Wawan Aries Widodo

Numerical study of aerodynamic analysis on wing airfoil NACA 43018 with the addition of forward and rearward wingtip fence

Winglet is one accessory on airplane wings that can be used to improve wing performance without widen wingspan wings (wingspan of the aircraft). Winglet serves to dampen the vortex flow at the wing tips that caused by the interaction airflow from upper and lower sides of the wing. [1]. This research was conducted numerical by using simulation model of turbulence k-e realizable. Freestream velocity is 40 m/s (Re = 5 × 106) with wing angle of attacks (α) = 0o, 2 o, 4 o, 6 o, 8 o, 10 o,12 o, 15 o and 19 o. The Model is NACA airfoil 43018 with and without winglets. Two types wing are used: wingtip fence with forward and rearward. The results show the addition of winglets minimize vorticity magnitude behind the wing. Besides the addition of winglets can improve the aerodynamic performance of the wing with an increase in CL / CD a maximum of 22.9% on a wingtip fence forward and rearward 17.05% on a wingtip fence on the angle of attack 2o. The pressure distribution on lower surface of the wing increase and distr...

Experimental Study of Drag Reduction on Circular Cylinder and Reduction of Pressure Drop in Narrow Channels by Using a Cylinder Disturbance Body

This paper present the results of drag reduction on circular cylinder and reduction of pressure drop in narrow rectangular channels by using circular disturbance body. This study focused on the phenomenon when the flow through the arrangement of the circular cylinder, separation will occur at a specific point on a circular cylinder resulting drag force. When the separation can be delayed so that the resulting drag force will be smaller. This can be done in various ways, one of which is by using a cylinder disturbance body on the upper and lower side near the bluff body. This study will be conducted in a wind tunnel experiments which have narrow channels with a square cross-sectional area of 125 mm x 125 mm and a blockage ratio of 26.4% and 36.4%. Specimens used circular cylinder with 25 mm diameter (d/D= 0.16) and 37.5 mm (d/D= 0.107) as well as the circular disturbance body with a diameter of 4 mm. cylinder disturbance body placed on the upper and lower side with the position α=200 to 600 and spacing (δ=0.4 mm) to the main circular cylinder. Reynolds number based on the hydraulic diameter of 5.21×104 to 15.6×104. The results of this research show the effect of using circular disturbance body on circular cylinder and the characteristics of fluid flow on a narrow channel square cross section. At a certain position of the circular disturbance body provide value pressure drop reduction on narrow channels and drag reduction when compared to a single circular cylinder. From the experimental data presented in this paper it is observed that the position angle of circular disturbance body to reduce drag force on a circular cylinder and reducing the pressure drop in the channel are at angle 200 and 300 for D=25 mm, and 200, 300 and 400, respectively, for D= 37.5 mm then the best reduction for both cylinders are at an angle of 300.

Flow Characteristics around Four Circular Cylinders in Equispaced Arrangement near a Plane Wall

The flow characteristics around four circular cylinders in equispaced arrangement located near a plane wall were investigated experimentally. The pressure distributions on the each cylinder surface and on the plane wall were measured for a spacing ratio L/D= 1.5 (L, center to center spacing between cylinders; D, diameter) and G/D= 0.2 (G, gap spacing between cylinder surface and the plane wall) in a uniform flow at a Reynolds Number of 5.3 x 104. The 2D U-RANS numerical simulation with k-ω SST as viscous model was used to visualize the flow phenomena occured around the cylinders. The results showed that the flow tend to be biased on the upper side of cylinders configuration. It causes the stagnation at the upstream cylinders occured at lower side of cylinders and results a formation of a narrower wake behind the third cylinder and a wider wake behind the fourth cylinder.Keywords: equispaced arrangement, circular cylinders, plane wall

CFD Based Investigations into Optimization of Diffuser Angle on Rear Bus Body

Fluid flow interaction around bluff body to create aerodynamic forces including drag and lift force. The strategy to improve arodynamic forces to modify the shape of rear body. This investigation is conducted to simulate fluid flow past a bus body with variation of diffuser angle on the rear. The diffuser angle was set to 0°, 6°, 12°, and 18°, respectively. The CFD simulation results shown that diffuser on rear body bus models able to improve the aerodynamic forces and wake structure are correspond with incresing diffuser angle. The drag coefficient was reduced until 2.3% is related with diffuser angle (β) 180, also, diffuser angle (β) 120 capable to increase downforce significantly until ten times are compared with zero diffuser angle.

Numerical study of flow characteristics around wing airfoil Eppler 562 with variations of rearward wingtip fence

To produce lift on the wing of the aircraft, pressure distribution on the upper surface of the wing must be lower than the pressure on the lower of the wing. This can be done by making the air passage on the upper surface is longer than that on the bottom surface, or making the wing’s relative angle to the direction of the incoming stream of air. Air will tend to flow from areas with high pressure to areas with low pressure. The pressure difference between lower surface of the wing higher than the top surface of the wing also results in the occurrence of this airflow. The place that allows for the occurrence of “leakage” of this air is at the tip of the wing. The flow from lower surface to the upper upper surface of the wings produces a vortex flow similar to a small tornado known as wingtip vortices. This whirl causes the air tend to flow downward on the wing area, and referred to as the term downwash. One modification on the aircraft wing to reduce the impact of the vortex tip is the use of the winglet on the tip of the aircraft wing. This has been widely applied to the latest commercial aircraft to improve the efficiency of the aircraft. The numerical study was done using CFD software with 3D geometry configuration. The geometry of the specimen is airplane wing Eppler 562 with chord length of 0.036 m, swept angle 0° and modification of winglet type rearward wingtip fence winglet with cant angle of 75°. The airflow with velocity at the inlet of 10 m/s. The turbulent modeling is k-ω SST. Present study uses hybrid mesh with boundary layer mesh method. From the simulation results it is shown that there is an increase in lift coefficient (CL) and an increase in drag coefficient (CD) along with the increase of angle of attack. In rearward wingtip fence with cant angle 0° produce CL/CD better than cant angle 75° and plain wing. Rearward wingtip fence shows optimum performance of α = 8° settings compared to plain wing.To produce lift on the wing of the aircraft, pressure distribution on the upper surface of the wing must be lower than the pressure on the lower of the wing. This can be done by making the air passage on the upper surface is longer than that on the bottom surface, or making the wing’s relative angle to the direction of the incoming stream of air. Air will tend to flow from areas with high pressure to areas with low pressure. The pressure difference between lower surface of the wing higher than the top surface of the wing also results in the occurrence of this airflow. The place that allows for the occurrence of “leakage” of this air is at the tip of the wing. The flow from lower surface to the upper upper surface of the wings produces a vortex flow similar to a small tornado known as wingtip vortices. This whirl causes the air tend to flow downward on the wing area, and referred to as the term downwash. One modification on the aircraft wing to reduce the impact of the vortex tip is the use of the winglet ...

The effect of width of single curtain on the performance of Savonius wind turbine

This is a preliminary results of the flow around the Savonius wind turbine with installing curtain plate in front of the returning blade turbine. It was investigated numerically in a uniform flow at Reynolds number of 30,000 and 90,000. The velocity vector and pressure distribution around the turbine were simulate by varying the width of curtain plate relative to the diameter of rotor blade (S/D) of = 1.00, 1.02, 1.03, 1.15, 1.41, and 2.00, using STAR CCM++ Software. The k- realizable as turbulence model was used to visualize the flow phenomena occurred around the turbine, and where in this simulation, the rotor turbine was set static. The results show that it seems the width of the curtain installed in front of the returning blade of the turbine plays an important role in the performance of the turbine. In general, the installing of the curtain in front of the returning blade of the turbine is more effective to improve the turbine performance. This is not necessarily, but depends on the width of the curtain and the number of Reynolds (Re). For the width of the large curtain of S/D = 2 at Re = 90,000, the performance of the turbine is estimated lower than when the turbine without

Drag reduction analysis of wing airfoil E562 with forward wingtip fence at cant angle variations of 75° and 90°

Airfoil modeling is very important especially in determining the airfoil’s performance. One very important in the airfoil design is how to make airfoil with high lift and low drag to obtain a large...

Studi Numerik Karakteristik Aliran Melalui Backward Facing Inclinesd Step dengan Penambahan Paparan Panas dari Gedung pada Sisi Upstream

Studi ini bertujuan untuk melihat karakteristik aliran fluida yang melalui backward facing inclined step dengan penambahan paparan panas dari high rise building pada sisi upstream. Peninjauan dilakukan dengan menggunakan perangkat lunak CFD (Computational Fluid Dynamic). Pemodelan ini menggunakan aliran steady flow, incompressible flow, dan uniformflow pada sisi inlet. Simulasi ini menggunakan model turbulen k-ω SST dengan kecepatan angin pada inlet 3 m/s dan 9 m/s (Re=2×10⁴ dan Re=6×10⁴). Meshing menggunakan Hexa-hedral dengan jumlah node 2,5×10⁶. Variasi inclined step 30⁰, 45⁰, dan 90⁰. Kecepatan fluida panas dari gedung yaitu 1,5 m/s dengan temperatur 64⁰ C. Angin lingkungan memiliki temperatur 27⁰ C. Hasil yang didapatkan dari penelitian ini adalah variasi sudut inclined step mempengaruhi kecepatan fluida, panjang reattachment, dan luas wilayah yang mengalami kenaikan temperatur. Perbandingan kontur kecepatan memperlihatkan luas area backflow paling sempit berada pada inclined step 30⁰. Pada pathline tiap variasi inclined step diketahui bahwa reattachment paling pendek berada pada model dengan sudut inclined step 30⁰. Berdasarkan kontur pada posisi y/h=0,5 dan y/h=1 pada daerah downstream, persebaran temperatur paling sempit ada pada domain dengan sudut inclined step 30⁰. Selain itu variasi bilangan Reynolds juga berpengaruh terhadap persebaran temperatur. Semakin tinggi nilai bilangan Reynolds maka semakin kecil kenaikan temperatur lingkungan yang terjadi.

Analysis of Turbulence Characteristics in the Laminar Sub-Layer Region of a Perturbed Turbulent Boundary Layer

Turbulent boundary layer plays an important role for generation of aerodynamic drag. Shear force and pressure force due to the presence of boundary layer separation from the body surface contribute to the total drag. Studies of drag reduction due the the boundary layer effect are continuously performed by many researchers. Present study is intended to evaluate the behaviour of the laminar sub-layer in a turbulent boundary layer using a hot-wire anemometer system. The study was conducted in a low-speed wind tunnel at a Reynolds number based on the momentum thickness of approximately Reθ = 1000. A smooth-flat plate and a plate with a single transverse square groove was used in the study of the boundary layer characteristics. The groove size of 10 mm x 10 mm was cut transversally across the test plate. The results show that no significant differences in the streamwise mean velocity, steamwise turbulence intensity, and velocity signals for the smooth-and grooved-wall cases. For the the energy spectra for the two cases, however, show significant differences.

Reduction of Drag Force on a Circular Cylinder and Pressure Drop Using a Square Cylinder as Disturbance Body in a Narrow Channel

Many studies related with characteristics of fluid flow acrossing in a bluff body have been conducted. The aim of this research paper was to reduce pressure drop occuring in narrow channels, in which there was a circular cylindrical configuration with square cylinder as disturbance body. Another goal of this research was to reduce the drag force occuring in circular cylinder. Experimentally research of flow characteristics of the wind tunnel had a narrow channel a square cross-section, with implemenred of Reynolds number based on the hydraulic diameter from 5.21x104 to 1.56x105. Wind tunnel that was used had a 125x125mm cross-sectional area and the blockage ratio 26.4% and 36.4%. Specimen was in the form of circular cylinder and square cylinder as disturbance body. Variation of angle position was the inlet disturbance body with α = 200, 300, 400, 500 and 600, respectively. The results was obtained from this study was Reynolds Number value was directly linear with pressure drop there, it was marked by increasing of Reynolds number, the value was also increasing pressure drop. Additional information was obtained by adding inlet disturbance body shaped of square cylinder on the upstream side of the circular cylinder that could reduce pressure drop in the duct and reduce drag happening on a circular cylinder. The position of the optimum angle to reduce pressure drop and drag force was found on the inlet disturbance body with angle α = 300.