Numerical Study on Flap Style Rudder Hydrodynamic Characteristics With Different Connections

2016 ◽  
Author(s):  
Zhenwei Dong ◽  
Zhijian Xiao ◽  
Shiqi Gong ◽  
Zhiguo Zhang ◽  
Dakui Feng
Keyword(s):  
Numerical Study ◽  
Angle Of Attack ◽  
Large Angle ◽  
Hydrodynamic Characteristics ◽  
Computation Method ◽  
Suction Surface ◽  
Drag Coefficients ◽  
Flow Field Characteristics ◽  
The Difference ◽  
Lift And Drag

The flow field characteristics of 2-D flap style rudders with and without gap are analyzed through 4 models. To explore the influence of different filling styles, one flap rudder with gap and three flap rudders without gap are simulated from 0 to 30 degrees angle of attack with k-omega SST turbulence model. Validation is done by comparing the results with EFD data from reference and the mesh independence verification is also made. Then lift and drag coefficients are compared among four models. Pressure, velocity distributions are given to explain the difference on hydrodynamic characteristics among them. Unsteady computation method is used to investigate the fluctuation characteristics of drag coefficients at large angle of attack. Stream lines are shown to better understand the vortex system on the suction surface.

Numerical Study on Thrust Generation Performance of Plunging Airfoils

2013 ◽  
Vol 312 ◽  
pp. 235-238
Author(s):  
Ji Gao ◽  
Rui Shan Yuan ◽  
Ming Hui Zhang ◽  
Yong Hui Xie
Keyword(s):  
Viscous Flow ◽  
Numerical Study ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Thrust Coefficient ◽  
Propulsive Efficiency ◽  
Propulsion Performance ◽  
Incompressible Viscous Flow ◽  
Thrust Generation ◽  
The Difference

In this paper, the effects of angle of attack, camber and camber location on propulsion performance of flapping airfoils undergoing plunging motion were numerically studied at Re=20000 and h=0.175. The unsteady incompressible viscous flow around four different airfoil sections was simulated applying the dynamic mesh. The results show that the time averaged thrust coefficient CTmean and propulsive efficiency η of the symmetric airfoil decrease with the increasing angle of attack, and the variation of CTmean is more obvious than that of CPmean. Both CTmean and η for NACA airfoils studied in this paper decrease with the increasing camber and the difference between the propulsion performances of different airfoils is not obvious, and the thrust generation and power of various NACA airfoils gradually increase during the downstroke and decrease during the upstroke. Under the same conditions, the airfoil with a further distance between the maximum camber location and the chord of the leading edge leads to higher propulsive efficiency.

scholarly journals An Experimental Analysis on the Effects of Stagger on the Aerodynamic Forces of Tandem Wings

AVIA ◽  
2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Y Parlindungan ◽  
S Tobing
Keyword(s):  
Experimental Analysis ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Performance ◽  
Open Loop ◽  
Aerodynamic Forces ◽  
Subsonic Wind Tunnel ◽  
Lift And Drag ◽  
Naca 0012

This study is inspired by the flapping motion of natural flyers: insects. Many insects have two pairs of wings referred as tandem wings. Literature review indicates that the effects of tandem wing are influenced by parameters such as stagger (the stream-wise distance between the aerodynamic center of the front and the rear airfoil), angle-of-attack and flow velocity. As a first stage, this study focuses on the effects of stagger (St) on the aerodynamic performance of tandem wings. A recent numerical study of stagger on tandem airfoils in turbulent flow (Re = 6000000) concluded that a larger stagger resulted in a decrease in lift force, and an increase in drag force. However, for laminar flow (Re = 2000), increasing the stagger was not found to be detrimental for aerodynamic performance. Another work also revealed that the maximum lift coefficient for a tandem configuration decreased with increasing stagger. The focus of this study is to perform an experimental analysis of tandem two-dimensional (2D) NACA 0012 airfoils. The two airfoils are set at the same angle-of-attack of 0° to 15° with 5° interval and three variations of stagger: 1c, 1.5c and 2c. The experiments are conducted using an open-loop-subsonic wind tunnel at a Reynolds number of 170000. The effects of St on the aerodynamic forces (lift and drag) are analyzed

scholarly journals Analysis on Flow Field Characteristics of Airfoil in Pitching Motion

2021 ◽  
Vol 2076 (1) ◽  
pp. 012069
Author(s):  
Rui Yin ◽  
Jing Huang ◽  
Zhi-Yuan He
Keyword(s):  
Flow Field ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Decisive Role ◽  
Aerodynamic Characteristics ◽  
Pitching Motion ◽  
Maximum Value ◽  
Flow Field Characteristics ◽  
Lift And Drag

Abstract Based on CFD, the flow field characteristics of NACA4412 airfoil are analyzed under pitching motion, and its aerodynamic characteristics are interpreted. The results show that streamline changes on the upper surface of the airfoil play a decisive role in the aerodynamic characteristics. The interaction between the vortex leads to fluctuations in the lift and drag coefficients. Under a big angle of attack, the secondary trailing vortex on the upper surface of the airfoil adheres to the trailing edge of the airfoil, resulting in an increased drag coefficient. Under a small angle of attack, the secondary trailing vortex can break away from the airfoil. The lift coefficient reaches the maximum value of 2.961 before the airfoil is turned upside down, and the drag coefficient reaches the maximum value of 1.515 after the airfoil is turned upside down, but the corresponding angles of attack of the two are equal.

A Numerical Study of Flow Around Different Hydrofoil Systems In Presence of the Free Surface

2021 ◽  
Author(s):  
Nutan Kumari ◽  
Arnab Chakraborty
Keyword(s):  
Free Surface ◽  
High Speed ◽  
Stokes Equations ◽  
Numerical Study ◽  
Turbine Blades ◽  
Essential Element ◽  
Vital Role ◽  
Hydrodynamic Characteristics ◽  
Tidal Turbine ◽  
Lift And Drag

Abstract The hydrofoils are essential element in tidal current turbine and in high speed marine crafts. Hence, the study of hydrodynamic characteristics of hydrofoils are important as they play a vital role in improving the performance of these propulsion devices (hydro-kinetic turbine, marine craft). In the present study, the dynamics of unsteady and viscous flow around a two hydrofoil system is investigated for two different configuration: (a) tandem, and in (b) stagger arrangement. The incompressible Navier-Stokes equations were solved using Finite Volume Solver in STAR-CCM+ commercial software package. k-ε turbulence model is incorporated in the present simulation in order to explain the turbulence flow physics while the free surface is captured using Volume of Fluid (VOF) technique. Further, the obtained numerical simulation results were compared with experimental data available in the literature as a validation purpose. The objective of the present study is to investigate the effects of spacing distance on the lift and drag coefficient generated by two foil system in tandem and stagger arrangements which is one of the important design parameter for a tidal turbine blades in presence of free sea surface. It could be observed that the hydrofoils are arranged in tandem configuration, the lift coefficients of the upstream and downstream hydrofoils are higher in comparison to single hydrofoil. Interference effect didn’t die out even at large spacing for 2-D hydrofoil.

Peak and Post-Peak Power Aerodynamics from Phase VI NASA Ames Wind Turbine Data

2005 ◽  
Vol 127 (2) ◽  
pp. 192-199 ◽  
Author(s):  
Brandon S. Gerber ◽  
James L. Tangler ◽  
Earl P. N. Duque ◽  
J. David Kocurek
Keyword(s):  
Performance Prediction ◽  
Peak Power ◽  
Tangential Force ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Drag Coefficients ◽  
Force Coefficients ◽  
Lift And Drag ◽  
Blade Element

Constant speed/pitch rotor operation lacks adequate theory for predicting peak and post-peak power. The objective of this study was to identify and quantify how measured blade element performance characteristics from the Phase VI NASA Ames 24m×36m80ft×120ft wind tunnel test of a two-bladed, tapered, twisted rotor relate to the prediction of peak and post-peak rotor power. The performance prediction code, NREL’s Lifting Surface Prescribed Wake code (LSWT), was used to study the flow physics along the blade. Airfoil lift and drag coefficients along the blade were derived using the predicted angle of attack distribution from LSWT and Phase VI measured normal and tangential force coefficients. Through successive iterations, the local lift and drag coefficients were modified until agreement was achieved between the predicted and Phase VI measured normal and tangential force coefficients along the blade. This agreement corresponded to an LSWT angle of attack distribution and modified airfoil data table that reflected the measured three-dimensional aerodynamics. This effort identified five aerodynamic events important to the prediction of peak and post-peak power. The most intriguing event was a rapid increase in drag that corresponds with the occurrence of peak power. This is not currently modeled in engineering performance prediction methods.

scholarly journals Numerical Study of the Effect of Wing Position on Autonomous Underwater Glider

2020 ◽  
Vol 70 (2) ◽  
pp. 214-220
Author(s):  
R.V. Shashank Shankar ◽  
Rajagopalan Vijayakumar
Keyword(s):  
Numerical Study ◽  
Reynolds Numbers ◽  
Hydrodynamic Characteristics ◽  
Underwater Glider ◽  
Low Reynolds Numbers ◽  
Underwater Gliders ◽  
Turning Motion ◽  
Computational Fluid Dynamics Cfd ◽  
Lift And Drag ◽  
Autonomous Underwater Glider

 Autonomous underwater gliders are a class of underwater vehicles that transit without the help of a conventional propeller. The vehicle uses a buoyancy engine to vary its buoyancy and with the help of the wings attached executes its motion. The hydrodynamic characteristics of the vehicle affect the longitudinal and turning motion. This paper discusses the effect of the wing’s position on the vehicle’s lift and drag characteristics. Computational fluid dynamics (CFD) tool is used to estimate the lift, drag, and pitching moment coefficients of the vehicle. The numerical methodology is validated using flow over NACA0012 wing results for low Reynolds numbers, and the results of CFD are discussed for possible application in estimation of glider motion.

Numerical Analysis of NACA Aerofoil Using Synthetic Jet

2017 ◽  
Author(s):  
Mayuresh Neve ◽  
V. R. Kalamkar ◽  
Akshay Wagh
Keyword(s):  
Flow Separation ◽  
Angle Of Attack ◽  
Synthetic Jet ◽  
Chord Length ◽  
Suction Surface ◽  
Maximum Increase ◽  
Jet Velocity ◽  
Lift And Drag ◽  
Parametric Analyses ◽  
Naca 0015

Usually at high angle of attack, aerofoil stalls due to flow separation on suction surface of aerofoil. To delay the flow separation, pulsating jet arrangement, known as Synthetic jet is used in aerofoil. It is produced by periodic suction and ejection of fluid from an orifice. This condition can be achieved by inducing movement to diaphragm or by giving a zero mass flux sinusoidal boundary condition to the jet. This allows the reattachment of boundary layer which improves the lift and drag performance and angle at also delays stalling angle. In present study, CFD analysis on NACA0015 aerofoil is performed for different angles of attack and the Co-efficients of Drag (Cd) and Lift (C1) are validated with the experimental results of Gilarranz et al. [1]. The flow is simulated by solving Unsteady RANS coupled with k-ε realizable turbulence model with enhanced wall treatment. Synthetic jet is placed in NACA0015 airfoil at 12% of the chord length with width as 0.53% of chord and is studied for a Reynolds number Re = 8.96 × 105 and for angle of attack from 12 to 20 degrees [2]. The jet is almost tangential to the wall at an angle, αjet = 10° and chord length is considered as 0.375m for the study. Further, parametric analyses are conducted on NACA 0015 aerofoil to investigate effect of parameters (frequency, jet angle, jet velocity). It is observed that aerofoil’s performance is improved significantly for jet angle (30°–40°), jet frequency (100 Hz) and non dimensional jet velocity (1.8–2.0). A maximum increase of approximately 26% in Lift was observed at AOA 20°.

scholarly journals Effects of Pitching Motion Elements on Aerodynamic Characteristics of Airfoil

2021 ◽  
Vol 2076 (1) ◽  
pp. 012078
Author(s):  
Rui Yin ◽  
Jing Huang ◽  
Zhi-Yuan He
Keyword(s):  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Initial Angle ◽  
Pitching Motion ◽  
The Difference ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract The aerodynamic characteristics of NACA4412 airfoil with different pitching motion elements were compared and analyzed based on CFD in this research. The results are acquired as follows: the difference between the lift and drag coefficients of the airfoil during pitch up and pitch down motions becomes larger with the increase of the pitching amplitude or initial angle of attack; as the pitching amplitude increases, the lift coefficient grows slightly greater and the drag coefficient grows much greater; as the initial angle of attack increases, the lift coefficient grows much greater and the drag coefficient grows slightly; the smaller the attenuation frequency is, the larger the lift-to-drag ratio of the airfoil will be.

Relations of Lift and Drag Coefficients of Flow around Flat Plate

2014 ◽  
Vol 518 ◽  
pp. 161-164 ◽  
Author(s):  
Hai Bo Jiang ◽  
Yan Ru Li ◽  
Zhong Qing Cheng
Keyword(s):  
Flat Plate ◽  
Small Angle ◽  
Total Pressure ◽  
Angle Of Attack ◽  
Vertical Component ◽  
Horizontal Component ◽  
High Angle ◽  
High Angle Of Attack ◽  
Drag Coefficients ◽  
Lift And Drag

In this paper, when Reynolds number is within the range of 10000 to 1000000, the horizontal component of the total pressure of flow around flat plate at high angle of attack was regarded as lift of high angle of attack, and the vertical component was regarded as drag of high angle of attack. The horizontal component of total pressure at small angle of attack was regarded as shape drag, and the total drag coefficient at small angle of attack was considered to the sum of the shape drag and frictional drag at zero angle of attack. For the two states of large and small angle of attack, the application scopes of the formulas of lift and drag coefficients were given. Final, the relations of lift and drag coefficients were obtained by eliminating all angles of attack. Research results show that lift - drag curve of small angles of attack is parabola, and the lift - drag curve of high angles of attack is circle.

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