The SHRL have been awarded a £1.3m EPSRC research grant to study the deformation of microscopic fuel droplets.
We are currently offering a fully funded PhD studentship on laser diagnostics for sprays.
This Franco-British Interreg IIIa research programme is focused on the development of a new physical and mathematical model of spray formation and dynamics with a view to engineering and environmental applications. The work brings together the expertise in mathematical modelling and experimental studies at the University of Brighton and the Univeristy of Rouen.
European Regional Development Fund, Franco-British INTERREG IIIa, Project Ref: 162/025/247
The main objective of the project is to develop a strategy for the computation of high-speed liquid atomisation. This strategy will provide a reliable basis for the calculation of sprays in internal combustion engines and other applications.
- Prof Sazhin (University of Brighton) Project Coordinator
- Dr Martynov (University of Brighton)
- Dr Crua (University of Brighton)
- Dr Sazhina (University of Brighton)
- Prof Gorokhovski (University of Rouen), Coordinator of the French Group
- Dr Chtab (University of Rouen)
- Mr Jouanguy (University of Rouen)
- Total Interreg III grant value: £350,254 for 2 years (July 2005 - July 2007)
- SHRL funding from Interreg III: £140,101
These are the main milestones of the research program:
- Literature review; analysis of mechanisms of breakup; comparison of deterministic and stochastic models of breakup.
- Development of a model of liquid spray formation in the conditions relevant to direct injection IC engines.
- Development of a new model of droplets dispersion taking into account the effect of turbulence at droplet level.
- Implementation of the new models into a computational code KIVA.
- Theoretical and numerical analysis of the influence of physical parameters on the distribution function of droplets by radii.
- Validation of the model against experimental measurements of fuel sprays.
- Numerical analysis of physical and chemical phenomena in direct injection IC engines with a view to optimising their performance and the reduction of pollutants.
- Application of the computational model for the optimisation of spray systems found in other engineering, environmental and medical applications.
The results of the research have been and will be published in international refereed journals and refereed conference proceedings.
Background and Methodology
The task of computation of flow and autoignition of Diesel fuel spray can be simplified, if we consider the following elementary processes (Fig. 1):
- flow inside the injection nozzle
- primary breakup of the liquid jet into ligaments and large droplets
- secondary breakup of large droplets into smaller droplets
- droplet heating
- droplet evaporation and mixing of fuel vapour with air
- autoignition of the air-fuel mixture
Fig. 1. Main integral characteristics of the spray are: breakup length, tip penetration length and spray cone angle.
A customised version of the Eulerian-Lagrangian computational fluid dynamics (CFD) code KIVA-II (Amsden et al, 1989) is used as a basis for modelling and analysis of the spray processes. Models implemented into the code are validated against available in-house measurements of sprays.
Results of studies
Breakup and Penetration of Accelerating Sprays
Several conventional models of spray breakup were implemented into the KIVA-II code, including:
- Taylor Analogy Breakup model (O'Rourke and Amsden, 1987),
- WAVE KH-RT breakup model (Patterson and Reitz, 1998),
- Stochastic breakup model (Gorokhovski and Saveliev, 2003).
These models were originally developed for quasi-steady-state sprays injected at constant or slightly varying velocity.
The current study is focused on analysis of the effect of high injection acceleration on breakup in Diesel sprays.
In order to improve predictions of spray penetration at the initial stage of injection, a new semi-phenomenological model of breakup, taking into account injection acceleration, is suggested. The model is developed based on the classical WAVE breakup model suggested by Reitz (1987).
The new model provides an equation for the spray breakup time as a function of jet acceleration. The model has been developed using an assumption that the spray liquid core can be approximated as a solid body. The instantaneous injection velocity was specified, based on the measured rate of injection and taking into account the effect of cavitation.
A customised version of the KIVA II code has been validated against in-house experimental observations of highly-transient Diesel sprays
The results of our study are summarised in the paper.
Fig. 2. Snap-shot from the video image of the spray and calculated velocity field in the gas phase and distribution of liquid droplets (droplet size zoomed by a factor of 30).
Transient Penetration of Spray Centre-of-Mass
An integral model for the dynamics of the centre-of-mass (CoM) of the fuel spray has been developed. This was based on the conservation of momentum of injected fuel mass in the presence of a realistic drag force, acting on the whole spray as a physical body. This approach is particularly suitable for dense sprays near the nozzle. The penetration of spray tip was associated with the height of the cone (Fig. 3).
Fig. 3. Schematic diagram showing dynamics of the spray Centre-of-Mass.
The CoM model was validated against experimental CoM data. The results of study were published in Proceedings of the PTNSS Congress (Krakow, 2007).
Autoignition in Diesel sprays
Models for the processes of droplet heating and evaporation have been reviewed . In order to describe autoignition of the fuel vapour in Diesel spray, the reduced-kinetics Shell model was applied.
Several advanced models of droplet heating and evaporation (Sazhin, 2006), as well as the Shell autoignition model (Halstead, 1977; Sazhina et al, 2000), have been implemented into a customised version of the KIVA-II code. The models have been validated against in-house measurements of autoignition in Diesel sprays.
The predicted decrease in autoignition delay with increasing incylinder gas pressure in the approximate range 5.5 MPa to 7 MPa, agrees with experimental observations based on the assessment of spray luminosity from spray video recordings capturing the ignition spark.
Fig. 4. Spatial distribution of droplets (top row) and gas temperature field (bottom row) at four moments of time, as predicted by the customised KIVA II code. Computations were performed for the spray injected at 160MPa and 375K into air at 6.2MPa and 750K. Droplets are shown with diameters magnified 500 times.
Progress Meetings and Seminars
- S. Sazhin. The project objectives and progress to-date
- M. Gorokhovski. Modeling of break-up and dispersion in two-phase flows
- S. Martynov. Modeling of spray break-up using KIVA CFD code
- S. Sazhin Summary of the project progress
- J. Jouanguy. Stochastic modeling of primary atomization : application to Diesel spray
- A. Chtab. Lagrangian dispersion of light solid particle in a high Re number turbulence; LES with stochastic process at sub-grid scales
- S. Martynov. Penetration of Accelerating sprays: modelling vs experiment
- M. Heikal. Experimental studies of the processes in internal combustion engines at the University of Brighton
- E. Sazhina. Development of an integral spray model: Transient Penetration of Spray Centre-of-Mass
- S. Sazhin and M. Gorokhovski. Summary of the project progress on the British and French sides.
- A. Chtab. Phenomenological stochastic modelling of primary break-up
- S. Martynov. Diesel fuel spray penetration, heating, evaporation and ignition: modelling versus experimentaion
- E. Sazhina. Autoignition of hydrocarbon vapour: the Shell model for forest fires
- E. Sazhina. Has INTERREG made any real difference in the way we work and research?
- I. Shishkova. A kinetic algorithm for modelling the droplet evaporation process in the presence of a heat flux and background gas
International conference presentations
- Multiple Scales in Spray ModellingSazhin, S.S. (2006) International Workshop on Multi-Scale Processes & Hysteresis, University College Cork, Ireland, April 3-8, 2006 (invited lecture). Published in J Physics, Conference Series v. 55, 191-202.
- Modelling of the dynamics and break-up of jets and sprays.Sazhin, S., Martynov, S., Crua, C., Sazhina, E., Heikal, M., Chtab, A., Gorokhovskii, M. and Katoshevski, D (2006) The 6th Euromech Fluid Mechanics Conference, KTH - Royal Institute of Technology, Stockholm 26-30 June 2006 (book of abstracts).
- Modelling of droplet heating, evaporation and breakup: recent developmentsSazhin, S., Martynov, S., Shishkova, I., Crua, C., Karimi, K., Gorokhovski, M., Sazhina, E., Heikal, M. (2006). In proceedings of the 13th Int.Heat Transfer Conference, 13-18 August, Sydney, Australia.
- Modelling of cavitation flow in a nozzle and its effect on spray developmentMartynov, S., Mason, D., Heikal, M., Sazhin, S. and Gorokhovski, M.(2006). In proceedings the 13th Int.Heat Transfer Conference, 13-18 August, Sydney, Australia.
- Developments in Diesel spray characterisation and modellingKarimi, K., Sazhina, E.M., Abdelghaffar, W.A., Crua, C, Cowell, T., Heikal, M.R., Gold, M.R. (2006)THIESEL 2006 Conference on Thermo- and Fluid Dynamics Processes in Diesel Engines, September 13-15, Valencia, Spain.
- A mathematical model of steady-state cavitationMartynov, S., Mason, D., Heikal, M., Sazhin, S. (2006) European PHOENICS User Meeting (30 November – 1 December 2006)
- Mathematical modeling of forest fire initiation and spreadPerminov, V.A. and Sazhina, E.M. (2006) Workshop INTAS – Siberian branch of the Russian academy of sciences, scientific cooperation and collaborative call10-12 May 2006, Novosibirsk, Russia.
- Fuel droplet heating and evaporation: analysis of liquid and gas phase modelsSazhin, S.S., Kristyadi, T., Heikal, M.R., Abdelghaffar, W.A., Shishkova, I.N.(2007) International Fuels & Emissions Conference, January 23-25, 2007, BMW Pavilion, Cape Town, SAE paper 07SFL-18 - 2007-01-0019.
- Advanced models for droplet heating and evaporation: effect on the autoignition of diesel fuel spraysSazhin, S.S., Crua, C., Martynov, S.P., Kristyadi, T. and Heikal, M. (2007) Proc of the Third European Comb Meeting ECM 2007, paper 15-2.
- Autoignition of n-pentane in a rapid compression machine: experiment versus modellingRibaucour, M., Minetti, R., Sazhina, E.M., Sazhin, S.S. (2007) Proc of the Third European Comb Meeting ECM 2007, paper 1-1.
- Models for droplet heating and evaporation: application to the autoignition process in Diesel enginesSazhin, S.S., Martynov, S.P., Kristyadi, T., Crua, C., and Heikal, M. (2007) Proc of the PTNSS Congress (Krakow, Poland 20-23 May 2007); Combustion Engines V. 2 Mixture Formation, Ignition & Combustion, pp. 246-257.
- Split Injection Strategy for Diesel Sprays: Experiment and ModellingKarimi, K., Crua, C., Heikal, M.R., Sazhina, E.M. (2007) Proc of the PTNSS Congress (Krakow, Poland 20-23 May 2007); Combustion Engines. V. 2 Mixture Formation, Ignition & Combustion, pp. 181-191.
- Droplet heating and evaporation: hydrodynamic and kinetic modelsSazhin, S.S., Shishkova, I.N., Kristyadi, T., Martynov, S.B., and Heikal, M. (2007) Proceedings of the 5th Baltic Heat Transfer Conf, St Petersburg, 19-21 Sept 2007.
Publications in International Refereed Journals
- Models for fuel droplet heating and evaporation: comparative analysisSazhin, S.S., Kristyadi, T., Abdelghaffar, W.A. and Heikal, M.R. (2006), Fuel, 85(12-13), 1613–1630.
- Advanced models of fuel droplet heating and evaporationSazhin, S.S. (2006) Progress in Energy and Combustion Science, 32(2), 162-214.
- Transient heating of a semitransparent spherical bodySazhin, S.S., Krutitskii, P.A., Martynov, S.B., Mason, D., Heikal, M.R., Sazhina, E.M. (2007), Int J Thermal Science, 46(5), 444-457.
- Approximate analysis of thermal radiation absorption in fuel dropletsSazhin, S.S., Kristyadi T., Abdelghaffar, W.A., Begg, S., Heikal, M.R., Mikhalovsky, S.V., Meikle S.T., Al-Hanbali, O. (2007), ASME J Heat Transfer (in press).
Papers submitted for publication in International Refereed Journals
- Monodisperse droplet heating and evaporation: experimental study and modellingMaqua, C., Castanet, G., Grish, F., Lemoine, F., Kristyadi, T., Sazhin, S.S. (2007), Submitted to Int J Heat Mass Transfer
- A modified WAVE model for transient liquid spraysMartynov, S., Sazhin, S., Gorokhovskii, M., Chtab, A., Karimi, K, Crua, C., and Heikal, M. (2007), Submitted to Int J Heat and Fluid Flow
- Diesel fuel spray penetration, heating, evaporation and ignition: modelling versus experimentationSazhin, S.S., Martynov, S., Crua, C., and Heikal, M.R. (2007), Submitted to Combustion and Flame
- Diesel spray characteristics of split-injection strategyKarimi, K., Sazhina, E.M., Crua, Heikal, M.R. (2007), Fuel (to be submitted)