Different Conditions Of The Round Hydrogen Jets Diffusion Combustion In Air

The purpose of this work is experimental study of diffusion combustion of the round hydrogen microjets with different nozzle diameter. The new phenomenon is revealed during combustion of a hydrogen microjet, which we have named «bottleneck». The special attention has been given to research of characteristics of the «bottleneck» development and its role during of a hydrogen round microjet combustion. It is shown, that «bottleneck» represents the closed spherical area of the hydrogen with air mixture combustion in a jet near-field. The «bottleneck» area is closed by a powerful density gradient. It is found, that the laminar hydrogen jet in this area overcomes a density gradient of gas, becomes turbulent and combustion process is accompanied both a turbulent jet, and a turbulent flame further downstream evolution. It is shown, that the spatial size of a «bottleneck» decreases with growth of a jet velocity.

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Diffusion Hydrogen Microjet Combustion (Round Bevelled Nozzle)

Siberian Journal of Physics ◽

10.54362/1818-7919-2015-10-2-42-51 ◽

2015 ◽

Vol 10 (2) ◽

pp. 42-51

Author(s):

Genrich Grek ◽

Mikhail Katasonov ◽

Grigory Kozlov ◽

Maria Litvinenko

Keyword(s):

Experimental Study ◽

Density Gradient ◽

Near Field ◽

Turbulent Flame ◽

Combustion Process ◽

Turbulent Jet ◽

Diffusion Combustion ◽

Side View ◽

Jet Velocity ◽

Spatial Size

The purpose of this work is experimental study of diffusion combustion of the round hydrogen microjet at the 45° bevelled nozzle. The new phenomenon is revealed during combustion of a given hydrogen microjet, which we have named «bottleneck», as well as in a situation of the round and plane microjet combustion. The special attention has been given to research of characteristics of the «bottleneck» development and its role during of a hydrogen round microjet combustion. It is shown, that «bottleneck» represents the closed spherical area of the hydrogen with air mixture combustion in a jet near-field. The «bottleneck» area is closed by a powerful density gradient. It is found, that the laminar hydrogen jet in this area overcomes a density gradient of gas, becomes turbulent and combustion process is accompanied both a turbulent jet, and a turbulent flame further downstream evolution. It is shown, that the spatial size of a «bottleneck» decreases with growth of a jet velocity. It is found, that shadow patterns of the microjet combustion obtained for two shooting positions (normal and side view to the bevelled nozzle) were identical.

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Structure Of The Attached Flame During Diffusion Hydrogen Microjet Combustion (Slotted Nozzle)

Siberian Journal of Physics ◽

10.54362/1818-7919-2015-10-2-52-66 ◽

2015 ◽

Vol 10 (2) ◽

pp. 52-66

Author(s):

Yuriy Litvinenko ◽

Genrich Grek ◽

Viktor Kozlov ◽

Oleg Korobeinichev ◽

Andrey Shmakov

Keyword(s):

Experimental Study ◽

Density Gradient ◽

Near Field ◽

Turbulent Flame ◽

Combustion Process ◽

Turbulent Jet ◽

Diffusion Combustion ◽

Jet Velocity ◽

Spatial Size

The purpose of this work is experimental study of diffusion combustion of the plane hydrogen microjet with different slotted nozzle dimensions. The new phenomenon is revealed during combustion of a plane hydrogen microjet, which we have named «bottleneck», as well as in a situation of a round microjet combustion. The special attention has been given to research of characteristics of the «bottleneck» development and its role during of a hydrogen plane microjet combustion. It is shown, that «bottleneck» represents the closed spherical area of the hydrogen with air mixture combustion in a jet near-field. The «bottleneck» area is closed by a powerful density gradient. It is found, that the laminar hydrogen jet in this area overcomes a density gradient of gas, becomes turbulent and combustion process is accompanied both a turbulent jet, and a turbulent flame further downstream evolution. It is shown, that the spatial size of a «bottleneck» decreases with growth of a jet velocity. It is found, that «bottleneck» does not arise in case of the big nozzle lengthening (l/h > 10)

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Experimental Study Of The Diffusion Combustion Of A High-Speed Round Hydrogen Microjet Part 2. Lifted Flame, Supersonic Flow

Siberian Journal of Physics ◽

10.54362/1818-7919-2017-12-2-46-59 ◽

2017 ◽

Vol 12 (2) ◽

pp. 46-59

Author(s):

Viktor Kozlov ◽

Genrich Grek ◽

Maria Litvinenko ◽

Yuriy Litvinenko ◽

Andrey Shmakov

Keyword(s):

Experimental Study ◽

High Speed ◽

Turbulent Flame ◽

Thermal Capacity ◽

Diffusion Combustion ◽

Lifted Flame ◽

Flame Region ◽

Thin Walled ◽

Spatial Size ◽

Supersonic Shock

Scenario of supersonic diffusion combustion of a round hydrogen microjet is presented in this work. The main features of supersonic diffusion combustion of a hydrogen round microjet are shown: disappearance of a «bottleneck flame» region, lifted flame from the nozzle exit and existence of supersonic «shock cells» in the lifted turbulent flame. The main reason for this scenario of diffusion combustion connected with a temperature factor is found i.e. with existence of thin-walled micronozzles with a small thermal capacity and a possibility of their quenching that doesn't give the chance to exist of the «bottleneck flame» region at big speeds of a microjet efflux. It is shown that with growth of temperature of a micronozzle heating from the «bottleneck flame» region at the same speed of a microjet efflux growth of its spatial size (l/d) is found.

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Diffusion Combustion Of The Round Microjet Mixture Of Hydrogen With Metane, Helium And Nitrogen

Siberian Journal of Physics ◽

10.54362/1818-7919-2016-11-2-56-76 ◽

2016 ◽

Vol 11 (2) ◽

pp. 56-76

Author(s):

Andrey Shmakov ◽

Genrich Grek ◽

Viktor Kozlov ◽

Yuriy Litvinenko ◽

Oleg Korobeinichev

Keyword(s):

Turbulent Flame ◽

Combustion Process ◽

Experimental Studies ◽

Diffusion Combustion ◽

Pure Hydrogen ◽

Hydrogen Mixture ◽

Combustion Features ◽

The Given ◽

Stabilization Of Combustion

The purpose of the given work will consist in an experimental studies of the diffusion combustion features of the hydrogen round microjet mixtures with the metane, helium and nitrogen. It is found, that the mechanism and characteristics of a microjet and a flame evolution at diffusion combustion of the hydrogen mixture with the metane, helium or nitrogen are connected with the «bottleneck» flame area formation, as well as in a situation of a pure hydrogen microjet diffusion combustion. It is revealed, that process of diffusion combustion of a hydrogen / metane mixture in a round microjet is accompanied by stage-by-stage stages of a turbulent flame detachment at preservation of combustion in the «bottleneck» flame area, and, at last extinction of microjet combustion that correlates with combustion process of a similar microjet of pure hydrogen. It is found, that all above-listed stages of a hydrogen / metane mixture combustion are realized in a range considerably smaller speeds of a microjet (200÷500 m/sec), than in a similar situation of a pure hydrogen microjet combustion (600÷800 m/sec). It is shown, that at diffusion combustion of a mixture of hydrogen with metane or helium or nitrogen in a round microjet for stabilization of combustion with growth of a microjet speed it is necessary to increase a portion of hydrogen (or to reduce a portion of an impurity) in a mixture of gases.

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Features Of The Diffusion Combustion Of Hydrogen Microjet At Various Spatial Orientation Of The Nozzle Exit With Top – Hat Mean Velocity Profile At The Nozzle Exit

Siberian Journal of Physics ◽

10.54362/1818-7919-2017-12-1-66-78 ◽

2017 ◽

Vol 12 (1) ◽

pp. 66-78

Author(s):

Genrich Grek ◽

Maria Litvinenko ◽

Grigory Kozlov ◽

Valentin Vikhorev

Keyword(s):

Velocity Profile ◽

Nozzle Exit ◽

Spatial Orientation ◽

Velocity Vector ◽

Turbulent Flame ◽

Diffusion Combustion ◽

Mean Velocity ◽

Jet Velocity ◽

Basic Characteristics ◽

Vector Orientation

The purpose of the given work will consist in the experimental studies of features diffusion combustion of a hydrogen round microjet, effusing from micronozzle with top – hat mean velocity profile at the nozzle exit, depending on spatial orientation of the nozzle exit. It is revealed, that in conditions of a jet velocity vector orientation towards terrestrial gravitation vector «g» (opposite or perpendicular) the basic characteristics of the flame evolution depending on gas consumption (Q) (or jet velocity U) are rather close to each other. To these characteristics concern such as ranges of the «bottleneck flame area» presence, flame separation at presence of the «bottleneck flame area», presence of the «bottleneck flame area» but absence of a turbulent jet combustion and finally ending of the microjet combustion. On the contrary, in situation of the hydrogen round microjet diffusion combustion in conditions of a jet velocity vector orientation towards terrestrial gravitation vector «g» (orientability – like) the basic characteristics of the flame evolution depending on a jet velocity are sharply differed from two previous cases. The range of existence of the «bottleneck flame area» is reduced, flame separation occurs in absence of the «bottleneck flame area», there is no situation of the «bottleneck flame area» combustion at turbulent flame separation and there is no situation of the «bottleneck flame area» combustion at burn termination of the turbulent part of a microjet and finally ending of the microjet combustion occurs at the much greater jet velocity.

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