Analysis of Quasi-Steady and Transient Burning of Hybrid Fuels in a Laboratory-Scale Burner by an Optical Technique

Paravan, Christian; Manzoni, Miriam; Rambaldi, G.; Luca, L.T. De

doi:10.1615/intjenergeticmaterialschemprop.2013005756

Cited by 9 publications

(26 citation statements)

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“…The effects of radiation are due to gas radiation (playing a minor role), to soot, and (if present) to radiating metal particles [1][2][3][4][5]20,[61][62][63]. Under the influence of radiation heat transfer, r f may exhibit p c dependence [4,20], and the r f (G) power law approximation shows n r < 0.8 [1][2][3][4][5]20,[61][62][63]. Liquefying fuels show a regression rate dependence on G similar to the polymeric formulations, although their r f exhibits percentage increases of 300-400% with respect to reference HTPB [7,8].…”

Section: Fundamentals Of Solid Fuel Combustion Processmentioning

confidence: 99%

“…Tested fuel formulations are reported in Table 3. Relative ballistic grading was performed considering a non-metallized HTPB baseline (for formulation details, see Reference [63]). The investigated compositions were all produced at lab-scale level.…”

Section: Tested Formulationsmentioning

confidence: 99%

“…Tested strand ignition was achieved by a primer charge whose combustion was initiated by a laser beam impinging on it. A scheme of the experimental set-up is shown in Figure 2, while its peculiarities were discussed elsewhere [63]. In the current study, gaseous oxygen (GOX) was taken as the oxidizer, and combustion tests were performed with of 5 g/s and 6 g/s (the two operating conditions were identified as A and B, respectively), with pc = 1.0 MPa.…”

Section: Lab-scale Two-dimensional (2d) Radial Micro-burnermentioning

confidence: 99%

“…Cylindrical-shaped fuel grains with a length of 30 mm, outer case diameter of 20 mm, and central port diameter (D 0 ) of 4 mm are typically tested. The SPLab facility features peculiar characteristics such as the visualization of the burning specimen head-end, and a quasi-steady p c during the combustion [63]. In the 2D radial burner, the p c (t) is monitored by a piezo-resistive pressure transducer and controlled by a pressure regulator commanding exhaust electro-valves.…”

Section: Lab-scale Two-dimensional (2d) Radial Micro-burnermentioning

confidence: 99%

“…An optical, time-resolved technique for r f measurement was developed and validated at SPLab [16,53,63]. The time-resolved r f was evaluated by central port diameter sampling during the combustion (see Figure 3).…”

Section: Time-resolved Regression Ratementioning

confidence: 99%

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Nano-Sized and Mechanically Activated Composites: Perspectives for Enhanced Mass Burning Rate in Aluminized Solid Fuels for Hybrid Rocket Propulsion

Paravan

2019

Aerospace

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This work provides a lab-scale investigation of the ballistics of solid fuel formulations based on hydroxyl-terminated polybutadiene and loaded with Al-based energetic additives. Tested metal-based fillers span from micron- to nano-sized powders and include oxidizer-containing fuel-rich composites. The latter are obtained by chemical and mechanical processes providing reduced diffusion distance between Al and the oxidizing species source. A thorough pre-burning characterization of the additives is performed. The combustion behaviors of the tested formulations are analyzed considering the solid fuel regression rate and the mass burning rate as the main parameters of interest. A non-metallized formulation is taken as baseline for the relative grading of the tested fuels. Instantaneous and time-average regression rate data are determined by an optical time-resolved technique. The ballistic responses of the fuels are analyzed together with high-speed visualizations of the regressing surface. The fuel formulation loaded with 10 wt.% nano-sized aluminum (ALEX-100) shows a mass burning rate enhancement over the baseline of 55% ± 11% for an oxygen mass flux of 325 ± 20 kg/(m2∙s), but this performance increase nearly disappears as combustion proceeds. Captured high-speed images of the regressing surface show the critical issue of aggregation affecting the ALEX-100-loaded formulation and hindering the metal combustion. The oxidizer-containing composite additives promote metal ignition and (partial) burning in the oxidizer-lean region of the reacting boundary layer. Fuels loaded with 10 wt.% fluoropolymer-coated nano-Al show mass burning rate enhancement over the baseline >40% for oxygen mass flux in the range 325 to 155 kg/(m2∙s). The regression rate data of the fuel composition loaded with nano-sized Al-ammonium perchlorate composite show similar results. In these formulations, the oxidizer content in the fuel grain is <2 wt.%, but it plays a key role in performance enhancement thanks to the reduced metal–oxidizer diffusion distance. Formulations loaded with mechanically activated ALEX-100–polytetrafluoroethylene composites show mass burning rate increases up to 140% ± 20% with metal mass fractions of 30%. This performance is achieved with the fluoropolymer mass fraction in the additive of 45%.

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Section: Fundamentals Of Solid Fuel Combustion Processmentioning

confidence: 99%

Section: Tested Formulationsmentioning

confidence: 99%

Section: Lab-scale Two-dimensional (2d) Radial Micro-burnermentioning

confidence: 99%

Section: Lab-scale Two-dimensional (2d) Radial Micro-burnermentioning

confidence: 99%

Section: Time-resolved Regression Ratementioning

confidence: 99%

See 3 more Smart Citations

Nano-Sized and Mechanically Activated Composites: Perspectives for Enhanced Mass Burning Rate in Aluminized Solid Fuels for Hybrid Rocket Propulsion

Paravan

2019

Aerospace

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Characterization and Combustion of Aluminum Nanopowders in Energetic Systems

et al. 2014

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Following a comprehensive literature survey about use of Al nanopowders in a range of HEM applications — including rocket propulsion, pyrotechnics, and explosives - a through treatment is offered of the ideal and delivered thermochemical performance of the most interesting metallic ingredients to augment solid and hybrid rocket propulsion. The particular but fundamental class of nAl powders is then investigated in detail: critical issues such as coating and characterization of the powders, rheological and mechanical properties, combustion and ballistic behavior are all examined under a variety of operating conditions. Although attractive for fundamental studies and much used in laboratory experiments, no rocket propulsion operational systems are yet reported in use for nAl powders. Loss of active metal, cold cohesion, and poor propellant castability globally overcome advantages such as increased burning rate (easily achievable by other ways) and reduced specific impulse losses associated with 2P flow (thanks to less agglomeration with respect to the corresponding micrometric powders). Use of dual metallic fuels, by properly blending μAl and nAl, and/or modification of the natural properties of nAl particles, by suitable coatings, represent two possible ways to exploit the potential of nanopowders. Several approaches are also discussed so as to improve dispersion and mechanical properties of solid propellants or solid fuels containing nAl. Overall, a good control of particle size, metal content, and dispersion is a crucial requirement for successful applications of nanoingredients in propulsion

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Effects of aluminum composites on the regression rates of solid fuels

Paravan

Penazzo

Dossi

et al. 2019

Progress in Propulsion Physics – Volume 11

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Innovative, mechanically activated Al–polytetrafluoroethylene (PTFE) composites and ammonium perchlorate (AP) coated nano-sized aluminum (C-ALEX) were produced, characterized, and tested as solid fuel additives. The ballistics of fuel formulations based on hydroxylterminated polybutadiene (HTPB) was investigated in a microburner by a time-resolved technique for regression rate (rf) data reduction. Both Al-composites show promising results in terms of rf and mass burning rate enhancement. In particular, the C-ALEX showed a percent rf increase over the baseline (HTPB) of 27% at an oxidizer mass flux of 350 kg/(m2s), without requiring dedicated dispersion procedures. This performance enhancement was nearly constant over the whole investigated range.

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Analysis of Quasi-Steady and Transient Burning of Hybrid Fuels in a Laboratory-Scale Burner by an Optical Technique

Cited by 9 publications

References 0 publications

Nano-Sized and Mechanically Activated Composites: Perspectives for Enhanced Mass Burning Rate in Aluminized Solid Fuels for Hybrid Rocket Propulsion

Nano-Sized and Mechanically Activated Composites: Perspectives for Enhanced Mass Burning Rate in Aluminized Solid Fuels for Hybrid Rocket Propulsion

Characterization and Combustion of Aluminum Nanopowders in Energetic Systems

Effects of aluminum composites on the regression rates of solid fuels

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