Macroscopic Spray Characteristics of a Porous Injector

Kim, Dohun; Lee, Inchul; Koo, Jaye

doi:10.1615/atomizspr.2013006408

Cited by 8 publications

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“…The spray from the PRS injector spread wider than the SHR injector due to the radial momentum transfer to the center liquid jet, as observed in the previous cold flow study. 8,12 Although the cold flow spray tests were conducted in an atmospheric condition, the disintegration behavior was quite similar with that of the reactive spray. The disintegration and phase change patterns could be observed more clearly by converting the shadowgraph image to the density gradient magnitude image, as shown in Fig.…”

Section: B Spray Patterns: Shadowgraph and Density Gradient Magnitudmentioning

confidence: 92%

Effects of Wall-injection Length on Spray Core and Combustion Performance in a Coaxial Porous Injector

Kim¹,

Koo

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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The mixing performance of an injector determines the combustion performance of a bipropellant rocket engine. A novel coaxial porous injector concept was developed to improve the mixing performance of a shear coaxial injector. It showed higher characteristic velocity efficiency than that of a shear coaxial injector. The combustion flow fields of both injectors were visualized using a high speed shadowgraph technique to observe the geometry factor effect on the spray core length and the combustion performance, as well as the difference of reactive spray behavior between the coaxial porous injector and the shear coaxial injector. Changes in wall-injection length had a non-monotonic effect on both the spray core length and the characteristic velocity efficiency. As opposed to the expected result, the coaxial porous injector with the highest combustion efficiency showed the longest spray core length. The phase change pattern width, caused by the evaporation of liquid fuel, was proportional to the efficiency. Nomenclature c * = characteristic velocity c * CEA = theoretical characteristic velocity D cc = diameter of combustion chamber D G = diameter of gas injector in shear coaxial injector D L = diameter of liquid injector in coaxial porous/shear coaxial injectors D P = diameter of center post in shear coaxial injector D PR = inner diameter of porous cylinder D VIS.= diameter of visualized region J tip = momentum flux ratio calculated at injector tip L cc = length of combustion chamber L ing.= axil distance from injector face to igniter center L PR = axial length of wall-injection area of porous cylinder O/F = oxidizer to fuel P cc = combustion chamber pressure P inj.O = oxidizer pressure upstream of injector P inj.F = fuel pressure upstream of injector R = length of recess in shear coaxial injector R A = ratio of gas to liquid injection area at injector tip t AG = thickness of annular gap in shear coaxial injector t f = thickness of coaxial porous injector face plate T inj.O = oxidizer temperature at injector t PR = thickness of porous cylinder

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Section: B Spray Patterns: Shadowgraph and Density Gradient Magnitudmentioning

confidence: 92%

Effects of Wall-injection Length on Spray Core and Combustion Performance in a Coaxial Porous Injector

Kim¹,

Koo

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Atomization Characteristics of a Porous Injector

Jegan¹,

Vadivukkarasan²

2021

Lecture Notes in Mechanical Engineering

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Combined visualisation of cavitation and vortical structures in a real-size optical diesel injector

et al. 2020

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A high-speed flow visualisation set-up comprising of combined diffuse backlight illumination (DBI) and schlieren imaging has been developed to illustrate the highly transient, two-phase flow arising in a real-size optical fuel injector. The different illumination nature of the two techniques, diffuse and parallel light respectively, allows for the capturing of refractive-index gradients due to the presence of both interfaces and density gradients within the orifice. Hence, the onset of cavitation and secondary-flow motion within the sac and injector hole can be concurrently visualised. Experiments were conducted utilising a diesel injector fitted with a single-hole transparent tip (ECN spray D) at injection pressures of 700–900 bar and ambient pressures in the range of 1–20 bar. High-speed DBI images obtained at 100,000 fps revealed that the orifice, due to its tapered layout, is mildly cavitating with relatively constant cavity sheets arising mainly in regions of manufacturing imperfections. Nevertheless, schlieren images obtained at the same frame rate demonstrated that a multitude of vortices with short lifetimes arise at different scales in the sac and nozzle regions during the entire duration of the injection cycle but the vortices do not necessarily result in phase change. The magnitude and exact location of coherent vortical structures have a measurable influence on the dynamics of the spray emerging downstream the injector outlet, leading to distinct differences in the variation of its cone angle depending on the injection and ambient pressures examined. Graphic abstract

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Macroscopic Spray Characteristics of a Porous Injector

Cited by 8 publications

References 0 publications

Effects of Wall-injection Length on Spray Core and Combustion Performance in a Coaxial Porous Injector

Effects of Wall-injection Length on Spray Core and Combustion Performance in a Coaxial Porous Injector

Atomization Characteristics of a Porous Injector

Combined visualisation of cavitation and vortical structures in a real-size optical diesel injector

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