The Status of Gel Propellants in Year 2000

Natan, Benveniste; Rahimi, Shai

doi:10.1615/intjenergeticmaterialschemprop.v5.i1-6.200

Cited by 150 publications

(109 citation statements)

References 62 publications

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“…The clear understanding of fluid flow characteristics is vital for efficient combustion, in order to gain optimum performance. As a result, a significant effort has been made worldwide to formulate, prepare, and study the rheological properties of gel propellants for various applications in rocket propulsion systems [1][2][3][4][5][6][7]. In the current study, hydrogen peroxide based gel is examined and discussed, because it is eco-friendly.…”

Section: Introductionmentioning

confidence: 99%

Rheological Characterization of Hydrogen Peroxide Gel Propellant

Jyoti¹,

Baek²

2014

International Journal of Aeronautical and Space Sciences

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An experimental investigation on the rheological behavior of gelled hydrogen peroxide at different ambient temperature (283.15, 293.15 and 303.15 K) was carried out in this study. The gel propellant was rheologically characterized using a rheometer, in the shear rate ranges of 1 to 20 s -1 , and 1 to 1000 s -1 . Hydrogen peroxide gel was found to be thixotropic in nature. The apparent viscosity value with some yield stress (in-case of shear rate 1 to 20 s -1 ) drastically fell with the shear rate.In the case of the shear rate range of 1 to 20 s -1 , the apparent viscosity and yield stress of gel were significantly reduced at higher ambient temperatures. In the case of the shear rate range of 1 to 1000 s -1 , no significant effect of varying the ambient temperature on the gel apparent viscosity was observed. The up and down shear rate curves for hydrogen peroxide gel formed a hysteresis loop that showed no significant change with variation in temperature for both the 1 to 20 s -1 and the 1 to 1000 s -1 shear rate ranges. No significant change in the thixotropic index of gel was observed for different ambient temperatures, for both low and high shear rates. The gel in the 1 to 20 s -1 shear rate range did not lead to a complete breakdown of gel structure, in comparison to that in the 1 to 1000 s -1 shear rate range.

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Section: Introductionmentioning

confidence: 99%

Rheological Characterization of Hydrogen Peroxide Gel Propellant

Jyoti¹,

Baek²

2014

International Journal of Aeronautical and Space Sciences

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“…The collision outcome affects the atomization characteristics, and substantially influences the subsequent combustion performance, because of the dependence of the vaporization and combustion of droplets on the droplet size, according to the well-known d 2 -law. Extensive numerical and experimental work has been carried out for Newtonian fluids in the past, in order to improve atomization characteristics and combustion efficiency [1].…”

Section: Introductionmentioning

confidence: 99%

“…Extensive numerical and experimental work has been carried out for Newtonian fluids in the past, in order to improve atomization characteristics and combustion efficiency [1]. However, conventional liquid and solid propellants cannot meet the demands of future high performance and improved safety rocket launchers, and the gel propellant seem to be a promising answer to these requirements by combining the advantages of both and neglecting the maximum number of disadvantages at the same time [2][3][4][5][6]. However, one serious problem is that the gels' viscosity increases with addition of gelling agents which change the fuel into a non-Newtonian fluid, making it more difficult to atomize.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation on Head-On Binary Collision of Gel Propellant Droplets

Liu

et al. 2013

Energies

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Binary collision of droplets is a fundamental form of droplet interaction in the spraying flow field. In order to reveal the central collision mechanism of two gel droplets with equal diameters, an axi-symmetric form of the Navier-Stokes equations are firstly solved and the method of VOF (volume of fluid) is utilized to track the evolution of the gas-liquid free interface. Then, the numerical computation model is validated with Qian's experimental results on Newtonian liquids. Phenomena of rebound, coalescence and reflexive separation of droplets after collision are investigated, and structures of the complicated flow fields during the collision process are also analyzed in detail. Results show that the maximum shear rate will appear at the point where the flow is redirected and accelerated. Rebound of droplets is determined by the Weber number and viscosity of the fluid together. It can be concluded that the gel droplets are easier to rebound in comparison with the base fluid droplets. The results also show that the alternant appearance along with the deformation of droplets in the radial and axial direction is the main characteristic of the droplet coalescence process, and the deformation amplitude attenuates gradually. Moreover, the reflexive separation process of droplets can be divided into three distinctive stages including the radial expansion, the recovery of the spherical shape, and the axial extension and reflexive separation. The variation trend of the kinetic energy is opposite to that of the surface energy. The maximum deformation of droplets appears in the radial expansion stage; in the case of a low Weber number, the minimum central thickness of a droplet appears later than its maximum deformation, however, this result is on the contrary in the case of a high Weber number. OPEN ACCESSEnergies 2013, 6 205

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“…[1]. The study of the combustion mechanisms of single droplets is necessary for characterizing and understanding the phenomena of spray vaporization and combustion.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Combustion and Microexplosion of Freely Falling Gelled Unsymmetrical Dimethylhydrazine (UDMH) Fuel Droplets

Liu

et al. 2012

Energies

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Abstract:The increasing demand for high energy density fuels and the concern for their safety have propelled research in the field of gelled propellants, where understanding the combustion of single gelled fuel droplets is the first stage to predict the spray combustion characteristics. The experiments utilized single-isolated freely falling gelled unsymmetrical dimethylhydrazine (UDMH) droplets instead of the conventional suspended droplet approach, in order to eliminate the perturbation associated with the suspension mechanism. Morphological transformations of the gelled droplet involved in the combustion processes were monitored by employing a high-speed digital camera, while the effects of ambient pressure and oxygen concentration on burning rate constants were also studied. The experimental results show that four main phenomena (droplet deformation, bubble formation and growth, vapor jetting and luminous jetting flame with "horn" shape) and three distinct phases were identified in the droplet combustion process; the high yield stress and polymer chain structure of polymer gellant are responsible for the appearance of bubbles with almost the same order of magnitude as the droplets. Increasing the ambient pressure can increase the burning rate, postpone the appearance of microexplosions, and weaken microexplosion intensity; while increasing the ambient oxygen concentration can promote the appearance of microexplosions, strengthen microexplosion intensity and increase the burning rate.

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The Status of Gel Propellants in Year 2000

Cited by 150 publications

References 62 publications

Rheological Characterization of Hydrogen Peroxide Gel Propellant

Rheological Characterization of Hydrogen Peroxide Gel Propellant

Numerical Simulation on Head-On Binary Collision of Gel Propellant Droplets

Experimental Study on the Combustion and Microexplosion of Freely Falling Gelled Unsymmetrical Dimethylhydrazine (UDMH) Fuel Droplets

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