Modelling of breakup processes in transient Diesel fuel sprays
Lead Research Organisation:
University of Brighton
Department Name: Sch of Computing, Engineering & Maths
Abstract
This proposal is concerned with the development of new mathematical models for transient Diesel fuel jets, taking into account their instabilities and acceleration, in a form suitable for implementation into computational fluid dynamics (CFD) codes. The distinction between convective, absolute and global instabilities and the effects of cavitation on the formation of Diesel fuel sprays will be taken into account. The latter effects are expected to appear via the modification of the boundary conditions for jets at the exit of the nozzle. Effects of boundary disturbances on the breakup of the jet will be studied experiementally using a three dimensional laser vibrometer. The jet acceleration is expected to lead to partial stabilisation of the jet. The effects of jet acceleration and jet instabilities will be used to develop a new stochastic model for the primary spray breakup in a form suitable for implementation into CFD codes. This stochastic model will be implemented into a customised in-house version of the KIVA-2 CFD code. This code will be used for modelling fluid dynamics, heat transfer and combustion processes in Diesel engines. The results of the modelling will be validated against in-house experimental data. This will open the way to implement new models to other CFD codes, including commercial ones.
Publications
Boronin S
(2013)
Non-modal stability of round viscous jets
in Journal of Fluid Mechanics
Boronin, S.A.
(2011)
Transient Diesel fuel jets and sprays: mathematical analysis and applications
in Proceedings of 22nd International Symposium on Transport Phenomena, Delft November 8-11, 2011, CD
Boronin, S.A.
(2012)
Modal and Non-modal stability of round viscous jets
in 6th International workshop on multi-rate processes and Hysteresis (MURPHYS), 21th-24th May 2012, Stefan cel Mare University of Suceava (Romania), Abstracts Book.
Boronin, S.A.,
(2011)
Transient unstable round jets: mathematical analysis and
in Book of Abstracts for 22nd International Symposium on Transport Phenomena, Delft November 8-11, 2011
Crua C
(2014)
Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry
in Measurement Science and Technology
Healey J.J.
(2010)
Transient unstable jets: mathematical analysis and applications
in 5th International workshop on multi-rate processes and Hysteresis (MURPHYS), University of Pecs, Pollack Mihaly Faculty of Engineering (Hungary). Book of Abstract
Sazhin S
(2013)
Jet and Vortex Ring-Like Structures in Internal Combustion Engines: Stability Analysis and Analytical Solutions
in Procedia IUTAM
Sazhin S.S.
(2011)
Transient Diesel fuel jets and sprays: mathematical analysis and applications
in Proceedings of ILASS Europe 2011, 24th European Conference on Liquid Atomization and Spray Systems, Estoril, Portugal, 5-7 September 2011
Sazhin S.S.
(2012)
Jet and Vortex Ring-Like Structures in Internal Combustion Engines: Stability Analysis and Analytical Solutions
in Proceedings of the IUTAM Symposium 12-3 'Waves in Fluids: Effects of Non-linearity, Rotation, Stratification and Dissipation. Book of Abstracts. MAKS Press, Moscow
Sazhin S.S.
(2011)
Transient Diesel fuel jets and sprays: mathematical analysis and applications
in Proceedings of ILASS Europe 2011, 24th European Conference on Liquid Atomization and Spray Systems, Estoril, Portugal, 5-7 September 2011
| Description | 1. It is found that the presence of a finite-thickness shear layer can lead to an absolute instability for a range of density ratios, not seen when a simpler plug flow velocity profile is considered. It is also found that the inclusion of surface tension has a stabilizing effect on the convective instability but a destabilizing effect on the absolute instability. The stability results were used to obtain estimates for the breakup length of a planar liquid jet as the jet velocity varies. 2. For a heavy fluid injecting into a lighter fluid, it is found that unsteady effects are mainly significant at early injection times where the jet velocity profile is changing fastest. When the shear layers in the jet thin with time, the unsteady effects cause the growth rate of the wave packet to be smaller than the corresponding quasi-steady jet, whereas for thickening shear layers the unsteady growth rate is larger than that of the quasi-steady jet. For large accelerations, the unsteady effect remains at later times but its effect on the growth rate of the wave packet decreases as the time after injection increases. As the rate of acceleration is reduced, the range of velocity values for which the jet can be considered as quasi-steady increases until eventually the whole jet can be considered quasi-steady. 3. A breakup model for analysing the evolution of transient fuel sprays characterised by a coherent liquid core emerging from the injection nozzle, throughout the injection process, is proposed. The spray breakup is described using a composite model that separately addresses the disintegration of the liquid core into droplets and their further aerodynamic breakup. The jet breakup model uses the results of hydrodynamic stability theory to define the breakup length of the jet, and downstream of this point, the spray breakup process is modelled for droplets only. The model is incorporated into the KIVA II Computational Fluid Dynamics (CFD) code. 4. Hydrodynamic stability of round viscous fluid jets is considered within the framework of the non-modal approach. Linear combinations of modes (optimal disturbances) leading to the maximum kinetic energy at a specified set of governing parameters are found. Parametric study of optimal disturbances is carried out for both an air jet and a liquid jet in air. For the velocity profiles under consideration, it is found that the non-modal instability mechanism is significant for non-axisymmetric disturbances. The maximum energy of the optimal disturbances to the jets at the Reynolds number of 1000 is found to be two orders of magnitude larger than that of the single mode. The largest growth is gained by the streamwise velocity component. |
| Exploitation Route | There was a noticeable interest in our paper Turner, M.R., Sazhin, S.S., Healey, J.J., Crua, C., Martynov, S.B. (2012) A breakup model for transient Diesel fuel sprays, Fuel 97, 288-305. In 2016 it was cited 33 times excluding self-citations (according to ISI Web of Science). |
| Sectors | Education,Energy,Transport |
| Description | There were preliminary discussions about the implementation of the model described in (Turner, M.R., Sazhin, S.S., Healey, J.J., Crua, C., Martynov, S.B. (2012) A breakup model for transient Diesel fuel sprays, Fuel 97, 288-305) in Ricardo software. |
| First Year Of Impact | 2017 |
| Sector | Energy,Transport |
| Impact Types | Economic |
| Description | Ricardo UK Ltd |
| Organisation | Ricardo UK Ltd |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | We developed a model which can be potentially used in automotive applications |
| Collaborator Contribution | Ricardo consulted us regarding the relevance of the models to automotive applications |
| Impact | See our publications |
| Start Year | 2013 |