Acknowledgements to the European Regional Development Fund

1. Highly Transient Dense Diesel Sprays: Experiment vs Parametric Modelling K Karimi, C Crua, M R Heikal, T Cowell, G De Sercey, E Sazhina Sir Harry Ricardo Laboratories, Internal Combustion Engines Group, Faculty of Science and Engineering, University of Brighton, Brighton, BN2 4GJ, UK Drag F A • An experimental programme on spray imaging by laser diagnostic techniques has been carried out by the Internal Combustion Engines Group (ICEG), University of Brighton, over a number of years. An extensive body of data on spray penetration and dispersion by sophisticated laser diagnostics techniques has been accumulated as a result. • The spray penetration was explored by laser diagnostics methods such as Laser Induced Fluorescence (LIF) and Mie scattering techniques. Both liquid and vapour phases of the spray were captured by the LIF technique whilst Mie scatter recorded only the liquid part of the spray. High-speed video (HSV) images of the liquid part of spray were recorded too. • A vast body of data on spray penetration has been supplemented by high resolution transient injection mass flow rate data obtained from off-engine experiments using the long-tube rate methodology. • The combination of several spray imaging techniques and the transient injection rate data has produced a unique suite of comprehensive experimental data for validation and benchmarking of numerical models. • Sophisticated spray configurations for Fuel Injection Equipment (FIE) trends such as multiple hole and multiple injection strategies: • These phenomena are highly transient by nature and present a challenge for the conventional approach to spray modelling based on average values of injection velocity. A parametric zero-dimensional study of spray Centre-of-Mass motion based on mass and momentum conservation for the injected liquid fuel is performed for various injection and in-cylinder pressures, and for various injection strategies. • Transient injection velocity profiles measured by the injection rate tube technique are taken as input to the model. • The drag model for a whole spray as a bluff body incorporates an expression • for the effective projected area derived from the instantaneous mass of the spray. • The conventional assumption of the conical shape of the spray allows • a straightforward calculation of the frontal area • Air entrainment was modelled by the exponential decay of liquid fraction in the spray • with a characteristic time τ: • Numerical integration of the equation of motion • gives calculated position of the Centre-of-Mass of injected fuel: • For validation purposes the image processing software was extended to characterise the position of the centre-of-mass (CoM) of injected fuel. The ratio of tip penetration to the position of the centre-of-mass, was assessed from LIF images by customised in-house software. An average value of the ratio, with a corresponding standard deviation , was accepted for the validation of the model calculations versus experiment . The CoM model gave a good agreement with experimental spray penetration data over a range of operating conditions and injection strategies using the modelling parameter for spray dispersion τ = 0.15ms. Acknowledgementsto the European Regional Development Fund Franco- British INTERREG IIIa (Project Ref 162/025/247) for financial support