3-D Simulation Of Flow Characteristics On Lubricating System Of A V Type Multi-cylinder Diesel Engine

The lubrication system is one of the most important systems of a diesel engine, and it guarantees efficient and reliable performance of a diesel engine. Piston cooling jet cools a piston down by injectting cool engine oil into the Cooling gallery of the piston, its work performance has great effects on the working reliability and power of a diesel engine. By using the three-dimensional fluid simulation software Fluent, the flow characteristics of the lubrication system and the piston cooling jet of a V typed multi cylinder diesel engine is studied.The model of the cooling system and piston cooling jet oil flow are built by Solidworks. The model of the cooling system includes assisting oil passage in the accessory shelf, oil cooler, oil cleaner and the main oil passage in the crankcase and the simplified oil passages of all the components that need lubrication. The model of piston cooling jet includes oil passage in the oil nozzle, the cavity under the piston and the cooling gallery.The simulation calculation of the cooling system when the pressure adjusting valve is open is conducted by Fluent. The results show that, among the main parts of the flow domain, the pressure loss at the accessory shelf is about 0.352 MPa, the pressure loss at the main oil passage is 0.145 MPa; among the three main oil passages, the the oil passage of oil supply camshaft bearings has the highest oil pressure while the left oil passage has the lowest, the right oil passage has the biggest amount of oil flow while the oil passage of oil supply camshaft bearings has the smallest. Among all the outlets, the valve camshaft bearings have the highest amount of flow, while the turbo charge bearings have the lowest. The valve camshaft bearings also have the highest unevenness of outflow distribution.The research also studies the flow characteristics of the lubrication system with the same working condition under the circumstances that, the pressure adjusting valve is shut. The results show that, the oil pressure in the flow domain is raised by about 0.18 MPa, in the main oil passage, the pressure raise of the right passage is higher, while the amount of flow at both sides are reduced. Another interesting phenomenon is that, at the end of the oil passage, the right side starts suppling oil to the left side. All of oulets except the pressure limiting valve experience raised outflow of oil. The unevenness of outflow distribution drops only at the turbo charge bearings, it incresses at all the other outlets.The research also studies the flow character of the piston cooling jet under different working conditions and at different piston positions. The results show that, after the oil is released from the nozzle, the diameter of the oil flow expands, there is a core of high-speed oil and a parameter of low-speed oil. When the piston is moving from the bottom dead point to 16 mm position, the impact point between the oil and the piston wall is moving closer to the inlet of the cooling gallery, when the piston is stationed at a distance of 16 mm to 48 mm to the bottom dead point, the impact point is in the inlet, when he piston is moving from 48 mm to 145 mm position, the impact point is moving away from the inlet. After the oil hits the piston wall, it continues to flow on the surface of the wall, but the oil flow separate into several oil flows. When the piston is stationed at a distance of 16 mm and 32 mm to the bottom dead point, all the oil released from the nozzle is injected into the cooling gallery, while none of the oil released from the nozzle is injected into the cooling gallery, when the piston is stationed at a distance of 96 mm to 145 mm to the bottom dead point. The oil volume fraction in the oil chamber is the highest when the the piston is stationed at a distance of 16 mm to the bottom dead point, while the oil volume fraction on the oil chamber wall is the highest when the the piston is at the bottom dead point.