Visualization and Measurements of Sub-Millisecond Transient Spray Dynamics Applicable to Direct Injection Gasoline Engine : Part3:Measurements of Instantaneous and Integrated Flow Rates in High Pressure Injection System Using LDA-Based Meter

Time-dependent centerline velocity is measured using LDA-flow meter. Swirl injector at frequencies of 22 and 46 Hz generates oscillated flow under high-pressure from 4 up to 7 MPa. The encoded time-series of velocity is used to reconstruct the time-variable series of instantaneous flow rate and pressure gradient. Transient injection dynamics are analyzed to obtain basec characteristics of an injection system that will be able to be used for real time monitoring or active controlling of high-pressure gasoline injectors. The results obtained through analyzing the integrated mass rates within a cycle, indicate that a certain injection system is characterized by the flow rate constant γ which independent on injection duration and can be obtained from only accurate measurement of centerline velocity in the fuel transport pipeline. The present technique allows us to simplify the injection model and can be effectively adopted for practical employment on active and passive control with respect to gasoline direct injection engines.