustion and Flame, Vol. 157, No. 6, pp. 1179-1193, 2010. ]23] J. Desantes, R. Payri, F. Salvador, J. De la Morena, Influence of cavitation phenomenon on primary break-up and spray behavior at stationary conditions, Fuel, Vol. 89, No. 7, pp. 3033-3041, 2010.
[24] N. Dombrowski, P. Hooper, The effect of ambient density on drop formation in sprays, Chemical Engineering Science, Vol. 17, No. 2, pp. 291- 305, 1962.