Tailoring Fuels for a Shockless Explosion Combustor

Cai, Liming; Pitsch, Heinz

doi:10.1007/978-3-319-11967-0_19

Cited by 9 publications

(16 citation statements)

References 23 publications

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“…Other researchers define the excitation time from the instant when a given fraction of the maximum heat release rate (e.g. 5% in [6] and 1% in [9]) is achieved until the instant of maximum heat release. For the considered mixtures these definitions are ambiguous due to the presence of multiple ignition stages for certain conditions.…”

Section: Resultsmentioning

confidence: 99%

“…The negative temperature coefficient (NTC) behavior of most hydrocarbons, which leads to an increase in ignition delay time with increased initial temperature over a certain range of temperatures, can be utilized to tailor the combustible mixture for SEC. Mixing fuels with and without NTC behavior yields a fuel blend with temperature independent ignition delay time over a range of initial temperatures, which ideally eliminates the effect of temperature perturbations in the SEC process [9].…”

Section: Introductionmentioning

confidence: 99%

“…To avoid the formation of a detonation caused by inhomogeneous ignition not only the temperature dependency of the mixture has to be decreased but an increase in excitation time would substantially reduce the demands on the accuracy of mixture stratification and temperature homogeneity. However, it was not possible to increase the excitation time by blending different fuels [9] because relevant fuels have similar excitation times.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Knock Control in Shockless Explosion Combustion by Extension of Excitation Time

Zander

Tornow

Klein

et al. 2018

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Shockless Explosion Combustion is a novel constant volume combustion concept with an expected efficiency increase compared to conventional gas turbines. However, Shockless Explosion Combustion is prone to knocking because it is based on autoignition. This study investigates the potential of prolonging the excitation time of the combustible mixture by dilution with exhaust gas and steam to suppress detonation formation and mitigate knocking. Analyses of the characteristic chemical time scales by zero-dimensional reactor simulations show that the excitation time can be prolonged by dilution such that it exceeds the ignition delay time perturbation caused by a difference in initial temperature. This may suppress the formation of a detonation because less energy is fed into the pressure wave running ahead of the reaction front. One-dimensional simulations are performed to investigate reaction front propagation from a hot spot with various amounts of dilution. They demonstrate that dilution with exhaust gas or steam suppresses the formation of a detonation compared to the undiluted case, where a detonation ensues from the hot spot.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Knock Control in Shockless Explosion Combustion by Extension of Excitation Time

Zander

Tornow

Klein

et al. 2018

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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“…For the chemical kinetics, the latest fuel suggestion and associated reaction mechanism for a 3 bar test rig, which will also be presented at AFCC 2014 [18], namely a composition of…”

Section: Numerical Investigationmentioning

confidence: 99%

Investigation of Fluidic Devices for Mixing Enhancement for the Shockless Explosion Combustion Process

Bobusch

Berndt

Paschereit

et al. 2015

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Abstract. Fuel-air mixing is a crucial process in low emission combustion systems. A higher mixing quality leads to lower emissions and higher combustion efficiencies. Especially for the innovative constant volume combustion processes "Shockless Explosion Combustion" (SEC) the mixing of fuel and air is an important parameter, since the whole combustion process is triggered and controlled via the equivalence ratio. To enhance the passive scalar mixing, fluidic oscillators are investigated and compared to the standard jet in crossflow fuel injection configurations. The mixing quality of the different geometries is assessed in a water test-rig by making use of planar laser induced fluorescence. After a short introduction to the SEC-process, the test-rig and the different injection configurations are introduced. To verify whether the mixing quality is sufficient for the SEC-process, a numerical investigation using the experimentally determined unmixedness is conducted. It is not only shown that the fluidic oscillators are able to enhance the mixing quality and create an independence of the mixing quality from the jet in crossflow momentum, but it is also verified in a first numerical calculation that the achieved mixing quality might be good enough for the Shockless Explosion Combustion process.

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“…In order to achieve a quasi-simultaneous auto-ignition, the ignition delay time must increase from the injection position to the outlet of the combustor. Further investigations have shown that a criteria for a quasisimultaneous ignition along the combustor is that the difference in ignition delay time Δτ ign between two neighboring infinitesimal small volumes should not exceed the excitation time τ et , which is a value for the rate of chemical energy release [7,8]:…”

Section: Introductionmentioning

confidence: 99%

Effect of the Switching Times on the Operating Behavior of a Shockless Explosion Combustor

Yücel

Völzke

Paschereit

2018

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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In the past, a wide range of investigations are made in order to increase the efficiency gain in gas turbines by using constant volume combustion. In comparison to detonation-based concepts, such as pulse detonation engine and rotation detonation engine, a new promising way was proposed by Klein and Paschereit and firstly assessed by Bobusch et al. (Combust Sci Technol 186(10-11):1680-1689 (2014), [1]), the so-called shockless explosion combustion (SEC). The principle is based on a quasi-homogeneous auto-ignition process that leads to an approximate constant volume combustion (aCVC). In order to achieve a quasi-homogeneous auto-ignition, it is necessary to achieve constant ignition delay times along the combustor. The combustion process in the SEC is similar to the one in internal combustion engines, namely Homogeneous Charge Compression Ignition (HCCI). This paper focuses on the use of wastegates to actively control filling and flow motion in the combustor dedicated to perform quasi-homogeneous auto-ignition. The results clearly show the ability to actively control the fuel distribution and purging time in the combustor which is an important step in the evolution of the SEC.

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Tailoring Fuels for a Shockless Explosion Combustor

Cited by 9 publications

References 23 publications

Knock Control in Shockless Explosion Combustion by Extension of Excitation Time

Knock Control in Shockless Explosion Combustion by Extension of Excitation Time

Investigation of Fluidic Devices for Mixing Enhancement for the Shockless Explosion Combustion Process

Effect of the Switching Times on the Operating Behavior of a Shockless Explosion Combustor

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