Abstract
The in-cylinder fluid-dynamic processes of fuel injection and air entrainment influence the structure and shape of evolving fuel sprays, which can subsequently alter the ignition, combustion, and pollutant formation processes in diesel engines. Different spray angle detection methods have been used in the literature to investigate the global and local spray characteristics. In this paper, the five most widely used diesel spray angle detection methods were identified and used to evaluate the characteristic features of each detection method: methods with a detection range based on the spray penetration length, methods with a fixed detection range in the near- and far-field spray regions, triangular-based methods, and methods based on averaging local data points. The sprays were acquired from our spray chamber and processed with different thresholding techniques to explore the differences between the spray angle detection methods. All five methods generated a similar global trend of spray angle variation for temporally evolving sprays over the complete injection period. However, the actual spray angle values detected by each method were not always comparable. The differences in spray angle values between the different detection methods were larger during the early start of injection, and these differences systematically decreased as the spray approached a steady state. The methods that detected the angle in the far field demonstrated lower spatio-temporal variability when compared with the methods that detected the angle in the near field. An assessment of the comparability between angle detection methods was made, and the outcome provides guidance for the selection of the spray angle detection method.
Highlights
Diesel engines are fuel efficient with low CO2 emissions, and they are of paramount importance for the energy industry and for the sector of heavy-duty vehicles, as there is no reliable alternative for road and waterborne transportation
This section is divided into 5 sub-sections: §4A, where the impact of thresholding on each of the spray angle detection methods has been presented; §4B, where a single shot in time was chosen to evaluate how the spray angle detection methods reflect the spray angle value in the quasi-steady regime; §4C, where the spray angle variations during the fuel injection period were investigated to evaluate how the methods captured the spray angle variations with time; §4D, where the method’s variability was assessed in terms of the standard deviation; and §4E, where each method’s capability of adapting to radially expanding sprays has been discussed
EFFECT OF THRESHOLDING ON ANGLE VALUES Even though this paper focuses on how the principles behind the implementation of each spray angle detection method affect the angle values, the effect of changing the boundary thresholding technique was briefly explored
Summary
Diesel engines are fuel efficient with low CO2 emissions, and they are of paramount importance for the energy industry and for the sector of heavy-duty vehicles, as there is no reliable alternative for road and waterborne transportation. Fuel is injected at high pressures into the cylinder where it mixes with air to form an ignitable mixture that subsequently undergoes diffusion dominated combustion [1]. The transient regime follows, which covers from the SOI to the time instant at which the needle inside the nozzle reaches a fully open position. In this transient, quasi-steady regime, the spray starts to exchange momentum with the surrounding gas [4]. The third regime is the stable one, where most of the fuel is injected and the spray tends to remain in a steady-state mode until the needle starts to close.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
