CFD investigation on the maximum lift coefficient degradation of rough airfoils

Abstract The two-dimensional flow around a stationary heated circular cylinder at low Reynolds numbers of 50 < Re < 210 is investigated numerically using the FLUENT commercial software package. The dimensionless vortex shedding frequency (St) reduces with increasing temperature at a given Reynolds number. The effective temperature concept was used and St-Re data were successfully transformed to the St-Reeff curve. Comparisons include root-mean-square values of the lift coefficient and Nusselt number. The results agree well with available data in the literature.

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Simulation of Unsteady Flow Around a Cylinder

Wasit Journal of Engineering Sciences ◽

10.31185/ejuow.vol3.iss2.38 ◽

2015 ◽

Vol 3 (2) ◽

pp. 28-49

Author(s):

Ridha Alwan Ahmed

Keyword(s):

Stokes Equations ◽

Lift Coefficient ◽

Reynolds Numbers ◽

Mean Value ◽

Navier Stokes ◽

Cylinder Surface ◽

Navier Stokes Equations ◽

Flow Around A Cylinder ◽

Numerical Grid ◽

Good Agreement

In this paper, the phenomena of vortex shedding from the circular cylinder surface has been studied at several Reynolds Numbers (40≤Re≤ 300).The 2D, unsteady, incompressible, Laminar flow, continuity and Navier Stokes equations have been solved numerically by using CFD Package FLUENT. In this package PISO algorithm is used in the pressure-velocity coupling. The numerical grid is generated by using Gambit program. The velocity and pressure fields are obtained upstream and downstream of the cylinder at each time and it is also calculated the mean value of drag coefficient and value of lift coefficient .The results showed that the flow is strongly unsteady and unsymmetrical at Re>60. The results have been compared with the available experiments and a good agreement has been found between them

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CFD study of aerodynamic performance of non-pneumatic tyre with hexagonal spokes

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/09544070211013124 ◽

2021 ◽

pp. 095440702110131

Author(s):

Daksh Bhatia ◽

Praneeth KR ◽

Babu Rao Ponangi ◽

Meghana Athadkar ◽

Carine V Dsouza

Keyword(s):

Comparative Study ◽

Lift Coefficient ◽

Aerodynamic Performance ◽

Practical Implementation ◽

Air Velocity ◽

Aerodynamic Forces ◽

Steering Angle ◽

Camber Angle ◽

Drag And Lift ◽

Yaw Angle

Non-pneumatic tyres (NPT) provide a greater advantage over the pneumatic type owing to their construct which increases the reliability of the tyre operation and effectively reduces maintenance involved. Analysing the aerodynamic forces acting on a NPT becomes a crucial factor in understanding it’s suitability for practical implementation. In the present work, the aerodynamic performance of a NPT using CFD tool – SimScale® is studied. This work includes a comparative study of a pneumatic tyre, a NPT with wedge spokes and a NPT with hexagonal spokes (NPT-HS). The effect of air velocity, steering (yaw) angle and camber angle on the aerodynamic performance of the NPT-HS is evaluated using CFD. By increasing the steering angle from 0° to 15°, the lift coefficient decreases by 37% approximately at all velocities. Whereas drag coefficient initially decreases by 21% till 7.5° steering angle and then starts increasing. Increasing camber angle from 0° to 1.5°, both drag and lift coefficients goes on decreasing by approximately 7% and 27% respectively.

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Design and simulation research of the double-spin folding mechanism based on a suspended missile

The Journal of Defense Modeling and Simulation Applications Methodology Technology ◽

10.1177/15485129211023169 ◽

2021 ◽

pp. 154851292110231

Author(s):

ZH Yuan ◽

SY Guo ◽

SN Zhang ◽

JQ Zhao ◽

WJ Lu ◽

...

Keyword(s):

High Reliability ◽

Lift Coefficient ◽

Great Influence ◽

Reference Value ◽

Aerodynamic Characteristics ◽

Simulation Software ◽

Fluid Simulation ◽

Simulation Research ◽

Double Spin ◽

Locking Mechanism

Based on the suspension of a missile using folding rotary wings and airbags, in order to improve the basic parameters and motion characteristics of the rotor during the unfolding process and analyze the aerodynamic characteristics of the entire device in the suspension state, after proposing a scheme of double-spin mechanism, the main folding and unfolding mechanism, initial driving device, rotating driving device, and locking mechanism were designed, and the simulation research is studied by the Automatic Dynamic Analysis of Mechanical System and Ansys Fluent Fluid Simulation software, respectively. The results show that the rotation rate was controlled at 41.8 mm/s, the various motion parameters are reasonable, and the operation process is relatively smooth, with high reliability. The speed and pressure value at the tip of the rotor are higher and the aerodynamic disturbance is obvious, which has a great influence on the aerodynamic performance. The speed and pressure distribution of the surrounding flow field is stable, the lift provided is 46 N, and the lift coefficient is 0.55, which can ensure the long-time suspension state of the missile. This paper puts forward a valuable design idea and has practical reference value for the research of the suspended missile.

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Unsteady Simulation of Transonic Buffet of a Supercritical Airfoil with Shock Control Bump

Aerospace ◽

10.3390/aerospace8080203 ◽

2021 ◽

Vol 8 (8) ◽

pp. 203

Author(s):

Yufei Zhang ◽

Pu Yang ◽

Runze Li ◽

Haixin Chen

Keyword(s):

Lift Coefficient ◽

Pressure Coefficient ◽

Flow Characteristics ◽

Control Effect ◽

Shock Control Bump ◽

Shock Control ◽

Eddy Simulation ◽

Large Eddy ◽

Unsteady Simulation ◽

Drag Ratio

The unsteady flow characteristics of a supercritical OAT15A airfoil with a shock control bump were numerically studied by a wall-modeled large eddy simulation. The numerical method was first validated by the buffet and nonbuffet cases of the baseline OAT15A airfoil. Both the pressure coefficient and velocity fluctuation coincided well with the experimental data. Then, four different shock control bumps were numerically tested. A bump of height h/c = 0.008 and location xB/c = 0.55 demonstrated a good buffet control effect. The lift-to-drag ratio of the buffet case was increased by 5.9%, and the root mean square of the lift coefficient fluctuation was decreased by 67.6%. Detailed time-averaged flow quantities and instantaneous flow fields were analyzed to demonstrate the flow phenomenon of the shock control bumps. The results demonstrate that an appropriate “λ” shockwave pattern caused by the bump is important for the flow control effect.

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Computational fluid dynamics of rectangular external loop airlift reactor

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0009 ◽

2020 ◽

Vol 18 (5-6) ◽

Author(s):

Shivanand M. Teli ◽

Channamallikarjun S. Mathpati

Keyword(s):

Large Scale ◽

Lift Coefficient ◽

Volume Ratio ◽

Reynolds Stress Model ◽

Airlift Reactor ◽

Experimental Results ◽

Turbulent Dispersion ◽

Drag Forces ◽

External Loop ◽

Turbulent Models

AbstractThe novel design of a rectangular external loop airlift reactor is at present the most used large-scale reactor for microalgae culture. It has a unique future for a large surface to volume ratio for exposure of light radiation for photosynthesis reaction. The 3D simulations have been performed in rectangular EL-ALR. The Eulerian–Eulerian approach has been used with a dispersed gas phase for different turbulent models. The performance and applicability of different turbulent model’s i.e., K-epsilon standard, K-epsilon realizable, K-omega, and Reynolds stress model are used and compared with experimental results. All drag forces and non-drag forces (turbulent dispersion, virtual mass, and lift coefficient) are included in the model. The experimental values of overall gas hold-up and average liquid circulation velocity have been compared with simulation and literature results. It is seemed to give good agreements. For the different elevations in the downcomer section, liquid axial velocity, turbulent kinetic energy, and turbulent eddy dissipation experimental have been compared with different turbulent models. The K-epsilon Realizable model gives better prediction with experimental results.

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A Flow Analysis Using a Water Tunnel of an Innovative Unmanned Aerial Vehicle

Applied Sciences ◽

10.3390/app11135772 ◽

2021 ◽

Vol 11 (13) ◽

pp. 5772

Author(s):

Dawid Lis ◽

Adam Januszko ◽

Tadeusz Dobrocinski

Keyword(s):

Unmanned Aerial Vehicles ◽

Unmanned Aerial Vehicle ◽

Rapid Development ◽

Lift Coefficient ◽

Flow Analysis ◽

Water Tunnel ◽

Dual Use ◽

Aerial Vehicles ◽

Aerial Vehicle ◽

Technical Construction

The purpose of this article is to present and discuss the results of a non-standard unnamed aerial vehicle construction with a constant cross-section square-shaped avionic profile. Based on the model’s in-air observed maneuverability, the research of avionic construction behavior was carried out in a water tunnel. The results show the model’s specific lift capabilities in comparison to classical avionic constructions. The characteristic results of the lift coefficient showed that the unmanned aerial vehicle presents favorable features than classic avionic constructions. The model was created with the prospect of using it in the future for dual-use purposes, where unmanned aerial vehicles are currently experiencing very rapid development. When creating the prototype, the focus was on low production cost, as well as convenience in operation. The development of this type of breakthrough avionic solution, which shows extraordinary maneuverability, may contribute to increasing the popularity and, above all, the availability of unmanned aerial vehicles for the largest possible group of recipients because of high avionic properties in relation to the technical construction complexity.

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Experimental investigations of flow over NACA airfoils 0021 and 4412 of wind turbine blades with and without Tubercles

Wind Engineering ◽

10.1177/0309524x211007178 ◽

2021 ◽

pp. 0309524X2110071

Author(s):

Usman Butt ◽

Shafqat Hussain ◽

Stephan Schacht ◽

Uwe Ritschel

Keyword(s):

Wind Tunnel ◽

Drag Coefficient ◽

Wind Turbine ◽

Critical Region ◽

Lift Coefficient ◽

Turbine Blades ◽

Leading Edge ◽

Reynolds Numbers ◽

Experimental Investigations ◽

Wind Turbine Blades

Experimental investigations of wind turbine blades having NACA airfoils 0021 and 4412 with and without tubercles on the leading edge have been performed in a wind tunnel. It was found that the lift coefficient of the airfoil 0021 with tubercles was higher at Re = 1.2×105 and 1.69×105 in post critical region (at higher angle of attach) than airfoils without tubercles but this difference relatively diminished at higher Reynolds numbers and beyond indicating that there is no effect on the lift coefficients of airfoils with tubercles at higher Reynolds numbers whereas drag coefficient remains unchanged. It is noted that at Re = 1.69×105, the lift coefficient of airfoil without tubercles drops from 0.96 to 0.42 as the angle of attack increases from 15° to 20° which is about 56% and the corresponding values of lift coefficient for airfoil with tubercles are 0.86 and 0.7 at respective angles with18% drop.

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COMPUTATIONAL FLUID DYNAMICS STUDY OF DUSTY AIR FLOW OVER NACA 63415 AIRFOIL FOR WIND TURBINE APPLICATIONS

Jurnal Teknologi ◽

10.11113/jt.v79.11877 ◽

2017 ◽

Vol 79 (7-3) ◽

Cited By ~ 1

Author(s):

Iham F. Zidane ◽

Khalid M. Saqr ◽

Greg Swadener ◽

Xianghong Ma ◽

Mohamed F. Shehadeh

Keyword(s):

Numerical Simulation ◽

Wind Turbine ◽

South African ◽

Stokes Equations ◽

Lift Coefficient ◽

Turbine Blades ◽

Aerodynamic Performance ◽

Accurate Estimation ◽

African Countries ◽

Sand Particles

Gulf and South African countries have enormous potential for wind energy. However, the emergence of sand storms in this region postulates performance and reliability challenges on wind turbines. This study investigates the effects of debris flow on wind turbine blade performance. In this paper, two-dimensional incompressible Navier-Stokes equations and the transition SST turbulence model are used to analyze the aerodynamic performance of NACA 63415 airfoil under clean and sandy conditions. The numerical simulation of the airfoil under clean surface condition is performed at Reynolds number 460×103, and the numerical results have a good consistency with the experimental data. The Discrete Phase Model has been used to investigate the role sand particles play in the aerodynamic performance degradation. The pressure and lift coefficients of the airfoil have been computed under different sand particles flow rates. The performance of the airfoil under different angle of attacks has been studied. Results showed that the blade lift coefficient can deteriorate by 28% in conditions relevant to the Gulf and South African countries sand storms. As a result, the numerical simulation method has been verified to be economically available for accurate estimation of the sand particles effect on the wind turbine blades.

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Dynamic Stall Simulation of Flow Over NACA0012 Airfoil at 1 Million Reynolds Number

Volume 7A: Fluids Engineering Systems and Technologies ◽

10.1115/imece2015-50827 ◽

2015 ◽

Author(s):

Venkata Ravishankar Kasibhotla ◽

Danesh Tafti

Keyword(s):

Reynolds Number ◽

Flow Field ◽

Lift Coefficient ◽

Three Dimensional ◽

Dynamic Stall ◽

Sharp Drop ◽

Airfoil Surface ◽

Naca0012 Airfoil ◽

Reduced Frequency ◽

Edge Vortex

The paper is concerned with the prediction and analysis of dynamic stall of flow past a pitching NACA0012 airfoil at 1 million Reynolds number based on the chord length of the airfoil and at reduced frequency of 0.25 in a three dimensional flow field. The turbulence in the flow field is resolved using large eddy simulations with the dynamic Smagorinsky model at the sub grid scale. The development of dynamic stall vortex, shedding and reattachment as predicted by the present study are discussed in detail. This study has shown that the downstroke phase of the pitching motion is strongly three dimensional and is highly complex, whereas the flow is practically two dimensional during the upstroke. The lift coefficient agrees well with the measurements during the upstroke. However, there are differences during the downstroke. The computed lift coefficient undergoes a sharp drop during the start of the downstroke as the convected leading edge vortex moves away from the airfoil surface. This is followed by a recovery of the lift coefficient with the formation of a secondary trailing edge vortex. While these dynamics are clearly reflected in the predicted lift coefficient, the experimental evolution of lift during the downstroke maintains a fairly smooth and monotonic decrease in the lift coefficient with no lift recovery. The simulations also show that the reattachment process of the stalled airfoil is completed before the start of the upstroke in the subsequent cycle due to the high reduced frequency of the pitching cycle.

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