Aerodynamic Coefficients for a Parafoil Wing with Arc Anhedral - Theoretical and Experimental Results

2003 ◽  
Author(s):  
Thomas Jann
Keyword(s):  
Experimental Results ◽  
Aerodynamic Coefficients

Understanding of flow features over a typical crew module at Mach 4

2015 ◽  
Vol 119 (1216) ◽  
pp. 727-746 ◽  
Author(s):  
S. L. N. Desikan ◽  
M. M. Patil ◽  
S. Subramanian
Keyword(s):  
Experimental Results ◽  
Leeward Side ◽  
Wake Vortex ◽  
Aerodynamic Coefficients ◽  
Near Wake ◽  
Sonic Line ◽  
Oil Flow ◽  
Flow Features ◽  
Experimental Values ◽  
Good Agreement

AbstractThis paper presents the numerical simulations of flowfield over a typical Crew Module at Mach 4 for different angles-of-attack ranging from 0 to –25°. Detailed flow features such as contour of density gradient over the model, numerical oil flow and near wake vortex structures are captured very well in the present simulations. The location of the sonic line and its behaviour due to angles-of-attack is also captured in the simulations. TheCPdistribution on the windward and leeward side shows excellent match with the experimental results. Also, the prediction of aerodynamic coefficients shows very good agreement with the experimental results. The numerical simulation predictsCMcg,CNandCAwithin 8%, 4% and 3·5% respectively with respect to experimental values.

Programa de Cómputo para Estimar el Rendimiento de una Hélice Empleando una Corrección por Número de Mach a la Teoría Combinada

2021 ◽  
Vol 2 (5) ◽  
pp. 6739-6753
Author(s):  
Tiburcio Fernández Roque ◽  
Braulio Vera García ◽  
José Arturo Correa Arredondo ◽  
Jorge Sandoval Lezama ◽  
Alejandro Mejía Carmona
Keyword(s):  
Mach Number ◽  
Experimental Results ◽  
Aerodynamic Coefficients ◽  
Aerodynamic Coefficient ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Empirical Correction ◽  
Para Determinar ◽  
Bem Theory ◽  
Blade Element

En este trabajo se propone una corrección empírica por número de Mach a la teoría combinada para hélices y se describe el programa de cómputo desarrollado para determinar el comportamiento de la misma. El programa requiere como datos de entrada la geometría de la hélice y los coeficientes aerodinámicos en función del número de Mach de los perfiles de la pala de la hélice. Éste calcula los coeficientes aerodinámicos y las velocidades inducidas de cada elemento de pala empleando la teoría combinada, corrige los coeficientes aerodinámicos por efecto de compresibilidad y calcula la eficiencia, así como los coeficientes de tracción y de potencia de la hélice para diferentes velocidades de avance y, finalmente, los presenta en forma gráfica. Se observa que los resultados obtenidos con la teoría combinada corregida por número de Mach fueron satisfactorios ya que se aproximan más a los resultados experimentales que la teoría combinada simple.   This work proposes an empirical correction by Mach number to the BEM (Blade-Element Momentum) Theory for propellers and describes the software developed to determine the behavior of it. The input for the software is the geometry of the propeller and the aerodynamic coefficient in function of the Mach number for the airfoils used for the propeller chosen. The software calculates the aerodynamic coefficients and the induced velocities at each station of the blade of the propeller using the BEM theory, then corrects these coefficients by the effect of compressibility and calculates the efficiency, the traction and power coefficients for a range of forward velocities, and finally presents a graph with the results obtained. We can observe that the results obtain are satisfactory comparing with the experimental results and obtaining lower difference error by this method than with the simple BEM theory.

Aerodynamic Forces of Vehicles on the Bridge under Crosswinds

2013 ◽  
Vol 639-640 ◽  
pp. 1206-1209
Author(s):  
Y. Han ◽  
Steve C.S. Cai
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Characteristics ◽  
Experimental Results ◽  
Experimental Setup ◽  
Aerodynamic Coefficients ◽  
Aerodynamic Forces ◽  
Wind Turbulence ◽  
Aerodynamic Interference

In the present study, an experimental setup was made to measure the aerodynamic characteristics of vehicles on the bridge for different cases in a wind tunnel considering the aerodynamic interference. The influence of the wind turbulence, the vehicle interference, and the distance of vehicle from the windward edge of the deck on the aerodynamic coefficients of vehicles were investigated based on the experimental results. The measured results showed that the wind turbulence, the vehicle interference, and the vehicle distance from the windward edge significantly affected the aerodynamic coefficients of vehicles.

Effect of Passenger Car’s Rear Deck Geometry on Its Aerodynamic Coefficients

1992 ◽  
Vol 114 (2) ◽  
pp. 186-190 ◽  
Author(s):  
J. Katz ◽  
L. Dykstra
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Experimental Results ◽  
Aerodynamic Coefficients ◽  
Wind Tunnel Model ◽  
Race Car ◽  
Rear Wing ◽  
Tunnel Model ◽  
Aerodynamic Interaction ◽  
Rear Spoiler

The effects of aerodynamic modifications near the rear deck of a passenger-car based race car were investigated experimentally. The modifications were evaluated on a quarter-scale wind tunnel model and included a rear spoiler and a wing. The experimental results indicate that these devices alter the flow field on the vehicle’s body resulting in considerable negative lift coefficients. Also, this aerodynamic interaction is sensitive to rear wing location and when properly placed the total lift owing to the rear wing, combined with its effect on the vehicle’s body, can amount to twice the lift of the isolated wing.

scholarly journals Unsteady Aerodynamic Characteristics of Antenna Rotating in Different Elevation Angles

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yanqi Zhang ◽  
Zhaoming Zhang
Keyword(s):  
Root Mean Square ◽  
Elevation Angle ◽  
Aerodynamic Characteristics ◽  
Experimental Results ◽  
Mean Square ◽  
Aerodynamic Coefficients ◽  
Servo Systems ◽  
Reduced Frequency ◽  
The Mean ◽  
Plate Antenna

The aerodynamic characteristics of radar antennas should be considered in computing their wind resistance and designing pedestal servo systems. In this paper, the aerodynamic characteristics of a flat plate antenna with azimuthal rotation are explored using a wind tunnel, and the effects of the antenna elevation angle and reduced frequency on the aerodynamic coefficients are analyzed. The corresponding results of numerical simulation are given to compare with the experimental results. The variation of aerodynamic coefficients with respect to the azimuth angle is found to depend on the reduced frequency and the antenna elevation angle. When the increase in antenna elevation angle is slight, the mean and root mean square values of the aerodynamic coefficients are not monotonic with respect to increases in elevation angle and may increase at individual elevation angles. When the elevation angle increases significantly, the mean, maximum, and root mean square values of the aerodynamic coefficients all significantly decrease. The simulation results are in good agreement with the experimental results, which verify the feasibility of using unsteady numerical simulations to obtain the flow field structure when the antenna is rotating. This approach allows the influence mechanism of the elevation angle change on the aerodynamic characteristics of the rotating antenna to be identified.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

Multislice calculations of RHEED patterns from vicinal Si (001)

1993 ◽  
Vol 51 ◽  
pp. 1000-1001
Author(s):  
Scott Lordi
Keyword(s):  
Misorientation Angle ◽  
Incident Angle ◽  
Incident Beam ◽  
Experimental Results ◽  
Bragg Condition ◽  
Vicinal Surfaces ◽  
Kinematic Theory ◽  
Step Edges

Vicinal Si (001) surfaces are interesting because they are good substrates for the growth of III-V semiconductors. Spots in RHEED patterns from vicinal surfaces are split due to scattering from ordered step arrays and this splitting can be used to determine the misorientation angle, using kinematic arguments. Kinematic theory is generally regarded to be inadequate for the calculation of RHEED intensities; however, only a few dynamical RHEED simulations have been attempted for vicinal surfaces. The multislice formulation of Cowley and Moodie with a recently developed edge patching method was used to calculate RHEED patterns from vicinal Si (001) surfaces. The calculated patterns are qualitatively similar to published experimental results and the positions of the split spots quantitatively agree with kinematic calculations.RHEED patterns were calculated for unreconstructed (bulk terminated) Si (001) surfaces misoriented towards [110] ,with an energy of 15 keV, at an incident angle of 36.63 mrad ([004] bragg condition), and a beam azimuth of [110] (perpendicular to the step edges) and the incident beam pointed down the step staircase.

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