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This research modifies the leading-edge structure of NACA 0015 and NACA 4415 to resemble the nose of a beluga whale. The focus of this modification is to improve the airfoil's aerodynamic performance and investigate the changing f...
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This research modifies the leading-edge structure of NACA 0015 and NACA 4415 to resemble the nose of a beluga whale. The focus of this modification is to improve the airfoil's aerodynamic performance and investigate the changing fluid flow patterns. Numerical equation used is RANS combined with the k-ε turbulence model. Mesh independence test shows that mesh with 200 elements is the best mesh. Validation results reveal that CFD data can follow the trend of experimental data, especially on the AoA before the stall. There was a significant increase in Cl from NACA 0015 and NACA 4415 at AoA>9°. On the other hand, the modification also had a positive effect by lowering the Cd value. The modification also provides an advantage by increasing the maximum Cl/Cd value. Furthermore, the separation point data shows that the modification can delay the separation of the fluid flow in the airfoil. Modifications can cause an increase in pressure on the lower side and a decrease in pressure on the upper side. Through velocity contours and streamlines, the modifications can reduce the recirculation area. Overall, modifying the leading edge has positive impacts on the NACA 0015 and NACA 4415 airfoils.
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One crucial characteristic of the aircraft structure are fatigue properties and rivets are usually critical areas in metal airframes due to fatigue cracks nucleation. According to literature, the NACA riveting method offers a huge...
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One crucial characteristic of the aircraft structure are fatigue properties and rivets are usually critical areas in metal airframes due to fatigue cracks nucleation. According to literature, the NACA riveting method offers a huge increase in fatigue life of riveted lap joints. This paper presents FE simulations of quasi-static riveting on a press for standard countersunk rivets and the NACA riveting in two configurations: with a normal brazier rivet and a brazier rivet with a compensator. The analyzed configurations have been compared based on the stress courses on the sheets faying surfaces after riveting process. Due to a lack of data, the rivet length and the squeezing force value were assumed for NACA riveting based on FE simulations. The results indicated beneficial influence of the NACA riveting in the outer sheet (with a countersunk) and disadvantageous influence in the inner sheet. This effect was stronger in the case of the rivet with a compensator.
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Airfoils generate lift in engineering applications such as for airplanes, wind turbines, automotive spoilers, etc. For accurate CFD analysis of airfoils, the quality of the mesh is of paramount importance, especially when dealing ...
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Airfoils generate lift in engineering applications such as for airplanes, wind turbines, automotive spoilers, etc. For accurate CFD analysis of airfoils, the quality of the mesh is of paramount importance, especially when dealing with turbulent flows commonly encountered in real life applications. Currently there are different tools that are available to improve the quality of the mesh required for CFD studies. This paper describes a study to assess the significant of the quality of the mesh on CFD analyses of NACA 23012 airfoil by using selected open source tools. The turbulence is modeled using the well-known k-?‰ Shear Stress Transport model. For validation, results have been compared with experimental datasets which were obtained from a€?TAG Stuttgart #1a€? tunnel.ABSTRAK: Sayap pesawat dapat menghasilkan daya angkat dalam aplikasi kejuruteraan seperti kapal terbang, turbin angin, spoiler automotif, dan sebagainya. Kualiti pada jaringan adalah amat penting bagi mendapatkan analisa CFD yang tepat pada sayap pesawat, terutamanya apabila berhadapan situasi aliran turbulen sebenar. Pada masa ini terdapat pelbagai perisian bagi meningkatkan mutu jaringan dalam kajian CFD. Kertas kerja ini membentangkan satu kajian bagi menilai kepentingan kualiti jaringan pada analisis CFD bagi sayap pesawat NACA 23012 dengan menggunakan sumber terpilih perisian terbuka. Model turbulen dibangunkan mengguna pakai model k-?‰ Shear Stress Transport (SST) yang terkenal. Bagi pengesahan, keputusan uji kaji telah dibandingkan dengan set data yang diperoleh dari terowong "TAG Stuttgart #1a€?."
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The drag reduction performance of a half airfoil attached to a trailer and the roof fairing at different positions was experimentally investigated in a wind tunnel. Half airfoils have NACA 0009 and NACA 0012 cross-section and the ...
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The drag reduction performance of a half airfoil attached to a trailer and the roof fairing at different positions was experimentally investigated in a wind tunnel. Half airfoils have NACA 0009 and NACA 0012 cross-section and the roof fairing position is changed from -4.5 mm to +4.5 mm. Smoke wire and surface oil flow visualization were also performed to elucidate the flow characteristic around the truck-trailer with drag reduction devices. While the drag reduction rate of the truck trailer with half airfoil is up to 10% higher than that of alone truck-trailer at all Reynolds number ranges, drag reduction of the truck trailer with the half airfoil and the roof fairing was exceeded 30% as compared to the alone truck trailer. Drag coefficient results indicated that the half NACA 0009 and NACA 0012 airfoil has an almost similar trend at the zero-roof fairing position. Laminar separation bubble formation was observed on the surface of roof fairing with the help of surface oil flow visualization.
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Unsteady turbulent cavitation flows in a Venturi-type section and around a NACA0012 hydrofoil were simulated by two-dimensional computations of viscous compressible turbulent flow model. The Venturi-type section flow proved numeri...
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Unsteady turbulent cavitation flows in a Venturi-type section and around a NACA0012 hydrofoil were simulated by two-dimensional computations of viscous compressible turbulent flow model. The Venturi-type section flow proved numerical precision and reliability of the physical model and the code, and further the cavitation around NACA0012 foil was investigated. These flows were calculated with a code of SIMPLE-type finite volume scheme, associated with a barotropic vapor/liquid state law which strongly links density and pressure variation. To simulate turbulent flows, modified RNG k-ε model was used. Numerical results obtained in the Venturi-type flow simulated periodic shedding of sheet cavity and was compared with experiment data, and the results of the NACA0012 foil show quasi-periodic vortex cavitation phenomenon. Results obtained concerning cavity shape and unsteady behavior, void ratio, and velocity field were found in good agreement with experiment ones.
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This work focuses on the design and development of a high manoeuvre penta rotor UAV (Unmanned Aerial Vehicle). The research is divided into two phases. In the first phase the UAV design calculations were done manually and modellin...
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This work focuses on the design and development of a high manoeuvre penta rotor UAV (Unmanned Aerial Vehicle). The research is divided into two phases. In the first phase the UAV design calculations were done manually and modelling is done in solid works. The penta rotor UAV design and its aerodynamic properties were analyzed using Computational Fluid Dynamics (CFD) for validation of the design. The airfoil used for the UAV is NACA4412. The airfoil design has been done and the aerodynamic properties were analyzed for various angle of attack. In the second Phase, a delta airframe of a quad rotor is constructed and the fifth rotor is used in pusher configuration to accelerate the flight in forward direction after reaching suitable altitude. The delta airframe consist of elevon for pitch and roll control and rudder for yawing motion. CFD analysis of the UAV with three different winglet configurations is presented.
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Installation of hydrofoil on a vessel results in lift force generation, especially at high speeds, and reduces its resistance. In the current paper, hydrodynamic performance of two NACA hydrofoils is numerically assessed under cav...
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Installation of hydrofoil on a vessel results in lift force generation, especially at high speeds, and reduces its resistance. In the current paper, hydrodynamic performance of two NACA hydrofoils is numerically assessed under cavitation and non-cavitation conditions. Simulations are conducted by Ansys-CFX software and RANS equations are solved using k-e turbulence model. The obtained results are compared against available experimental data and good compliance is displayed. Results of simulations indicate that hydrodynamic forces of lift and drag of the hydrofoils vary in different operating conditions. Based on numerical findings, one may conclude that lift and drag forces of two-dimensional Naca6612 hydrofoil are larger than those of Naca0012 hydrofoil. This is true in both cavitation and non-cavitation conditions. Overall, it is also concluded that under these conditions, Naca6612 hydrofoil performs much better than Naca0012 hydrofoil, and lift-to-drag ratio of Naca6612 is larger than that of Naca0012 at all angles of attack.
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The present paper studies the cavitation characteristics in thermodynamic condition. The present work modifies thermodynamic cavitation mass transfer expression based on the Rayleigh-Plesset equation. The pressure difference, surf...
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The present paper studies the cavitation characteristics in thermodynamic condition. The present work modifies thermodynamic cavitation mass transfer expression based on the Rayleigh-Plesset equation. The pressure difference, surface tension and thermodynamic effects are considered in new mass transfer expression on the basics of the evaporation and condensation mechanics according to the micro-kinetic theory. The hydrofoil NACA0015's thermal cavitation characteristic is calculated at 25°C, 50°C, 70°C with the improved model. The shear stress transport model is adopted as turbulence kinetic energy transport equation. The pressure coefficient is compared with experiment data at different temperatures to validate the model. The temperature difference between local temperature and ambient temperature is obtained and the cavitation volume fraction is calculated.
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High-fidelity computations of the flow control around a pitching NACA63(3) - 618 airfoil by a plasma actuator are conducted. The effectiveness of the plasma actuator and the effects of its installation position are investigated. T...
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High-fidelity computations of the flow control around a pitching NACA63(3) - 618 airfoil by a plasma actuator are conducted. The effectiveness of the plasma actuator and the effects of its installation position are investigated. The plasma actuator is installed at x/c = 0%, 10%, and 60% from the leading edge of the airfoil. The installation position of 60% is chosen based on the investigation of the uncontrolled flow field; the case with this position successfully enhanced the aerodynamic performances of the airfoil. The results show the importance of a priori investigation of the separation and the reattachment points for an uncontrolled flow-field. In addition, the results illustrate that a properly installed and actuated plasma actuator is capable of controlling the dynamic flowfields and improving the aerodynamic performances of an airfoil. (C) 2016 Elsevier Inc. All rights reserved.
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Cavitation is a complex two-phase flow phenomenon that includes unsteady characteristics. This work performs an unsteady 2D numerical analysis of cavitating flow on (i) cambered NACA4412 hydrofoil and (ii) the same hydrofoil geome...
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Cavitation is a complex two-phase flow phenomenon that includes unsteady characteristics. This work performs an unsteady 2D numerical analysis of cavitating flow on (i) cambered NACA4412 hydrofoil and (ii) the same hydrofoil geometry modified with dimple. The analysis is done with the objective of estimating the effect of the dimple on the hydrodynamic performance of the cavitating hydrofoil. The numerical simulations are performed using a flow solver by employing Realizable kappa-epsilon turbulence model and Zwart-Gerber-Belamri (ZGB) cavitation model. The hydrodynamic performance is quantified in terms of coefficient of lift, coefficient of drag, lift to drag ratio, static pressure distribution, and cavity length at various cavitation numbers and angles of attack. From the assessment, it is observed that for 8 degrees angle of attack, the coefficient of drag on NACA4412 hydrofoil with the dimple is less as compared to NACA4412 without dimple. For higher angles of attack (alpha = 12 degrees & 16 degrees) NACA4412 hydrofoil with the dimple has higher coefficient of lift compared to NACA4412 without dimple.
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