Gasification of solid fuel pellets in a pressurized combustion chamber

2002 ◽  
Vol 2002.42 (0) ◽  
pp. 86-87
Author(s):  
Atsushi FUJII ◽  
Shinichiro KURITA ◽  
Harunori NAGATA ◽  
Tsuyoshi TOTANI ◽  
Isao KUDO
Author(s):  
Rifat Mehdi ◽  
Naveed Raza ◽  
Salman Raza Naqvi ◽  
Asif Hussain Khoja ◽  
M. Taqi Mehran ◽  
...  

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 190
Author(s):  
Francesco Barato

Ablative-cooled hybrid rockets could potentially combine a similar versatility of a liquid propulsion system with a much simplified architecture. These characteristics make this kind of propulsion attractive, among others, for applications such as satellites and upper stages. In this paper, the use of hybrid rockets for those situations is reviewed. It is shown that, for a competitive implementation, several challenges need to be addressed, which are not the general ones often discussed in the hybrid literature. In particular, the optimal thrust to burning time ratio, which is often relatively low in liquid engines, has a deep impact on the grain geometry, that, in turn, must comply some constrains. The regression rate sometime needs to be tailored in order to avoid unreasonable grain shapes, with the consequence that the dimensional trends start to follow some sort of counter-intuitive behavior. The length to diameter ratio of the hybrid combustion chamber imposes some packaging issues in order to compact the whole propulsion system. Finally, the heat soak-back during long off phases between multiple burns could compromise the integrity of the case and of the solid fuel. Therefore, if the advantages of hybrid propulsion are to be exploited, the aspects mentioned in this paper shall be carefully considered and properly faced.


2020 ◽  
Vol 36 (6) ◽  
pp. 933-941
Author(s):  
A. M. Tahsini

ABSTRACTThe performance of the solid fuel ramjet is accurately predicted using full part simulation of this propulsion system, where the flow fields of the intake, combustion chamber, and the nozzle are numerically studied all together. The conjugate heat transfer is considered between the solid phase and the gas phase to directly compute the regression rate of the fuel. The finite volume solver of the compressible turbulent reacting flow is utilized to study the axisymmetric three dimensional flow fields, and two blocks are used to discretize the computational domain. It is shown that the combustion chamber's pressure is changed due to the fuel flow rate's increment which must be taken into account in predictions. The results demonstrate that omitting the pressure dependence of the regression rate and also the effect of the combustor's inlet profile on the regression rate, which specially exists when simulating the combustion chamber individually, under-predicts the solid fuel burning rate when the regression rate augmentation technique is applied to improve the performance of the solid fuel ramjets. It is also illustrated that using the inlet swirl to increase the regression rate of the solid fuel augments considerably the thrust level of the considered SFRJ, while the predictions without considering all parts of the ramjet is not accurate.


2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Adebanjo O Ojomo ◽  
Folayan R Falayi ◽  
Agboola S Ogunlowo

In South Western Nigeria, after the harvesting of maize cobs from the field, large amount of maize stock remains as agricultural residues and wastes. The maize stock constitutes a menace to the environment if not property handled. In this study, densification equipment was designed, fabricated and tested using maize stock grind as raw material. The equipment consists of mixer/ moisture conditioner and a pelleting machine. The power rating for the mixer/moisture conditioner is 0.069 kW with an input capacity of 81 kg/h while the power consumption of the pellet machine is 0.8 kW with throughout capacity of 40 kg/h. The result of the test showed that the highest product temperature, which gives an indication of the quality and durability of the pellets produced was 930C at 0.8 mm hammer mill screen size, 10% moisture content and 150 rpm die speed, at this temperature the machine is operating at optimum efficiency of 74%. High product temperature is an important parameter during pelleting/briquetting operations because it gives the degree of compaction and binding of the pellets/briquettes. The densification equipment for organic biomass was developed using locally sourced materials as a means of converting agricultural wastes into pellets for domestic cooking and cottage industry uses.


Author(s):  
T.S. Sultanov ◽  
G.A. Glebov

Eulerian --- Lagrangian method was used in the Fluent computational fluid dynamics system to calculate motion of the two-phase combustion products in the solid fuel rocket motor combustion chamber and nozzle. Condensed phase is assumed to consist of spherical particles with the same diameter, which dimensions are not changing along the motion trajectory. Flows with particle diameters of 3, 5, 7, 9, and 11 μm were investigated. Four versions of the engine combustion chamber configuration were examined: with slotted and smooth cylindrical charge channels, each with external and submerged nozzles. Gas flow and particle trajectories were calculated starting from the solid fuel surface and to the nozzle exit. Volumetric fields of particle concentrations, condensed phase velocities and temperatures, as well as turbulence degree in the solid propellant rocket engine flow duct were obtained. Values of particles velocity and temperature lag from the gas phase along the nozzle length were received. Influence of the charge channel shape, degree of the nozzle submersion and of the condensate particles size on the solid propellant rocket engine specific impulse were determined, and losses were estimated in comparison with the case of ideal flow


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