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Performance of buoyant shell horizontal axis wind turbine under fluctuating yaw angles
Saleem, Arslan,Kim, Man-Hoe Pergamon Press 2019 Energy Vol.169 No.-
<P><B>Abstract</B></P> <P>The paper presents the effect of fluctuating yaw angle and wind speed on the performance of a horizontal axis airborne wind turbine of three different shell shapes for the high altitude operational conditions. For this purpose, a numerical analysis has been performed by considering the ranges of yaw angle and wind speed of 0 ° − 20 ° and 10 m / s − 25 m / s , respectively. The turbine shell shapes are based on the three aerofoil profiles of NACA-5415, NACA-9415 and NACA-5425 to investigates the influence of the aerofoil camber and thickness. The turbine has been modelled using a NREL Phase IV rotor with the fixed rotor radius of 2 m for all shell configurations. A 3-D numerical analysis has been conducted by implementing k − ω SST turbulence model to solve the Reynolds-averaged Navier-Stokes equations. Numerical results demonstrated that the increment in both the tip speed ratio and yaw angle augmented the rotor thrust coefficient. At the high yaw angles, the buoyant shell is prone to encounter instability due to unbalancing of the aerodynamic forces subjected to the shell body. Among all the studied shell configurations, the NACA-9415 aerofoil based shell displayed the relatively higher turbine power coefficient as well as the stable operation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Provide aerodynamic performance of BAWT under fluctuating yaw angles. </LI> <LI> Investigate three NACA airfoil based shell configurations. </LI> <LI> Report turbine power and rotor thrust coefficients and pressure profile across shell. </LI> </UL> </P>
Saleem, Arslan,Kim, Man-Hoe Elsevier 2017 Energy conversion and management Vol.151 No.-
<P><B>Abstract</B></P> <P>Wind energy has been one of the most widespread types of intermittent renewable energy harvesting source. Airborne wind turbine (AWT) stands out among other available techniques for harvesting wind energy because of its ability to operate at multiple times higher altitudes. This paper presents the aerodynamic performance of an AWT system at an altitude of 400m with NREL Phase IV rotor position variation within the buoyant shell. The unsteady numerical simulations have been carried out at rotor axial positions of 0.25L, 0.3L, 0.35L, 0.4L and 0.45L (L is the shell length) from the inlet, in order to investigate rotor torque variation in one complete rotor revolution. Additionally, steady-state simulations of the AWT system have been performed at various wind speeds ( 7 m / s – 20 m / s ) and yaw angles ( 0 ° – 15 ° ) , to investigate the optimum aerodynamic performance of buoyant shell and rotor. Results demonstrate that by placing the rotor at the shell inlet (0.25L) with step placed at the shell outlet, maximum torque enhancement of 25.3% can be attained at wind speed of 15 m / s . Buoyant shell exhibits equilibrium at 0 ° yaw angle due to symmetric pressure distributions on the shell body. Whereas for yaw angle > 0 ° , instability instigated by non-uniform pressure distributions results in the oscillation of shell. However restoring torque damps out these vibrations and provides assistance in re-establishing equilibrium position.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Conduct both steady and unsteady state simulations for an AWT system at different free stream wind speeds. </LI> <LI> Optimal position prediction of the wind turbine in an airborne shell at an altitude of 400m above sea level. </LI> <LI> Effect of wind turbine positioning on the aerodynamic performance of Buoyant Airborne Turbine (BAT). </LI> <LI> Aerodynamic characteristics prediction of buoyant shell and rotor with different turbine positions in an airborne system. </LI> </UL> </P>
Saleem, Arslan,Kim, Man-Hoe Elsevier 2017 Applied thermal engineering Vol.125 No.-
<P><B>Abstract</B></P> <P>This paper presents three-dimensional steady state analysis of compact multi-louvered fin and flat tube heat exchangers applicable in domestic and mobile air conditioning systems. Conjugate heat transfer analysis has been conducted for five geometric configurations of the heat exchanger based on the louver pitch values (0.8, 1.0, 1.4, 1.7 and 2.0mm) in the laminar range of Reynolds number 50–450. For all geometric configurations, local air-side heat transfer coefficient and pressure drop are presented in terms of Colburn <I>j</I> factor and Fanning friction <I>f</I> factor, respectively. In addition, the effect of fin height on thermal hydraulic performance has also been addressed based on local Nusselt number distribution along the fin height. The results reveal that geometric configuration with the louver pitch of l.0mm showed the highest average Nusselt number of 123% at the penalty of 116% pressure drop compared to louver pitch of 2.0mm at the Reynolds number of 50.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Investigate air-side thermal hydraulic performance for microchannel heat exchangers. </LI> <LI> Local air-side heat transfer coefficient and pressure drop are addressed. </LI> <LI> Fin configuration with louver pitch of 1.0mm has the maximum Nusslet number. </LI> <LI> Provide the effect of fin height on air-side thermal hydraulic performance. </LI> </UL> </P>
Effect of Peritectic Banded Structure on Magnetic Properties of SmCo<SUB>5</SUB> Sintered Magnets
Saleem Akhtar,A. Nusair Khan,Mushtaq Khan,Syed Husain Imran Jaffery,Arslan Saleem 한국자기학회 2020 Journal of Magnetics Vol.25 No.4
SmCo5 is well known for its high coercivity. However, still room is available to increase the coercive power of SmCo5, since the theoretical values of the compound is far higher than the achieved values. Different attempts, in this regard, have been made either by controlling the microstructure or the chemical composition. However, it is noted that no or very few literature is available regarding the control of microstructure through solidification. Three types of SmCo5 compound were prepared through induction melting technique so that final solidification be manipulated by controlling the mold temperature. Fractrographic analysis revealed a unique peritectic structure in SmCo5 compound. It was observed that the peritectic plates, having nano-size thickness, remain present even after high temperature sintering operation. The nano-scale peritectic plates may affect the final magnetic properties, especially the coercivity of the subject compound.
Expression and Purification of Transmembrane Protein MerE from Mercury-Resistant Bacillus cereus
( Aatif Amin ),( Arslan Sarwar ),( Mushtaq A. Saleem ),( Zakia Latif ),( Stanley J. Opella ) 한국미생물 · 생명공학회 2019 Journal of microbiology and biotechnology Vol.29 No.2
Mercury-resistant (Hg<sup>R</sup>) bacteria were isolated from heavy metal polluted wastewater and soil collected near to tanneries of district Kasur, Pakistan. Bacterial isolates AZ-1, AZ-2 and AZ-3 showed resistance up to 40 μg/ml against mercuric chloride (HgCl<sub>2</sub>). 16S rDNA ribotyping and phylogenetic analysis were performed for the characterization of selected isolates as Bacillus sp. AZ-1 (KT270477), Bacillus cereus AZ-2 (KT270478) and Bacillus cereus AZ-3 (KT270479). Phylogenetic relationship on the basis of merA nucleotide sequence confirmed 51-100% homology with the corresponding region of the merA gene of already reported mercuryresistant Gram-positive bacteria. The merE gene involved in the transportation of elemental mercury (Hg0) via cell membrane was cloned for the first time into pHLV vector and transformed in overexpressed C43(DE3) E. coli cells. The recombinant plasmid (pHLMerE) was expressed and the native MerE protein was obtained after thrombin cleavage by size exclusion chromatography (SEC). The purification of fusion/recombinant and native protein MerE by Ni-NTA column, dialysis and fast protein liquid chromatography (FPLC/SEC) involved unfolding/refolding techniques. A small-scale reservoir of wastewater containing 30 μg/ml of HgCl<sub>2</sub> was designed to check the detoxification ability of selected strains. It resulted in 83% detoxification of mercury by B. cereus AZ-2 and B. cereus AZ-3, and 76% detoxification by Bacillus sp. AZ-1 respectively (p < 0.05).