1,720,991 research outputs found
Numerical analysis of ignition transient in an axisymmetric solid rocket motor equipped with rear ignition system
No full textA numerical simulation is completed to analyze the ignition transient in a solid rocket motor with rear ignition system. Time-dependent compressible SIMPLER algorithm for gas phase governing equations and finte volume method (FVM) for radiative transfer equation are employed, respectively. Two dimensional conduction equation for propellant grain is combined as well. While the standard k - epsilon model with wall function is used for turbulence, the eddy break-up (EBU) model is used for gas phase reaction rate. A detailed development of unsteady flow and temperature fields is obtained. Especially, the radiation is found to play a significant role in igniting the solid propellant by promoting the heat feedback to propellant surface. When the radiation transport was not considered, the predicted ignition and flame spreading sequence was in error, based on a limited experimental data
Numerical Analysis of Ignition Transient in an Axisymmetric Solid Rocket Motor Equipped with Rear Ignition System
No full textUnsteady cooling of a solid sphere in a radiatively active medium
No full textThe transient thermal characteristics of a hot spherical body were investigated when it was suddenly introduced to an initially coal radiatively active medium. The governing equations modeled were solved numerically. The radiative transfer equation was solved by the discrete ordinates method. The results were discussed of changing various physical parameters. The heat transfer mode inside the spherical body was conduction only. But both conduction and radiation were assumed to occur in the medium. Faster cooling of the sphere was accompanied by a decrease in optical thickness, an increase in medium thermal conductivity, an increase in sphere surface emissivity, ora decrease in thermal diffusivity of the sphere. However, faster cooling of the sphere body did not always induce faster heating of the medium. This was found to be dependent on the physical properties of the medium
Thermoelastic analysis of a kick motor nozzle incorporating spatially reinforced composites
No full textThe mechanical and thermal properties of spatially reinforced composites are predicted using volume average and rules of mixture of the rods and matrix properties for stiffness, thermal conductivity, and coefficient of thermal expansion. The distribution of Young's modulus, thermal conductivity, and coefficient of thermal expansion for three-dimensional/four-dimensionaI spatially. reinforced composites are demonstrated. The study examines the elastic behavior, the temperature distribution, and the thermoelastic behavior of a kick motor nozzle, which includes a carbon/carbon spatially reinforced composite as a throat part. The elastic deformation of the nozzle composed of three-dimensional carbon/carbon spatially reinforced composite shows asymmetry, whereas the elastic deformation of four-dimensional carbon/carbon spatially reinforced composite nozzle shows uniformity in the circumferential, direction. The thermoelastic deformations of both the three- and four-dimensional spatially reinforced composite nozzles are uniform in the circumferential direction. The deformation of the three-dimensional spatially reinforced composite nozzle is slightly smaller than that of the four-dimensional spatially reinforced composite nozzle in the nozzle throat. Circumferential stress is the critical stress component of the kick motor nozzle
A Numerical Simulation of Axisymmetric Solid Rocket Motor Ignition Transient with Radiation Effect
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
