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<p>The response of a hollow-cone n-heptane spray in a swirling airflow to forced acoustic disturbances is investigated using compressible Large-Eddy Simulations (LES) of the two-phase flow, with the dispersed fuel phase described in a Lagrangian framework. Phase-averaged numerical simulations with respect to the acoustic forcing are compared against phase-averaged phase-Doppler velocimetry (PDV) measurements of gaseous and droplet velocities, as well as phase-averaged measurements of droplet diameters over a forcing cycle. Liquid injection is modeled using the semi-empirical FIM-UR approach, a well-established framework for simulating fuel spray injection in gas turbines. Under steady injection conditions for both the gaseous and dispersed phases, simulations and experiments show excellent agreement in terms of gaseous velocity fields, droplet velocities, and droplet diameter distributions. In the acoustically forced regime, simulations also reproduce the gaseous-phase velocity response with good accuracy. Minor differences in negative velocity fluctuations at the burner outlet, attributed to pressure-drop mismatches across the air swirler, vanish downstream and can be mitigated by refining the mesh resolution in the air injection channels. For the dispersed fuel phase, however, droplet velocities are significantly overpredicted in the acoustically forced simulations. The difference arises because the simulations cannot fully reproduce the acoustically forced swirling flow, particularly in the internal recirculation zone, which is narrower than observed in experiments. Acoustic disturbances induce oscillations of the angle of hollow cone but also spatial and temporal fluctuations of the particle diameter and velocity distributions that are not accurately reproduced by the model. These findings highlight the critical importance of accurately modeling the unsteady response of the fuel injector in order to capture the complex swirling flow-spray-acoustic coupling. This coupling is shown to strongly influence the spray cone angle, as well as the distributions of droplet diameter and velocity.</p>

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Experimental and Numerical Investigation of the Acoustic Response of a Hollow-cone Fuel Spray in a Swirling Air Flow

  • 期刊论文

  • 发表日期：

    2025年12月3日

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  • Titouan Morinière,
  • Davide Laera,
  • Thierry Schuller

摘要

The response of a hollow-cone n-heptane spray in a swirling airflow to forced acoustic disturbances is investigated using compressible Large-Eddy Simulations (LES) of the two-phase flow, with the dispersed fuel phase described in a Lagrangian framework. Phase-averaged numerical simulations with respect to the acoustic forcing are compared against phase-averaged phase-Doppler velocimetry (PDV) measurements of gaseous and droplet velocities, as well as phase-averaged measurements of droplet diameters over a forcing cycle. Liquid injection is modeled using the semi-empirical FIM-UR approach, a well-established framework for simulating fuel spray injection in gas turbines. Under steady injection conditions for both the gaseous and dispersed phases, simulations and experiments show excellent agreement in terms of gaseous velocity fields, droplet velocities, and droplet diameter distributions. In the acoustically forced regime, simulations also reproduce the gaseous-phase velocity response with good accuracy. Minor differences in negative velocity fluctuations at the burner outlet, attributed to pressure-drop mismatches across the air swirler, vanish downstream and can be mitigated by refining the mesh resolution in the air injection channels. For the dispersed fuel phase, however, droplet velocities are significantly overpredicted in the acoustically forced simulations. The difference arises because the simulations cannot fully reproduce the acoustically forced swirling flow, particularly in the internal recirculation zone, which is narrower than observed in experiments. Acoustic disturbances induce oscillations of the angle of hollow cone but also spatial and temporal fluctuations of the particle diameter and velocity distributions that are not accurately reproduced by the model. These findings highlight the critical importance of accurately modeling the unsteady response of the fuel injector in order to capture the complex swirling flow-spray-acoustic coupling. This coupling is shown to strongly influence the spray cone angle, as well as the distributions of droplet diameter and velocity.