Les Sprays

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https://research.brighton.ac.uk/en/projects/les-sprays

established May 2024

 

 

This Franco-British 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 91¶¶Òõ and the University of Rouen.

European Regional Development Fund, Franco-British Interreg IIIA, Project Ref: 162/025/247

Project summary

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.

These are the main milestones of the research programme:

  • 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 internal combustion (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 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

Illustration of a spray

Fig. 1. Main integral characteristics of the spray are: breakup length, tip penetration length and spray cone angle.

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 was validated against in-house experimental observations of highly-transient Diesel sprays

The results of our study are summarised in the paper.

Two graphs showing spray velocity and distribution

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).

The CoM model was validated against experimental CoM data. The results of the study were published in Proceedings of the PTNSS Congress (Krakow, 2007).

Illustration of the dynamics of a spray and the drag force

Fig. 3. Schematic diagram showing dynamics of the spray Centre-of-Mass.

Autoignition in diesel sprays

Models for the processes of droplet heating and evaporation were 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), were implemented into a customised version of the KIVA-II code. The models were validated against in-house measurements of autoignition in diesel sprays.

The predicted decrease in autoignition delay with increasing in-cylinder 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.

Four graphs and four heat maps

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.

Project participants

Professor Sergei Sazhin, Project Coordinator

Dr Sergey Martynov

Professor Cyril Crua 

Dr Elena Sazhina

Professor Gorokhovski (University of Rouen), Coordinator of the French Group

Dr Chtab (University of Rouen)

Mr Jouanguy (University of Rouen)

Project partners

Related output

Progress meetings and seminars

January 2006

  • 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

July 2006

June 2007

Publications

International conference presentations

  • Multiple Scales in Spray Modelling
Sazhin, 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 developments
Sazhin, 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 development
Martynov, 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 modelling
Karimi, 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 cavitation
Martynov, S., Mason, D., Heikal, M., Sazhin, S. (2006) European PHOENICS User Meeting (30 November – 1 December 2006)
  • Mathematical modelling of forest fire initiation and spread
Perminov, 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 models
Sazhin, 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 sprays
Sazhin, 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 modelling
Ribaucour, 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 engines
Sazhin, 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 Modelling
Karimi, 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 models
Sazhin, 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 analysis
Sazhin, 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 evaporation
Sazhin, S.S. (2006) Progress in Energy and Combustion Science, 32(2), 162-214.
  • Transient heating of a semitransparent spherical body
Sazhin, 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 droplets
Sazhin, 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 modelling
Maqua, 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 sprays
Martynov, 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 experimentation
Sazhin, S.S., Martynov, S., Crua, C., and Heikal, M.R. (2007), Submitted to Combustion and Flame
  • Diesel spray characteristics of split-injection strategy
Karimi, K., Sazhina, E.M., Crua, Heikal, M.R. (2007), Fuel (to be submitted) 

National conference presentations

  • Interreg project 'Les Sprays' S. Sazhin, M. Heikal, C. Crua, S. Martynov, E. Sazhina, M. Gorokhovski, and A. Chtab Poster at the Interreg Showcase Event, 1 March, 2006, Ashford.
  • Modelling of cavitation flow in a diesel injection nozzle
 S. Martynov, D. Mason, M. Heikal and S. Sazhin. Poster presented at UK national science week 2006. Annual Presentations by Britain Top Younger Scientists, Engineers and Technologists at the House of Commons, London, 13 March 2006.
  • Oscillating jets and sprays in modern technologies S. Martynov, S. Sazhin, and M. Heikal. Poster submitted to the BISME conference, KTP, September 10-12, 2006, 91¶¶Òõ.
  • CFD modelling of spray processes 
S. Martynov. The opening of the ''Sir Harry Ricardo Laboratories'', Tuesday 14 Nov, 2006.
  • CFD modelling of spray processes S. Martynov. 91¶¶Òõ Sci and Eng Fair, Univ of 91¶¶Òõ, 14 March, 2007.
  • Modelling of cavitation flow in a diesel injection nozzle
 S. Martynov, D. Mason and M. Heikal Poster submitted to the UK-Israel Workshop "Sprays: modelling versus experimentation", 91¶¶Òõ, 16-18 July, 2007.
  • Effects of droplet breakup, heating and evaporation on autoignition of diesel sprays 
 S. Martynov, S. Sazhin, C. Crua, M. Gorokhovski, A. Chtab, E. Sazhina, K. Karimi, T. Krisyadi and M. Heikal Poster submitted to the UK-Israel Workshop "Sprays: modelling versus experimentation", 91¶¶Òõ, 16-18 July, 2007.
  • Highly transient dense diesel sprays: Experiment vs parametric modelling
 K. Karimi, C. Crua, M. Heikal, T. Cowell, G. De Sercey, E. Sazhina Poster submitted to the UK-Israel Workshop "Sprays: modelling versus experimentation", 91¶¶Òõ, 16-18 July, 2007.

Project funding

Total Interreg III grant value: £350,254 for 2 years (July 2005 - July 2007) (European Regional Development Fund, Franco-British INTERREG IIIa)

EPSRC grants: GR/R51711 (2001), GR/S98368/01 (2004), EP/C527089/1 (2005), EP/D002044/1 (2006).
 

SHRL funding from Interreg III: £140,101