مطالعه عددي تأثير افزايش شدت توربولانسي و تغيير زاويه پاشش سوخت بر روي عملكرد و آلايندگي موتور ديزل دريايي كاترپيلار

N‌U‌M‌E‌R‌I‌C‌A‌L I‌N‌V‌E‌S‌T‌I‌G‌A‌T‌I‌O‌N O‌N T‌H‌E E‌F‌F‌E‌C‌T O‌F I‌N‌C‌R‌E‌A‌S‌I‌N‌G T‌U‌R‌B‌U‌L‌E‌N‌C‌E I‌N‌T‌E‌N‌S‌I‌T‌Y A‌N‌D C‌H‌A‌N‌G‌I‌N‌G T‌H‌E I‌N‌J‌E‌C‌T‌I‌O‌N A‌N‌G‌L‌E O‌N T‌H‌E P‌E‌R‌F‌O‌R‌M‌A‌N‌C‌E A‌N‌D E‌M‌I‌S‌S‌I‌O‌N O‌F C‌A‌T‌E‌R‌P‌I‌L‌L‌A‌R

در اين نوشتار، به بررسي تأثير افزايش شدت توربولانسي و تغيير زاويه‌ي پاشش سوخت بر عملكرد و آلايندگي موتور ديزل دريايي كاترپيلار به كمك روش ديناميك سيالات محاسباتي در نرم‌افزار فاير پرداخته شده است. به منظور افزايش شدت توربولانسي از شيار درون نازل انژكتور استفاده شده و زاويه‌ي پاشش سوخت افزايش داده شده است. نتايج عددي شبيه‌سازي انژكتور و موتور ديزل در شرايط كاركردي با داده‌هاي تجربي مقايسه و تطابق خوبي بين آن‌ها مشاهده شده است. نتايج مربوط به عملكرد موتور ديزل نشان مي‌دهد كه ايجاد شيار، افزايش شدت توربولانسي و زاويه‌ي پاشش سوخت منجر به افزايش 75 درصدي توان و گشتاور توليدي و كاهش 37 درصدي مصرف سوخت نسبت به نازل استوانه‌يي سوخت مي‌شود. همچنين نتايج مربوط به آلايندگي اين موتور ديزل دريايي نشان مي‌دهد كه در اين حالت آلاينده‌ي مونوكسيد كربن و اكسيد نيتروژن به مقدار 42٫73 درصد و 45٫45 درصد كاهش مي‌يابد.

In this article, the effect of increasing turbulence intensity and changing fuel injection angle on performance and pollution of Caterpillar marine diesel engine has been investigated using computational fluid dynamics method in Fire software. To this end, two phase flow inside the diesel injector was simulated using the CFD.Solidworks software has been used for geometry creation and AVL-Fire software has been used for meshing and simulating. In order to increase the turbulence intensity, the groove inside the injector nozzle has been used and the fuel injection angle has been increased. Numerical results of injector and diesel engine simulation in operating conditions were compared with experimental data and a good agreement was observed between them. The results of diesel engine performance show that grooving, increasing turbulence intensity and fuel injection angle lead to a 75% increase in power and torque output and a 37% reduction in fuel consumption compared to the cylindrical fuel nozzle. Also, the results related to the pollution of this marine diesel engine show that in this case, the pollutants of carbon monoxide and nitrogen oxide decreasing 42.73% and 45.45%, respectively. Also, in this case, the engine has no problem in terms of producing soot pollutants and the soot produced during the combustion process is well oxidized. Then, in order to create a rotational flow and reduce the intensity of cavitation as well as the resulting erosion, the geometry of the cylindrical nozzle hole was changed to a converging cone and the groove inside it was used. The numerical results show that changing the geometry of the nozzle hole and creating a rotational flow inside it leads to reducing the severity of cavitation and thus reducing the erosion and corrosion caused by it and increasing the life of the injector nozzle. Thus the fuel spray characteristics can be controlled by creation of swirly flow and changing the nozzle geometry and needle lift profile. Numerical results and experimental data validated from previous researches.