scholarly journals Time-Dependent Effects of Glaze Ice on the Aerodynamic Characteristics of an Airfoil

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Narges Tabatabaei ◽  
Michel J. Cervantes ◽  
Chirag Trivedi
Keyword(s):  
Strouhal Number ◽  
Fluid Dynamic ◽  
Low Frequency ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Time Dependent ◽  
Frequency Mode ◽  
Flat Plates ◽  
Computational Fluid Dynamic Analysis ◽  
Pressure Profiles

The main objective of this study is to estimate the dynamic loads acting over a glaze-iced airfoil. This work studies the performance of unsteady Reynolds-averaged Navier-Stokes (URANS) simulations in predicting the oscillations over an iced airfoil. The structure and size of time-averaged vortices are compared to measurements. Furthermore, the accuracy of a two-equation eddy viscosity turbulence model, the shear stress transport (SST) model, is investigated in the case of the dynamic load analysis over a glaze-iced airfoil. The computational fluid dynamic analysis was conducted to investigate the effect of critical ice accretions on a 0.610 m chord NACA 0011 airfoil. Leading edge glaze ice accretion was simulated with flat plates (spoiler-ice) extending along the span of the blade. Aerodynamic performance coefficients and pressure profiles were calculated and validated for the Reynolds number of 1.83 × 106. Furthermore, turbulent separation bubbles were studied. The numerical results confirm both time-dependent phenomena observed in previous similar measurements: (1) low-frequency mode, with a Strouhal number Sth≈0,013–0.02, and (2) higher frequency mode with a Strouhal number StL≈0,059–0.69. The higher frequency motion has the same characteristics as the shedding mode and the lower frequency motion has the flapping mode characteristics.

scholarly journals Analisis karakteristik aerodinamika telescopic wing dengan konfigurasi sayap flying wing dan glider menggunakan metode pendekatan simulasi CFD

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Azhim Asyratul Azmi ◽  
Satriawan Dini Hariyanto ◽  
Arif Hidayat
Keyword(s):  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Morphing Wing ◽  
Aircraft Wing ◽  
High Lift ◽  
Tip Vortices ◽  
Wing Tip

A telescopic wing is a shape-changing method of the aircraft wing known as the morphing wing system. Wingspan extends capability on telescopic wing increasing the aspect ratio to get a high lift force. The telescopic wing on a flying wing configuration as an external wing and glider wing as an internal wing can be used to increase the coefficient lift (CL) when carrying out special missions. The aerodynamic characteristics using the Computational Fluid Dynamic (CFD) simulation approach is presented. For the 40% internal wingspan, the highest CL increment was 12.9% at a 10o angle of attack. For the 50% internal wingspan, the highest CL increment was 14.9% at a 10o angle of attack. on the 40% internal wing, the highest coefficient drag (CD) increment was 4.7%, and the largest CD increment on 50% internal was 9.5% at the angle of attack of 20o. The pressure distribution along the internal wingspan was uneven from an angle of attack of 15o due to the wing tip vortices of the external wing. Streamline pattern shown a bubble separation from the leading edge at an internal wing root by external wing tip vortices.Keywords: Morphing wing, telescopic wing, flying wing, glider

scholarly journals Computational Fluid Dynamic Analysis of Vortex Generators on MAV.

2022 ◽  
pp. 58-73
Author(s):  
Vadla Raghavender ◽  
Priyanka Vatte ◽  
V Varun ◽  
M. Pala. Prasad Reddy
Keyword(s):  
Reynolds Number ◽  
Fluid Dynamic ◽  
Low Reynolds Number ◽  
Leading Edge ◽  
Vortex Generators ◽  
Computational Fluid Dynamic Analysis ◽  
Aerial Vehicle ◽  
Low Reynolds ◽  
Low Reynolds Number Airfoil ◽  
And Control

Micro Vortex generators are very small components deployed on the wings to control airflow over the upper surface of the wing to affect the boundary layer over it. These are employed onto a Micro aerial vehicle (MAV) of fixed wing type with an S5010 which is a low Reynolds number airfoil. This airfoil provides good aerodynamic results as compared to many low Reynolds number airfoils. Micro vortex generators are used to enhance the performance through controlling airflow at different speeds and angle of attack. The comparison of a half part of the MAV wing which is designed in CATIA, with and without the vortex generators on its leading edge at 10% of its chord length is done to show how the vortex generators improve the performance and control authority at different speeds and angle of attacks. These are shown with the velocity and pressure distribution around the wing by considering laminar flow in the simulation.

Wind Tunnel Test of Effect of Sound-Absorbing Material on Lift of Two-Element Airfoil

2013 ◽  
Vol 830 ◽  
pp. 17-23
Author(s):  
Yong Wei Gao ◽  
Qi Liang Zhu ◽  
Long Wang
Keyword(s):  
Wind Tunnel ◽  
High Frequency ◽  
Lift Coefficient ◽  
Wind Tunnel Test ◽  
Low Frequency ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Fluctuating Pressure ◽  
Flow Parameters ◽  
Absorbing Material

The flow parameters of fluctuating pressure and fluctuating velocity in the gap can be changed by the porous absorption material on the leading edge of upper surface of the flap of multi-element airfoil (GAW-1),and the aerodynamic characteristics is also altered. Experiment was conducted in the NF-3 wind tunnel. It turns out that porous absorption material has a significant effect on fluctuating velocity (i.e. turbulent kinetic energy), and the lift coefficient drops when fluctuating velocity increases ; but the influence on RMS of fluctuating pressure on upper surface is not obvious; the average speed in gap is reduced. The PSD of fluctuating pressure and fluctuating velocity show that low-frequency signal has a more obvious influence on lift of multi-element airfoils than high-frequency.

Computational Fluid Dynamic Analysis of the Flow Around a Propeller Blade of Multirotor Unmanned Aerodynamic Vehicle

2021 ◽  
Author(s):  
Victor H. Martinez ◽  
Kiran Bhaganagar
Keyword(s):  
Fluid Dynamic ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Power Coefficient ◽  
Navier Stokes ◽  
Propeller Blade ◽  
Computational Fluid Dynamic Analysis ◽  
Thrust Coefficient ◽  
Emergency Rescue ◽  
Propeller Blades

Abstract Multirotor Unmanned Aerodynamic Vehicles (MUAV) have been a high interest topic in the aerodynamic community for its many applications, such as, logistics, emergency rescue, agriculture data collection, and environmental sensing to name a few. MUAV propeller blades create a highly complex turbulent fluid flow around the body and the environment around it. The flow physics generated from the rotation of the propeller blades were studied in this paper along with the analysis of aerodynamic characteristics. A Reynolds Average Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) analysis of a propellor blade from a MUAV has been performed to quantify the aerodynamic effects. For this purpose, the verification and validation of the commercially available CFD solver COMSOL Multiphysics v5.5 was performed using the NACA 0012 airfoil which is one of the most highly studied of the NACA family. With this validation it created confidence on the results for simulating a MUAV propeller and evaluate the aerodynamic characteristics of thrust coefficient (KT), power coefficient (KP), and Efficiency (η). These characteristics were compared against experimental data and results showed to have a similar trend. This showed that the CFD solver is capable of solving the aerodynamic characteristics of any propeller blade geometry.

Aerodynamic characteristics of dragonfly wing sections compared with technical aerofoils

2000 ◽  
Vol 203 (20) ◽  
pp. 3125-3135 ◽  
Author(s):  
A.B. Kesel
Keyword(s):  
Negative Pressure ◽  
Leading Edge ◽  
Longitudinal Axis ◽  
Aerodynamic Characteristics ◽  
Force Balance ◽  
Flat Plates ◽  
Cross Sectional ◽  
Drag Coefficients ◽  
Balance System ◽  
Lift And Drag

During gliding, dragonfly wings can be interpreted as acting as ultra-light aerofoils which, for static reasons, have a well-defined cross-sectional corrugation. This corrugation forms profile valleys in which rotating vortices develop. The cross-sectional configuration varies greatly along the longitudinal axis of the wing. This produces different local aerodynamic characteristics. Analyses of the C(L)/C(D) characteristics, where C(L) and C(D) are the lift and drag coefficients, respectively (at Reynolds numbers Re of 7880 and 10 000), using a force balance system, have shown that all cross-sectional geometries have very low drag coefficients (C(D, min)<0.06) closely resembling those of flat plates. However, the wing profiles, depending upon their position along the span length, attain much higher lift values than flat plates. The orientation of the leading edge does not play an important role. The detectable lift forces can be compared with those of technical wing profiles for low Re numbers. Pressure measurements (at Re=9300) show that, because of rotating vortices along the chord length, not only is the effective profile form changed, but the pressure relationship on the profile is also changed. Irrespective of the side of the profile, negative pressure is produced in the profile valleys, and net negative pressure on the upper side of the profile is reached only at angles of attack greater than 0 degrees. These results demonstrate the importance of careful geometrical synchronisation as an answer to the static and aerodynamic demands placed upon the ultra-light aerofoils of a dragonfly.

Noise source location and scaling of subsonic upper-surface blowing

2020 ◽  
Vol 19 (3-5) ◽  
pp. 191-206
Author(s):  
Trae L Jennette ◽  
Krish K Ahuja
Keyword(s):  
Strouhal Number ◽  
Noise Source ◽  
Low Frequency ◽  
Directivity Pattern ◽  
Source Location ◽  
Dipole Source ◽  
Frequency Noise ◽  
Noise Sources ◽  
Trailing Edge ◽  
Trailing Edge Noise

This paper deals with the topic of upper surface blowing noise. Using a model-scale rectangular nozzle of an aspect ratio of 10 and a sharp trailing edge, detailed noise contours were acquired with and without a subsonic jet blowing over a flat surface to determine the noise source location as a function of frequency. Additionally, velocity scaling of the upper surface blowing noise was carried out. It was found that the upper surface blowing increases the noise significantly. This is a result of both the trailing edge noise and turbulence downstream of the trailing edge, referred to as wake noise in the paper. It was found that low-frequency noise with a peak Strouhal number of 0.02 originates from the trailing edge whereas the high-frequency noise with the peak in the vicinity of Strouhal number of 0.2 originates near the nozzle exit. Low frequency (low Strouhal number) follows a velocity scaling corresponding to a dipole source where as the high Strouhal numbers as quadrupole sources. The culmination of these two effects is a cardioid-shaped directivity pattern. On the shielded side, the most dominant noise sources were at the trailing edge and in the near wake. The trailing edge mounting geometry also created anomalous acoustic diffraction indicating that not only is the geometry of the edge itself important, but also all geometry near the trailing edge.

Sign in / Sign up

Export Citation Format

Share Document