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. 2023 Jul 28;23(15):6747.
doi: 10.3390/s23156747.

Macroscopic Parameters of Fuel Sprays Injected in an Optical Reciprocating Single-Cylinder Engine: An Approximation by Means of Visualization with Schlieren Technique

Lis Corral-Gómez  1 , Fernando J Castillo-García  1 , José A Soriano  1 , Octavio Armas  1
Affiliations

Macroscopic Parameters of Fuel Sprays Injected in an Optical Reciprocating Single-Cylinder Engine: An Approximation by Means of Visualization with Schlieren Technique

Lis Corral-Gómez et al. Sensors (Basel). .

Abstract

This paper proposes a sensor system for an internal combustion engine based on a new vision-based algorithm supported by the Schlieren sensorization technique, which allows to acquire the macroscopic parameters of the fuel spray injected in a reciprocating internal combustion engine under unmanned aerial vehicle-like conditions. The sensor system proposed here is able to automatically determine the spray cone angle, its area and its penetration. In addition, the external surface and the volume of the fuel spray is estimated together with the injector opening delay and the ignition delay. The developed algorithm was experimentally tested using a conventional diesel fuel in a single-cylinder engine with an optically adapted head but with easy application and other configurations of reciprocating internal combustion engines. These spray macroscopic parameters allow to analyze, among others, the effect of the spray on the development of both the injection and combustion processes under different operating conditions. The estimation of the external surface of the spray makes it possible to determine the amount of fuel in the spray that is in contact with the surrounding air, with the possibility to link this parameter to the combustion efficiency and emission reduction. Consequently, obtaining the injector opening delay and the ignition delay are important parameters in the combustion phenomenon. In addition, the ignition delay has a great influence on both the engine design and its performance in the study of the air-fuel blending process, in the efficient combustion process and in the reduction of emissions.

Keywords: Schlieren technique; internal combustion engine sensor; macroscopic parameters of fuels; vision algorithm.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
General view of the engine with optically adapted head for Schlieren visualization studies.
Figure 2
Figure 2
Functional scheme of the experimental facility. Configuration for studies under reactive atmosphere.
Figure 3
Figure 3
Scheme of the used Schlieren system and views of the mounting on the engine.
Figure 4
Figure 4
Example of the fuel spray Schlieren image.
Figure 5
Figure 5
Injection and combustion processes. A descriptive summary of visualization.
Figure 6
Figure 6
Flowchart of the image-processing algorithm.
Figure 7
Figure 7
Example of the image preprocessing sequence. (a) Background mean image. (b) Fuel spray. (c) Subtracting the fuel spray image from the background image. (d) Binary image. (e) Spray contour and position of the injector.
Figure 8
Figure 8
Visualization example of the sprays macroscopic parameters.
Figure 9
Figure 9
Image example of the spray-corrected contour.
Figure 10
Figure 10
Representation of the spray surface and volume estimation through image processing.
Figure 11
Figure 11
Graphical description of the start of injection, start of combustion and ignition delay calculations through image processing.
Figure 12
Figure 12
Images acquired during the injection process.
Figure 13
Figure 13
Processed images with the spray contour (blue), the position of the injector (green) and the symmetrical spray contour (red) calculated.
Figure 14
Figure 14
Example of the calculated spray macroscopic parameters.
Figure 15
Figure 15
Example of the calculated spray surface and volume.
Figure 16
Figure 16
Example of spray area curve and second derivative of spray area curve.
Figure 17
Figure 17
Example of the in-cylinder pressure and its second derivative.
See this image and copyright information in PMC

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