Influence of a Swirling Air Flow on an Evaporating Diesel Spray from a Common Rail Injection System under Realistic Engine Conditions
The aim of the present paper is to provide an insight into the fluid dynamic processes that occur during the air/fuel mixture formation period in direct injection diesel engines. An experimental and numerical investigation has been performed to analyse the mixing process between an evaporating diesel spray and a swirl air flow under realistic engine conditions. Experimental tests have been carried out spraying the fuel within an optically accessible prototype 2-stroke Diesel engine equipped with an external combustion chamber having cylindrical shape. The intake air flow, coming from the engine cylinder, is forced within the combustion chamber by means of a tangential duct generating a well structured swirl flow similar to that developing in a real light duty diesel engine with a high swirl ratio. A micro-sac 5-hole, 0.13 mm diameter, 150° spray angle electro-hydraulic injector supplies the fuel by a common rail injection system able to manage multiple injection strategies.