As the prices of the fuel and power had fluctuated many times in the last decade and new policies appeared and signed by most of the world countries to eliminate global warming and environmental impact on the earth surface and humanity exciting, an urgent need appeared to develop the renewable energy harnessing technologies on the short-term and long-term and one of these promising technologies are the vertical axis wind turbines, and mostly the combined types. The purpose of the present work is to combine a cavity type Savonius with straight bladed Darrieus to eliminate the poor self-starting ability for Darrieus type and low performance for Savonius type and for this purpose, a three-bladed Darrieus type with symmetrical S1046 airfoil was tested experimentally and numerically at different wind speeds (4.5 m/s, 8 m/s and 10 m/s) and it showed a poor self-starting ability at low wind speed although its higher performance at high wind speed. However when adding the cavities in two setup configuration and testing it at the same conditions, it was found that when adding the cavities as reversed cups in the core of the turbine, the performance increased and the power coefficient reached a maximum value at 10 m/s wind speed and it was observed to be 0.0914 , but when the solidity increased by adding three cavities, the performance was higher at low wind speed (4.5 m/s) but it tragically decreased at higher wind speed which indicates that the performance depends on the solidity and the turbine configuration. On the other hand, the numerical simulation showed a good match with the experimental results although it under-predicted the performance.
The design was distinguished in Late Twenty-First Century With new and new methods Through which the ability to adapt all technical media in the formation of two-dimensional and three-dimensional figures and shapes was achieved .
Which led to the emergence of endless sets of design ideas characterized by the heterogeneity of design forms and design solutions that preceded it. The designer could not access these creations in various architectural and artistic fields only through computer programs, especially those related to the activation of mathematical logic and what is known as algorithms in the formation and construction of the form, which led to the emergence of the "parametric direction" and the problem of research is summarized
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In this work, an experimental investigation has been done for heat transfer by natural-convection through a horizontal concentric annulus with porous media effects. The porous structure in gap spacing consists of a glass balls and replaced by plastic (PVC) balls with different sizes. The outer surface of outer tube is isothermally cooled while the outer surface of inner tube is heated with constant heat flux condition. The inner tube is heated with different supplied electrical power levels. Four different radius ratios of annulus are used. The effects of porous media material, particles size and annulus radius ratio on heat dissipation in terms of average Nusselt number have been analyzed. |
Natural convection heat transfer is experimentally investigated for laminar air flow in a vertical circular tube by using the boundary condition of constant wall heat flux in the ranges of (RaL) from (1.1*109) to (4.7*109). The experimental set-up was designed for determining the effect of different types of restrictions placed at entry of heated tube in bottom position, on the surface temperature distribution and on the local and average heat transfer coefficients. The apparatus was made with an electrically heated cylinder of a length (900mm) and diameter (30mm). The entry restrictions were included a circular tube of same diameter as the heated cylinder but with lengths of (60cm, 120cm), sharp-edge and
... Show MoreThe current work studies the effect of adding chopped carbon fiber (CCF) on gypsum plaster properties (precisely the compressive strength and the modulus of rupture). The research plan consists of using six mixes of gypsum plaster; these mixes are divided into two groups according to the (Water/Gypsum) ratios (0.5 & 0.6). Each group was divided into three subgroups according to CCF volume fraction (Vf): 0.0%, 0.2% and 0.4%. Three cubic (50×50×50) mm and three prismatic (40×40×160) mm samples were performed for each mix. It was found that, the addition of CCF to the gypsum plaster mixes increases both the compressive strength and the modulus of rupture for both (W/G) ratios, an
Mersing is one of the places that have the potential for wind power development in Malaysia. Researchers often suggest it as an ideal place for generating electricity from wind power. However, before a location is chosen, several factors need to be considered. By analyzing the location ahead of time, resource waste can be avoided and maximum profitability to various parties can be realized. For this study, the focus is to identify the distribution of the wind speed of Mersing and to determine the optimal average of wind speed. This study is critical because the wind speed data for any region has its distribution. It changes daily and by season. Moreover, no determination has been made regarding selecting the average wind speed used for w
... Show MoreThe pumping station became widely used in many fields. Free surface vortices at intakes of pumps are not favorable. It may cause noise, excessive vibration, damage to the pumping structure, reduction in efficiency and flow for hydro-turbines, etc. One of the important problems encountered during the pump intake design is the depth of submergence and other design parameters to avoid strong free-surface vortices formation. This study aims to compute the critical submergence depth with some geometrical and hydraulic limitations by using Computational Fluid Dynamic (CFD) package. The mathematical model was validated with a laboratory model that had been conducted. The model of three intake pipes was investigated under five d
... Show MoreThe loose sand is subject to large settlement when it is exposed to high stresses. This settlement is due to the nature of the high drainage of sand, which displays foundations and constructions to a large danger. The densification of loose sandy soils is required to provide sufficient bearing capacity for the structures. Thus soil stabilization is used to avoid failure in the facilities. Traditional methods of stabilized sandy soil such as fly ash, bituminous, and cement often require an extended curing period. The use of polymers to stabilize sandy soils is more extensive nowadays because it does not require a long curing time in addition to being chemically stable. In this study, the effect of adding different percent
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