http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Minseok Jung,Hisashi Kihara,Ken-ichi Abe,Yusuke Takahashi 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.11
A three-dimensional numerical simulation model that considers the effect of the angle of attack was developed to evaluate plasma flows around reentry vehicles. In this simulation model, thermochemical nonequilibrium of flowfields is considered by using a four-temperature model for high-accuracy simulations. Numerical simulations were performed for the orbital reentry experiment of the Japan Aerospace Exploration Agency, and the results were compared with experimental data to validate the simulation model. A comparison of measured and predicted results showed good agreement. Moreover, to evaluate the effect of the angle of attack, we performed numerical simulations around the Atmospheric Reentry Demonstrator of the European Space Agency by using an axisymmetric model and a three-dimensional model. Although there were no differences in the flowfields in the shock layer between the results of the axisymmetric and the three-dimensional models, the formation of the electron number density, which is an important parameter in evaluating radio-frequency blackout, was greatly changed in the wake region when a non-zero angle of attack was considered. Additionally, the number of altitudes at which radio-frequency blackout was predicted in the numerical simulations declined when using the three-dimensional model for considering the angle of attack.
Minghao Yu,Hisashi Kihara,Ken-ichi Abe,Yusuke Takahashi 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.12
A relatively simple method for calculating accurately the third-order electron transport properties of nitrogen and air thermal plasmas is presented. The electron transport properties, such as the electrical conductivity and the electron thermal conductivity, were computed with the best and latest available collision cross-section data in the temperature and pressure ranges of T = 300 - 15000 K and p = 0.01 - 1.0 atm, respectively. The results obtained under the atmospheric pressure condition showed good agreements with the experimental and the high-accuracy theoretical results. The presently-introduced method has good application potential in numerical simulations of nitrogen and air inductively-coupled plasmas.
Park Soomin,Hisashi Kihara,Ken-ichi Abe 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.5
One of the problems relating to frost formation in the field of aviation is the effects of Cold Soaked Frost. It is hazardous problem for which various solutions are the responsibility of several aviation administrations. Owing to the lack of computational research on frost formation such as on a wing surface, an advanced model for predicting frost thickness under a various range of flow conditions was developed and validated in this study. In evaluating the growth rate of the solid layer, the relation between the partial vapor pressure and the saturation pressure was used to determine the supersaturation degree. Frost thickness was assumed on the basis that the mass transfer effects associated with the diffusivity of the vapor are related mainly to the growth rate of crystallization. We performed a favorable regression procedure to find constant values for the correlation of the growth rate. The proposed frost thickness model was validated through the comparison of the simulation results with various experimental data for the case of a flat plate. The results obtained using the proposed model agree satisfactorily with the experimental data.
Prediction and Evaluation of Frosting Surface on Cylindrical Structure Using Growth Rate Model
Park Soomin,Hisashi Kihara,Ken-ichi Abe 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.1
Icing and frosting on a surface can cause critical degradation in mechanical performance. In the aviation and astronautical fields, lots of accidents and safety issues have been attributed to this problem. Various prediction models for frost formation have been developed to address this issue. In the present study, we apply a newly developed model to numerical prediction of frost formation on a cylindrical surface. The proposed model in the present study is based on the growth rate from the Arrhenius formula considering Gibbs free energy term with the entropy difference. The overall frost properties are calculated using the correlation for the diffusivity of vapor in humid air. The approach is validated by comparing the computational results with the experimental data obtained from previous literatures. The results generally show similar trends to the measurement data. It is expected that a better treatment for the heat and mass balances in the early period of the growth would rectify the discrepancy between the measurements and the computation. The predicted results are within an error range of ± 25%, and thus the present model is expected to be applicable not only to a flat surface but also to more complex surfaces with curvature.