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Hirotoshi Sasaki,Yuka Iga 한국유체기계학회 2019 International journal of fluid machinery and syste Vol.12 No.4
Liquid droplet impingement erosion occurs at the elbows in steam pipes where droplets impinge at high speed. In the actual pipe wall which numerous droplets always impinge, it is predicted that both a liquid film exists on a pipe wall surface and, on the other hand, this surface is also eroded by repeated droplet impingement. Therefore, the liquid film and roughness on the material surfaces are considered to exist mixed on the actual impinged point of droplets. In this study, by using an in-house fluid/material two-way coupled numerical method that considers reflection and transmission on the fluid/material interface, the numerical analysis of the phenomenon of liquid droplet impingement on a pitted surface with a water pool is conducted. From the analysis results, the impinged pressure at the moment of impingement is reduced by a water pool. However, as the cavitation bubbles are generated in the bottom and top of the droplet after the impingement and then the cavitation bubble of the bottom side collapses, the collapse pressure which greatly exceeds the pressure of the droplet impingement occurs, and the equivalent stress also increases greatly there. Therefore, this analysis result may indicate one reason why the erosion progresses deeply at the pit part in an actual pipe wall thinning.
Hirotoshi Sakaida,Takeshi Yamasaki,Hiroyuki Takano,Yoriaki Baba 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
This paper presents an integrated navigation system for a guidance and control system of a small UAV The navigation part consists of GPS/INS navigation suits equipped with various MEMS sensors and a small general purpose GPS receiver, which are low cost and have been achieved the miniaturization. Since a state estimation algorithm for feedback control uses highly nonlinear equations, the Unscented Kalman Filter (UKF) which is one of the most well-known, nonlinear and maximum likelihood estimation methods, is expected to perform as an excellent filter. In this research, the possibility of the system's installment with high accuracy is researched using the UKF. The effectiveness of the integrated navigation system will be performed by several simulations, along with a series of experiments.
Hirotoshi Sasaki,Naoya Ochiai,Yuka Iga 한국유체기계학회 2016 International journal of fluid machinery and syste Vol.9 No.1
By high speed Liquid Droplet Impingement (LDI) on material, fluid systems are seriously damaged, therefore, it is important for the solution of the erosion problem of fluid systems to consider the effect of material in LDI. In this study, by using an in-house fluid/material two-way coupled method which considers reflection and transmission of pressure, stress and velocity on the fluid/material interface, high-speed LDI on wet/dry material surface is simulated. As a result, in the case of LDI on wet surface, maximum equivalent stress are less than those of dry surface due to damping effect of liquid film. Empirical formula of the damping effect function is formulated with the fluid factors of LDI, which are impingement velocity, droplet diameter and thickness of liquid film on material surface.
Sasaki, Hirotoshi,Ochiai, Naoya,Iga, Yuka Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.1
By high speed Liquid Droplet Impingement (LDI) on material, fluid systems are seriously damaged, therefore, it is important for the solution of the erosion problem of fluid systems to consider the effect of material in LDI. In this study, by using an in-house fluid/material two-way coupled method which considers reflection and transmission of pressure, stress and velocity on the fluid/material interface, high-speed LDI on wet/dry material surface is simulated. As a result, in the case of LDI on wet surface, maximum equivalent stress are less than those of dry surface due to damping effect of liquid film. Empirical formula of the damping effect function is formulated with the fluid factors of LDI, which are impingement velocity, droplet diameter and thickness of liquid film on material surface.