| 研究実績の概要 |
The main objective in the first year of this project was to realize a new burner for the fundamental study of ammonia spray flame, to be used for numerical modeling validation by comparison with experiment. This first target was achieved by the realization of a modular burner which enables to observe the spray in ideal conditions, with a well-controlled environment, which can be simply modeled numerically. Cold flow experiments, including backlight images, PDPA and temperature measurements, were done to study the spray characteristics for a range of commercial nozzles. Results shows that temperature decreases quickly after the nozzle, down to 210 K, under the boiling temperature of ammonia, and is attributed to the flash-boiling phenomenon. Those experiments also revealed that spray patterns, and particularly the spray opening angle, are strongly affected by the injection temperature, with narrower spray at room temperature then when the spray is cooled down. To further understand the phenomenon at stake, a simpler injection configuration was considered, and simple single-hole nozzles were designed. Finally, preliminary combustion experiments have shown that the burner and nozzles designed were suitable for flame stabilization and the flame stabilization range investigated.
In parallel to the experimental part of this project, preliminary modeling of the cold flow spray using the OpenFOAM sprayFoam solver was performed. The comparison of numerical results with experimental measurement showed an overall good agreement for both temperature and droplet diameters distributions.
|
| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The project is currently close to on time with a slight delay in the cold flow experiments for the detailed characterization of the spray with the newly designed single-hole nozzle. PDPA and temperature measurements were initially performed for the commercial nozzles selected, but remain to be performed for the newly designed single-hole nozzles, for which only backlight images have been taken. Indeed, the spray characteristics, and effect of flash-boiling, showed a strong dependency on the injection geometry during preliminary experiments. Detailed mapping of the occurrence of the phenomenon observed was thus required, before moving toward the detailed PDPA study to characterize droplet size and velocity. Nonetheless, the first combustion experiments could be realized, and the flame conditions which should be used for the flame-spray interaction investigation (OH-PLIF / Schlieren) were established. The initial cold-flow velocity measurements were taken and can be used for simulations.
The first results of this study will be submitted for poster presentation in the coming 39th international symposium on combustion (July 2022).
|
| 今後の研究の推進方策 |
As mentioned in the “current status section”, and in addition to the injection temperature effect, the single hole orifice characteristics (diameter D, aspect ratio L/D) strongly affected the spray. The quality of the surface and material employed might also be parameters that affect strongly affect the spray pattern and should be considered in ammonia spray nozzle design. In the work in the second year, temperature measurements and PDPA will be performed for the detailed characterization of spray obtained with the newly designed single-hole nozzles.
The numerical modeling of the spray for single-hole nozzles was started but will be further refined and adapted based on the experimental results. In addition, to study the effect of the injection geometry of single-hole nozzles, more complete modeling of the two-phase flow inside the nozzle will be considered.
The first combustion experiment performed will be employed for the detailed investigation of the flame. As a first approach, Schlieren images will be observed. Then, OH-PLIF will be attempted to observe the location of the flame front and its interaction with the spray.
In parallel, a detailed numerical combustion study will be performed to analyze this interaction as well as the formation of pollutants in the flame.
Finally, the writing and submission of one journal article summarizing the main achievements of the present work will be done.
|
