Impact of Dilution Air Flow Rate Modulation on Exit Temperature of Gas Turbine Combustion Chamber
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The management of exit temperature in gas turbine combustors is critical for ensuring turbine blade life, thermal efficiency, and operational flexibility. Dilution air injection is a primary method for cooling combustion products, yet the quantitative effect of modulating its flow rate on exit temperature remains insufficiently understood. This study employs a Computational Fluid Dynamics (CFD) approach using ANSYS FLUENT to investigate the impact of dilution air flow rate modulation on the exit temperature of a can‑type gas turbine combustion chamber operating under steady‑state conditions with methane fuel. A three‑dimensional model of the combustor was developed, and simulations were performed for dilution air mass flow rates ranging from 0.001 kg/s to 0.005 kg/s. Results show a strictly monotonic decrease in exit temperature with increasing dilution air flow, yielding a total reduction of 87 °C (approximately 4.0%) across the tested range. However, diminishing marginal cooling effectiveness is observed, with the largest reduction (43 °C) occurring between 0.001kg/s and 0.002 kg/s and progressively smaller reductions at higher flow rates. The midpoint exit temperature decreases by about 20 °C when dilution air is increased from 100% to 400% of baseline. The study quantitatively demonstrates that while increased dilution air flow significantly reduces thermal loading, benefits diminish beyond an optimal range (approximately 0.003–0.004 kg/s or a 200–250% increase). These findings provide design engineers with quantitative criteria for balancing exit temperature reduction against pressure loss, combustion efficiency, and flame stability.
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Lou, F. (2022). Approximating Gas Turbine Combustor Exit Temperature Distribution Factors Using Spatially Under-Sampled Measurements. Journal of Engineering for Gas Turbines and Power, 144(10). https://doi.org/10.1115/1.4055218
Zhang, M., Wu, H., & Wang, H. (2013). Numerical Prediction of NOx Emission and Exit Temperature Pattern in a Model Staged Lean Premixed Prevaporized Combustor. https://doi.org/10.1115/gt2013-95235
Kotzer, C., LaViolette, M., & Allan, W. (2009). Effects of Combustion Chamber Geometry Upon Exit Temperature Profiles. 913–922. https://doi.org/10.1115/gt2009-60156
Cai, W., Wu, J., Hu, Y., Yang, Z., Xue, X., & Lin, Y.-Z. (2024). Experimental Study of Fuel-Air Mixing and Dilution Jets on Outlet Temperature Distribution in a Small Gas Turbine Combustor. Journal of Thermal Science, 33(5), 1883–1896. https://doi.org/10.1007/s11630-024-1983-3
Pang, L., Zhao, N., Xu, H., Li, Z., Zheng, H., & Yang, R. (2023). Numerical Simulations on Effect of Cooling Hole Diameter on the Outlet Temperature Distribution for a Gas Turbine Combustor. Applied Thermal Engineering. https://doi.org/10.1016/j.applthermaleng.2023.121308.
Muduli, S. K., Mishra, R. K., & Mishra, P. C. (2019). Assessment of Exit Temperature Pattern Factors in an Annular Gas Turbine Combustor: An Overview. International Journal of Turbo and Jet Engines, 38(4), 351–361. https://doi.org/10.1515/tjj-2019-0009
Shang, M., Lu, S., & Mao, R. (2013). Numerical Investigation of the Effects of Dilution Hole Geometry on the Exit Temperature Profile and Emissions of an Aero-Engine LPP Combustor. https://doi.org/10.1115/gt2013-95395
Gupta, A., Ibrahim, M. S., Wiegand, B., & Amano, R. (2013). Computational and Experimental Study of Enhanced Mixing in a Gas Turbine Combustor Using Guide Vanes. https://doi.org/10.1115/ht2013-17186
Gulati, A., Tolpadi, A., VanDeusen, G., & Burrus, D. (1995). Effect of dilution air on the scalar flow field at combustor sector exit. Journal of Propulsion and Power, 11(6), 1162–1169. https://doi.org/10.2514/3.23955
Xiao, Y., Cao, Z., & Wang, C. (2019). The Effect of Dilution Air Jets on Aero-Engine Combustor Performance. International Journal of Turbo and Jet Engines, 36(3), 257–269. https://doi.org/10.1515/tjj-2018-0045
Hu, Y., Zhang, C., An, Q., Cai, W., & Xue, X. (2024). Impact of swirler sleeve length on outlet temperature distribution of a small gas turbine combustor. Physics of Fluids, 36(12). https://doi.org/10.1063/5.0243479
Tang, C., Yao, Q., Jin, W., Li, J., Yan, Y., & Yuan, L. (2024). Effect of swirler geometry on the outlet temperature profile performance of a model gas turbine combustor. Applied Thermal Engineering, 260, 124946–124946. https://doi.org/10.1016/j.applthermaleng.2024.124946
Wang, K., Li, F., Zhou, T., & Wang, D. (2023). Numerical simulations on the effect of swirler installation angle on outlet temperature distribution in gas turbine combustors. Applied Thermal Engineering, 240, 122252–122252. https://doi.org/10.1016/j.applthermaleng.2023.122252
Leonetti, M., Lynch, S., O’Connor, J., & Bradshaw, S. (2017). Combustor Dilution Hole Placement and Its Effect on the Turbine Inlet Flow field. Journal of Propulsion and Power, 33(3), 750–763. https://doi.org/10.2514/1.b36308
Kumuk, O. (2024). CO2, Ar, and He dilution effects on combustion dynamics and characteristics in laboratory-scale combustor. Fuel, 369, 131745–131745. https://doi.org/10.1016/j.fuel.2024.131745
Cao, Z., Li, J., Song, W., Li, J., Zhou, Q., Wang, C., Xu, Z., Meng, G., Hou, K., & Ding, P. (2025). Experimental study on measurement of outlet temperature and component concentration in a aeroengine combustor. Energy, 322, 135458–135458. https://doi.org/10.1016/j.energy.2025.135458
Gobbato, P., Lazzaretto, A., & Masi, M. (2012). Improvement of the Outlet Temperature Distribution of a Dual-Fuel Gas Turbine Combustor by a Simplified CFD Model. , 1407-1416. https://doi.org/10.1115/gt2012-69914.
Ji, C., Shi, W., Ke, E., Cheng, J., Zhu, T., Zong, C., & Li, X. (2024). Numerical Investigations on the Effects of Dome Cooling Air Flow on Combustion Characteristics and Emission Behavior in a Can-Type Gas Turbine Combustor. Aerospace. https://doi.org/10.3390/aerospace11050338.
Schaeffer, C., Barringer, M., Lynch, S., & Thole, K. (2024). Influence of Dilution and Effusion Flows in Generating Variable Inlet Profiles for a High-Pressure Turbine. Volume 7: Heat Transfer: Combustors; Heat Transfer: Film Cooling. https://doi.org/10.1115/gt2024-123899
Afia, E. R., Akam, F. N., Philip, P. E., Inyang, A. B., Bassey, N. I., Kporna, M. N., John, J. A., Etim, E. J., Isaiah, S. B., Umoh, S. J (2026). Impact of Methane Mass Flow Rate Variations on the Thermal Field of Gas Turbine Combustion Chamber. International Journal of Advances in Engineering and Management.8(1), 309- 319.DOI :10.35629/5252-0801309319
Tenango-Pirin, O., Espinosa, S., García, J., & Rodriguez, J. (2023). Analysis of Gas Turbine Combustor Exhaust Emissions: Effects of Transient Inlet Air Pressure. Energy Technology. https://doi.org/10.1002/ente.202301093.
Mohammad, B., Volk, B., & Mcmanus, K. (2020). Impact of Secondary Air Flow on Combustor Emissions. Volume 4B: Combustion, Fuels, and Emissions. https://doi.org/10.1115/gt2020-15304.
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