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Papers by Michael Delichatsios

Fire and Materials, 2012

ABSTRACTThis work investigates how the inflow, the burning and the outflow develop in a corridor ... more ABSTRACTThis work investigates how the inflow, the burning and the outflow develop in a corridor open to one end having a fire at either the closed or open end. The situation of a corridor fire having a fire source at the close end is a situation similar to a tunnel having a fire source at the centre of the tunnel without ventilation. A gaseous propane burner is used to produce the fire at a prescribed fuel flow rate in a long corridor of aspect ratio up to 6:1 having a rectangular cross section and varying door‐like openings. Gas temperatures using thermocouple trees, heat fluxes in the corridor and on its façade, flame heights of emerging flames and total heat release rates (HRRs) are measured as the fuel flow rate of propane increases gradually and linearly with time to a preset maximum value. For over‐ventilated conditions, the flames remain near the fire source at the closed end of the corridor. Unexpectedly, it is established for under‐ventilated conditions that the inflow of ...

Fire Safety Journal, 2011

In this study, a global soot formation model based on the LSP (Laminar Smoke Point) concept in co... more In this study, a global soot formation model based on the LSP (Laminar Smoke Point) concept in combination with the soot oxidation model developed by Leung et al. [40] is validated in three laminar flames: a non-smoking and a smoking ethylene flame, as well as a non-smoking propane flame, and then applied in two turbulent pool fires fueled by ethylene and methane, respectively. In this global soot model, the sooting propensities of different fuels are accounted for by a pre-exponential factor determined from the LSP height, providing a general and practical solution for soot modeling in multifueled fires. The flame fields are solved by FLUENT with UDFs to provide material properties and add additional soot governing equations. A-CSE (Alternative Conditional Source-term Estimation) approach is adopted to handle the interaction between soot chemistry and turbulent flow in the turbulent fires. The model parameters such as the pre-exponential factor, soot inception limits and soot particulate surface area are determined and calibrated against the experimental data. Mixture fraction and temperature are first verified to provide a good premise for soot modeling. Good agreements between the predicted and measured soot volume fraction, as well as the reproduction of transition from non-smoking to smoking flames, demonstrate the capability of current global soot model in accurately predicting soot for both laminar flames and turbulent fires. Using the A-CSE soot modeling approach together with the global soot model, this study presents a general effective yet computationally efficient global soot modeling framework for fires.

Fire Safety Science, 2014

Facade fires being a disastrous hazard for high rise building, as several historical and recent i... more Facade fires being a disastrous hazard for high rise building, as several historical and recent incidents have shown, have attracted the interests of numerous fire scientists, engineers and regulators. This work has as an objective to present issues in this area that are challenging and need further attention. It focuses on characterizing the flame height and heat fluxes from facade flames produced from under-ventilated enclosure fires on a facade that is not flammable. Such an investigation is an important consideration for practical applications as well as a prerequisite for examining fire spread on flammable facades and for designing a test for modern facade assemblies. The mass pyrolysis rates and burning of real fuels are discussed in under ventilated enclosures, rectangular or corridor like, for various openings presenting the current state and some critical issues. Facade flames are analyzed from experiments using gaseous burners to have control on the fuel supply rate by introducing physical length scales for the opening geometries to model flame heights and heat fluxes. An important parameter for the facade flames is the excess heat release rate of the fuel burning outside the enclosure. Finally, applications for facade flames with sidewalls and facade flames from two openings are presented.

Fire Science and Technology, 2007

Fire Safety Science, 1994

A methodology and a model are presented for the calculation of radiation distribution from fires.... more A methodology and a model are presented for the calculation of radiation distribution from fires. Extensive application of the model is discussed with regard to turbulent buoyant jet fires wherein radiation is controlled by soot and the flame size is such that it produces optically thin conditions. The local soot concentration is modelled, according to previous results, to be 1) proportional to the inverse smoke-point heat release rate, Y,-l /~, and 2) a function of the local mixture fraction and temperature. The local volumetric emissive power is averaged over the turbulent fluctuations to obtain the radiation losses for optically thin flame situations. Combustion is modelled, in a standard way, by an ensemble of laminar flamelets whose chemical composition of species is known from state relationships. The combustion model is an integral model that has been validated by extensive data from turbulent buoyant jet flames whereas the radiation model is validated here by comparison with propane turbulent jet flames; this comparison allows the determination of a proportionality coefficient for the soot concentration and radiation term. The generality and soundness of the model has been determined by applying it to predict the jet flame radiation from another fuel, propylene (while maintaining the same proportionality constant for the soot as for the propane). Preliminary results and favorable comparisons with experiments are also shown for pool fires of diameter up to 1 m. The proposed methodology and the model can be applied to an arbitrary burning material whose laminar smoke-point heat release rate has been measured in laboratory experiments.

Fire Safety Journal, 2011

In this study, a global soot formation model based on the LSP (Laminar Smoke Point) concept in co... more In this study, a global soot formation model based on the LSP (Laminar Smoke Point) concept in combination with the soot oxidation model developed by Leung et al. [40] is validated in three laminar flames: a non-smoking and a smoking ethylene flame, as well as a non-smoking propane flame, and then applied in two turbulent pool fires fueled by ethylene and methane, respectively. In this global soot model, the sooting propensities of different fuels are accounted for by a pre-exponential factor determined from the LSP height, providing a general and practical solution for soot modeling in multifueled fires. The flame fields are solved by FLUENT with UDFs to provide material properties and add additional soot governing equations. A-CSE (Alternative Conditional Source-term Estimation) approach is adopted to handle the interaction between soot chemistry and turbulent flow in the turbulent fires.

Fire and Materials, 2012

ABSTRACTThis work investigates how the inflow, the burning and the outflow develop in a corridor ... more ABSTRACTThis work investigates how the inflow, the burning and the outflow develop in a corridor open to one end having a fire at either the closed or open end. The situation of a corridor fire having a fire source at the close end is a situation similar to a tunnel having a fire source at the centre of the tunnel without ventilation. A gaseous propane burner is used to produce the fire at a prescribed fuel flow rate in a long corridor of aspect ratio up to 6:1 having a rectangular cross section and varying door‐like openings. Gas temperatures using thermocouple trees, heat fluxes in the corridor and on its façade, flame heights of emerging flames and total heat release rates (HRRs) are measured as the fuel flow rate of propane increases gradually and linearly with time to a preset maximum value. For over‐ventilated conditions, the flames remain near the fire source at the closed end of the corridor. Unexpectedly, it is established for under‐ventilated conditions that the inflow of ...

Fire Safety Journal, 2011

In this study, a global soot formation model based on the LSP (Laminar Smoke Point) concept in co... more In this study, a global soot formation model based on the LSP (Laminar Smoke Point) concept in combination with the soot oxidation model developed by Leung et al. [40] is validated in three laminar flames: a non-smoking and a smoking ethylene flame, as well as a non-smoking propane flame, and then applied in two turbulent pool fires fueled by ethylene and methane, respectively. In this global soot model, the sooting propensities of different fuels are accounted for by a pre-exponential factor determined from the LSP height, providing a general and practical solution for soot modeling in multifueled fires. The flame fields are solved by FLUENT with UDFs to provide material properties and add additional soot governing equations. A-CSE (Alternative Conditional Source-term Estimation) approach is adopted to handle the interaction between soot chemistry and turbulent flow in the turbulent fires. The model parameters such as the pre-exponential factor, soot inception limits and soot particulate surface area are determined and calibrated against the experimental data. Mixture fraction and temperature are first verified to provide a good premise for soot modeling. Good agreements between the predicted and measured soot volume fraction, as well as the reproduction of transition from non-smoking to smoking flames, demonstrate the capability of current global soot model in accurately predicting soot for both laminar flames and turbulent fires. Using the A-CSE soot modeling approach together with the global soot model, this study presents a general effective yet computationally efficient global soot modeling framework for fires.

Fire Safety Science, 2014

Facade fires being a disastrous hazard for high rise building, as several historical and recent i... more Facade fires being a disastrous hazard for high rise building, as several historical and recent incidents have shown, have attracted the interests of numerous fire scientists, engineers and regulators. This work has as an objective to present issues in this area that are challenging and need further attention. It focuses on characterizing the flame height and heat fluxes from facade flames produced from under-ventilated enclosure fires on a facade that is not flammable. Such an investigation is an important consideration for practical applications as well as a prerequisite for examining fire spread on flammable facades and for designing a test for modern facade assemblies. The mass pyrolysis rates and burning of real fuels are discussed in under ventilated enclosures, rectangular or corridor like, for various openings presenting the current state and some critical issues. Facade flames are analyzed from experiments using gaseous burners to have control on the fuel supply rate by introducing physical length scales for the opening geometries to model flame heights and heat fluxes. An important parameter for the facade flames is the excess heat release rate of the fuel burning outside the enclosure. Finally, applications for facade flames with sidewalls and facade flames from two openings are presented.

Fire Science and Technology, 2007

Fire Safety Science, 1994

A methodology and a model are presented for the calculation of radiation distribution from fires.... more A methodology and a model are presented for the calculation of radiation distribution from fires. Extensive application of the model is discussed with regard to turbulent buoyant jet fires wherein radiation is controlled by soot and the flame size is such that it produces optically thin conditions. The local soot concentration is modelled, according to previous results, to be 1) proportional to the inverse smoke-point heat release rate, Y,-l /~, and 2) a function of the local mixture fraction and temperature. The local volumetric emissive power is averaged over the turbulent fluctuations to obtain the radiation losses for optically thin flame situations. Combustion is modelled, in a standard way, by an ensemble of laminar flamelets whose chemical composition of species is known from state relationships. The combustion model is an integral model that has been validated by extensive data from turbulent buoyant jet flames whereas the radiation model is validated here by comparison with propane turbulent jet flames; this comparison allows the determination of a proportionality coefficient for the soot concentration and radiation term. The generality and soundness of the model has been determined by applying it to predict the jet flame radiation from another fuel, propylene (while maintaining the same proportionality constant for the soot as for the propane). Preliminary results and favorable comparisons with experiments are also shown for pool fires of diameter up to 1 m. The proposed methodology and the model can be applied to an arbitrary burning material whose laminar smoke-point heat release rate has been measured in laboratory experiments.

Fire Safety Journal, 2011

In this study, a global soot formation model based on the LSP (Laminar Smoke Point) concept in co... more In this study, a global soot formation model based on the LSP (Laminar Smoke Point) concept in combination with the soot oxidation model developed by Leung et al. [40] is validated in three laminar flames: a non-smoking and a smoking ethylene flame, as well as a non-smoking propane flame, and then applied in two turbulent pool fires fueled by ethylene and methane, respectively. In this global soot model, the sooting propensities of different fuels are accounted for by a pre-exponential factor determined from the LSP height, providing a general and practical solution for soot modeling in multifueled fires. The flame fields are solved by FLUENT with UDFs to provide material properties and add additional soot governing equations. A-CSE (Alternative Conditional Source-term Estimation) approach is adopted to handle the interaction between soot chemistry and turbulent flow in the turbulent fires.