Vortex Combustion in a Lab-Scale Hybrid Rocket Motor

Paravan, Christian; Glowacki, Jakub; Carlotti, Stefania; Maggi, F.; Galfetti, L.

doi:10.2514/6.2016-4562

Cited by 15 publications

(12 citation statements)

References 5 publications

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“…A VFP motor for the investigation of the combustion behaviour of this system was designed and implemented at the Space Propulsion Laboratory (SPLab) of Politecnico di Milano (Paravan et al, 2016;. Figs.…”

Section: Logic Of the Vfp Developmentmentioning

confidence: 99%

“…The target of these activities is to contribute to the implementation of this system in operating scenarios where HRE advantages may play a crucial role, as in-space propulsion (orbital manoeuvring, deorbiting) or specific missions where throttleability and multiple ignitions are the main drivers (as soft-landing, or sample return missions). A preliminary characterization phase was performed through the internal flow-field analysis (CFD and high-speed visualizations), and firing tests (Paravan, 2016). The flow-field investigation is crucial to evaluate the effective onset of a drain type vortex in the combustion chamber, under conditions representing the whole burning envelope of the motor (i.e., from the initial fuel grain thicknesses to the combustion chamber height corresponding to burnout) (Paravan, 2016).…”

Section: Logic Of the Vfp Developmentmentioning

confidence: 99%

“…A preliminary characterization phase was performed through the internal flow-field analysis (CFD and high-speed visualizations), and firing tests (Paravan, 2016). The flow-field investigation is crucial to evaluate the effective onset of a drain type vortex in the combustion chamber, under conditions representing the whole burning envelope of the motor (i.e., from the initial fuel grain thicknesses to the combustion chamber height corresponding to burnout) (Paravan, 2016). The combustion tests are currently performed considering the combustion in gaseous O 2 (GOX) and in nitrous oxide (N 2 O).…”

Section: Logic Of the Vfp Developmentmentioning

confidence: 99%

“…In GOX, the propellant-grade HTPB runs are performed with a lower ḿox than the S40W1 tests (8 g/s vs. 10 g/s): the achieved r f is similar for both fuels, while the c * ¿ η ❑ of HTPB-GOX shows higher values than the S40W1 counterpart (Table 9). The low combustion efficiency of the S40W1 is mainly due to issues with the nozzle throat thermal protection and erosion during the S40W1 runs (Paravan et al, 2016). These effects yield rough combustions and marked throat diameter changes during the experimental runs.…”

Section: Quasi-steady Burningmentioning

confidence: 99%

See 3 more Smart Citations

Combustion Processes in Hybrid Rockets

Paravan¹,

Galfetti²,

Bisin³

et al. 2019

Int J Energetic Materials Chem Prop

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This paper presents the latest results achieved at the Space Propulsion Laboratory (SPLab) of Politecnico di Milano in the area of hybrid propulsion. Focus is put on four specific research topics, currently under investigation, and strongly linked: 1. solid fuel formulations development; 2. investigation of liquefying fuel formulations responsible for the entrainment phenomenon; 3. development of a vortex flow pancake (VFP) designed for in-space missions; 4. numerical simulation approaches. A wide chemical, thermal, rheological, mechanical and ballistic investigation of traditional polymeric formulations and paraffin-based solid fuels has been performed in the last years and is shortly summarized here. Firing tests are performed in a radial lab-scale burner enabling timeresolved regression rate measurements. The results of this activity pave the way to the challenging horizon of liquefying fuel formulations. The entrainment of melted fuels is investigated by a dedicated setup designed for the study of the oxidizer stream/melt surface interaction under cold-flow conditions, to understand the droplet formation mechanism and to measure their size distribution. The effects of liquid layer entrainment on the combustion processes seem attractive for the development of unusual geometries, such as the VFP. The VFP hybrid rocket configuration offers a compact implementation with motor length-to-diameter ratio lower than 1, giving a breakthrough opportunity for inspace missions that could strongly benefit from the system affordability, with low recurring costs joined to high operating flexibility. The VFP development requires a strong support of numerical simulation activities, developed through OpenFOAM, and described in the last part of the paper.

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Section: Logic Of the Vfp Developmentmentioning

confidence: 99%

Section: Logic Of the Vfp Developmentmentioning

confidence: 99%

Section: Logic Of the Vfp Developmentmentioning

confidence: 99%

Section: Quasi-steady Burningmentioning

confidence: 99%

See 2 more Smart Citations

Combustion Processes in Hybrid Rockets

Paravan¹,

Galfetti²,

Bisin³

et al. 2019

Int J Energetic Materials Chem Prop

Self Cite

View full text Add to dashboard Cite

show abstract

“…The diffusion-limited combustion of HREs implies low combustion efficiency, thus requiring specific countermeasures such as enhanced oxidizer-fuel vapors mixing in the aft-combustion chamber and/or the use of diaphragms [67], non-conventional oxidizer injection implementations (playing a role in r f enhancement) [68][69][70], and/or design of special engine configurations [71].…”

Section: Fundamentals Of Solid Fuel Combustion Processmentioning

confidence: 99%

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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Evaluation of Regression Rate Enhancing Concepts and Techniques for Hybrid Rocket Engines

Glaser

Hijlkema

Anthoine

2022

Aerotec. Missili Spaz.

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The low regression rate of Hybrid Rocket Engines (HREs) is one prominent characteristic that is addressed in most abstracts concerning hybrid propulsion. Over the years, researchers developed and investigated numerous ways to tackle the low regression rate problem of HREs. This article is a collection and assessment of these diverse methods and designs. It allows for a quick overview of the different mechanisms that are being employed and can serve both as information and inspiration. The enhancement ideas are grouped together as (a) adjustments to the solid fuel chemical properties, (b) advanced injection methods and concepts and (c) improving the combustion chamber design. These different techniques are discussed and their individual impact on the regression rate is assessed both qualitatively and quantitatively. All methods that are presented come with a different set of advantages and disadvantages, making the regression rate enhancement a trade-off problem. In our view, the most promising designs and methods are those that only call for minor adjustments to the HRE design, as they can be also added to already existing engines. Above all, it is to be said that regression rate enhancing techniques that change the unique features of HREs (namely safety, simplicity and low cost) are to be employed with caution. Only if the achievable regression rate increase is justifying the implications for the HRE in the envisioned use-case, these concepts represent promising alternatives to the status quo.

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Vortex Combustion in a Lab-Scale Hybrid Rocket Motor

Cited by 15 publications

References 5 publications

Combustion Processes in Hybrid Rockets

Combustion Processes in Hybrid Rockets

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

Evaluation of Regression Rate Enhancing Concepts and Techniques for Hybrid Rocket Engines

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