Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Particle tracking velocimetry (PTV) measurement technique for a experimental investigation of a surrounding air behaviour in ethanol spray development
Submission Author:
Antonio Pacifico , SP
Co-Authors:
Victor Ganino, Rafael Hauckewitz Todaro, Rafael da Cruz Ribeiro Berti, GUENTHER Krieger Filho, Antonio Pacifico
Presenter: GUENTHER Krieger Filho
doi://10.26678/ABCM.COBEM2023.COB2023-0537
Abstract
Sustainable internal combustion engines associated with lower fuel consumption and lower levels of pollutant emissions are in demand for the next generation of vehicles. Ethanol fuel is a good alternative to meet market demands when equipped with a direct injection system. In the development of the spray formation, understanding the dynamics of the inlet surrounding air is fundamental to establishing a more robust understanding of the internal combustion chamber environment. Fluid velocity measurement techniques are widely used, and the most reliable techniques nowadays are non-intrusive optical measurements, such as Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV). Despite the popularity of PIV, the PTV technique is gaining attention with new algorithms developed to handle higher-seeded flows, as its demands were specific for evaluating sparsely seeded flows. This work aims to advance the studies previously carried out on ethanol spray development using the Isothermal Ethanol Spray Chamber (IESC). The experimental methodology operated with a constant flow chamber with optical access to the spray’s surrounding environment. The injection pressure of the spray was 60 bar, and the average air mass flow was 0.066 kg/s. Air flow doped with tracer particles and captured with recording cameras represented the surrounding air movement. The objective was to use the experimental data obtained with the PIV technique and compare it with the PTV technique using the same raw images of the surrounding air of the spray. The PIV measurements showed excessive noise in areas of low seeding segments or high-velocity gradients of the flow. Through image pre-processing, it was possible to achieve a 150% better signal-to-noise ratio (SNR). The results were averaged, and outlier detection averaged about 15%. Analyses were also conducted to ensure the quality of the resultant flow field with peak-locking analysis. The PTV vector field provided valuable information, with a global velocity magnitude ranging from 2 to 15 m/s. The horizontal and vertical velocity components of these vectors were determined and related to the spray development stage and injection pressures. Recirculation structures, air drag into spray cavities, and global drag behind the spray could be observed using the PTV technique. The two-phase flow was challenging due to differences in particle concentration, but the PTV provided information about air movement in the experimental conditions representative of real engine operation, except for low rotational speed and high load conditions.
Keywords
Particle Tracking Velocimetry, Particle image velocimetry, Sprays, surrounding air
