Investigation of fuel injection in the Common Rail system on the unique scientific facility “Injection”

Abstract

A description of the unique scientific facility “Injection” for experimental investigations of the dynamics development of fuel torches under various conditions of injection into a constant-volume chamber is given. The facility is equipped with the Common Rail fuel systems with adjustable fuel pressure, compressed air supply from the cylinder, scavenging of the constant volume chamber, control of the bench, registration of control pulses, and high-speed video recording of processes inside the chamber. With the help of the controller-synchronizer, the moments of the beginning and the end of the electric pulse of the electromagnetic nozzle were controlled, simultaneous video recording of the Photron FASTCAM SA-X2 color high-speed video camera and the recording of oscillograms on a Tektronix TDS-2014C digital oscilloscope. The duration of the control electric pulse of the nozzle was set from 0,5 ms to 3,0 ms. The pressure in the fuel rail was set from 100 MPa to 165 MPa. The actual moments of the beginning and the end of the fuel injection were determined by the results of the video shooting and counted from its start. The delays of the beginning and the end of injection were determined by comparison the results of video-recording with recording the control electric pulses of fuel nozzle on the oscilloscope. The dynamics of the change in the length and angle of the cone of fuel torches were determined by measuring the contours of the visible parts of the fuel torches on the photorecordings. The delays in the beginning and end of fuel injection were practically 0,3 ms and 1,0 ms, respectively, at all the investigated modes. As a result the duration of the fuel injection process as a rule by 0,7 ms exceeded the duration of the control pulse. At the beginning of injection during 0,5 ms the velocity of the vertices motion of the fuel torches was 35…50 m/s, depending on the pressure, then it decreased to 31…38 m/s. It has been established that when the pressure in the fuel rail increases from 100 MPa to 165 MPa, the angles of cones of fuel torches decrease from 20º…22º to 17,5º…18,5º, that is, on average by 15%.