Agglomerate Sizing in Aluminized Propellants Using Digital Inline Holography and Traditional Diagnostics

Powell, Michael; Gunduz, Ibrahim W.; Shang, Weixiao; Son, Steven F.; Chen, Yi; Guildenbecher, Daniel Robert

doi:10.2514/1.b36859

Cited by 33 publications

(12 citation statements)

References 34 publications

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“…Here, the measured reflectivity scales as a function of tan 2 , which matches the functional form of Eq. (7). These reflectivity values are relatively low when compared to picosecond implementations 35 due to differences in peak intensities of picosecond versus nanosecond beams with similar energies per pulse.…”

Section: Experimental Measurementsmentioning

confidence: 95%

“…C oherent imaging methods like digital in-line holography (DIH) 1,2 are essential for three-dimensional (3D) object tracking along a single line-of-sight. Traditional DIH techniques have been successfully applied in various systems, from high-speed multi-phase flows 3,4 to combustion environments [5][6][7] . Supersonic, hypersonic, and explosive environments, however, create challenges for coherent imaging methods like DIH due to phase distortions generated by shock-waves.…”

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confidence: 99%

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Megahertz-rate shock-wave distortion cancellation via phase conjugate digital in-line holography

et al. 2020

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Holography is a powerful tool for three-dimensional imaging. However, in explosive, supersonic, hypersonic, cavitating, or ionizing environments, shock-waves and density gradients impart phase distortions that obscure objects in the field-of-view. Capturing time-resolved information in these environments also requires ultra-high-speed acquisition. To reduce phase distortions and increase imaging rates, we introduce an ultra-high-speed phase conjugate digital in-line holography (PCDIH) technique. In this concept, a coherent beam passes through the shock-wave distortion, reflects off a phase conjugate mirror, and propagates back through the shock-wave, thereby minimizing imaging distortions from phase delays. By implementing the method using a pulse-burst laser setup at up to 5 million-frames-persecond, time-resolved holograms of ultra-fast events are now possible. This technique is applied for holographic imaging through laser-spark plasma-generated shock-waves and to enable three-dimensional tracking of explosively generated hypersonic fragments. Simulations further advance our understanding of physical processes and experiments demonstrate ultra-high-speed PCDIH techniques for capturing dynamics.

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Section: Experimental Measurementsmentioning

confidence: 95%

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confidence: 99%

Megahertz-rate shock-wave distortion cancellation via phase conjugate digital in-line holography

et al. 2020

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“…Nevertheless, some morphological changes may occur during the finite quench time, which could be shown as fewer nonspherical structures are observed in Figure (a). The edge detection of particles regions requires high contract to distinguish between the collection surface and agglomerates . Assuming reasonable relative contrast of the images, most image processing software is capable of isolating the particles from the background.…”

Section: Methodsmentioning

confidence: 99%

Ultra‐Fine Aluminium Characterization and its Agglomeration Features in Solid Propellant Combustion for Various Quenched Distance and Pressure

Tejasvi

Rao

Setty

et al. 2020

Propellants Explo Pyrotec

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Addition of micrometer‐sized aluminium powder in solid propellant increases the specific impulse whereas it also contributes to thrust loss due to two‐phase flow. Aluminium particles form large sized agglomerates during propellant burning. In this context, agglomeration feature of ultra‐fine aluminium (UFAL) in solid propellant combustion is investigated using experimental study. The synthesized UFAL powder is used with the intensity weighted harmonic mean size of 438 nm which is produced by RF induction plasma method. The morphology and purity of the UFAL is verified using SEM and EDAX studies respectively. The ultra‐fine particles are also characterized using gas volumetric method, surface area measurement and XRD analysis. Quench particle collection technique is adopted to estimate the aluminium agglomerate measurement over the pressure ranges from 2 MPa to 8 MPa. The flame quenching distance from the propellant burning surface is varied from 5 mm to 71 mm to estimate the effect on agglomerate size. The inherited residual forces of UFAL strongly influences the agglomeration process, and also the aluminium agglomerate sizes vary from propellant burning surface towards the complete aluminium combustion. The XRD and XPS results of the agglomerates show that the aluminium content decreases and alumina content increases far away from the burning surface, invariably represents the initiation of combustion process over the considered quenching distances. UFAL powder exhibits significant agglomeration with the size ranging from 11–21 μm. This will substantially benefit from exhaust signature point of view and also reduction in two‐phase flow losses to thrust in contrast to micron sized‐aluminium particles in propellant which displays large sized aluminium agglomerates.

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“…Aluminum agglomerate collection has been conducted both near the burning surface and far downstream [109]. Such studies have suggested large variations in the agglomerate size depending on the propellant formulation [129,109], and significant differences in particle size were evident from pyrometry experiments and high-speed video of the propellant compositions discussed previously and reported in Barkley et al [6].…”

Section: Digital In-line Holography For Particle Sizes and Velocitiesmentioning

confidence: 92%

“…Digital in-line holography focuses on the quantification of the particle size distributions and provides insight into agglomerate formation at the burning surface. Particle size distributions are typically reported through number and volumetric probability density functions (PDF) [109]. Raw counts are binned logarithmically to have equal bin sizes in a log-normal plot.…”

Section: Particle Sizes and Agglomerate Melt Diametermentioning

confidence: 99%

Optical measurements in multiphase combustion

Zhu¹

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Agglomerate Sizing in Aluminized Propellants Using Digital Inline Holography and Traditional Diagnostics

Cited by 33 publications

References 34 publications

Megahertz-rate shock-wave distortion cancellation via phase conjugate digital in-line holography

Megahertz-rate shock-wave distortion cancellation via phase conjugate digital in-line holography

Ultra‐Fine Aluminium Characterization and its Agglomeration Features in Solid Propellant Combustion for Various Quenched Distance and Pressure

Optical measurements in multiphase combustion

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