Communication Dans Un Congrès Année : 2025

Optical depth characterization of superheated ammonia spray using a collimated laser illumination with Fourier filtering

Résumé

Today, the research on the direct injection of liquid ammonia remains limited, especially in internal combustion engines, even if it can improve the global efficiency. The liquid ammonia injection results in flash-boiling and provides a strong cooling effect due to the higher latent heat of vaporization. Generally, superheat degree (Rp) represents the level of flash boiling, given by the ratio of the saturated vapor pressure of the fuel and ambient pressure. It was found that the sprays show different extents of flash boiling and spray morphology for the same degree of superheating. This indicates the dependency of spray morphology on other criteria in addition to Rp. In flash-boiling conditions, the rapid breakup of liquid ammonia injection results in a high optically dense droplet cloud.

Besides, the interference from the enormously produced vapor phase could be more problematic and challenging to perform droplet sizing. Therefore, doing it by using optical techniques is of significant interest, but it needs to remove multiple scattering to provide reliable data acquisition. Hence, to mitigate multiple scattering, the knowledge of the optical depth (OD), the average number of statistical scattering events occurring in the spray, is relevant. In this present experimental study, a novel Collimated Laser Illumination with Fourier Filtering (CLIFF) technique was considered. This imaging technique measures the spray evolution of an ECN Spray G multi-hole injector fed with ammonia at superheated conditions. Hence, this study extends our previous work and investigates the spray characteristics at a constant Rp = 9. The multi-hole GDI injector injects ammonia at a fuel injection pressure (FIP) of 75 bar in the constant volume spray chamber. The fuel temperature varies from -10 to 50 °C in increments of 10°C, while the ambient pressure is adjusted to maintain a constant Rp of 9. The setup consists of a continuous laser emitting light at 532 nm, which forms a homogeneous collimated beam as an illumination source. The transmitted light signals are collected by the positive lens and displayed on the sensor through a Fourier filter. This can be done by placing an iris diaphragm at the center of the focal plane of the positive lens.

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Dates et versions

hal-05227150 , version 1 (28-08-2025)

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Identifiants

  • HAL Id : hal-05227150 , version 1

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Utkarsha Sonawane, Camille Hespel, Christine Mounaïm-Rousselle. Optical depth characterization of superheated ammonia spray using a collimated laser illumination with Fourier filtering. 12th European Combustion Meeting, British Section of the Combustion Institute, Apr 2025, Edinbugrh, Scotland, France. ⟨hal-05227150⟩
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