Investigation of Spray Angle Measurement Techniques

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 spatiotemporal 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. INDEX TERMS Diesel engines, fossil fuels, image processing, spray angle measurement.

An Intelligent Multi-Sensor Variable Spray System with Chaotic Optimization and Adaptive Fuzzy Control

“…dt + w 2 σ + w 3 t r (7) where J is the objective function; w 1 , w 2 , w 3 are positive weighting factor, w 1 + w 2 + w 3 = 1; σ is the overshoot of the spray system; and t r is the rise time of the spray system.…”

“…Luo et al [6] realized variable spraying of concrete by checking the thickness and area of sprayed concrete, thereby to improve the variable spraying effect of concrete. Ruiz-Rodriguez et al [7] studied the influence of the spray angle of the nozzle on the global and local spray characteristics with the help of the fuel injection and fluid dynamics inside the cylinder in attempt to improve the spray oil combustion effect. This is followed by Giménez et al [8] who managed to use electronic spray to control the droplet diameter aiming at the study of biological effects.…”

Diesel Spray Macroscopic Parameter Estimation Using a Synthetic Shapes Database

“…Table 3 sums up the four adopted cone angle definitions. Apex-angle of a triangle having height equal to 0.5 S and corresponding equivalent area [4,9,20] Penetration S is evaluated from the binarized images, as the distance from the hole of a line orthogonal to the spray axis that individuates a region including the 99% of white pixels (the spray). Cone angle definitions (b) and (d) are based on such definition.…”

“…Alternatively, it can be measured by fitting two straight lines to the spray contour or even as the apex angle of an isosceles triangle having the corresponding spray area at a given percentage of the penetration length. A comprehensive description and comparison of different spray angle definitions can be found in [4] where a variation up to 95% has been observed in the cone angle evaluated by different methods. This disagreement arises from the fact that the spray cone features irregular and faded boundaries, thus making it intrinsically difficult to discern what is to be considered as spray from the surrounding.…”

“…These methods, which arise for general segmentation purposes, show good performances also in segmenting spray images. However, different algorithm results in a different threshold level, which in turn leads to different macroscopic spray parameters, mainly affecting the cone angle [4,17]. A better understanding can be achieved considering a typical spray image and the corresponding pixel intensity over three transverse profiles (Figure 2a-c) and along the longitudinal direction (Figure 2d).…”