Abstract
In order to evaluate the flow field characteristics of a marine diesel engine cooling water jacket, and provide a theoretical basis for further optimizing the water jacket structure. A computational fluid dynamics (CFD) method was used to calculate the three-dimensional flow field of the water jacket. Based on the CFD simulation model of the engine water jacket, the analysis of pressure field, velocity field, streamline distribution and flow uniformity of water jacket of diesel engine under rated condition were carried out. The results show that: the total pressure loss of water jacket is 30.3 kPa, in which the pressure loss of cylinder block is 8.4 kPa, and the one of cylinder head and outlet manifold is 21.9 kPa, which indicates that the flow resistance design of the cylinder block and head is reasonable; the flow rate of coolant in the nose zone of cylinder head is above 1.5 m/s, which meets the cooling demand of cylinder head; the cooling water flows circumferentially in the engine block water jacket, and the flow dead zones are easily formed by the mutual extrusion and collision of the water flows; the outlet of the cylinder head water jacket is connected with the outlet manifold at right angle, which leads to large energy loss of the flow field; the maximum non-uniformity of flow rate of water jacket of each cylinder is 5.85%, which can be further optimized by adjusting the position of water jacket inlet.
Highlights
With the rapid increase of the power per unit volume and the power per liter of modern marine diesel engine, the heat load is obviously increased, and the cooling problem is becoming more and more prominent
The pressure field, flow field and the non-uniformity of the flow rate of each cylinder of the cooling water jacket under the rated working condition are analyzed, which points out the direction for the structure optimization of the cooling water jacket
The results are as follows: (1) Under the rated condition, the total water pressure loss of the water jacket is 30.3 kPa, in which the water pressure loss of the engine block is 8.4 kPa, the water pressure loss of the cylinder head and the water outlet main pipe is 21.9 kPa, which is equivalent to the water pressure loss of the same type of diesel engine, indicating that the flow resistance design of the cylinder block and the cylinder head is reasonable
Summary
With the rapid increase of the power per unit volume and the power per liter of modern marine diesel engine, the heat load is obviously increased, and the cooling problem is becoming more and more prominent. It is of great significance to analyze the flow field characteristics of the cooling water jacket for optimizing the structure of the cooling system, improving the cooling efficiency and reducing the heat load of the cylinder head and block. Junjie of Zhejiang University used computational fluid dynamics (CFD) to calculate the flow field of water jacket in cylinder head of diesel engine, and compared and analyzed the streamline diagram and velocity vector diagram measured by CFD simulation and PIV test. In order to evaluate the flow field characteristics of the cooling water jacket of a marine diesel engine and provide the basis for further improving the structure of the cooling water jacket, the 3D CFD simulation of the cooling water jacket of the engine block and cylinder head was carried out by using FLUENT software, and the accuracy of the simulation results was verified by experiments. It points out the direction for further improving the structure of cooling water jacket
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