Research on swirler for intake induced swirl in di diesel engine

Swirl is an important flow pattern of air motion; it not only affects the fuel-air mixing and combustion processes in diesel engine, but also has a significant impact on heat transfer, combustion quality, and engine-raw emissions. For generating swirl efficiently, many researches have been performed; however, almost the methods have more or less crucial disadvantages. For overcoming these shortcomings and generating more efficient swirl during the intake process, the authors design a new device, swirler, to induce intake swirl in non-swirl intake port diesel engine. In this paper, the authors design four types of swirler including one straight-shaped swirler and three arc-shaped swirlers. In order to research the fundamental characteristics of swirler, the authors make series of experiments researches. The total researches can be divided into three stages: in the first stage, steady flow tests are carried for researching the swirl capability and the discharge capability of swirler from the macro-level; in the second stage, flow fields in the cylinder are measured by Particle Image Velocimetry (PIV) technique in the water analog tests for researching the swirl performance from the micro-level; at last stage, the tested swirler is installed on a certain type of actual diesel engine for studying whether swirler can improve the engine operation performance noticeably. The results show that this new device can induces intake swirl efficiently and can improve fuel economy at on an optimized swirl ratio.