Performance of mini jet engine combustor

• Main Author: Chan, Wai Lek
• Other Authors: Fei Duan
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Aeronautical engineering
• Online Access: http://hdl.handle.net/10356/65282
• Institution: Nanyang Technological University

Reverse-flow combustor are normally installed on mini turbojet engines due to its smaller size and space required. A numerical study on a reverse-flow combustor was conducted to investigate its performance using ANSYS Fluent. A mesh independence study was carried out prior to the numerical simulation. The realizable turbulence model and the nonpremixed combustion model coupled with PDF methods were adopted to predict the turbulence-chemistry interaction within the combustor. The results from the numerical study were then compared against a set of experimental data. The performance analysis of the simulation results is based on the temperature, flow field (pressure and velocity), energy (enthalpy and entropy) and carbon emission. The results show that the temperature profile is uniform at the combustor outlet in the radial and cicumferential orientation. The predicted outlet temperature has a deviation of less than 6%. Within the combustor, hot spots are found anchored towards the inner liner wall. This causes the inner liner wall to be subjected to temperature beyond its melting temperature. Besides, the pressure drop across the combustor is within 4% to 9% for all operating shaft speeds. Apart from that, the enthalpy and entropy within the system are greatly affected by the temperature. A parameter study is also included to investigate the effect of shaft speed on the mentioned varaibles. As the shaft speed increases, the equivalence ratio of the mixture increases (richer mixture). Likewise, the mass flow rate of reactants and turbulent intensity becomes higher as the shaft speed increases. In the analysis of these variables, it is found that as the shaft speed increases, the effect of higher equivalence ratio (richer mixture) is overcomed by the effect of higher mass flow rate of reactants and higher rate of turbulent mixing. Lastly, a few recommendations are presented by the author for related studies in the future. Reverse-flow combustor are normally installed on mini turbojet engines due to its smaller size and space required. A numerical study on a reverse-flow combustor was conducted to investigate its performance using ANSYS Fluent. A mesh independence study was carried out prior to the numerical simulation. The realizable turbulence model and the nonpremixed combustion model coupled with PDF methods were adopted to predict the turbulence-chemistry interaction within the combustor. The results from the numerical study were then compared against a set of experimental data. The performance analysis of the simulation results is based on the temperature, flow field (pressure and velocity), energy (enthalpy and entropy) and carbon emission. The results show that the temperature profile is uniform at the combustor outlet in the radial and cicumferential orientation. The predicted outlet temperature has a deviation of less than 6%. Within the combustor, hot spots are found anchored towards the inner liner wall. This causes the inner liner wall to be subjected to temperature beyond its melting temperature. Besides, the pressure drop across the combustor is within 4% to 9% for all operating shaft speeds. Apart from that, the enthalpy and entropy within the system are greatly affected by the temperature. A parameter study is also included to investigate the effect of shaft speed on the mentioned varaibles. As the shaft speed increases, the equivalence ratio of the mixture increases (richer mixture). Likewise, the mass flow rate of reactants and turbulent intensity becomes higher as the shaft speed increases. In the analysis of these variables, it is found that as the shaft speed increases, the effect of higher equivalence ratio (richer mixture) is overcomed by the effect of higher mass flow rate of reactants and higher rate of turbulent mixing. Lastly, a few recommendations are presented by the author for related studies in the future.