Simultaneous rainbow schlieren deflectometry and OH* chemiluminescence imaging of a diesel spray flame in constant pressure flow rig

Parker, A; Wanstall, C.L.; Reggeti, Shawn A.; Bittle, Joshua A.; Agrawal, Ajay K.

doi:10.1016/j.proci.2020.05.045

Cited by 9 publications

(7 citation statements)

References 12 publications

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“…The methodology presented in this work was applied to a fuel spray experiment conducted in a CPFR operated at elevated pressures and temperatures to achieve autoignition and combustion of n-heptane fuel within a few milliseconds. The CPFR has been detailed in [4,11] but in brief, preheated compressed air flows through a diffuser/flow conditioner and then into the chamber. Fuel is injected into the chamber from a single 104 µm axial orifice.…”

Section: Methodsmentioning

confidence: 99%

“…Measurements in internal combustion engines (ICEs) have motivated researchers to expand the understanding of various phenomena, especially the pollutant formation processes (e.g. [1][2][3][4]). Quantitative diagnostics at engine-relevant conditions are increasingly needed to evaluate the performance of bioderived fuels/blendstocks and/or advanced combustion techniques to reduce key criteria pollutant emissions such as soot [5] in compression ignition (diesel) engines.…”

Section: Introductionmentioning

confidence: 99%

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Robust two-colour pyrometry uncertainty analysis to acquire spatially-resolved measurements

Reggeti¹,

Agrawal²,

Bittle³

2022

Meas. Sci. Technol.

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Two-colour pyrometry (2CP) has been used over several decades to study engine-relevant combustion processes, but results are generally regarded as qualitative or semi-quantitative. In many current 2CP systems, large measurement errors are introduced by parallax because the two measured wavelengths are not from the same line of sight. This work presents a spatially-resolved 2CP system with the objective to quantify and reduce the measurement uncertainty. An optical setup that eliminates parallax in 2CP is used together with pixel-by-pixel calibration of the camera sensor to increase the measurement accuracy. Primary uncertainty terms are identified, and an error propagation analysis is performed to compute uncertainties in the final results of soot temperature, soot concentration parameter, KL, and soot mass. These methodologies are applied to investigate an auto-igniting fuel spray in a constant pressure flow rig at diesel-like conditions of high ambient pressure and temperature. Results show bias uncertainty of around 200 K (~10%) for temperature and about 40-60% for KL. High uncertainty was found to occur on the diffusion flame front where both optical thickness and soot concentrations are small. However, these uncertain measurement zones with relatively low soot concentrations contribute minimally to the total soot mass present in the reacting jet during the temporal evolution of the flame.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Robust two-colour pyrometry uncertainty analysis to acquire spatially-resolved measurements

Reggeti¹,

Agrawal²,

Bittle³

2022

Meas. Sci. Technol.

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“…Hundreds of transient spray combustion experiments are performed in quick succession in a high-pressure, high-temperature environment, and fuel injection, mixing, and combustion processes are probed at high spatial and temporal resolutions simultaneously by three optical diagnostics, each focused on different aspects of the jet behavior. The diagnostics include Rainbow Schlieren Deflectometry (RSD) to visualize the early, noncombusting jet Reggeti et al (2021); Parker et al (2021), OH*CL to detect ignition and reaction zones Blocquet et al (2013), and 2CP to quantify produced soot mass Xuan et al (2019); Reggeti et al (2021). The data-set is of sufficient size to accurately discern injection-to-injection variations Donkerbroek et al (2011); Xuan et al (2019); Reggeti et al (2021); Parker et al (2021); Li et al (2017).…”

Section: Introductionmentioning

confidence: 99%

“…The diagnostics include Rainbow Schlieren Deflectometry (RSD) to visualize the early, noncombusting jet Reggeti et al (2021); Parker et al (2021), OH*CL to detect ignition and reaction zones Blocquet et al (2013), and 2CP to quantify produced soot mass Xuan et al (2019); Reggeti et al (2021). The data-set is of sufficient size to accurately discern injection-to-injection variations Donkerbroek et al (2011); Xuan et al (2019); Reggeti et al (2021); Parker et al (2021); Li et al (2017).…”

Section: Introductionmentioning

confidence: 99%

Representative Phenomena of Cyclic Turbulent Combustion in High-Pressure Fuel Sprays

Parker

Agrawal

Bittle

2023

Flow Turbulence Combust

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Cyclic variations in conventional diesel combustion engines can lead to large differences in engine out emissions even at steady operation. This study uses an optically accessible constant-pressure flow chamber to acquire fuel injections in quick succession to analyze mixing, auto-ignition, and combustion of diesel-surrogate n-heptane using multiple high-speed optical diagnostics. Prior studies have utilized fewer injections and/or they rely on analysis of ensemble average behavior. These approaches do not yield information on injection-to-injection variation or provide confidence in utilizing individual injection measurements for high-fidelity computational fluid dynamics(CFD) model validation. In this study, a large set of 500 injections is used to obtain global parameters including liquid length, vapor penetration length, ignition delay time, and lift-off length. Results for multiple injections are presented to illustrate large injection to injection variations. Potential sources for these variations are analyzed to conclude localized, small scale turbulence and rate of injection variations as the likely sources. Then, a statistical method based on z-scores is proposed and implemented to identify instantaneous injections that best represent the bulk data-set of jet boundaries measured independently by three different diagnostics. This synthesis of statistics-guided screening of data set and ensemble-average analysis offers higher confidence for CFD model validation relying upon both a representative single and average injection results.

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“…To determine these parameters, experimental setups with optical accesses are used to allow studying the combustion process inside the combustion chamber [30]. Several experimental setups can be used as high-temperature, high-pressure vessels (HTHPs) [31][32][33][34][35][36] and optically accessible engines [37][38][39][40]. These experimental setups allow researchers to reproduce thermodynamic conditions, such as those present inside the cylinder of a reciprocating IC engine [37,41].…”

Section: Introductionmentioning

confidence: 99%

An Optical Engine Used as a Physical Model for Studies of the Combustion Process Applying a Two-Color Pyrometry Technique

et al. 2022

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This work describes an experimental installation for the investigation of the combustion and injection processes. This installation is based on a two-stroke direct injection diesel engine with a total displacement of 3 L and a cylinder head equipped with three quartz windows. The windows are optical accesses that allow studying the process of injection, the atomization and evaporation of the fuel jet in an inert atmosphere (nitrogen), and the combustion process in a reactive atmosphere (ambient air). Additionally, the application of a two-color pyrometry technique to measure soot formation in this facility is presented. A methodological study is carried out regarding the influence of the dynamic range of the detectors and the wavelengths used. Maps of KL2C, flame temperature, and error probability are presented. The use of cameras with high dynamic range provides better results since the system seems to be less sensitive to measurement noise, and fewer points are obtained with a non-physical solution. Moreover, an appropriate combination of interference filters can improve the reliability of the solution. The greater the difference between the wavelengths of both interference filters, the fewer points with a non-physical solution, which improves the reliability of results.

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Simultaneous rainbow schlieren deflectometry and OH* chemiluminescence imaging of a diesel spray flame in constant pressure flow rig

Cited by 9 publications

References 12 publications

Robust two-colour pyrometry uncertainty analysis to acquire spatially-resolved measurements

Robust two-colour pyrometry uncertainty analysis to acquire spatially-resolved measurements

Representative Phenomena of Cyclic Turbulent Combustion in High-Pressure Fuel Sprays

An Optical Engine Used as a Physical Model for Studies of the Combustion Process Applying a Two-Color Pyrometry Technique

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