Measurement of spray characteristics using the background-oriented schlieren technique

Abstract

The background-oriented schlieren (BOS) technique has not yet been used in the visualization of fuel spray in automotive research despite its great promise. To investigate the potential of this technique, the density distribution of a cross section of the spray was obtained by applying a filtered back projection (FBP) to the BOS results. Using the density distribution, the penetration lengths of the liquid and vapor phases of the fuel were measured and compared with the results of Mie scattering and shadowgraph images. The results show that the BOS technique is applicable for measuring the liquid and vapor penetration lengths simultaneously. Furthermore, the analysis of the back-projected density distribution revealed that the BOS technique is capable of visualizing the difference in the transient change in the density distribution due to changes in the injection pressure and the fuel volatility.

Background-oriented schlieren (BOS) techniques

“…Challenging wind tunnel applications under cryogenic conditions have been reported by Germain and Quest (2005), Loose et al (2006), andFey et al (2010). Combustion research can take advantage of the ability of BOS to visualize and measure heat plumes and flames (Iffa et al 2011), but also to determine concentration levels of different fuel sprays (Bang and Lee 2013; Lee et al 2011Lee et al , 2013Tillmann et al 2014) or gas jets as performed by Iffa et al (2010), Ducasse et al (2010) and Veser et al (2011).…”

Experimental Characterization of Two-Phase Aerated Liquid Ethanol and Jet A Spray Flames

“…Three optical diagnostic tools (shadowgraph, Mie scattering, and high-speed chemiluminescence imaging) are used to characterize the developed region of two-phase liquid ethanol and Jet A spray flames at atmospheric pressures. Shadowgraphy is a well-known line-of-sight diagnostic [17] that has been used to measure liquid spray penetration depth, angle, spray area, and spray development upon wall impingement [10,[18][19][20][21]. Mie scattering from the interaction of laser light with liquid sprays has been utilized for quantitative measurements of the concentration of liquid droplets and soot particles in sprays.…”

Spray dynamics of HVO and EN590 diesel fuels

“…Only a few studies focus on the quantitative spray density measurement. A recent example can be found in [6], which implemented the background-oriented schlieren (BOS) technique to visualize the difference in the temporary change in the density distribution by solving Poisson's equation. This method can be applied to obtain full-scale visualization of the density fields with a promising spatial resolution.…”