1D-3D 결합을 이용한 디젤엔진의 비정상 가스유동 해석

Abstract

To meet the regulations on emissions of environmental pollutants from ships, air pollution control devices were installed or dual fuel engines were used. The dual fuel engines should install explosion relief valves in the intake and exhaust systems because they use gas fuel. In order to install air pollution control devices or explosion relief valves in the intake and exhaust systems and to predict their performance, it is necessary to analyze the gas flow of the entire engine system. A gas flow analysis of the entire engine system in a 3D(three-dimensional) format needs a high-resolution workstation and an enormous amount of time for the computation. A gas flow analysis in a 1D(one-dimensional) format has a high-speed computing and high accuracy in a straight pipe, but poor accuracy in complex geometries such as curved pipes, tapered pipes and pipe junctions, etc. Therefore 1D-3D coupling format is needed for the analysis of unsteady gas flow in diesel engines. In this paper, 1D-3D coupling algorithm suitable for the analysis of unsteady gas flow in diesel engines was developed to analyze the entire diesel engine system and save computational time. The 1D-3D coupling algorithm was coded using UDFs(User-Defined Functions), and the MOC(method of characteristics) and the commercial CFD(computational fluid dynamics) code, ANSYS FLUENT R15.0 were used to couple 1D and 3D. An unsteady gas flow analysis was performed using the 1D-3D coupling algorithm for a diesel engine and the experimental results were compared for validation. The 1D-3D coupling gas flow analysis was able to compute complex geometries into a 3D zone, and it computed about 300 times faster than the 3D gas flow analysis. The unsteady gas flow analysis using 1D-3D coupling algorithm was expected to be used to analyze accurate results for the cylinders, intake and exhaust systems of diesel engines to save computational time.