• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.377-382
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• 2010

The Present study uses non-Newtonian simulant gel propellant mixed by Water, Carbopol 941, and NaOH solution in order to analyze the gel propellant flow behavior. Rheological data have been measured and obtained prior to the analysis of flow characteristics where water-gel propellant as well as water-gel propellant with $Al_2O_3$ nano particles are both used. The critical Dean number were examined by numerical simulation of gel propellant in the U-shape duct flow. It is found that though gel-nano propellants have higher apparent viscosity, the critical Dean number did not showed notable difference with respect to the water-gel propellant. It is believe that this is due to the fact that the power law index of both propellants have close value, as was demonstrated by Fellouah et al.[1]

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.47-55
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• 2013

Curved duct channel flow characteristics for non-Newtonian gel fluid is investigated. A simulant gel propellant mixed by Water, Carbopol 941 and NaOH solution has been chosen to analyze the gel propellant flow behavior. Rheological data have been measured prior to the flow analysis where water-gel propellant and water-gel propellant with $Al_2O_3$ nano particles are both used. The critical Dean number examined by the numerical simulation in the U-shape duct flow reveals that although water-gel-nano propellants have higher apparent viscosity, the critical Dean number do show no notable difference for both the two gel propellant. It is found that the power-law index may be a dominant parameter in determining the critical Dean number and that the gel with particles addition may be more vulnerable to Dean instability.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.96-106
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• 2011

There are many advantages in applying gel propellant to a gel propulsion system. These include higher performances, the energy management of liquid propulsion system, reliable storability and low leakage characteristics. Additionally, gel propulsion system are preferable to the high density impulse of propulsion system. Also, when compared to liquid propellants, the gel propellants acquire greater heat energy. Gel propellants achieve a high specific impulse when metal particles with aluminum and boron are added. With respect to atomization, an inactive process occurs due to the variable viscosity of the metal particles and gelling agents. To improve the defect of atomization and combustion characteristics of gel propellant, a variety of issues related to spray and combustion is introduced here.

• Journal of ILASS-Korea
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• v.24 no.2
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• pp.82-88
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• 2019

Shear coaxial injectors were commonly used in rocket engine combustor. They showed good combustion performance. However it is not easy to control the thrust. Pintle injectors were not as popular as the coaxial injectors so far, they have a great advantage over the coaxial injectors. That is, it is relatively easy to control the thrust. Spray characteristics of gel type propellant from movable sleeve pintle injector were investigated. Water with 0.05% of Carbopol 940 was used as gel simulant instead of kerosene gel combined with Thixarol ST for academic purpose. Experiments were performed in various temperature, pressure and pintle opening condition. The results were compared with neat liquid spray. It is also verified that the capabilites of the injector by adjusting the pintle opening.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.300-303
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• 2010

The present study investigates the flow characteristics of simulant gel propellant(carbopol 0.5%wt) in a variety of injectors. Rheological data for gel propellant has been measured and injector flow characteristics for plain-orifice, chamfered-orifice and venturi type injector have been numerically analyzed. The apparent viscosity of plain-orifice and chamfered-orifice have tendency to increase along axial direction, whereas for venturi type injector, low viscosity has been achieved in the injector flow. This phenomenon was clearly pronounced as Reynolds number is increased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.467-470
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• 2011

In this study, two different kind of impeller, commercial hand blender and manual type were used to investigate the most effective mixing method for simulant gel propellant. Ionized Water, Carbopol 941 and NaOH were used to produce the simulant gel for temperature of $25^{\circ}C$ and $50^{\circ}C$. The amount of bubbles produced during mixing of simulant gel at $50^{\circ}C$ were higher than that of simulant gel at $25^{\circ}C$. After 24 hours, bubbles of simulant gel made at $50^{\circ}C$ disappeared rapidly with respect to the bubbles of gel made at $25^{\circ}C$. Bubbles from blender did show notable amount even after 24 hours. Among mixing type, it was found that the pitched paddle impeller was the best candidate for the production of simulant gel.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.337-340
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• 2011

This study investigates the rheological characteristics of $SiO_2$-Kerosene gel propellants with Aerosil(R) R972, Silica 230, Silica 530. Power-law rheological model is used to confirm whether or not gelification is achieved. It was found that the produced gel have shear-thinning effect, and that the viscosity of the gel propellants increases with increasing $SiO_2$ concentration. Among gellants used in this study, gel propellant with Aerosil(R) R972 fits most to the power law model as the shear rate increases. However, gels produced with Silica 230 and Silica 530 gellant deviate from the power law model when the shear rate regime is below 100 [1/s].

• International Journal of Aeronautical and Space Sciences
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• v.15 no.2
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• pp.199-204
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• 2014

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 $20s^{-1}$, and 1 to $1000s^{-1}$. 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 $20s^{-1}$) drastically fell with the shear rate. In the case of the shear rate range of 1 to $20s^{-1}$, 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 $1000s^{-1}$, 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 $20s^{-1}$ and the 1 to $1000s^{-1}$ 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 $20s^{-1}$ shear rate range did not lead to a complete breakdown of gel structure, in comparison to that in the 1 to $1000s^{-1}$ shear rate range.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.456-461
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• 2017

In this study, the rheological properties of nitromethane gel propellants on nano/micron sized gelling agent are investigated. Silicon dioxide is used as the gellant with 5 wt%, 6.5 wt% and 8 wt% concentration, respectively, where the measurements are conducted under steady-state shear flow conditions using a rotational rheometer. The nitromethane/silicon dioxide gel showed non-Newtonian flow behavior for the entire experimental shear rate ranges. The gel fuels with nano-sized gellant had a slightly higher viscosity than the gel fuels with micron-sized one for low shear rate range. Additionally, it was found that Herschel-Bulkley model can hardly describe the rheological behavior of nitromethane gel propellant, but the NM model(by Teipel and Forter-Barth) is better suited to explain the rheological behavior of nitromethane gel propellant.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.34-40
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• 2017

In this study, the surface tension of simulant gel propellants was measured by Du $No{\ddot{u}}y$ ring method. The variation of the surface tension was investigated with respect to the amount of the gelling agent, and metal particle addition. Distilled water was used as the base fluid for the preparation of the simulant gel propellant where Carbopol 941 was used as a gelling agent and SUS304 spherical metal particles (mean diameter : 100 nm) as simulant energetic particles. As a result of measurements, surface tension increased with increasing gelling agent concentration while, in the presence of metal particle, different behavior of surface tension has been observed.