scholarly journals Experimental modeling of the interaction of hard and aeriform body and the onset of a drag crisis with a significant change in velocity

2021 ◽  
Vol 2131 (2) ◽  
pp. 022124
Author(s):  
N V Kudinov ◽  
A M Atayan
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Drag Coefficient ◽  
Air Flow ◽  
Aerodynamic Characteristics ◽  
Spherical Body ◽  
Experimental Modeling ◽  
Numerical Information ◽  
Physical Experiments ◽  
Glue Method

Abstract The paper deals with the possibilities and prospects of experimental modeling of the interaction of a solid and a gaseous body. It is assumed that reliable experimental data have already been obtained and published. The problem of approximating the complex aerodynamic characteristics of air flow around a spherical body is posed and solved. The study was carried out using the «Cut-Glue» method for approximating numerical information about blowing experiments. Generally, this information reflects the dependence of the drag coefficient on the Reynolds number. The choice of the Cut-Glue method for the approximation of complex, multiextremal characteristics that can be obtained in physical experiments is substantiated.

A model of interfacial stress and spray generation by gas flowing over a deep, wavy pool

1987 ◽  
Vol 179 ◽  
pp. 327-344 ◽  
Author(s):  
Y. L. Sinai
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Wave Height ◽  
Air Flow ◽  
Present Theory ◽  
Interfacial Stress ◽  
Controlling Parameter

A wave Reynolds number is the controlling parameter in Wang & Street's (1978) correlation for spray generation in developing air flow over a pool. A novel feature of the present theory is the prediction of the time-mean interfacial stress which, together with a wave-height correlation, is proposed and tested as a tool for quantifying that Reynolds number. The validation exercise shows that the results are generally acceptable, although the technique tends to underestimate the interfacial stress and droplet flux at high gas speeds. The analysis of experimental data has revealed some differences in the correlations which should be resolved.

Experimental Aerodynamic Characteristics of a Compound Wing in Ground Effect

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Saeed Jamei ◽  
Adi Maimun Abdul Malek ◽  
Shuhaimi Mansor ◽  
Nor Azwadi Che Sidik ◽  
Agoes Priyanto
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Ground Effect ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Ground Clearance

Wing configuration is a parameter that affects the performance of wing-in-ground effect (WIG) craft. In this study, the aerodynamic characteristics of a new compound wing were investigated during ground effect. The compound wing was divided into three parts with a rectangular wing in the middle and two reverse taper wings with anhedral angle at the sides. The sectional profile of the wing model is NACA6409. The experiments on the compound wing and the rectangular wing were carried to examine different ground clearances, angles of attack, and Reynolds numbers. The aerodynamic coefficients of the compound wing were compared with those of the rectangular wing, which had an acceptable increase in its lift coefficient at small ground clearances, and its drag coefficient decreased compared to rectangular wing at a wide range of ground clearances, angles of attack, and Reynolds numbers. Furthermore, the lift to drag ratio of the compound wing improved considerably at small ground clearances. However, this improvement decreased at higher ground clearance. The drag polar of the compound wing showed the increment of lift coefficient versus drag coefficient was higher especially at small ground clearances. The Reynolds number had a gradual effect on lift and drag coefficients and also lift to drag of both wings. Generally, the nose down pitching moment of the compound wing was found smaller, but it was greater at high angle of attack and Reynolds number for all ground clearance. The center of pressure was closer to the leading edge of the wing in contrast to the rectangular wing. However, the center of pressure of the compound wing was later to the leading edge at high ground clearance, angle of attack, and Reynolds number.

scholarly journals Numerical Analysis of the Aerodynamic Characteristics of NACA-4312 Airfoil

2020 ◽  
Vol 01 (02) ◽  
pp. 29-36
Author(s):  
Md Rhyhanul Islam Pranto ◽  
Mohammad Ilias Inam
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Numerical Results ◽  
Ansys Fluent ◽  
Coefficient Increase ◽  
Lift And Drag ◽  
Lift And Drag Coefficient

The aim of the work is to investigate the aerodynamic characteristics such as lift coefficient, drag coefficient, pressure distribution over a surface of an airfoil of NACA-4312. A commercial software ANSYS Fluent was used for these numerical simulations to calculate the aerodynamic characteristics of 2-D NACA-4312 airfoil at different angles of attack (α) at fixed Reynolds number (Re), equal to 5×10^5 . These simulations were solved using two different turbulence models, one was the Standard k-ε model with enhanced wall treatment and other was the SST k-ω model. Numerical results demonstrate that both models can produce similar results with little deviations. It was observed that both lift and drag coefficient increase at higher angles of attack, however lift coefficient starts to reduce at α =13° which is known as stalling condition. Numerical results also show that flow separations start at rare edge when the angle of attack is higher than 13° due to the reduction of lift coefficient.

Three-Dimensional Wing Design Towards the Future Mars Airplane

2011 ◽  
Author(s):  
Ryoji Kojima ◽  
Donghi Lee ◽  
Tomoaki Tatsukawa ◽  
Taku Nonomura ◽  
Akira Oyama ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Viscous Drag ◽  
Stream Velocity ◽  
Main Stream ◽  
Lower Reynolds Number

The effects of aspect ratio and Reynolds number on aerodynamic characteristics of three-dimensional rectangular wing at low Reynolds number of 103 to 105, are investigated with Reynolds-averaged Navier-Stokes solver with the Baldwin-Lomax model. Present results show that lift coefficient decreases drastically at lower aspect ratio than 4. Besides, the much larger viscous drag coefficient is obtained at the lower Reynolds number, especially lower than 104. In order to focus on designing practical wings, the particular cases under the condition of fixed wing-surface area and fixed main stream velocity are conducted. The results show that there is trade-off between the decrease in viscous drag coefficient with increasing Reynolds number and the increase in lift coefficient with increasing aspect ratio. At the lower Reynolds number condition, as the former effect is stronger than the latter one, maximum lift-to-drag ratio is obtained at lower aspect ratio.

Influence of Particle Shape on the Drag Coefficient for Isometric Particles

1994 ◽  
Vol 59 (12) ◽  
pp. 2583-2594 ◽  
Author(s):  
Miloslav Hartman ◽  
Otakar Trnka ◽  
Karel Svoboda ◽  
Václav Veselý
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Drag Coefficient ◽  
Fluidized Beds ◽  
Fluid Velocity ◽  
Particle Diameter ◽  
Free Fall ◽  
Fall Velocity ◽  
Gas Cleaning ◽  
Explicit Formulae

A comprehensive correlation has been developed of the drag coefficient for nonspherical isometric particles as a function the Reynolds number and the particle sphericity on the basis of data reported in the literature. The proposed formula covers the Stokes, the transitional and the Newton region. The predictions of the reported correlation have been compared to experimental data measured in this work with the dolomitic materials in respect to their use in calcination and gas cleaning processes with fluidized beds. Approximative explicit formulae have also been reported that make it possible to estimate the terminal free-fall velocity of a given particle or to predict the particle diameter corresponding to a fluid velocity of interest.

scholarly journals Lift and Drag Coefficient Map of NACA4415 Airfoil

2021 ◽  
Vol 2076 (1) ◽  
pp. 012066
Author(s):  
Rui Yin ◽  
Jing Huang ◽  
Zhi-Yuan He
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Optimal Angle ◽  
Fluent Software ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract The NACA4415 airfoil was numerically simulated with the help of the Fluent software to analyze its aerodynamic characteristics. Results are acquired as follows: The calculation accuracy of Fluent software is much higher than that of XFOIL software; the calculation result of SST k-ω(sstkw) turbulence model is closest to the experimental value; within a certain range, the larger the Reynolds number is, the larger the lift coefficient and lift-to-drag ratio of the airfoil will be, and the smaller the drag coefficient will be; when the angle of attack is less than the optimal angle of attack, the Reynolds number has less influence on the lift-to-drag coefficient and the lift-to-drag ratio; as the Reynolds number increases, the optimal angle of attack increases slightly, and the applicable angle of attack range for high lift-to-drag ratios becomes smaller.

scholarly journals Redchyts Numerical simulation of the viscous incompressible flow around of the group of two bodies

2019 ◽  
Vol 3 (122) ◽  
pp. 117-132
Author(s):  
Serhii Serhiiovych Myrnyi ◽  
Dmytro Oleksandrovych Redchyts
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Steady State ◽  
Drag Coefficient ◽  
Flow Pattern ◽  
Aerodynamic Characteristics ◽  
Tandem Arrangement ◽  
Cylinders And Spheres ◽  
Two Bodies

Analysis of recent research and publications. It is known that the presence near the body of another body or a solid wall in a flow can significantly change both the overall flow pattern and the aerodynamic characteristics of bodies in a group. Studies of the interaction of bodies in the flow are conducted for a long time. In [6], the results of a study of changes in the overall flow pattern and the form of interaction of vortices behind tandem-arranged circular cylinders are presented. Further, experimental studies of the flow around a group consisting of two cylinders were aimed at classifying flow patterns depending on the position of the group in the flow, the distance between the cylinders and the Reynolds number [1, 2, 9]. A rather complete identification and classification of the pattern of flow was performed in [6, 7]. Studies on the classification and analysis of flow patterns are still being conducted [1]. Studies on the classification of patterns of the flow around group of spheres are currently performed mainly with the help of numerical simulation. In [3, 4, 5], simulation of the flow around spheres on the side-by-side position was performed. In [8], the classification of typical patterns of the flow around two spheres (Re = 300) with considering of different positions of the spheres relative to the flow direction was made. The authors of [8] describe nine typical patterns of the flow around two spheres in analogy with the patterns of the flow of the two cylinders.The purpose of the study. The main goal of this work is study the mutual influence of two bodies in a flow of a viscous incompressible fluid and a change in the flow structure with a change in the position of the bodies in the group relative to the incoming flow. Also, the aim of the work was to study the influence of the mutual arrangement of bodies in a group on the non-stationary and time-averaged aerodynamic characteristics of bodies in a group.Modeling of the flow around groups of cylinders and spheres. Numerical simulation of the flow around the group of cylinders was carried out with the values of the angle θ = 0°, 15°, 30°, 45°, 60°, 75°, 90° and the gap between the cylinders h = 0.2D, 0.4D, 0.6D, 0.8D, 1.0D, 2.0D, 3.0D, 4.0D, 5.0D. The flow parameters was corresponded to the flow around a circular cylinder at Re = 80 and 1.66 105. Eight patterns (regimes) of flow around a group of two cylinders at Re = 80 were found. Regimes 1 and 2 are steady state flows. In regime 1, the drag coefficient is Cx2 <0, and for regime 2, Cx2> 0. Regimes 3-8 are unsteady flows. Regime 8 is an aperiodic change in Cx, Cy. Regimes 3 - 7 are periodic, characterized by different values of the coefficients Cx, Cy, as well as those oscillations of Cx and Cy that occur in phase or antiphase. Simulation of the turbulent flow around a group of two cylinders took place at the tandem and the side-by-side positions at distances between cylinders centers 1.435D and 3.7D.Similarly, in this work, was performed the parametric study of the flow around two spheres for Reynolds number 750 with the distances between the centers of the spheres along axis Δx = 0.0, 1.0, 2.0, 3.0 and Δy = 0.0, 1.0, 2.0, 3.0. The drag and lift coefficients were obtained, as well as the patterns of flow around two spheres were analyzed.Conclusions. Depending on the position of the group relative to the flow, the average drag coefficient of the cylinders and spheres in the group can be both smaller and larger than the drag coefficient of a single body with the same parameters of the free flow. With a tandem arrangement, the second cylinder has a stabilizing effect and with a decrease in the gap of less than three diameters, the flow becomes steady state. For all cases with staggered arrangement of spheres the symmetry restoration of vortex structures is observed. In the case of the tandem arrangement of spheres, the separation of loop-shaped vortex structures is realized as in the case of a flow around a single sphere.

Prediction of Aerodynamic Characteristics of an Elliptic Airfoil at Low Reynolds Number

2012 ◽  
Author(s):  
Varun Chitta ◽  
D. Keith Walters
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Models ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Transitional Flow ◽  
Suction Surface ◽  
Turbulent Models ◽  
Lift And Drag ◽  
Elliptic Airfoil

This study focuses on modeling the effects of transitional flow and surface curvature on aerodynamic characteristics of an elliptic airfoil. Numerical simulations have been performed on a 16% thick elliptic airfoil for a range of angle of attack (α) from 0° to 20° and flow Reynolds number (Re) of 3 × 105, using relatively new transition-sensitive and traditional fully turbulent eddy viscosity turbulence models. Test conditions were matched to experiments by Kwon and Park (2005) and numerical results were compared with available experimental data. Results indicate that the transition-sensitive models, namely k-kL-ω and Transition SST, accurately predict the laminar-to-turbulent transition locations and reproduce the laminar separation bubbles on the suction surface of the airfoil in agreement with the experimental data. Also, transition-sensitive models yield improved predictions of lift and drag performance when compared with results from fully turbulent models. The fully turbulent models; including SA and k-ω SST, and a newly developed curvature-sensitive model (SST k-ω-ν2) fail to capture the flow separation and reattachment locations near the leading edge of airfoil. However, the curvature-sensitive SST k-ω-ν2 model predicts the stall point of the airfoil close to experimental results, while all other tested RANS models failed to accurately predict the stall point. Taken as a whole, the results suggest that accurate aerodynamic predictions at both low and high angles of attack might be achieved by using a model that includes the effects of both transition and curvature.

Aerodynamic Characteristics and Trajectory of Projectile with a Deflectable Nose

2014 ◽  
Vol 543-547 ◽  
pp. 16-19
Author(s):  
Ji Feng Wei ◽  
Xiong Li ◽  
Shu Shan Wang ◽  
Yu Xin Xu
Keyword(s):  
Experimental Data ◽  
Mach Number ◽  
Drag Coefficient ◽  
Aerodynamic Characteristics ◽  
Pitching Moment ◽  
Flight Trajectory ◽  
Start Time ◽  
Aerodynamic Efficiency ◽  
Moment Coefficient ◽  
Maximum Range

The basic experiment and detailed simulations are carried out to study the aerodynamic characteristics of projectile with deflectable nose. The parameters of computation are revised on the basis of experimental data. Further simulations show that the influence of mach number and deflectable angle on drag, lift, pitching moment and flight trajectory. The drag coefficient increases firstly and then decreases with the change of mach number, while drag coefficient and pitching moment coefficient grows exponentially. It can be seen that the ratio of lift to drag increases consistently, which means the aerodynamic efficiency of projectile would be improved with the increase of deflectable angle and mach number. The range is influenced by the start time of deflection. For the projectile with deflectable angle 10, the maximum range can be obtained if the forehead deflects at 3s.

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