Aerospace Science and Technology
Sahar Noori; Mohamad Saleh Afshar; Nima Karimi
Abstract
Airships usually have low cruising speed due to their large volume and high drag level. This makes the aerodynamic design of the vehicle, including the surfaces shape, the length-to-diameter ratio and the position of the fins, all very important. Furthermore, an important parameter in the vehicle aerodynamic ...
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Airships usually have low cruising speed due to their large volume and high drag level. This makes the aerodynamic design of the vehicle, including the surfaces shape, the length-to-diameter ratio and the position of the fins, all very important. Furthermore, an important parameter in the vehicle aerodynamic drag is determining the flow separation area at the rear of the air vehicle. The flow separation plays an essential role in the amount of drag and lift force, so the location of the fins and the design of the rear of the airship will be very important. By using both analytical and numerical methods, this study examines the aerodynamic efficiency of an airship in three different configurations, focusing on the location, type, and angle of attack of the fin, and compares analytical and numerical results. According to studies conducted among the types of fins, the cross-type will have the best performance among the fins in terms of lift-drag ratio. Also, moving the fins forward and distancing them from the rear of the vehicle disrupts the flow pattern at the rear of the vehicle and delays separation. This will improve aerodynamic efficiency and improve the lift-drag ratio of the vehicle.
Hossein H. Shahverdi; A.S Nobari; H Bahrami Torabi
Volume 11, Issue 1 , June 2017
Abstract
The aim of this paper is to provide an aeroelastic computational tool which determines the induced wing loads during flapping flight. For this purpose, a Finite Element (FE) code based on a four-node plate bending element formulation is developed to simulate the aeroelastic behavior of flapping wings ...
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The aim of this paper is to provide an aeroelastic computational tool which determines the induced wing loads during flapping flight. For this purpose, a Finite Element (FE) code based on a four-node plate bending element formulation is developed to simulate the aeroelastic behavior of flapping wings in low incompressible flow. A quasi-steady aerodynamic model is incorporated into the aeroelastic model for predicting the aerodynamic loads. In order for the validation of the present tool, the modal and dynamic response analyses of a rotating flat plate under pure flapping motion are firstly examined and the effect of dynamic stiffness on the plate response, due to the presence of shortening terms in the equations of motion, is also investigated. Finally, the aeroelastic analysis of an insect-like wing under a specified motion is carried out and the induced loads including shear force and bending moment at the wing root are determined. The obtained results signify the contribution of wing structural elasticity to the induced loads.