MODELLING AND SIMULATION OF THE COMBUSTION OF BIODERIVED FUELS IN A PT6A-27 TURBOPROP ENGINE
Keywords:PT6A-27, nonpremixed Combustion, NOx, Turbulence model
The motivation for venturing in alternative jet fuels has partly been due to the elevated level and volatility of the price of Jet A and environmental impacts on global climate change and air quality. The model of the annular combustor for the PT6A-27 engine was created using SOLIDWORKS and exported to ANSYS DESIGN MODELER. Creation of the computational mesh for the geometry using ANSYS MESHING was done in preparation for the setting up of the CFD simulation in ANSYS FLUENT. The simulation included, setting material properties and boundary conditions for a non-premixed combustion problem. Initiating the calculation with residual plotting, calculating the solution using the pressure-based solver and visually examining the flow and temperature fields using the post-processing in ANSYS FLUENT with the Standard k-ε 2 equation turbulence model used.
The fuel blend from the range of 30% bioethanol and 70% biodiesel (BE30-BD70) to 70% bioethanol and 30% biodiesel (BE70-BD30) indicated a combustion characteristic consistency with that obtained from the combustion of Jet-A1. Further, from the comparisons of the blends in terms of performance and single biofuel combustion simulation the best blend combination was 40% bioethanol with 60% biodiesel (BE40-BD60) whose adiabatic flame temperature was about 2260 Kelvins.
The blend of 40% bioethanol to 60% biodiesel was observed to have a reduced Fuel NOx footprint and the observed production rate values of Thermal NOx were a range of to Whereas a pure JetA-1 hydrocarbon fuel had a production rate of Thermal NOx ranging from to . This was indicative of a reduction in Thermal NOx when the two groups of fuels (Jet-A against 40BE & 60BD blend) were compared.
These results showed that reduction of NOx emissions is achievable for a blend of 40% bioethanol and 60% biodiesel in a combustion reaction as a substitute for the hydrocarbon JetA-1 in the PT6A-27 turboprop engine.