Research On The Performance Of A 16V Type Diesel Engine Using Stc

The sequential turbocharging (STC) technology is one of the most effective methods to improve the low condition performance of the highly turbocharged diesel engines. In this paper, in order to improve the low load performance of a 16V-type marine diesel engine, the structure of the STC is designed by using the software of GT-POWER and STAR-CD.By using GT-POWER software, a calculating model of the 16V-type turbocharging diesel working process is set up. The calculated results tend to be in agreement with the experimental ones and then the STC diesel working process model is built. The results indicate that after employing STC,the diesel engine improves its low load performance distinctively. Based on the steady performance simulation model, the transition model is built for the STC diesel. The status switch process of the sequential is studied, and the calculated results show that the butterfly delay time step must be set properly during the controlled turbocharger switch-in process, that is the air valve must be opened later than gas valve, if the time step is too short, then the controlled turbocharger may be surge, but if the time step is too long, the basic turbocharger would appear unsteady phenomenon.The structures of the STC system include the control valves and the intake and exhaust system. The calculation and analysis of the selection of air valve and gas valve are done in this paper, gains the valve that satisfies the STC system and the installation position of the gas valve is determined.The exhaust system of the STC diesel is one of the main contents in this paper. Three types of the exhaust connective pipe model are designed. Then the three-dimensional mathematical models can be set up by using STAR-CD. And an appropriate type of the exhaust connective pipe can be obtained by analyzing the results comprehensively. One-dimensional and three-dimensional coupling model can not only consider the dynamic effect on one-dimensional model, but also reflect on the diesel engine performance influenced by three-dimensional structure. Based on the software of GT-POWER and STAR-CD, a one-dimensional and three-dimensional coupling model for the STC diesel is set up. This model can simulation the actual intermittent operation of the exhaust system, and gains the velocity distributing at different crank angle. The results has provided the evidence for the exhaust system design and set the stage for the further research.