Review of 1D Spray Tip Penetration Models and Fuel Properties Influence on Spray Penetration

In this article different one-dimensional (1D) models for spray penetration have been reviewed and investigated to confirm their validity. For each model, the underlying assumptions and the main equations were discussed in detail. A comparison between calculated data using these models and measured data showed that one specific semiempirical model exhibits the best agreement with the experimental data. Starting from this semiempirical model, a new model was derived based on the momentum theory. However, the calculated penetrations using both correlations appear to be very similar for diesel fuel (DF). Furthermore, experiments were carried out in a constant volume spray chamber in nonvaporizing conditions using DF and heavy fuel oil (HFO). The experimental data analysis showed that the physical properties influence the tip penetration strongly and indicated that the influence of the fuel properties on spray penetration depends on more than just the flow characteristics at the nozzle hole outlet. For further investigation, the new general correlation based on momentum theory was used. It could remarkably capture the fuel property effects on spray penetration in the far-field zone. Moreover, the model indicates that increased fuel density and/or viscosity leads to decreased spray penetration if the same fuel mass is injected. However, spray penetration increases with the fuel density if the volume of the injected fuel is kept constant. Further validation was made using data for different fuels (diesel, n-dodecane, and n-heptane) from the Engine Combustion Network (ECN) website. Finally, the new correlation reveals another important aspect of the impact of the nozzle orifice shape on spray penetration. At constant boundary conditions (gas density, fuel properties), it suggests that the spray penetration from a small nozzle is higher than that from a larger nozzle if the same fuel mass is injected. This observation was validated using data from the ECN and literature.