Description

This project aimed to develop a model of aerosols and sprays for medical and automotive applications and involved a collaboration between researchers from the University of Brighton (UoB) and Kazan University (KU) in Russia.

The first year of the project focused on the development of the new model, its implementation into Fluent and the generation of experimental data for gasoline engines to be used in validating the model. The second year focused on the application of the customised version of Fluent to medical and gasoline fuel sprays and comparison of the results with experimental data where possible. In the case of gasoline engines, comparison will be carried out using in-house experimental data.

The Royal Society and the Russian Foundation for Basic Research (RFBR) made an international exchanges cost share award to enable overseas travel between collaborators in the UK and Russia.

The main aim of this project was to develop a novel spray model, which could be used both to analyse the processes involved in internal combustion (mainly gasoline) engines and to simulate drug delivery processes via medical sprays.

The project brought together the respective expertise and experience of the groups to create a model that combined the method of moments, developed at Kazan University (KU), and the models for multicomponent droplet heating and evaporation, developed at the University of Brighton. We anticipate that both models will be extended: firstly, the model developed at the UoB will be generalised to allow for the presence of solid particles in droplets, which is essential for the application of the model to the analysis of the drug delivery process. Secondly, the method of moments, developed at KU, will be generalised to take into account the effects of finite Stokes numbers, which is essential for the application of the model to internal combustion engines as fuel droplets in engines are expected to be about two orders of magnitude larger than those in medical sprays (typical droplet sizes 1-5 mkm).

The newly-developed model will be implemented in commercial CFD code ANSYS Fluent via User Defined Functions (UDF) (both groups in Kazan and Brighton have experience of implementing similar models in this code). We will apply the customised version of this code to the simulation of specific medical sprays and will evaluate its advantages compared to the conventional version of this code. This code will also be applied to the analysis of sprays in gasoline engines. In this case, the engine enclosure will be split into two regions: one in the vicinity of the nozzle, where the method of moments is not applicable with analysis based either on the conventional Eulerian-Lagrangian or Eulerian-Eulerian approaches implemented in ANSYS Fluent; and the other, remaining region where the new model will be applied.

Predictions resulting from the customised version of Fluent were validated against in-house experimental data. A Dantec Dynamics Classical two-component phase Doppler anemometer (PDA) was used to measure particle size and velocity distributions at the grid locations. Optimisation of the PDA system for dense spray measurements formed an important part of the study. We used a forward scattering angle of 75 degrees. We recorded axial and radial particle velocity components and diameter during injection, between injection events and over consecutive fuel injections. Data acquisition and validation rates varied across measurement locations.

Contact between the two groups during reciprocal visits was vital for successful completion of the project. During these visits the Kazan group familiarised itself with experimental facilities at the University of Brighton, while the Brighton group familiarised themselves with the medical sprays environment. In addition to the scientific dimension of the project, exchange visits between project participants enabled he team to organise a series of workshops, and lectures to be delivered by Professor Zaripov and Dr Gilfanov in the UK and Professors Heikal and Sazhin in Russia, benefiting the staff and students of both universities.

Key findings

We managed to achieve all original aims of the project except the application of the new model to simulate drug delivery processes in human lungs. These are the main achievements of our work on the project:

1.A new model for droplet drying, based on the analytical solutions to the heat transfer and species diffusion equations inside spherical droplets, is suggested. In this model, small solid particles dispersed in an ambient evaporating liquid, or a non-evaporating substance dissolved in this liquid, are treated as non-evaporating components. The model was used to analyse the drying of a spray consisting of chitosan dissolved in water. The prediction of the model were shown to be consistent with those observed experimentally.

2.The fully Lagrangian approach (FLA) to the calculation of the number density of inertial particles in dilute gas-particle flows was implemented into the CFD code ANSYS Fluent alongside the previously developed model for droplet heating and evaporation. The new version of ANSYS Fluent is applied to modelling dilute gas-particle flow around a cylinder and liquid droplets in a gasoline fuel spray.

3.A new model for heating and evaporation of a multi-component liquid film, based on the analytical solutions to the heat transfer and species diffusion equations inside the film, was suggested. The Dirichlet boundary condition was used at the wall and the Robin boundary condition was used at the film surface for the heat transfer equation.

4.A new model for heating and evaporation of a suspended droplet, taking into account temperature gradient and recirculation inside the droplet and the effect of a supporting rod, is suggested. This model was based on the assumption that the heat transferred from the rod to the suspended droplet is homogeneously distributed inside the droplet; its effect was modelled similarly to the effect of external thermal radiation, using the previously developed model for droplet heating in the presence of this radiation.

Apart from the abovementioned achievements, confirmed by the publications in international refereed journals (see below), our work on the project still continues although on unfunded bases. One of the focuses of our work is on the development of a modified version of the conditional quadrature method of moments (CQMOM) in view of its possible application to modelling the processes inside internal combustion engines.

The achievements of the project were described in the article published on the website of Kazan State University (Russia)
https://media.kpfu.ru/news/uchenyy-kfu-sovmestno-s-kollegami-iz-universiteta-braytona-sozdal-model-ispareniya
StatusFinished
Effective start/end date1/09/1631/08/18

Keywords

  • Sprays