Secondary Droplet Formation During Binary Suspension Droplet Collisions

Kurt, O.; Fritsching, Udo; Schulte, Günther

doi:10.1615/atomizspr.v19.i5.40

Cited by 5 publications

(4 citation statements)

References 13 publications

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“…The most interesting findings on micro-explosive breakup have been obtained for immiscible two-and three-liquid droplets [40,65], emulsions [6,17,66], slurries [55,[67][68][69], and solutions [62,[70][71][72][73]. The concentration of the combustible and non-combustible components has a strong impact on the micro-explosive breakup [74].…”

Section: The Phenomenon Of Micro-explosionmentioning

confidence: 99%

See 1 more Smart Citation

Physical and Mathematical Models of Micro-Explosions: Achievements and Directions of Improvement

Antonov,

Fedorenko,

Yanovskiy

et al. 2023

Energies

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The environmental, economic, and energy problems of the modern world motivate the development of alternative fuel technologies. Multifuel technology can help reduce the carbon footprint and waste from the raw materials sector as well as slow down the depletion of energy resources. However, there are limitations to the active use of multifuel mixtures in real power plants and engines because they are difficult to spray in combustion chambers and require secondary atomization. Droplet micro-explosion seems the most promising secondary atomization technology in terms of its integral characteristics. This review paper outlines the most interesting approaches to modeling micro-explosions using in-house computer codes and commercial software packages. A physical model of a droplet micro-explosion based on experimental data was analyzed to highlight the schemes and mathematical expressions describing the critical conditions of parent droplet atomization. Approaches are presented that can predict the number, sizes, velocities, and trajectories of emerging child droplets. We also list the empirical data necessary for developing advanced fragmentation models. Finally, we outline the main growth areas for micro-explosion models catering for the needs of spray technology.

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Section: The Phenomenon Of Micro-explosionmentioning

confidence: 99%

“…Micro-explosive breakup is classified as a secondary atomization approach [30,[54][55][56]. Other approaches for secondary droplet atomization include droplet-droplet collisions in a gas, droplet impingement on solid walls, and droplet collisions with gas flows.…”

Section: Introductionmentioning

confidence: 99%

Physical and Mathematical Models of Micro-Explosions: Achievements and Directions of Improvement

Antonov,

Fedorenko,

Yanovskiy

et al. 2023

Energies

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“…Numerous experimental (Sommerfeld and Kuschel 2016;Kuschel and Sommerfeld 2013;Kurt et al 2007Kurt et al , 2009Gotaas et al 2007;Brenn and Kolobaric 2006;Orme 2003, 2000;Estrade et al 1999;Qian and Law 1997;Jiang et al 1992;Ashgriz and Poo 1990;Arkhipov et al 1978) and numerical studies (Pan and Suga 2005;Li and Fritsching 2011;Nikolopoulos et al 2009;Nobari and Tryggvason 1996;Focke et al 2013) on Newtonian droplet collisions have already been performed in the last half century. The major objectives of these works consisted of investigating collision outcomes and their characteristics as well as the Ashgriz and Poo (1990) performed binary water droplet collisions experiments for various impact conditions.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of non-Newtonian droplet collisions: the role of extensional viscosity

Finotello

Vrouwenvelder

et al. 2018

Exp Fluids

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We investigate the collision behaviour of a shear thinning non-Newtonian fluid xanthan, by binary droplet collision experiments. Droplet collisions of non-Newtonian fluids are more complex than their Newtonian counterpart as the viscosity no longer remains constant during the collision process. Despite the complex collision dynamics, we are able to present a complete regime map based on non-dimensional Weber (We) number and impact parameter (B). We compare the collision outcomes of xanthan, glycerol and a milk concentrate at similar impact conditions. These experiments reveal very rich and complex collision morphologies for shear thinning xanthan solution, strikingly different from Newtonian droplet collisions. Unlike glycerol and milk, xanthan collisions show no reflexive separation even at very high We number. Instead of breakup, we observe disc-like shapes with an oscillating behaviour of the colliding droplets. A detailed analysis reveals that this outcome is related to increased viscous energy dissipation and extensional effects.

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“…Piezoelectic droplet-on-demand droplet generator, modal analysis, compressible two-phase flow Introduction Piezoelectric droplet generators are used commercially in inkjet printers as well as scientific instruments to, e.g., investigate single droplet phenomena like combustion [1] or drop collisions [2]. For controlled production of monodisperse droplets, drop-on-demand offer the possibility of generating droplets of different size solely by applying appropriate electrical signals to the piezoelectric actuator in 'w'-waveform [3] or in the form of staircase voltages [4].…”

Section: Introductionmentioning

confidence: 99%

Flexible Piezoelectric Drop-On-Demand Droplet Generation

Riefler

Wriedt

Fritsching

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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The size of droplets generated by piezoelectric drop-on-demand (DOD) droplet generators can be varied to a certain degree within one order of magnitude. This variation means that the droplet size is not solely determined by the nozzle diameter, and the droplet generation process is not restricted to drops extruded through a nozzle in conventional operation. By varying the electronic driving pulse, different droplet sizes can be obtained. To investigate the interaction of piezoelectric pulse excitation and the finally produced droplets, different approaches are applied. A comparison of a modal analysis of a pure piezo based on mechanical admittance calculations proofs the usability of electrical impedance measurements. This kind of measurements are then compared to finite-element simulations of a coupled piezo system -one as actuator, the other as pressure sensor -to extend the usable methods with the result that the fluid is of minor influence on the modal frequencies. Last, two phase fluid flow simulations with consequent pressure wave evaluations of the fluid show different pressure wave frequency specta than the modal analysis. KeywordsPiezoelectic droplet-on-demand droplet generator, modal analysis, compressible two-phase flow Introduction Piezoelectric droplet generators are used commercially in inkjet printers as well as scientific instruments to, e.g., investigate single droplet phenomena like combustion [1] or drop collisions [2]. For controlled production of monodisperse droplets, drop-on-demand offer the possibility of generating droplets of different size solely by applying appropriate electrical signals to the piezoelectric actuator in 'w'-waveform [3] or in the form of staircase voltages [4]. Temple [5] suppossed that droplets can be generated with a much smaller diameter than the nozzle orifice and this is related to a 'Faraday Resonance', i.e. a resonance phenomenon that occurs in vertical oscillation of a column of liquid with a free surface. These surface wave resonances are a consequence of a pressure rise near the nozzle and lead to a transfer of energy and momentum from the acoustic field to the droplet. The generation of droplets smaller than the nozzle orifice is of interest, e.g., to produce small droplets of a suspension. In this case, typical DOD droplet generators with a nozzle diamater well below 70 µm tend to clogg with the consequence of a laborious cleaning process. Therefore, a dismountable droplet generator is developed to enable simple cleaning. Additionally, the nozzle diameter is increased to 200 -300 µm which is unusual for common fluids like water [6]. The generation parameters (i.e. pulse voltage and pulse time) for fluids with different viscosities and surface tension is experimentally tested. The transfer of momentum of a piezo actuator to the tube structure in the way of a modal analysis is also investigated and delivers preferred excitation frequencies of the solid tube part to the fluid. Last, the response of a compressible fluid to a pressure pulse is analyzed ...

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Secondary Droplet Formation During Binary Suspension Droplet Collisions

Cited by 5 publications

References 13 publications

Physical and Mathematical Models of Micro-Explosions: Achievements and Directions of Improvement

Physical and Mathematical Models of Micro-Explosions: Achievements and Directions of Improvement

Experimental investigation of non-Newtonian droplet collisions: the role of extensional viscosity

Flexible Piezoelectric Drop-On-Demand Droplet Generation

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