ガス燃料噴射エンジンにおけるガス噴流解析精度向上のためのガスパーセル法の提案

抄録

Generally, for numerically analyzing gas jets, computational mesh spacing must be smaller than the diameter of an injector nozzle. However, in performing three-dimensional flow analysis in the combustion chamber of a gas fuel injection engine, it is not realistic due to very long calculation time to use a fine mesh with spacing comparable to the diameter of an injector nozzle. Then, the authors devised a gas parcel method expressing local gas velocity distribution within mesh spacing, and verified its validity as follows:
Firstly, an air jet injected into air was numerically analyzed using this method with a mesh having ten times larger spacing than the diameter of an injector nozzle. Basic characteristics (maximum velocity, velocity distribution and half width) of the calculated results were compared with theoretical values. It was found that the calculated results nearly reproduce the tendencies of theoretical values. Secondly, this method was applied to the numerical analysis of a hydrogen gas jet injected into air. It was found that the penetration, concentration distribution and shape of the jet are qualitatively in agreement with experimental results. As a result, it was shown that the proposed gas parcel method is effective in improvement of the accuracy of practical gas jet analysis.