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Showing 3 results for Shroud
N. Keramat Siavash, Gh.h. Najafi, T. Tavakoli, B. Ghobadian, E. Mahmoodi,
Volume 19, Issue 5 (5-2019)
Abstract
In this study, the performance of a wind turbine is compared with a bare one using wind tunnel results. wind turbines, which consist of a diffuser surrounding the rotor. The duct makes more air flow in rotor plain and as a result augments power production. The blade was fabricated, using armed by glass fiber. Duct is formed sheet metal rolling in slope to have an acceptable appearance. According to BEM design, predicted power the bare turbine is 300W in wind velocity 10 m/s considering due to bearing resistant, rotor inertia, and generator efficiency. Wind tunnel investigation revealed 165W for The evaluation of the system in the wind tunnel showed that the power augmentation of the system compared to the bare one was 37% higher on average. The maximum power augmentation of the turbine was 286W. The rotor 61% more than the bare turbine, which increased the speed of the tip of the blade.
S. Koohestani,
Volume 19, Issue 8 (8-2019)
Abstract
In this study, effect of shroud on dynamic characteristics of a rotating multi blade system is investigated. The main aim of this study is to investigate the effect of shroud stiffness and shroud configuration on the system natural frequency. For this purpose, natural frequencies of various systems (in terms of the position, where the blade is connected to the shroud and number of blades, which are connected together with a shroud) via different degrees of shroud stiffness and different configurations of shroud have been compared to show how this parameters affect the natural frequencies of the system. In this study, the shrouds have been considered as the discrete springs with corresponding stiffness values. The vibration frequency characteristics have been analyzed, using assumed mode method along with Hamilton’s law. Since in multi blade systems such as turbines it is crusial to keep the system working frequencies far away from natural frequencies (in order to prevent the resonance phenomenon), based on the results of this paper, it is shown how the parameters of shroud can remove the natural frequencies associated with some of the modes of the system from the work area.
Volume 28, Issue 1 (3-2021)
Abstract
Based on Islamic era sources, inscribed robes were one of the valuable art works during the Ale- Buyid period that were gifted to courtiers in official ceremonies as a sign of honor for their loyalty. These robes normally contained the name of the ruler. In the Ale-Buyid period, a combination of both Shi’a and Iranian-Sasanian led to the creation of a new style of art. From the remains of that period, number of textiles with inscriptions was discovered from two enclosures of Broj-e Nagharekhane and Bibi Shahrbanu in Ray. According to archaeological reports, the scripted textiles were used as shrouds or to cover graves. The inscriptions are in both plain and ornamental Kufic styles and in most of the cases, beside its function to convey a massage, had decorative functions too. Based on 25 scripted textile pieces from Ale-Buyid period which mostly were discovered from Ray, this research attempts to reveal the meaning and also the literature sources of the inscriptions. The data has been collected through library studies. This research shows that the texts contain prayers, ethical massage and some poems from Arab poets from the first Hijri to the Ale-Buyid period. In some cases, embroidery has changed the shape of the letters to create a rhythmic pattern in the text and for this reason; the text is illegible or contains a visual or written error. This shows that writing was as important as its content. Most of the fabrics obtained based on the content were robes, and the content of the inscriptions often had an individual audience and a prayer sentence.
