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Experimental investigation of diffusion flames with different baffle-plate air-hole diameters
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  • Published: 20 February 2026

Experimental investigation of diffusion flames with different baffle-plate air-hole diameters

  • Ebrahim S. Mohammed1,
  • Hamada. M. Gad1,
  • Ibrahim A. Ibrahim1,2,
  • Saad E. Habik1 &
  • …
  • Mohamed M. Elsakka1,3 

Scientific Reports , Article number:  (2026) Cite this article

We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Subjects

  • Energy science and technology
  • Engineering
  • Environmental sciences

Abstract

Diffusion flames are widely used in industrial combustion systems; however, the influence of baffle-plate air-hole diameter on flame characteristics and combustion performance remains insufficiently quantified through experimental studies. The present work experimentally investigates Liquefied Petroleum Gas (LPG) diffusion flames stabilized by multi-hole baffle plates with varying air-hole diameters. Five baffle-plate configurations with eight radially distributed air holes were tested at a constant thermal load of 32 kW over air–fuel ratios (AFR) of 15–30, while flame stability, temperature distributions, flame length, species concentrations, and combustion efficiency were systematically measured. The experimental facility consisted of an integrated setup linking air and fuel supply lines to the baffle plate and combustor chamber. The study involved the development of an empirical relation expressing flame length in terms of air-hole diameter (da) and AFR, where the discrepancy between predicted and experimental results averaged approximately 2.5%. Combustion efficiency decreased with increasing air hole diameters. Specifically, the da increased from 10 mm to 15 mm, the combustion efficiency dropped by approximately 10.17% at AFR = 15 and 11.04% at AFR = 20.

Data availability

Data are available from the corresponding author upon reasonable request.

Abbreviations

AFR:

Air fuel mass ratio

\({C}_{Pg}\) :

Specific heat capacity of the exhaust gases, J/kg·K

\({C}_{Pw}\) :

Specific heat capacity of water, J/kg·K

D:

Combustor inner diameter, mm

da :

Air hole diameter, mm

dn :

Nozzle fuel diameter, mm

da/dn :

Dimensionless air hole diameter to fuel diameter

L:

Combustor length, mm

Lf :

Flame length, mm

Lf/ dn :

Dimensionless flame length

LPG:

Liquefied petroleum gas

Na :

Number of air holes

R:

Combustor inner radius, mm

Ra :

Radial air hole positions for baffle plate, mm

r/R:

Dimensionless radial distance

\({T}_{a}\) :

Ambient temperature, K

\({T}_{w\left(in\right)}\) :

Inlet water temperature, °C

\({T}_{w\left(out\right)}\) :

Outlet water temperature, °C

T.L:

Input thermal load, kW

x/L:

Dimensionless axial distance

\({\dot{m}}_{cw}\) :

Mass flow rate of cooling water, kg/s

\({\dot{m}}_{f}\) :

Fuel mass flow rate, g/s

\({\dot{m}}_{g}\) :

Mass flow rate of exhaust gases, kg/s

\({\dot{Q}}_{convection}\) :

Heat transferred by convection, kW

\({\dot{\text{Q}}}_{\text{cw}}\) :

Heat transfer to the cooling water, kW

\({\dot{Q}}_{exhaust}\) :

Heat carried by exhaust gases, kW

\({\dot{Q}}_{radiation}\) :

Heat transferred by radiation, kW

\({\eta }_{comb}\) :

Combustion efficiency

Ф:

Equivalence ratio

References

  1. Saied, O. M. & Abdelwahab M. 1D hydrogen engine modeling to investigate air-fuel ratio, spark timing, and water injection effects on performance and emissions. Sci. Rep. 15, 17184 (2025).

    Google Scholar 

  2. Huang, Y. et al. Fundamental advances in biomass autothermal/oxidative pyrolysis. ACS Sustain. Chem. Eng. 8, 11888–11905 (2020).

    Google Scholar 

  3. Mubashir, M. et al. Machine learning assisted CFD optimization of fuel-staging natural gas burners for enhanced combustion efficiency and reduced nox emissions. Sci. Rep. 5, 23547 (2022).

    Google Scholar 

  4. Ramalingam, K. et al. Production and utilization of hydrogen enriched fifth generation biofuel in LTC engines with reformed EGR. Sci. Rep. 15, 25922 (2025).

    Google Scholar 

  5. Chen, Y. et al. The influence of cooling air jets on the premixed flame structure and stability of air-cooled bluff-body flameholder. Fuel 310, 122239 (2022).

    Google Scholar 

  6. Khelladi, F. Z. et al. The effect of bluff body shape on flame stability in a non-premixed hydrogen-methan-air mixture combustion. In Annales de Chimie-Science des Matériaux. 45, 385–392 (2021).

  7. Choi, M., Mohiuddin, K. & Park, S. Effects of methane ratio on MPDF (micro-pilot dual-fuel) combustion characteristic in a heavy-duty single cylinder engine. Sci. Rep. 11, 9740 (2021).

    Google Scholar 

  8. Hussien, A. & Qasem, I. Performance analysis of novel perforated LPG burner for domestic application. Int. J. Heat Technol.. 42, 481–489 (2024).

    Google Scholar 

  9. Sun, X. et al. Effect of hydrogen enrichment on the flame propagation, emissions formation and energy balance of the natural gas spark ignition engine. Fuel 307, 121843 (2022).

    Google Scholar 

  10. Jia, J. et al. Experimental study on the explosion characteristics of hydrogen-methane premixed gas in complex pipe networks. Sci. Rep. 11, 21204 (2021).

    Google Scholar 

  11. Dekhatawala, A., Bhale, P. V. & Shah, R. Effect of equivalence ratio on flame morphology, thermal and emissions characteristics of inverse diffusion porous burner. J. Appl. Fluid Mech. 17, 1217–1229 (2024).

    Google Scholar 

  12. Abdelrahman, I., Gad, H. M., Elsaeed, A. & Amer, A. Experimental study of the impact of flue gas recirculation on the combustion characteristics of LPG diffusion flame. J. Adv. Eng. Trends. 44, 98–105 (2025).

    Google Scholar 

  13. Nayak, G. M., Kolhe, P. & Balusamy, S. Experimental study of buoyancy-induced instability in the DME and LPG jet diffusion flame. Fuel 291, 120173 (2021).

    Google Scholar 

  14. Vance, F. H., Shoshin, Y., de Goey, L. P. H. & van Oijen, J. A. Flame stabilization regimes for premixed flames anchored behind cylindrical flame holders. Proceedings of the Combustion Institute. 38, 1983–1992 (2021).

  15. Aniello, A. et al. Experimental and numerical investigation of two flame stabilization regimes observed in a dual swirl H2-air coaxial injector. Combustion and flame. Combust. Flame. 249, 112595 (2023).

    Google Scholar 

  16. Paterakis, G., Souflas, K., Naxakis, A. & Koutmos, P. A study of recirculating flow fields downstream of a diverse range of axisymmetric bluff body geometries suitable for flame stabilization. Aerospace 8, 339 (2021).

    Google Scholar 

  17. Xu, L., Zhou, M., Wang, Y. & Liu, D. Probing sooting limits in counterflow diffusion flames via multiple optical diagnostic techniques. Exp. Thermal Fluid Sci. 136, 110679 (2022).

    Google Scholar 

  18. Van Gool, C. E. A. G., Hazenberg, T., van Oijen, J. A. & de Goey L. P. H. Numerical determination of iron dust laminar flame speeds with the counter-flow twin-flame technique. Combust. Flame. 266, 113524 (2024).

    Google Scholar 

  19. Avila Jimenez, C. D. et al. Influence of the pilot flame on the morphology and exhaust emissions of NH3-CH4-Air swirl flames using a reduced-scale burner at atmospheric pressure. Energies 16, 231 (2022).

    Google Scholar 

  20. Pignatelli, F. et al. Pilot impact on turbulent premixed methane/air and hydrogen-enriched methane/air flames in a laboratory-scale gas turbine model combustor. Int. J. Hydrog. Energy. 47, 25404–25417 (2022).

    Google Scholar 

  21. Wei, J., Xie, Q., Zhang, J. & Ren, Z. Flow, mixing, and flame stabilization in bluff-body burner with decreased central jet velocity. Phys. Fluids. 33, 067122 (2021).

    Google Scholar 

  22. Umyshev, D. R. et al. Effects of different fuel supply types on combustion characteristics behind group of V-gutter flame holders. Therm. Sci. 24, 379–391 (2020).

    Google Scholar 

  23. Ji, L. et al. Effect of confinement ratio on flame structure and blow-off characteristics of swirl flames. Exp. Thermal Fluid Sci. 135, 110630 (2022).

    Google Scholar 

  24. Sellan, D. & Balusamy, S. Experimental study of swirl-stabilized turbulent premixed and stratified LPG/air flames using optical diagnostics. Exp. Thermal Fluid Sci. 121, 110281 (2021).

    Google Scholar 

  25. Zhang, C. et al. Numerical study on combustion characteristics and heat transfer enhancement of the micro combustor embedded with Y-shaped fin for micro thermo-photovoltaic system. Appl. Therm. Eng. 211, 118427 (2022).

    Google Scholar 

  26. Bagheri, G., Hosseini, S. E. & Wahid, M. A. Effects of bluff body shape on the flame stability in premixed micro-combustion of hydrogen–air mixture. Appl. Therm. Eng. 67, 266–272 (2014).

    Google Scholar 

  27. Shahriari, B., Farrokhfal, H. & Nazari, M. R. Optimizing the aerodynamics of bluff bodies applying the adjoint method. Int. J. Multiphys. 18, 110281 (2024).

    Google Scholar 

  28. Ibrahim, I. A., Shokry, A. H., Shabaan, M. M. & Gad, H. M. A comparative study of gaseous fuel flame characteristics for different bluff body geometries. Case Stud. Therm. Eng. 34, 101951 (2022).

    Google Scholar 

  29. Abdel-Rehim, A. A., El-Nagar, K. H. & ElSemary, I. M. Effect of bluff body geometry on flame stabilization with the assist of Langmuir probe. Cairo: Benha University (2013).

  30. Zhang, C. et al. Comparative analysis of combustion stability and flow performance in micro combustor based on the synergistic action of slotted blunt body and front-baffle. Appl. Therm. Eng. 237, 121802 (2024).

    Google Scholar 

  31. Kim, W. H. & Park, T. S. Flame and heat transfer characteristics of a micro combustor with multihole baffle-induced inflows for a thermo-photovoltaic application. Numer. Heat. Transf. 84, 550–568 (2024).

    Google Scholar 

  32. Mola, A. H., Wahhab, A. & Naji, Z. H. H. A., Effects of nozzle diameter and number of carbon atoms in fuel on flame quenching in counter burner. In: International Conference on Production, Energy and Reliability. 123–131 (2022).

  33. Kim, W. H., Park, Y. S., Park, S. M. & Park, T. S. Effect of hole size on flow structure and mixing characteristic in a multi-hole baffled micro combustor. J. Appl. Math. Phys. 5, 7–16 (2017).

    Google Scholar 

  34. Namazian, Z. Effect of air velocity on the length of flame in turbulent non-premixed flames. Int. J. Mech. Prod. Eng. 4, 9–12 (2016).

    Google Scholar 

  35. Kim, W. H. & Park, T. S. Flame characteristics depending on recirculating flows in a non-premixed micro combustor with varying baffles. Appl. Therm. Eng. 148, 591–608 (2019).

    Google Scholar 

  36. Kim, W. H. & Park, T. S. Effects of number of air holes on flame and heat transfer characteristics in a multihole baffled combustor combined with micro-thermophotovoltaic and micro-thermoelectric systems. Appl. Therm. Eng. 208, 118180 (2022).

    Google Scholar 

  37. Kim, W. H. & Park, T. S. Effects of noncircular air holes on reacting flow characteristics in a micro can combustor with a seven-hole baffle. Appl. Therm. Eng. 100, 378–391 (2016).

    Google Scholar 

  38. Kim, W. H. & Park, T. S. Reacting flow characteristics based on the axis-switching phenomenon in a baffled micro combustor with rotated noncircular holes for micro-thermophotovoltaic system. Int. J. Heat Mass Transf. 195, 123169 (2022).

    Google Scholar 

  39. Kim, W. H. & Park, T. S. Non-premixed lean flame characteristics depending on air hole positions in a baffled micro combustor. Appl. Therm. Eng. 129, 431–445 (2018).

    Google Scholar 

  40. Moghtaderi, B., Shames, I. & Djenidi, L. Microfluidic characteristics of a multi-holed baffle plate micro-reactor. Int. J. Heat Fluid Flow. 27, 1069–1077 (2006).

    Google Scholar 

  41. Yahagi, Y., Sekiguti, M. & Suzuki, K. Flow structure and flame stability in a micro can combustor with a baffle plate. Appl. Therm. Eng. 27, 788–794 (2007).

    Google Scholar 

  42. Bariha, N., Mishra, I. M. & Srivastava, V. C. Fire and explosion hazard analysis during surface transport of liquefied petroleum gas (LPG): A case study of LPG truck tanker accident in Kannur, Kerala, India. J. Loss Prev. Process Ind. 40, 449–460 (2016).

    Google Scholar 

  43. Pundkar, A. H., Lawankar, S. M. & Deshmukh, S. Performance and emissions of LPG fueled internal combustion engine: a review. Int. J. Sci. Eng. Res. 14, 15–15 (2012).

    Google Scholar 

  44. Bradley, D. & Matthews, K. J. Measurement of high gas temperatures with fine wire thermocouples. J. Mech. Eng. Sci. 10, 299–305 (1968).

    Google Scholar 

  45. Shehata, M., Gad, H. M., Alshete, M. Y., Shamso, E. & Ibrahim, I. A. Effect of confinement ratio on LPG diffusion flame characteristics. Fuel 391, 134809 (2025).

    Google Scholar 

  46. Pitts, W. M. et al. Temperature uncertainties for bare-bead and aspirated thermocouple measurements in fire environments. NISTIR 6242. (1998).

  47. Ibrahim, I. A., El-Kashef, I. K. & Gad, H. M. Experimental study of gaseous fuel inverse diffusion flame. J. Adv. Eng. Trends 43, (2024).

  48. Salman, A. M., Ibrahim, I. A., Gad, H. M. & Farag, T. M. Effects of air temperature on combustion characteristics of LPG diffusion flame. Mater. Sci. Forum. 1008, 128–138 (2020).

    Google Scholar 

  49. Ibrahim, I. A., Farag, T. M., Abdel-baky, M. E., Abd El-samed, A. K. & Gad, H. M. Experimental study of spray combustion characteristics of air-blast atomizer. Energy Rep. 6, 209–215 (2020).

    Google Scholar 

  50. Chen, K., Kahangamage, U., Tan, K. & Leung, C. W. Heat transfer analysis of premixed low calorific value landfill gas impinging flame under oxygen and hydrogen enrichment. Results Eng. 25, 104118 (2025).

    Google Scholar 

  51. Tamilvanan, A., Balamurugan, K. & Vijayakumar, M. Effects of nano-copper additive on performance, combustion and emission characteristics of Calophyllum Inophyllum biodiesel in CI engine. J. Therm. Anal. Calorim. 136, 317–330 (2019).

    Google Scholar 

  52. Gad, H. M., Ibrahim, I. A., Habik, S. E., Mohammed, E. S. & Elsakka, M. M. Experimental investigation on the impact of radial air hole position of baffle plates on flame characteristics. Results Eng. 27, 106226 (2025).

    Google Scholar 

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Funding

Open access funding provided by The Science, Technology & Innovation Funding Authority (STDF) in cooperation with The Egyptian Knowledge Bank (EKB).

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Authors and Affiliations

  1. Mechanical Power Engineering Department, Faculty of Engineering, Port Said University, Port Said, 42526, Egypt

    Ebrahim S. Mohammed, Hamada. M. Gad, Ibrahim A. Ibrahim, Saad E. Habik & Mohamed M. Elsakka

  2. Faculty of Industry and Energy, East Port Said University of Technology, Salam Misr City, East Port Said, 45619, Egypt

    Ibrahim A. Ibrahim

  3. Faculty of Engineering, East Port Said National University, Salam Misr City, East Port Said, 45619, Egypt

    Mohamed M. Elsakka

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Contributions

E.S.M. carried out the experimental work, formal analysis, and contributed to methodology, conceptualization, and manuscript drafting. H.M.G., I.A.I., and S.E.H. contributed to conceptualization, methodology, supervision, and writing (original draft and review & editing). M.M.E. contributed to conceptualization, methodology, investigation, data curation, formal analysis, supervision, and writing (review & editing). All authors reviewed and approved the final manuscript.

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Correspondence to Ebrahim S. Mohammed.

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Mohammed, E.S., Gad, H.M., Ibrahim, I.A. et al. Experimental investigation of diffusion flames with different baffle-plate air-hole diameters. Sci Rep (2026). https://doi.org/10.1038/s41598-026-38141-2

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  • Received: 29 November 2025

  • Accepted: 29 January 2026

  • Published: 20 February 2026

  • DOI: https://doi.org/10.1038/s41598-026-38141-2

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Keywords

  • LPG
  • Baffle plate
  • Air hole diameter
  • Temperature distributions
  • Species concentrations
  • Diffusion flame characteristics
  • Combustion efficiency
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