Experimental-Numerical Analysis of Gasoline Spray-Wall Impingement at Ultra-High Injection Pressure for GCI Application

Nowadays, in the perspective of a full electric automotive scenario, internal combustion engines can still play a central role in the fulfilment of different needs if the efficiency will be improved, and the tailpipe emission will be further limited. Gasoline Compression Ignition engines can offer a favourable balance between NOx, particulate, operating range. Stable operations are ensured by ultra-high gasoline injection pressure and tailored injection patterns in order to design the most proper local fuel distribution. In this context, engine simulations by means of CFD codes can provide insights on the design of the injection parameters, and emphasis must be placed on the capture of spray-wall impingement behaviour under those non-conventional conditions. This paper aims to analyse the spray-wall impingement behaviour of ultra-high gasoline spray using a combined experimental-CFD approach. The fuel is injected inside a vessel through a single-hole nozzle at GCI-like injection pressure (500-700 bar) against a metal surface. At the test bench, optical measures were performed by means of the Mie-scattering technique in order to capture the impact morphology. Furthermore, some synthetic features of the impact were calculated, namely the thickness and the width of the rebound cloud. In order to focus on the wall film formation mechanism, the tests were conducted at room temperature. Then, the experimental data were used to validate the CFD spray-wall impingement methodology and tuning.