Mosfequr Rahman

University of Alabama,

Ph.D.

University of Alabama,

M.S.

Bangladesh University of Engineering and Technology

M.S.

Numerical and Experimental Investigation of Aerodynamic Performance of Vertical-Axis Wind Turbine Models with Various Blade Designs

Mosfequr Rahman, Travis E Salyers, Adel El-Shahat, Marcel Ilie, Mahbub Ahmed, Valentin Soloiu

2018

Due to the importance and advantages of Vertical-axis wind turbines (VAWTs) over traditional horizontal-axis wind turbines (HAWTs), this paper is implemented. Savonius turbines with drag-based rotors are adopted from the two more extensive arrangements of vertical wind turbines because of their advantages. In this paper, six diverse rotor plans with measure up to cleared regions are analyzed with exploratory wind burrow testing and numerical reenactments. These proposed models incorporate a conventional Savonius with two different edges criteria and 90 degree helical bend models with two, three and four sharp edges. The models were designed using SolidWorks software then the physical models were 3D printed for testing. A subsonic open-sort wind burrow was utilized for Revolution per Minute (RPM) and torque estimation over a scope of wind speeds. ANSYS Fluent reenactments were utilized for dissecting streamlined execution by using moving reference outline and sliding lattice display methods. A 3-dimensional and transient strategy was utilized for precisely tackling torque and power coefficients. The five new rotor geometries have important advantages such as making a focal point of weight advance from the hub of revolution and causing more noteworthy torque on the turbine shaft contrasted with the customary Savonius turbine. Our new models with the names of CC model and QM model display cross-areas lessen the aggregate scope of negative torque on the edges by 20 degrees, contrasted with the customary Savonius demonstrate. Helical plans are better spread the connected torque over a total transformation resulting in positive torque over every single operational point. Moreover, helical models with 2 and 3 cutting edges have the best self-starting ability in low wind speeds. Helical VAWT with 3 edges starts revolution of 35 RPM at only 1.4 m/s wind speed under no generator stacking. The most noteworthy power coefficient is accomplished, both tentatively and numerically, by the helical VAWT with 2 sharp edges.

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Experimental Investigation of Photostrictive Materials for MEMS Application

Mosfequr Rahman, Mahbub Ahmed, Masud Nawaz, Gustavo Molina, Abdur Rahman

2017

Micro-Electro-Mechanical-Systems (MEMS) is an emerging technology that integrates micromachined mechanical structures with integrated circuits (IC). During the last two decades, it has grown vastly as a prominent research area among scientists and engineers. Usually the main components of MEMS are sensors, actuators, and structures with all in microscale. A photostrictive mate-rial has high potential to be used in a MEMS application to develop an ad-vanced optical actuator. A strain is induced when a photostrictive material is il-luminated by high intensity light, which is known as photostriction. This phe-nomenon can be generally described as the combined effect of the photovoltaic effect and the converge-piezoelectric effect. When an incident light strikes a photostrictive material, a photovoltage is produced and this photovoltage develops strain in the material. Lanthanum modified lead zirconate titanate (Pb, La) (Zr, Ti) O3 ceramic doped with WO3, called PLZT, is one of the photostrictive ceramics which has an advantageous use as a wireless remote control over traditional actuators. Traditional actuators require wire connections to transmit the control signal; these wires yield noise via external electromagnetic fields. Whereas, PLZT actuators can transmit the control signal without wires which can eliminate possible noise due to the external electromagnetic field. In this current research, the photostrictive effect of a thin PLZT film on a silicon wafer is investigated experimentally. The transverse deflection of the PLZT optical actuator cantilever beam has been measured for stationary continuous light as well as for pulses of light using an optical chopper at various light intensities and focused locations. Results indicate that transverse deflection increases with the increase of light intensity. Also, the maximum transverse deflection at the free end of the cantilever beam for stationary light has been found to be three times larger than that for the pulses of light.

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Design and Testing of a Jet-Impingement Instrument to Study Surface-Modification Effects by Nanofluids

Gustavo J Molina, Fnu Aktaruzzaman, Valentin Soloiu, Mosfequr Rahman

2017

The growing research interest on nanofluids, the suspensions of nano-size powders in ordinary fluids with enhanced cooling properties, has led the authors to study surface modifications (i.e., possible erosion-corrosion effects) from nanofluid interactions with typical heat-exchanger materials. This article discusses existing instruments and the rationale for designing a new ad-hoc test rig using jet-impingement at speeds from 3.5 m/s to 35 m/s. Preliminary tests used typical nanofluids—2% volume alumina-nanopowder in water—which were jet-impinged at 15.5 m/s speed on aluminum and copper specimens. The instrument, methodologies and assessment tools proved to be appropriate to test for the nanofluid interactions with material surfaces. The studied surface modifications, which were assessed by roughness measurements, weighing for removed-material, and optical-microscopy, suggest that addition of nano-powders can lead to patterns of erosion-corrosion that are substantially different than those typically obtained from base fluids.

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