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N. Naseh,M. Mohseni,B. Ramezanzadeh 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
The aim of this study is enhancing an automotive clearcoat easy-to-clean property against simulated tree gum (Arabic gum) using hydroxyl-functional silicone polyacrylate additives having different hydroxyl contents. The clearcoat surface, mechanical and chemical properties were studied using a contact angle measuring device, dynamic mechanical thermal analysis (DMTA) and Fourier Transform Infrared spectroscopy (FT-IR) respectively. It was found that additive with lower hydroxyl content gave rise to better easy-to-clean properties of the clearcoat against Arabic gum. This additive also resulted in lower contact angles and higher cross-linking density, tensile stress and work of break of the clearcoat.
Mahdi N. Mahyari,Hasan Karimi,Hasan Naseh,Mehran Mirshams 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.10
The focus of the present study is to investigate the effectiveness of installing vortex breakers at the outlet of launch vehicle tanks on postponing vortex formation and decreasing the critical height of propellants while discharging. Analytical results in the absence of a vortex breaker show that the effects of the Weber and Reynolds numbers in the flow field can be ignored for values greater than 720 and 1.1 × 105, respectively; and critical height can be considered as a function of Froude number under aforementioned conditions. The analytical criteria are verified by two-dimensional, axis symmetrical, transient and two-phase numerical model. Eventually, some experiments are conducted to examine the effectiveness of the applied vortex breakers in reduction of the critical height of propellant. Experimental results show that a 30% decrease can be achieved in critical height by using a particular type of vortex breaker. Additionally, the carried out simulations for an existing two-stage launch vehicle indicate a 13% increase in orbital altitude, which in turn proves the considerable improvement in launch vehicle mass/energetic capabilities.