Papers by Rashid Naseer
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The concept of harvesting energy from vortex-induced vibrations with introducing magnetic force i... more The concept of harvesting energy from vortex-induced vibrations with introducing magnetic force is investigated. The objective is to design enhanced broadband VIV-based piezoelectric energy harvesting. A modified van der Pol wake oscillator is considered for modeling the lift fluctuation force. The magnetic force representation is based on the dipole-dipole interaction representation. The results show that the harvester's parameters can be adjusted for efficient and broadband energy harvesting. a b s t r a c t The concept of harvesting energy from vortex-induced vibrations (VIVs) by introducing nonlinear attractive magnetic forces is proposed and investigated for the first time. The objective is to design broadband synchronization regions for efficient piezoelectric energy harvesting from VIVs of circular cylinders. A lumped-parameter model is constructed by coupling the dynamics of the energy harvesting system subjected to VIV with the generated voltage across the electrical load resistance. A modified van der Pol wake oscillator is considered for modeling the vortex-induced fluctuating lift force. The magnetic force representation is based on the dipole-dipole interaction. Firstly, the effects of the spacing distance between the two magnets on the buckling configuration of the energy harvester is studied through a static analysis. Then, a linear analysis is performed to determine the impacts of the spacing distance on the natural frequency and damping ratio of the energy harvester in the monostable configuration. A nonlinear dynamic analysis is carried out to determine the impacts of the spacing distance and electrical load resistance on the output performance of the harvester in terms of the synchronization region and levels of the harvested power. The results show that changing the spacing distance produces a variation of the natural frequency and hence a shift of the lock-in region, which is significant for low wind speed energy harvesting. Furthermore, it is demonstrated that depending on the available wind speed in the environment, the spacing distance and load resistance can be adjusted for efficient and broadband energy harvesting from VIV.
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In this paper, an operable strategy to enhance the output power of piezoelectric energy harvestin... more In this paper, an operable strategy to enhance the output power of piezoelectric energy harvesting from vortex-induced vibration (VIV) using nonlinear magnetic forces is proposed for the first time. Two introduced small magnets with a repulsive force are, respectively , attached on a lower support and the bottom of a circular cylinder which is subjected to a uniform wind speed. Experiments show that the natural frequency of the VIV-based energy harvester is significantly changed by varying the relative position of the two magnets and hence the synchronization region is shifted. It is observed that the proposed energy harvester displays a softening behavior due to the impact of nonlinear magnetic forces, which greatly increases the performance of the VIV-based energy harvesting system, showing a wider synchronization region and a higher level of the harvested power by 138% and 29%, respectively, compared to the classical configuration. This proposed design can provide the groundwork to promote the output power of conventional VIV-based piezoelectric generators, further enabling to realize self-powered systems .
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The concept of harvesting energy from vortex-induced vibrations of a circular cylinder when inclu... more The concept of harvesting energy from vortex-induced vibrations of a circular cylinder when including attractive magnetic forces is investigated. The purpose is to design efficient low-speed synchronization regions piezoelectric energy harvesters. Including the attractive magnetic force is beneficial in order to decrease the structural natural frequency of the energy harvester and hence decrease the needed shedding frequency to obtain resonant regions of harvested power. In this study, a lumped-parameter model is utilized which couples the dynamics of the structure and the generated voltage across the electrical load resistance. A modified van der Pol wake oscillator is considered to model the fluctuating lift coefficient. A dipole-dipole interaction is also assumed in order to represent the magnetic force which is acceptable for high spacing distances between the two magnets. The effects of the spacing distance on the buckling configuration of the energy harvester are first studied through a static analysis. Second, a frequency analysis is performed to determine the impacts of the spacing distance on the natural frequency of the harvester in both monostable and bistable regimes. A nonlinear dynamic analysis is then carried out to determine the impacts of the spacing distance and electrical load resistance on the performance of the piezoelectric energy harvester. The performed dynamical analysis in the monostable regime shows that a decrease in the attractive spacing distance results in lower resonant wind speeds which is beneficial for energy harvesting purposes. It is also shown that the electrical load resistance significantly affects the levels of the harvested power.
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Applied Energy, 2017
The concept of harvesting energy from vortex-induced vibrations with introducing magnetic force i... more The concept of harvesting energy from vortex-induced vibrations with introducing magnetic force is investigated. The objective is to design enhanced broadband VIV-based piezoelectric energy harvesting. A modified van der Pol wake oscillator is considered for modeling the lift fluctuation force. The magnetic force representation is based on the dipole-dipole interaction representation. The results show that the harvester's parameters can be adjusted for efficient and broadband energy harvesting. a b s t r a c t The concept of harvesting energy from vortex-induced vibrations (VIVs) by introducing nonlinear attractive magnetic forces is proposed and investigated for the first time. The objective is to design broadband synchronization regions for efficient piezoelectric energy harvesting from VIVs of circular cylinders. A lumped-parameter model is constructed by coupling the dynamics of the energy harvesting system subjected to VIV with the generated voltage across the electrical load resistance. A modified van der Pol wake oscillator is considered for modeling the vortex-induced fluctuating lift force. The magnetic force representation is based on the dipole-dipole interaction. Firstly, the effects of the spacing distance between the two magnets on the buckling configuration of the energy harvester is studied through a static analysis. Then, a linear analysis is performed to determine the impacts of the spacing distance on the natural frequency and damping ratio of the energy harvester in the monostable configuration. A nonlinear dynamic analysis is carried out to determine the impacts of the spacing distance and electrical load resistance on the output performance of the harvester in terms of the synchronization region and levels of the harvested power. The results show that changing the spacing distance produces a variation of the natural frequency and hence a shift of the lock-in region, which is significant for low wind speed energy harvesting. Furthermore, it is demonstrated that depending on the available wind speed in the environment, the spacing distance and load resistance can be adjusted for efficient and broadband energy harvesting from VIV.
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Conference Presentations by Rashid Naseer
—The 1 st compression ring sustains the maximum thermal loads during the operation of an internal... more —The 1 st compression ring sustains the maximum thermal loads during the operation of an internal combustion engine. In the initial engine start up at a very low speed, the secondary displacements of the piston affect the lubrication of the 1 st compression ring adversely in the absence of a fully developed elastohydrodynamic lubricating (EHL) film. The adverse effects may allow a physical contact and wear of the ring and the liner surfaces. This study develops the numerical models of the hydrodynamic and EHL of the 1 st compression ring at a very low initial engine start up speed. Then the results are compared with those at the other two low speeds, considered separately. The secondary dynamics of the piston ring assembly and the barrel-face profile of the ring are incorporated in the models. The Reynolds equation is solved to generate the hydrodynamic pressures, developed over the circumferential length of the ring. The inverse solution technique is employed to study the rising EHL pressures and the EHL film profiles after incorporating the elastic surface displacements in the models. The simulation results show the hydrodynamic and EHL film thicknesses as the function of the 720-degree crank rotation cycle. The simulation results show that a low engine start up speed affects the ring lubrication and the load carrying capacity of the film of a low-viscosity grade lubricant. The low engine start up speed is optimized based on the findings of the comparative analysis of the results to improve the ring lubrication for a few initial cycles.
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In normal IC engine operation 1 st compression ring sustains thermal loads effectively. At large ... more In normal IC engine operation 1 st compression ring sustains thermal loads effectively. At large radial clearance in low-speed engine start up it has to act as effective seal against thermal loading. Absence of elastohydrodynamic lubricating (EHL) film and secondary displacements expose the ring to adhesive wear in initial engine start up. Isothermal hydrodynamic and EHL models of parabolic-faced ring are developed numerically after incorporating secondary dynamics of piston assembly at a low engine start up speed. Reynolds equation is solved to generate hydrodynamic pressures and film profiles in 4-stroke cycle. In EHL model inverse solution technique and elastic displacements of ring and liner are employed to generate pressures and film profiles. The simulation results suggest that a large ring-to-bore clearance increases eccentricity and affects EHL of 1 st compression ring when a low-viscosity grade oil is used in initial engine start up.
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Papers by Rashid Naseer
Conference Presentations by Rashid Naseer