Relationship between flame speed, maximum pressure and pulsation velocity in a variable volume combustion chamber

The article analyzes the influence of chemical composition of hythane (a mixture of natural gas with hydrogen) on pressure in an engine combustion chamber. A review of the literature has showed the relevance of using hythane in transport energy industry, and also revealed a number of scientific papers devoted to studying the effect of hythane on environmental and traction-dynamic characteristics of the engine. We have studied a single-cylinder spark-ignited internal combustion engine. In the experiments, the varying factors are: engine speed (600 and 900 min-1), excess air ratio and hydrogen concentration in natural gas which are 29, 47 and 58% (volume).The article shows that at idling engine speed maximum pressure in combustion chamber depends on excess air ratio and proportion hydrogen in the air-fuel mixture – the poorer air-fuel mixture and greater addition of hydrogen is, the more intense pressure increases. The positive effect of hydrogen on pressure is explained by the fact that addition of hydrogen contributes to increase in heat of combustion fuel and rate propagation of the flame. As a result, during combustion, more heat is released, and the fuel itself burns in a smaller volume. Thus, the addition of hydrogen can ensure stable combustion of a lean air-fuel mixture without loss of engine power. Moreover, the article shows that, despite the change in engine speed, addition of hydrogen, excess air ratio, type of fuel (natural gas and gasoline), there is a power-law dependence of the maximum pressure in engine cylinder on combustion chamber volume. Processing and analysis of the results of the foreign and domestic researchers have showed that patterns we discovered are applicable to engines of different designs, operating at different speeds and using different hydrocarbon fuels. The results research presented allow us to reduce the time and material costs when creating new power plants using hythane and meeting modern requirements for power, economy and toxicity.

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THE STUDY OF SPECIAL ASPECTS OF COMBUSTION IN A VARIABLE VOLUME COMBUSTION CHAMBER

Vektor nauki Tol yattinskogo gosudarstvennogo universiteta ◽

10.18323/2073-5073-2019-1-64-71 ◽

2019 ◽

pp. 64-71

Author(s):

A. P. Shaikin ◽

◽

P. V. Ivashin ◽

I. R. Galiev ◽

I. N. Bobrovsky ◽

...

Keyword(s):

Combustion Chamber ◽

Variable Volume

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Predicting Flashback Limits of a Gas Turbine Model Combustor Based on Velocity and Fuel Concentration for H2-Air-Mixtures

Volume 4A: Combustion, Fuels and Emissions ◽

10.1115/gt2016-56245 ◽

2016 ◽

Author(s):

Matthias Utschick ◽

Daniel Eiringhaus ◽

Christian Köhler ◽

Thomas Sattelmayer

Keyword(s):

Combustion Chamber ◽

Gas Turbine ◽

High Speed ◽

Air Flow ◽

Turbulent Flame ◽

Flame Speed ◽

Fuel Injector ◽

Trailing Edge ◽

Fuel Concentration ◽

Turbine Model

This study investigates the influence of the fuel injection strategy on safety against flashback in a gas turbine model combustor with premixing of H2-air-mixtures. The flashback propensity is quantified and the flashback mechanism is identified experimentally. The A2EV swirler concept exhibits a hollow, thick walled conical structure with four tangential slots. Four fuel injector geometries were tested. One of them injects the fuel orthogonal to the air flow in the slots (jet-in-crossflow-injector, JICI). Three injector types introduce the fuel almost isokinetic to the air flow at the trailing edge of the swirler slots (trailing edge injector, TEI). Velocity and mixing fields in mixing zone and combustion chamber in isothermal water flow were measured with High-speed-Particle-Image-Velocimetry (PIV) and Highspeed-Laser-Induced-Fluorescence (LIF). The flashback limit was determined under atmospheric pressure for three air mass flows and 673 K preheat temperature for H2-air-mixtures. Flashback mechanism and trajectory of the flame tip during flashback were identified with two stereoscopically oriented intensified high-speed cameras observing the OH* radiation. We notice flashback in the core flow due to Combustion Induced Vortex Breakdown (CIVB) and Turbulent upstream Flame Propagation (TFP) near the wall dependent on the injector type. The Flashback Resistance (FBR) defined as the ratio between a characteristic flow speed and a characteristic flame speed measures the direction of propagation of a turbulent flame in the flow field. Although CIVB cannot be predicted solely based on the FBR, its distribution gives evidence for CIVB-prone states. The fuel should be injected preferably isokinetic to the air flow along the entire trailing edge in oder to reduce the RMS fluctuation of velocity and fuel concentration. The characteristic velocity in the entire cross section of the combustion chamber inlet should be at least twice the characteristic flame speed. The position of the stagnation point should be tuned to be located in the combustion chamber by adjusting the axial momentum. Those measures lead to safe operation with highly reactive fuels at high equivalence ratios.

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Simulation studies of combustion in a constant-mass variable-volume combustion chamber

FME Transaction ◽

10.5937/fmet1804475a ◽

2018 ◽

Vol 46 (4) ◽

pp. 475-488

Author(s):

Lucky Anetor ◽

Edward Osakue

Keyword(s):

Combustion Chamber ◽

Simulation Studies ◽

Constant Mass ◽

Variable Volume

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Predicting Flashback Limits of a Gas Turbine Model Combustor Based on Velocity and Fuel Concentration for H2–Air Mixtures

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4034646 ◽

2016 ◽

Vol 139 (4) ◽

Author(s):

Matthias Utschick ◽

Daniel Eiringhaus ◽

Christian Köhler ◽

Thomas Sattelmayer

Keyword(s):

Combustion Chamber ◽

Gas Turbine ◽

High Speed ◽

Air Flow ◽

Turbulent Flame ◽

Flame Speed ◽

Fuel Injector ◽

Trailing Edge ◽

Fuel Concentration ◽

Turbine Model

This study investigates the influence of the fuel injection strategy on safety against flashback in a gas turbine model combustor with premixing of H2–air mixtures. The flashback propensity is quantified and the flashback mechanism is identified experimentally. The A2EV swirler concept exhibits a hollow, thick-walled conical structure with four tangential slots. Four fuel injector geometries were tested. One of them injects the fuel orthogonal to the air flow in the slots (jet-in-crossflow injector (JICI)). Three injector types introduce the fuel almost isokinetic to the air flow at the trailing edge of the swirler slots (trailing edge injector (TEI)). Velocity and mixing fields in mixing zone and combustion chamber in isothermal water flow were measured with high-speed particle image velocimetry (PIV) and high-speed laser-induced fluorescence (LIF). The flashback limit was determined under atmospheric pressure for three air mass flows and 673 K preheat temperature for H2–air mixtures. Flashback mechanism and trajectory of the flame tip during flashback were identified with two stereoscopically oriented intensified high-speed cameras observing the OH* radiation. We notice flashback in the core flow due to combustion-induced vortex breakdown (CIVB) and turbulent flame propagation (TFP) near the wall dependent on the injector type. The flashback resistance (FBR) defined as the ratio between a characteristic flow speed and a characteristic flame speed measures the direction of propagation of a turbulent flame in the flow field. Although CIVB cannot be predicted solely based on the FBR, its distribution gives evidence for CIVB-prone states. The fuel should be injected preferably isokinetic to the air flow along the entire trailing edge in order to reduce the RMS fluctuation of velocity and fuel concentration. The characteristic velocity in the entire cross section of the combustion chamber inlet should be at least twice the characteristic flame speed. The position of the stagnation point should be tuned to be located in the combustion chamber by adjusting the axial momentum. Those measures lead to safe operation with highly reactive fuels at high equivalence ratios.

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Effects of each operating condition on the maximum pressure in an imploding detonation apparatus with a pre-combustion chamber

Journal of Thermal Science and Technology ◽

10.1299/jtst.2015jtst0010 ◽

2015 ◽

Vol 10 (1) ◽

pp. JTST0010-JTST0010 ◽

Cited By ~ 1

Author(s):

Yohichi UDAGAWA ◽

Minoru SUZUKI

Keyword(s):

Combustion Chamber ◽

Maximum Pressure ◽

Operating Condition

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Combustion Characteristics and Laminar Flame Speed of Premixed Ethanol-Air Mixtures with Laser-Induced Spark Ignition

Biofuels Engineering ◽

10.1515/bfuel-2017-0005 ◽

2017 ◽

Vol 2 (1) ◽

pp. 63-72 ◽

Cited By ~ 3

Author(s):

Cangsu Xu ◽

Anhao Zhong ◽

Chongming Wang ◽

Chaozhao Jiang ◽

Xiaolu Li ◽

...

Keyword(s):

High Speed ◽

Laminar Flame ◽

Pressure Rise ◽

Spark Ignition ◽

Laser Wavelength ◽

Combustion Characteristics ◽

Flame Speed ◽

Maximum Pressure ◽

Laminar Flame Speed ◽

Combustion Duration

AbstractLaser-induced spark-ignition (LISI) has an advanced ignition technique with a few benefits over spark ignition. In this study, flame morphology, laminar flame characteristics and combustion characteristics of premixed anhydrous ethanol and air mixtures were investigated using LISI generated by a Q-switched Nd: YAG laser (wavelength: 1064 nm). Experiments were conducted in a constant volume combustion chamber (CVCC) at the initial condition of T0=358 K and P0=0.1 MPa, respectively, and with equivalence ratios (ɸ) of 0.6-1.6. Flame images were recorded by using the high-speed Schlieren photography technique, and the in-vessel pressure was recorded using a piezoelectric pressure transducer. Tests were also carried out with spark ignition, and the results were used as a reference. It has been found that the laminar flame speed of ethanol-air mixtures with LISI was comparable with those of spark ignition, proving that ignition methods have no influence on laminar flame speed which is an inherent characteristic of a fuel-air mixture. The peak laminar burning velocities for LISI and spark ignition with nonlinear extrapolation methods were approximately 50 cm/s at ɸ=1.1. However, LISI was able to ignite leaner mixtures than spark ignition. The maximum pressure rise rate of LISI was consistently higher than that of spark ignition at all tested ɸ, although the maximum pressure was similar for LISI and spark ignition. The initial combustion duration and main combustion duration reached the minimum at ɸ=1.1.

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Effect of Argon Concentration on Laminar Burning Velocity and Flame Speed of Hydrogen Mixtures in a Constant Volume Combustion Chamber

Journal of Energy Resources Technology ◽

10.1115/1.4048019 ◽

2020 ◽

Vol 143 (3) ◽

Author(s):

Mohammadrasool Morovatiyan ◽

Martia Shahsavan ◽

Jonathan Aguilar ◽

J. Hunter Mack

Keyword(s):

Combustion Chamber ◽

Burning Velocity ◽

Internal Combustion ◽

Hydrogen Combustion ◽

Flame Speed ◽

Constant Volume ◽

Working Fluid ◽

Laminar Burning Velocity ◽

Efficient Energy ◽

Constant Volume Combustion Chamber

Abstract Hydrogen combustion, coupled with the use of argon as a working fluid, is a promising approach to delivering clean and efficient energy from internal combustion (IC) engines. The use of hydrogen-oxygen-argon (H2/O2/Ar) mixtures in combustion aids in mitigating harmful environmental pollutants and enables a highly efficient energy conversion process. The use of argon as a working fluid decreases the NOx emissions and increases the thermal efficiency of internal combustion engines due to the high specific heat ratio of noble gases. In this study, premixed hydrogen combustion was investigated with the purpose of examining the effect of the full or partial substitution of argon for nitrogen in air on laminar burning velocity (LBV), flame speed, flame morphology, and instability. The experimental approach uses an optically accessible constant volume combustion chamber (CVCC) with central ignition; the spherical flame development was studied using a high-speed Z-type Schlieren visualization system. Moreover, a numerical model was developed to convert the experimental dynamic pressure rise data to laminar burning velocity. Coupling the model to a chemical equilibrium code aids in determining the burned gas properties. Additionally, an image processing technique has been suggested to compute the flame propagation speed. The experimental and numerical investigations indicate that increasing the concentration of argon as the working fluid in the mixture increases the laminar burning velocity and flame speed while extending the lean flammability limit.

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Wittgenstein's combustion chamber

Notes and Records the Royal Society journal of the history of science ◽

10.1098/rsnr.2008.0031 ◽

2009 ◽

Vol 63 (1) ◽

pp. 95-104 ◽

Cited By ~ 1

Author(s):

John Cater ◽

Ian Lemco

Keyword(s):

Combustion Chamber ◽

Ludwig Wittgenstein ◽

Western World ◽

Propeller Blade ◽

Engineering Research ◽

Probable Function ◽

Variable Volume ◽

Aero Engine ◽

Blade Tip ◽

Aeronautical Engineering

Ludwig Wittgenstein, destined to be one of the most influential philosophers of the western world, entered Manchester University in 1908 as an aeronautical engineering research student. At Manchester he devised and patented a novel aero-engine that employed propeller-blade tip-jets. As a first practical step to the realization of this device, Wittgenstein constructed a variable-volume combustion chamber, but on departing for Cambridge he abandoned all further work on the project. The plans of this chamber survived and are presented in this paper. This article includes a detailed description of the drawings and an analysis of the probable function of the system.

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Converting an automobile turbocharger into a micro gas turbine

E3S Web of Conferences ◽

10.1051/e3sconf/20199502008 ◽

2019 ◽

Vol 95 ◽

pp. 02008 ◽

Cited By ~ 1

Author(s):

M Usman Butt

Keyword(s):

Combustion Chamber ◽

Gas Turbine ◽

Low Cost ◽

Outer Cylinder ◽

Maximum Pressure ◽

Complete Combustion ◽

Micro Gas Turbine ◽

Flame Tube ◽

Liquid Petroleum Gas ◽

Automobile Components

A low cost micro turbojet made by using an automobile turbocharger and other automobile components for research is presented in this paper. The machine comprises mainly of three main assemblies, the compressor & turbine assembly, the combustion chamber and the lubrication & cooling accessories. Carefully selected turbocharger with correct compressor & turbine combination by taking into account their efficiencies and losses associated with their small size and suitably designed combustion chamber results in a self-sustaining turbojet. The combustion chamber is composed of a combustion liner/flame tube and an outer cylinder. The flame tube is divided into three different zones to allow complete combustion and cooling of hot gases. The fuel used is liquid petroleum gas (LPG). The maximum pressure recorded in the combustion chamber was 11.5 psi and a pressure loss of about 4%. The maximum rpm (revolutions per minute) of the engine ranged to 84000.

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