The effect of the rate of change of fresh air inside passengers’ wagons for Underground Metro on the spreading of airborne diseases like COVID-19 is investigated numerically. The study investigates two extreme scenarios for the location of the source of infection within the wagon with four different air change rates for each. The first scenario considers the source of infection at the closest point to the ventilation system while the other places the infection source at the farthest point from the wagon ventilation system. The effect of the wagon windows’ status (i.e. closed or open) is also studied. It is found that under all conditions, open windows are always favored to decrease the infection spreading potential. A higher air change rate also decreases the infection spreading up to a certain value, beyond which the effect is not noticeable. The location of the infection source was found to greatly affect the infection spreading as well. The paper gives recommendations on the minimum air change rate to keep the infection spreading potentials to a minimum considering different times the passengers stay in the wagon.
Recently, a great interest in search of alternate means of power for the traditional fuel for aircraft propulsion is raised so as to decrease gas emissions and reduce operating costs. For the small and micro unmanned aerial vehicles or small transportation aircraft, there are many challenges in the direction of constructing an electric or solar powered airplane whose wings may possibly be sheltered with photo voltaic PV solar panels to harvest sun’s energy for propulsion. Greatest remarkably success solar powered aircraft has attracted the attention of researchers other than UAV and small aircraft supporters. Although the solar panel is thin, its thickness is considerable compared to the airfoil thickness. This paper aims to evaluate the impact of adding the solar panel over a low camber airfoil suitable for low-Reynolds number flights, as mini UAVs. Three panel installation configurations are examined to stand on the most suitable configuration, in terms of aerodynamic efficiency. The analysis is based on the airfoil characteristics (lift, drag, and moment) and the pressure distribution over the airfoil surface. A parametric study is conducted to study the effect of the solar panel size, thickness, and position on the aerodynamic performance.
Generally, unmanned aerial vehicles and micro aerial vehicles depend on batteries or conventional fuel as a source of energy. These sources of energy have limited flight time, relatively high cost, and also a certain level of pollutants. Solar energy applied to aerial vehicles is an excellent alternative way to overcome other sources of energy’s disadvantage. This study aimed to design a solar-powered aerial vehicle to achieve continuous flight on Earth. The efficiency of the solar system is related to the absorbed sun rays. The concept of an anti-symmetric N-shaped morphing wing is a good idea to increase the collected solar energy during the daily sun path. But this comes with the penalty of side forces and moments due to the anti-symmetry of the wing. This paper introduces a study for two parameters that strongly affect the aerodynamics of the N-shaped morphing wing; the dihedral part angle and the dihedral part length. The impact of the dihedral angle decreases the lift coefficient and increases the drag coefficient. The impact of the morphing wing on the aircraft performance is also considered.
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