Fuel Combustion Modelling
Understanding how a fuel will perform is essential for turbine and engine designs and optimisation of fuels.
Chain-branching chemistry models reveal the role of intermediate chemical species on flame structure and stability.
A novel turbulent two-phase flow model helps to predict droplet evaporation in engine fuel sprays.
Work on intrinsic thermal-diffusive (cellular) and hydrodynamic instabilities of premixed flames includes investigation chain branching chemistry models, which predict the stabilizing role of intermediate chemical species such as radicals in the flame structure and stability.
Modelling and direct numerical simulation of expanding flames in combustion vessels are revealing the effects of ignition transients, vessel geometry and thermo-diffusive and acoustic effects on the flame propagation. The results are being used to help interpret the experimental fuel characterisation studies.
We are developing a model of turbulent two-phase flow that can be incorporated into existing CFD (Computational Fluid Dynamics) allowing designers to predict the:
- size and density of droplets
- droplet size distribution
- rate of evaporation or condensation
- rates of heat exchange between gas and spray
- effects that different propellants and nebuliser designs will have on these factors
The model has been used to help predict and control the atomisation and vaporisation of different fluids across a range of environments including gas turbines and diesel engines.
We have proposed novel formula for the vaporisation rate, based on the fact that the vaporisation is affected by small-scale turbulence, a concept which is ignored in currently employed models. This work has allowed us to improve our predictions of fuel evaporation rate. This mathematical model is supported by experimental results.