Single-element combustor experiments are conducted for three shear coaxial geometry configuration injectors by using gaseous oxygen and gaseous hydrogen(GO2/GH2) as propellants. During the combustion process, several ...Single-element combustor experiments are conducted for three shear coaxial geometry configuration injectors by using gaseous oxygen and gaseous hydrogen(GO2/GH2) as propellants. During the combustion process, several spatially and time- resolved non-intrusive optical techniques, such as OH planar laser induced fluorescence(PLIF), high speed imaging, and infrared imaging, are simultaneously employed to observe the OH radical concentration distribution, flame fluctuations, and temperature fields. The results demonstrate that the turbulent flow phenomenon of non-premixed flame exhibits a remarkable periodicity, and the mixing ratio becomes a crucial factor to influence the combustion flame length. The high speed and infrared images have a consistent temperature field trend. As for the OH-PLIF images, an intuitionistic local flame structure is revealed by single-shot instantaneous images. Furthermore, the means and standard deviations of OH radical intensity are acquired to provide statistical information regarding the flame, which may be helpful for validation of numerical simulations in future. Parameters of structure configurations, such as impinging angle and oxygen post thickness, play an important role in the reaction zone distribution. Based on a successful flame contour extraction method assembled with non-linear anisotropic diffusive filtering and variational level-set, it is possible to implement a fractal analysis to describe the fractal characteristics of the non-premixed flame contour. As a result, the flame front cannot be regarded as a fractal object. However, this turbulent process presents a self-similarity characteristic.展开更多
Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector...Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector. To increase atomization performance and mixing efficiency of two-phase jets, a coaxial porous injector which can be applicable to liquid rocket combustors was designed and tested. The characteristics of atomization and spray from a porous and a shear coaxial injector were characterized by the momentum flux ratio. The breakup mechanism of the porous injector is governed by Taylor-Culick flow and axial shear forces. Momentum of injected gas flow through a porous material which is composed of sintered metal is radically transferred to the center of the liquid column, and then liquid column is effectively broken up. Although the shapes of spray from porous and shear coaxial jets were similar for various momentum ratio, spray structures such as spray angle and droplet sizes were different. As increasing the momentum flux ratio, SMD from the porous injector showed smaller value than the shear coaxial展开更多
In order to get a high flowrate gas-gas injector and its design methodology,the combustion flow field of a typical shear-coaxial injector was analyzed firstly.The dimensional analysis was applied in the phenomenon of ...In order to get a high flowrate gas-gas injector and its design methodology,the combustion flow field of a typical shear-coaxial injector was analyzed firstly.The dimensional analysis was applied in the phenomenon of gas-gas combustion,and design parameter optimization and a structure improvement were also carried out.A high flowrate single-element injector with high H2/O2 momentum ratio and tapered O2 post tip was obtained and validated by both numerical and experimental studies.This high flowrate injector has simple construction and it can effectively enhance the mixing,decrease the combustion completion length and also has a benign heat environment.Furthermore,based on the study of the single-element injector,numerical optimization and validation experiments were conducted successively on a multi-element injector equipped with high flowrate injection elements.The multi-element injector with the high flowrate elements started up and shut down smoothly,and operated steadily without any stability aids.In the combustor designed with nominal parameters,this injection element can obtain high combustion efficiency with a flowrate of 3.7 times that of SSME main injector element and shows a benign chamber wall heat compatibility.This injector design and the design methodology can become a reference for the design of other types of injectors for liquid rocket engines.展开更多
文摘Single-element combustor experiments are conducted for three shear coaxial geometry configuration injectors by using gaseous oxygen and gaseous hydrogen(GO2/GH2) as propellants. During the combustion process, several spatially and time- resolved non-intrusive optical techniques, such as OH planar laser induced fluorescence(PLIF), high speed imaging, and infrared imaging, are simultaneously employed to observe the OH radical concentration distribution, flame fluctuations, and temperature fields. The results demonstrate that the turbulent flow phenomenon of non-premixed flame exhibits a remarkable periodicity, and the mixing ratio becomes a crucial factor to influence the combustion flame length. The high speed and infrared images have a consistent temperature field trend. As for the OH-PLIF images, an intuitionistic local flame structure is revealed by single-shot instantaneous images. Furthermore, the means and standard deviations of OH radical intensity are acquired to provide statistical information regarding the flame, which may be helpful for validation of numerical simulations in future. Parameters of structure configurations, such as impinging angle and oxygen post thickness, play an important role in the reaction zone distribution. Based on a successful flame contour extraction method assembled with non-linear anisotropic diffusive filtering and variational level-set, it is possible to implement a fractal analysis to describe the fractal characteristics of the non-premixed flame contour. As a result, the flame front cannot be regarded as a fractal object. However, this turbulent process presents a self-similarity characteristic.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean Government(MEST)(NRF-2011-0015435 and NRF-2012M 1A3A3A02033146)
文摘Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector. To increase atomization performance and mixing efficiency of two-phase jets, a coaxial porous injector which can be applicable to liquid rocket combustors was designed and tested. The characteristics of atomization and spray from a porous and a shear coaxial injector were characterized by the momentum flux ratio. The breakup mechanism of the porous injector is governed by Taylor-Culick flow and axial shear forces. Momentum of injected gas flow through a porous material which is composed of sintered metal is radically transferred to the center of the liquid column, and then liquid column is effectively broken up. Although the shapes of spray from porous and shear coaxial jets were similar for various momentum ratio, spray structures such as spray angle and droplet sizes were different. As increasing the momentum flux ratio, SMD from the porous injector showed smaller value than the shear coaxial
文摘In order to get a high flowrate gas-gas injector and its design methodology,the combustion flow field of a typical shear-coaxial injector was analyzed firstly.The dimensional analysis was applied in the phenomenon of gas-gas combustion,and design parameter optimization and a structure improvement were also carried out.A high flowrate single-element injector with high H2/O2 momentum ratio and tapered O2 post tip was obtained and validated by both numerical and experimental studies.This high flowrate injector has simple construction and it can effectively enhance the mixing,decrease the combustion completion length and also has a benign heat environment.Furthermore,based on the study of the single-element injector,numerical optimization and validation experiments were conducted successively on a multi-element injector equipped with high flowrate injection elements.The multi-element injector with the high flowrate elements started up and shut down smoothly,and operated steadily without any stability aids.In the combustor designed with nominal parameters,this injection element can obtain high combustion efficiency with a flowrate of 3.7 times that of SSME main injector element and shows a benign chamber wall heat compatibility.This injector design and the design methodology can become a reference for the design of other types of injectors for liquid rocket engines.
