S1910105 The Difference by Line of Sight in Emission Spectroscopy around Stagnation Point in an Arc Heated Wind Tunnel

2014 ◽  
Vol 2014 (0) ◽  
pp. _S1910105--_S1910105-
Author(s):  
Hisashi KIHARA
Keyword(s):  
Wind Tunnel ◽  
Stagnation Point ◽  
Emission Spectroscopy ◽  
Line Of Sight ◽  
The Difference

scholarly journals Study on the Simulation Method of the Ground Test in the Arc-Heated Wind Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Wanqing Luo ◽  
Yuanjian Yang ◽  
Jianhan Liang ◽  
Songhe Zhang ◽  
Yilei Shi
Keyword(s):  
Heat Flux ◽  
Wind Tunnel ◽  
Oxygen Atom ◽  
Stagnation Point ◽  
Mass Fraction ◽  
Simulation Method ◽  
Test Conditions ◽  
Ground Test ◽  
The Difference ◽  
Stagnation Point Heat Flux

To analyze the effectiveness of the thermal assessment test, the simulation method of the ground test in the arc-heated wind tunnel is studied. Based on the solution of the thermochemical nonequilibrium Navier-Stokes equations, the flowfield around the spherical cylinder is simulated in the flight and ground test conditions, and the difference in the high enthalpy flowfield between the flight and ground test conditions is investigated. The flight parameters and ground test conditions are selected according to the criterion that the total enthalpy and the stagnation point heat flux of the fully catalytic cold wall (calibrated heat flux) are similar. The flowfield for different temperature boundaries and different catalytic walls is solved under the same free stream conditions, and the stagnation point heat flux and oxygen atom mass fraction are compared and analyzed. It is found that the heat flux on the fully catalytic wall for the radiation balance temperature boundary in the ground test is lower than that in the corresponding flight condition, but the difference is not obvious on the noncatalytic wall. In addition, the oxygen atom mass fraction after the shock wave in the ground test is higher than that in the corresponding flight condition. To make the stagnation point heat flux and oxygen atom mass fraction after the shock wave similar to those of the flight, the simulation method of the arc-heated wind tunnel test needs to be adjusted.

Structuring, Motions and Shapes of Corona Emission Line Profiles

1994 ◽  
Vol 144 ◽  
pp. 421-426
Author(s):  
N. F. Tyagun
Keyword(s):  
Emission Line ◽  
Filling Factor ◽  
Direct Relationship ◽  
Coronal Plasma ◽  
Line Of Sight ◽  
Line Profiles ◽  
The Difference ◽  
Yellow Line ◽  
Red Line

AbstractThe interrelationship of half-widths and intensities for the red, green and yellow lines is considered. This is a direct relationship for the green and yellow line and an inverse one for the red line. The difference in the relationships of half-widths and intensities for different lines appears to be due to substantially dissimilar structuring and to a set of line-of-sight motions in ”hot“ and ”cold“ corona regions.When diagnosing the coronal plasma, one cannot neglect the filling factor - each line has such a factor of its own.

First models for structural energy transmission decoupling in the high frequency regime under aerodynamic excitations

2021 ◽  
pp. 095440622110200
Author(s):  
G Mazzeo ◽  
MN Ichchou ◽  
G Petrone ◽  
O Bareille ◽  
S De Rosa ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Vibrational Energy ◽  
Complex Structure ◽  
Structural Response ◽  
Test Case ◽  
Analysis Model ◽  
Quick Method ◽  
Vibrational Velocity ◽  
Frequency Regime ◽  
The Difference

In the wind tunnel facility, a test structure is often used for measuring its vibrational response to the aerodynamic excitation. A support is needed to sustaining the structure and it is mandatory that this support does not influence the vibrational energy to be measured. To this aim, the maximum amount of energy decoupling between the structure and the support is desired. This work is focused around a quick method to estimate this decoupling by using simplified models for the Turbulent Boundary Layer (TBL) excitation and for the structural response. Specifically, the Equivalent Rain-on-the-roof excitation is invoked with a Statistical Energy Analysis model for the structure. Some simple design rules are proposed and based on little information leading to foresee the difference of vibrational velocity levels between the two structural systems. A simplified test-case is used for the first investigations and a complex structure is finally conceived thinking to vibroacoustic measurements in a large wind tunnel facility. Although some results are largely expected, the global approach is promising.

The Influence of Reynolds Number at High Mach Numbers

1944 ◽  
Vol 48 (398) ◽  
pp. 45-48 ◽  
Author(s):  
A. Ferri
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Pressure Distribution ◽  
Stagnation Point ◽  
Pressure Difference ◽  
High Speed ◽  
Total Drag ◽  
Air Jet ◽  
Variable Point ◽  
High Mach

The experiments were carried out in the high speed wind tunnel at Guidonia on three brass spheres of 40, 60 and 80 mm. diameter, supported on rear spindles and on two steel cylinders of 15 and 30 mm. diameter respectively, which passed through the air jet.Both the total drag and pressure difference between the front stagnation point and a variable point at the rear were measured.The pressure distribution on similar models which could be rotated and which were provided with pressure holes was also determined.

scholarly journals Expansion parallaxes and intrinsic stellar properties for 15 simple planetary nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 354-356 ◽  
Author(s):  
Detlef Schönberner ◽  
Ralf Jacob ◽  
Bruce Balick
Keyword(s):  
Hubble Space Telescope ◽  
Planetary Nebulae ◽  
Line Of Sight ◽  
Radiation Hydrodynamics ◽  
Proper Motions ◽  
Imaging Data ◽  
The Difference ◽  
Stellar Properties ◽  
Angular Expansion ◽  
Shock Fronts

AbstractWe determined individual distances to a small number of rather round, quite regularly shaped planetary nebulae by combining their angular expansion in the plane of the sky with a spectroscopically measured expansion along the line of sight. For this goal, we combined up to three epochs of Hubble Space Telescope imaging data and determined the respective proper motions of rim and shell edges, and of other features as well. Ground-based radial velocities are assigned separately to the nebular rims and shells and used to determine individual distances, thereby assuming that the expansions in the line-of-sight and in the plane of sky are equal. We employed 1D radiation-hydrodynamics simulations of planetary nebulae evolution to correct for the difference between the spectroscopically measured expansion velocities of rim and shell and the expansion speeds of their respective shock fronts.

scholarly journals Emission Spectroscopy of OH Radical in Water-Argon Arc Plasma Jet

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Alan Mašláni ◽  
Viktor Sember
Keyword(s):  
Central Region ◽  
Emission Spectroscopy ◽  
Plasma Torch ◽  
Emission Spectra ◽  
Plasma Jet ◽  
Line Of Sight ◽  
Thermal Processes ◽  
Oh Radical ◽  
Arc Plasma ◽  
Large Area

Emission spectra of OH radical are studied in the plasma jet generated by a plasma torch with hybrid water-argon stabilization. Plasma jet is located in a chamber with pressures 4 kPa and 10 kPa. In spite of high temperatures of produced plasma, OH spectra are observed in a large area of the jet. OH spectra are used to obtain rotational temperatures from the Boltzmann plots of resolved rotational lines. Due to line-of-sight integration of radiation, interpretation of the temperatures is not straightforward. It seems that excited OH molecules can be formed by various mechanisms, mainly in the outer parts of the jet, where thermal processes are not as dominant as in the hot central region.

scholarly journals A technique to predict the aerodynamic effects of battle damage on an aircraft’s wing

2015 ◽  
Vol 119 (1218) ◽  
pp. 937-960 ◽  
Author(s):  
T.W. Pickhaver ◽  
P.M. Render
Keyword(s):  
Wind Tunnel ◽  
Lower Surface ◽  
Surface Flow ◽  
Internal Cavity ◽  
Flow Visualisation ◽  
Pitching Moment ◽  
Wind Tunnel Tests ◽  
Tunnel Model ◽  
Circular Holes ◽  
The Difference

Abstract A technique is developed that can be used to predict the effects of battle damage on the aerodynamic performance of an aircraft’s wing. The technique is based on results obtained from wind tunnel tests on a NASA LS(1)-0417MOD aerofoil with simulated gunfire damage. The wind tunnel model incorporated an internal cavity to represent typical aircraft construction and this was located between 24% and 75% of chord. The damage was simulated by circular holes with diameters between 20% and 40% of chord. To represent different attack directions, the inclination of the hole axis relative to the aerofoil chord was varied between ±60° pitch and 45° of roll. The aerofoil spanned the wind tunnel to create approximate two-dimensional conditions and balance measurements were carried out at a Reynolds number of 500,000 for incidences, increased in 2° increments, from –4° to 16°. Surface flow visualisation and pressure measurements were also carried out. For a given hole size, the increments in lift, drag and pitching moment coefficients produced trends when plotted against the difference between the upper and lower surface pressure coefficients on the undamaged aerofoil taken at the location of the damage. These trends are used as the basis of the predictive technique. The technique is used to predict the effects of a previously untested damage case, and these are compared with wind tunnel tests carried out on a half model finite aspect ratio wing. For all coefficients the trends in the predicted data are similar to experiment, although there are some discrepancies in absolute values. For the drag coefficient these discrepancies are partly accounted for by limitations in the technique, whilst discrepancies in the lift and pitching moment coefficients are attributed to limitations in the aerofoil test arrangements.

scholarly journals Effect of Angle of Attack on Airfoil NACA 0012 Performance

2020 ◽  
Vol 5 (1) ◽  
pp. 35-40
Author(s):  
Ali Akbar
Keyword(s):  
Fluid Flow ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Lift Force ◽  
Angle Of Attack ◽  
Lower Surface ◽  
Wind Tunnel Experiments ◽  
A Value ◽  
The Difference ◽  
Naca 0012

Airfoil is an aerodynamic form intended to produce a lift force with the smallest drag force. When an airfoil is passed through a fluid flow that causes interaction between the air flow and the surface, variations in velocity and pressure will occur along the top and bottom surfaces of the airfoil, as well as the front and back of the airfoil. The difference in pressure between the upper and lower surface of the airfoil is what causes the resultant force in the direction perpendicular to the direction of fluid flow, this force is called the lift force (lift). In this experiment NACA 0012 airfoil experiments have been carried out using simple wind tunnel. Experiments were conducted with the aim to determine the effect of the angle of attack on the performance of the NACA 0012 airfoil which then analyzed the lift force of the NACA 0012 airfoil. The variation of the angle of attack used was 0 °, 3 °, 6 °, 9 °, 12 °, and 15 ° and used wind speed of 21.5 m / s. The greatest lift force is obtained at an angle of attack of 9 ° with a value of 0.981 while the largest lifting coefficient with a value of 0.106. The greater the angle of attack the greater the airfoil lift force, but for symmetrical airfoil stall at an angle that is too large

scholarly journals Numerical method for an assessment of steady and motion-excited flowfields in a transonic cascade wind tunnel

2017 ◽  
Vol 1 ◽  
pp. QL9XVI ◽  
Author(s):  
Atsushi Tateishi ◽  
Toshinori Watanabe ◽  
Takehiro Himeno ◽  
Seiji Uzawa
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Numerical Method ◽  
Aerodynamic Characteristics ◽  
Pressure Amplitude ◽  
Tunnel Wall ◽  
Flow Simulations ◽  
Influence Coefficients ◽  
The Difference ◽  
Transonic Cascade

AbstractThis article presents a numerical method and its application for an assessment of the flow field inside a wind tunnel. A structured computational fluid dynamics (CFDs) solver with overset mesh technique is developed in order to simulate geometrically complex configurations. Applying the developed solver, a whole transonic cascade wind tunnel is modeled and simulated by a two-dimensional manner. The upstream and downstream periodicity of the cascade and the effect of the tunnel wall on the unsteady flow field are focused on. From the steady flow simulations, the existence of an optimum throttle position for the best periodicity for each tailboard angle is shown, which provides appropriate aerodynamic characteristics of ideal cascades in the wind tunnel environment. Unsteady simulations with blade oscillation is also conducted, and the difference in the influence coefficients between ideal and wind tunnel configurations becomes large when the pressure amplitude increases on the lower blades.

scholarly journals A New Planar Microwave Sensor for Building Materials Complex Permittivity Characterization

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6328
Author(s):  
João G. D. Oliveira ◽  
José G. Duarte Junior ◽  
Erica N. M. G. Pinto ◽  
Valdemir P. Silva Neto ◽  
Adaildo G. D’Assunção
Keyword(s):  
Relative Permittivity ◽  
Building Materials ◽  
Dielectric Materials ◽  
Line Of Sight ◽  
Scattering Parameters ◽  
Microwave Sensor ◽  
Sensor Structure ◽  
Measurement Results ◽  
Concrete Blocks ◽  
The Difference

A new microwave sensor is proposed to characterize the complex relative permittivity of building non-magnetic materials and used in the characterization of three concrete samples. The proposed sensor structure consists of a log-periodic planar antenna with microstrip elements tilted forward by an angle β and printed, alternately, on the top and bottom sides of a dielectric layer. The operation principle is based on the measurement of the scattering parameters S11 and S21 in a free space propagation transmitter-receiver setup, for both cases with the material under test (MUT) sample (non-line-of-sight, NLOS) and without it (line-of-sight, LOS). A prototype is fabricated and measured to determine the scattering parameters of concrete samples. After measurements, the obtained results are used in the efficient and accurate Nicolson–Ross–Weir (NRW) method, making it possible to estimate the values of the complex relative permittivity of the concrete blocks. The sensor design is demonstrated from initial simulations to measurements for validation of the developed prototype. The obtained results for the complex relative permittivity of concrete are in agreement with those available in the literature and the difference between the simulated and measurement results for the sensor antenna resonant frequency is 4.71%. The used measurement setup can be applied to characterize different types of solid or liquid dielectric materials.

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