Cooling Water Jacket Structure Horizontal Diesel Engine Cooling Water Flow Characteristics

Engine is the heat power machine that is applied the most widely in the modern world. Its power, economic, emission, reliable and durable performances will comprehensively deteriorate if it is not properly cooled. But if the cooling effect is too strong, the engine's performance is also becoming bad. Therefore designing better cooling system is not only the basis for the engine's normal operating, but also is an important factor for the comprehensive performance promoting of the engine. In the process of engine's developing for the trend of high speed, high strengthening and high power, the problem of thermal load is becoming more arid more serious, and the design and research of cooling system have aroused more and more concern among the people. The three dimensional flow of coolant in the cooling water jacket can be simulated by means of numerical simulation method based on computational fluid dynamics (CFD) technology, having become an important method to do research on the cooling system of engine.Aiming at the existing technology problems of horizontal, one-cylinder or two-cylinder-diesel engine, the new, horizontal 2115 diesel engine was designed and created for oneself. Therefore, aiming at the designing performance request of cooling system for diesel engine, three dimensional models of cylinder head and cylinder block were established by means of three dimensional modeling software Unigraphics NX, providing geometry model for CFD calculation., also designing testing plans of water flow of cooling water jacket, providing boundary conditions for CFD calculation, and CFD simulation calculation was done for cooling water jacket of the sample engine by means of AVL-FIRE of CFD analysis software as calculation tool. The results indicate that total average flow speed of cooling water jacket for diesel engine is 1.0036m/s, and total average heat transfer coefficient is 7767 W/(m2·K), meeting cooling requests comprehensively. But the cooling effect is not sufficient around exhaust port and in the bridge of the nose whose thermal loads are big, and cooling effect is uneven for the two cylinder, needing structure improvement. Designing nine calculation plans based on DOE theory, discussing the effects of flux of inlet, water cavity section, inlet and water holes distribution on cylinder cushion on the characteristics of cooling water flow, the structure improvement plans of water jacket for 2115 diesel engine were brought forward on the basis of the work above. When the structure is improved, total average flow speed of cooling water jacket for diesel engine is 1.346m/s, and total average heat transfer coefficient is 9826 W/(m2·K), and average speed of the bottom surface of cylinder head is 1.051 m/s, evenness of cooling for each cylinder gaining improvement, providing theoretical references for improvement and final design of cooling water jacket structure of this type of new diesel engine.