A Study of Impinging Spray G on Transient Thermal Loading and Fuel1 Film Deposition

Abstract

Under engine cold-start conditions, gasoline injections result in fuel deposition on the cylinder surfaces, due to inhibited fuel vapourisation when the contact surfaces are cold. This can lead to the presence of unburnt hydrocarbons and the formation of soot. The Engine Combustion Network’s (ECN) Spray G impinging on a wall, under various temperature conditions, was investigated using surface temperature measurements a suite of optical diagnostics including Low-Coherence Interferometry (LCI). PACE20 under different injection and ambient temperatures was tested. The measurements reported are of non-reacting conditions, whereby the focus of the study is to analyse spray-wall interaction, prior to flame arrival. The experiments were performed inside a spray vessel under engine-relevant conditions, with sprays impinging on a temperature-controlled wall equipped with nine fast-response, surface thermocouples. The wall was placed 40 mm downstream from the injector to represent the typical distance between the piston surface and injector during cold-start injections in the intake cycle. The injector was mounted on a rotational stage, causing different regions of the plume to impinge on the thermocouple array. This enabled high spatial and temporal resolution of the surface temperature measurements. LCI was used for film thickness quantification, which provided insights on the film dynamics upon impingement and the evaporation rates. High-speed visualisation techniques further aided in the understanding of transient fuel distribution on the wall.