JPH0223824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of measuring the behavior of particulates in a combustion flame in an internal combustion engine or other various combustion devices using a shadow graph.

When a parallel light beam of uniform illuminance is incident on a flame to be measured and a still photograph or high-speed photograph of the transmitted light is taken, a so-called shadow graph can be obtained. In this shadow graph, if the object to be measured contains a solid that blocks the transmission of light, its shadow will be photographed, and if the object to be measured is a fluid, refraction and scattering will occur depending on the density difference. You can shoot shadows according to the situation. However, since the combustion light from the flame is generally strong, the transmitted light is buried in the combustion light, making it impossible to obtain a good shadow graph. Therefore, it is conceivable to make the incident light on the measurement object sufficiently stronger than the combustion light, but in this case as well, a clear shadow graph cannot be obtained.

The present invention blocks the above-mentioned combustion light as much as possible by simple improvement of the optical system, and makes it possible to obtain a clear shadow graph of the flame, thereby understanding the distribution, concentration, and other particulate behavior in the combustion flame. , making it possible to measure accurately.

That is, in the measurement method of the present invention, light from a light source enters a flame in an observation area as a parallel beam of uniform illuminance through a collimator lens, and the parallel beam that has passed through the flame is converged again. The light is projected onto the observation surface through a small-diameter diaphragm placed in the convergence section, thereby shielding the combustion light of the flame to obtain a shadow graph for measuring particle behavior.

According to the method of the present invention, it is possible to obtain a clear shadow graph for observing the behavior of particulates in a flame. etc. can be measured.

Hereinafter, the method of the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows an optical system for carrying out the method of the invention. In the figure, a laser beam emitted from a light source 1 such as a He-Ne laser passes through a condenser lens 2, a pinhole 3 placed at its focal point, and a collimator lens 4, and becomes a parallel beam of uniform illuminance. The light is made to enter the observation area 6 through a mask 5 provided as necessary. The observation area 6 is formed, for example, by a combustion chamber in an internal combustion engine 7 in which the combustion chamber walls 8, 8 are made of transparent heat-resistant material such as quartz, or in other various combustion devices. The parallel transmitted light whose transmission is partially blocked by solid particles such as soot in the combustion flame in the combustion chamber is refocused by the collimator lens 9, and the mask 10 and the mask 10 disposed as necessary The collimator lens 9 is projected through the filter 11 onto the film surface of the high-speed camera 12 or other suitable viewing surface.
A small-diameter diaphragm 13 is placed at the focal point of the transmitted light, and the light is projected onto the observation surface through the diaphragm 13. In this case, the combustion light of the flame in the observation area 6 is also projected onto the observation surface through the collimator lens 9, but the light projected onto the observation area 6 as a parallel beam by the collimator lens 4 is placed at its convergence part. Almost all of the combustion light emitted in the observation area 6 passes through the aperture 13 and reaches the observation surface, whereas substantially only the light emitted from the parallel light flux in the parallel direction passes through the aperture 13, and the others Even if the light emitted in the direction is converged by the collimator lens 9, it does not pass through the aperture 13 and is blocked around it. Therefore, on the observation plane, it is possible to obtain a shadow graph for measuring particle behavior by shielding the combustion light of the flame.

Such a method can be effectively used not only for internal combustion engines but also for two-dimensional measurement of the behavior of particulates in combustion flames in external combustion engines and other combustion apparatuses, particularly the soot particle concentration in the flames. That is, in the so-called Rayleigh scattering region where the particle diameter D and the irradiation light wavelength λ satisfy the relationship πD/λ<0.2, the particle concentration can be immediately determined from the light transmittance, regardless of the wavelength and particle size. Therefore, the two-dimensional measurement of the soot concentration described above can be easily performed.

For example, when measuring the concentration of soot particles in a diesel combustion chamber, it is difficult to select representative measurement points by measuring at a fixed point in the combustion chamber using conventional methods.
Furthermore, although it is difficult to follow the overall process of soot production and disappearance, according to the method of the present invention described above,
These problems are solved at once, and the behavior of soot can be measured two-dimensionally and image-wise.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an optical system for carrying out the method of the present invention. 1... Light source, 4, 9... Collimator lens, 6
...Observation area, 13...Aperture.

Claims (1)

[Claims] 1. The light from the light source enters the flame in the observation area as a parallel beam of uniform illuminance through a collimator lens, and the parallel beam that passes through the flame is converged again, and a small-diameter diaphragm is placed at the convergence part. 1. A method for measuring the behavior of particulates in a combustion flame, which comprises projecting the particulate behavior through a combustion flame onto an observation surface, thereby shielding the combustion light of the flame to obtain a shadow graph for measuring particulate behavior.