Effect of Changing Compression Ratio on Ignition Delay Times of Iso-Octane in a Rapid Compression Machine

During a rapid compression machine (RCM) experiment, the temperature field that develops is expected to strongly depend on the initial temperature of the gas and, thus, the wall boundary temperatures. Two computational fluid dynamics (CFD) studies, one with buoyancy and one without buoyancy, have been conducted to investigate the role of nonuniform boundary temperatures and buoyancy as a potential cause for the top-to-bottom flame propagation behavior observed in previous ethanol autoignition experiments using a RCM. The effect of these boundary conditions and buoyancy on the initial temperature field development and how it evolves during and after compression has been investigated for ethanol autoignition using a creviced piston. Simulations with and without buoyancy showed that a unique temperature gradient forms in each case over the piston surface due to the nonuniformities present in the initial temperature fields. Finally, the simulations demonstrated the effect of these unique nonuniformities on ethanol autoignition behavior. It was determined through this work that simulations with buoyancy considered closely reproduced the features of the ethanol autoignition that were observed in the experiments.

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“…Figure b shows the crevice dimensions of the piston utilized in the MSU RCM. More details regarding the MSU RCM can be found in refs , , , − .…”

Section: Numerical Specificationsmentioning

confidence: 99%

CFD Study of the Effect of Initial Temperature Inhomogeneities and Buoyancy on the Autoignition Behavior of Ethanol in an RCM

Wadkar

Toulson

2021

Energy Fuels

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“…More recently, Wadkar et al studied the effect of changing the compression ratio of an RCM on the autoignition of iso-octane. Despite reaching similar thermodynamic conditions, the different surface area to volume ratios of the compression ratios changed the thermal flux of the system.…”

Section: Introductionmentioning

confidence: 99%

“…They found that the diluent used directly impacted the ignition delay of the mixture by changing the rate of heat transfer during autoignition. More recently, Wadkar et al 25 studied the effect of changing the compression ratio of an RCM on the autoignition of isooctane. Despite reaching similar thermodynamic conditions, the different surface area to volume ratios of the compression ratios changed the thermal flux of the system.…”

Section: Introductionmentioning

confidence: 99%

Rapid Compression Machine Ignition Delay Time Measurements under Near-Constant Pressure Conditions

2020

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This work presents and validates a new methodology that determines the adiabatic ignition delay of a hydrocarbon-based fuel using several nonadiabatic ignition delay measurements. The new methodology was developed and validated in a numerical modeling and then applied to propane autoignition experiments to determine the adiabatic ignition delay of the fuel, the so-called measured adiabatic ignition delay. Propane ignition delays were measured in a wide range of low to intermediate gas temperatures ranging from 769 to 952 K, at pressures of 23–30 bar, and at equivalence ratios of approximately 0.5 and 1.0 for a rapid compression machine (RCM). Application of the new methodology removed the effect of heat transfer on measured ignition delay, thus reporting the adiabatic ignition delay free from facility heat-transfer effects. The measured adiabatic ignition delays from the RCM are close to the ones measured by a shock tube.

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A numerical study of the effect of changing compression ratio on the auto-ignition of iso-octane in an RCM

Wadkar

Toulson

2021

Fuel

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Effect of Changing Compression Ratio on Ignition Delay Times of Iso-Octane in a Rapid Compression Machine

Cited by 6 publications

References 67 publications

CFD Study of the Effect of Initial Temperature Inhomogeneities and Buoyancy on the Autoignition Behavior of Ethanol in an RCM

CFD Study of the Effect of Initial Temperature Inhomogeneities and Buoyancy on the Autoignition Behavior of Ethanol in an RCM

Rapid Compression Machine Ignition Delay Time Measurements under Near-Constant Pressure Conditions

A numerical study of the effect of changing compression ratio on the auto-ignition of iso-octane in an RCM

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