Study of diesel fuel multiple injection characteristics using shadow-graphic imaging technique with CRDI system in constant volume chamber

The behaviour of injection spray characteristics is an essential part to better understand the combustion. Thus, to address the hurdles faced during physical measurement of spray structural properties an efficient visual technique is required. With the point of promoting the estimation of injected spray split-positional characterisation along with fuel injection time duration is being performed on multiple injection strategy with diesel as working fluid. Further, through visual examination characteristics of spray tip penetration along with the motion of the injected spray is performed. A visualisation set called shadowgraph optical technique is implemented to capture the injected fluid spray inside the combustion chamber by common rail direct injection. The developed MATLAB algorithm is validated from the obtained results, the effective estimation of spray intensity between 1st spray injection and 2nd spray injection supports in a way to choose the appropriate dwell time between successive injections which avoid the formation of the pocketed fuel-rich region. From the results of the case example, observed that 1st spray injection duration take persists throughout for 1680 mu s, dwell time duration is 67.2 mu s and 2nd spray injection duration occurs for 1276.8 mu s. So, the choice of 2nd spray injection after 1680 mu s from the injection point of 1st spray is advisable. Further, fuel spray tip penetration is observed as 50.6122 mm length and cone angle as 152 degrees, examined and visualised during the operation. The developed MATLAB algorithm for an optical spray visualization technique has an efficient impact in determining the characteristics of fuel spray injected throughout the multiple injection process.