1D-3D Coupling for Gas Flow Analysis of the Air-Intake System in a Compression Ignition Engine

Devices for reducing environmental pollutant emissions are being installed in ship compression ignition (CI) engines; alternatively, the designs of intake and exhaust pipes and ports are being modified to tune the performance according to the user's needs. In both cases, substantial computation time and cost are required to simulate the gas flow of the CI engine with an air-intake system. In order to simulate the air-intake system of the CI engine, which changes according to the user's needs, at a low cost and in a short time, we aimed to analyze the gas flow using a 1D-3D coupled method. The 1D zone was analyzed using the method of characteristics, and the 3D zone was analyzed using the commercial computational fluid dynamics (CFD) code Ansys Fluent R15.0, whereas their coupling was achieved by applying the developed 1D-3D coupling algorithm to Ansys Fluent R15.0 using user-defined functions (UDFs). In the comparison of the pressure of the intake pipe with the experimental result, the average error was 0.58%, thereby validating the approach. In addition, when analyzing the intake pipe and port in a 3D zone, the results of the velocity and pressure were expressed as contours, allowing them to be visualized. It is expected that the 1D-3D coupling algorithm of the air-intake system can be used to reflect the user's needs and can be used as a method to quickly and accurately calculate the gas flow within tens of minutes.