커먼레일 디젤인젝터에서 분사성능 개선을 위한 내부유로형상 최적화에 관한 연구

In recent years, common-rail injection(CRDI) engines have become more common as power sources for passenger cars and light duty trucks because of stricter exhaust emission standards, satisfaction of consumer demands for better fuel efficiency and increased power. Specifically, common-rail diesel injectors are the most critical component of the CRDI engines that determine engine performances through high pressure injection with exact control. Therefore, the studies on the numerical and experimental analysis of the diesel injector focus on a optimum geometry to induce proper injection rate. In this study, design parameters of an entire injector duct are optimized by using a three-dimensional computational fluid dynamics(CFD) analysis and Response Surface Method(RSM). The CFD analysis is simulated by employing STAR-CCM+ 7.06 code, and the entire internal flow was assumed to be steady-state at the maximum needle lift. The design parameters are optimized by using the L16 orthogonal array and polynomial regression, local-approximation characteristics of RSM. Meanwhile, the optimum values are confirmed to be similar in 95% confidence and 5% significance level through analysis of variance(ANOVA). Futhermore, optimal design and prototype design were compared by calculating the injection quantities, resulting in the improvement of the injection performance more than 54%.