Phenol interaction with different nano-cages with and without an electric field: A DFT study

The adsorption properties of the phenol molecule (C6H5OH) upon the outer surfaces of C24, B12P12, B12N12, Al12N12, and Al12P12 were investigated using density functional theory calculations. Our calculations reveal that the phenol molecule can be chemisorbed on the sidewalls of Al12N12 and Al12P12 with adsorption energies of -1.03 and -0.76 eV, respectively. While the adsorption energy of C6H5OH on Al12N12 is typically more than that of Al12P12 cluster. We also considered the adsorption of the C6H5OH molecule under a strong electric field over Al12N12. The results indicate that Al12N12 has high sensitivity to the phenol molecule in the presence of an electric field. © Springer Science+Business Media 2014

Experimental investigation of leading-edge roughness effects on stationary crossflow instability of a swept wing

AbstractWind tunnel experiments were conducted to evaluate surface pressure distribution over a semi span swept wing with a sweep angle of 33°. The wing section has a laminar flow airfoil similar to that of the NACA 6-series. The tests were conducted at speeds ranging from 50 to 70 m/s with and without surface roughness. Surface static pressure was measured on the wing upper surface at three different chordwise rows located at the inboard, middle, and outboard stations. The differences between pressure distributions on the three sections of the wing were studied and the experimental results showed that roughness elements do not influence the pressure distribution significantly, except at the inboard station. On the other hand, spectral analysis of the pressure–time signals acquired from the pressure orifices over the wing upper surface showed that roughness had significantly affected the zero frequency amplitude. In this study, the zero frequency amplitude and its variations with roughness elements was investigated at three different chordwise positions; inboard, middle, and outboard stations. Results showed that the 3-D roughness elements amplified zero frequency amplitude over the wing surface. Zero frequency distribution at the inboard station, closer to the wing root, in comparison with the middle station, was reduced after an initial amplification along the chord. Moreover, the effect of roughness on the zero frequency instability at the first section was negligible due to the narrow instability amplification region. On the other hand, at the outboard station, closer to the wing tip, the instabilities were amplified over a larger region, with respect to the middle station

An experimental study of buzz instability in an axisymmetric supersonic inlet

AbstractAn experimental study was carried out on an axisymmetric supersonic inlet with external compression. The scope of this study was to investigate the general characteristics of the inlet buzz under various design and off-design conditions. The model was equipped with accurate and high frequency pressure sensors and the tests were conducted at Mach numbers varying from 1.8 to 2.5, at various angles of attack, and at different mass flow rates. Shadowgraph flow visualization, together with a high speed camera, was used to capture the external shock structure in front of the inlet. Frequencies of buzz were obtained from both the shadowgraph pictures and analysis of the pressure data. The amplitude of the shock wave motion was measured from the visualization pictures, too. The results show that for low mass flow rates, buzz frequency is almost independent of Mach number, while at a higher mass flow rate, the frequency of the shock oscillation increases with Mach number. Further, for each free stream Mach number, as the mass flow rate decreased, the amplitude of the shock movement grew, but its frequency decreased

Effects of wing geometry on wing-body-tail interference in subsonic flow

AbstractExtensive wind tunnel tests were performed on several wing- body-tail combinations in subsonic flow to study the effects of wing geometric parameters on the flow field over the tail. For each configuration, tail surface pressure distribution, as well as the velocity contour at a plane perpendicular to the flow direction behind the wing was measured. The results show a strong effect of wing to tail span ratio, as well as wing aspect ratio, on the flowfield downstream of the wing. For low sweep wings, as those considered here, wing and body interference effects on the tail are associated with the wing tip vortex and nose-body vortex

Flow quality improvement in a transonic wind tunnel

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.An originally designed trisonic wind tunnel was upgraded to improve its performance criterion in the transonic regimes. In this research, the test section was modified according to the operational requirements of the existing transonic wind tunnels. Suitable perforated walls were designed, manufactured and installed. The flow in the test section of the wind tunnel with the new test section walls was surveyed for the empty condition, using specially designed long tube static probe and a rake. The rake was used to survey Mach number distribution in the test section. Finally, a 2D model (NACA 0012) and a 3D standard model for the transonic wind tunnels (AGARD-B) were manufactured and tested at various conditions for the purpose of the integral calibration and validation of the tunnel data. Surface pressure distribution along with the force and moment data compared well with the existing data from other tunnels when operated in similar stream conditions. Keywords: transonic wind tunnel/ perforated wall/ side suction/ standard models/ test section.dc201

Investigation of the pressure distribution over a MAV model

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.An intensive experimental study was conducted to investigate the effects of various parameters on the surface pressure distribution of a Zimmerman type wing wildly used for MAVs. A full scale wing was designed, fabricated, and tested in a low speed, low turbulence wind tunnel. The model cross section was an airfoil of a type which is usually used in MAV wings. The wing planform was of Zimmerman type. The model was equipped with several static pressure ports located at different span-wise and chord-wise sections of the wing. Surface static pressure data at various angles of attack ranging from -10 to 20 degrees, and at three different Reynolds numbers equal to that of the full scale model were obtained. It should be noted that to author’s knowledge, no experimental pressure data for this type of wing having an airfoil in its cross section are available in the literature. All data that the authors were able to find, dealt with aerodynamic force and moment of a flat plate wing of Zimmerman planform. The measured pressure data over the wing surface shows several interesting results which are different from those for the conventional wing planforms, i.e., rectangular, triangular, etc.dc201

An experimental study of a plunging airfoil in the post stall region

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.A series of low speed wind tunnel tests were conducted to study the unsteady flow events on an airfoil oscillating in plunge mode beyond its static-stall angle of attack. Data were acquired at a Reynolds number of 0.42*106, over a range of reduced frequencies, k=0.03-0.1 and plunging amplitude of ±15cm. It was found that in the post stall region, there existed a fully separated flow over the upper surface of the airfoil and the dynamic stall vortex formed in the vicinity of the leading edge region. Also, the effect of the reduced frequency was investigated.cs201

Computational and Experimental Investigations of Boundary Layer Tripping

Supersonic flow over a tapered body of revolution has been investigated both experimentally and numerically. The experimental study consisted of a series of wind tunnel tests on an ogive-cylinder body. Static pressure distributions on the body surfaces at several longitudinal cross sections, as well as the boundary layer profiles at various angles of attack have been measured. Further, the flow around the model was visualized using Schlieren technique. Tests with a natural development of the boundary layer and with tripping were also carried out. All tests were conducted in the trisonic wind tunnel of Qadr Research Center. Our results show that artificial boundary layer tripping has minor effect on the static surface pressure distribution (depending on its diameter and installation location), while the changes in total pressure around the body were significant. Tripping the boundary layer increased its thickness, changed its profile particularly near the body surface. Two oblique shock waves were formed in the front and behind the trip wire. In this study, using multi-block grid, the thin layer Navier-Stokes (TLNS) equations were solved around the above models. Also patched method was used near the interfaces. Good agreements were achieved when the numerical results were compared with the corresponding experimental data

Effects of organophosphate, diazinon on some haematological and biochemical changes in Rutilus frisii kutum (Kamensky, 1901) male brood stocks

The acute toxicity and effects of diazinon on some haematological parameters of kutum (Rutilus frisii kutum, Kamensky, 1901) weighing 613.33 ± 157.06 g were studied under static water quality conditions at 15 °C ± 2 ºC. These experiments were carried out based on the standard TRC, 1984 method over 4 days, and controlled for the effective water physicochemical factors having pH ranges of 7-8.2, total hardness 300 mgl^-1 (CaCO3), dissolved oxygen 7 mgl^-1. The results showed that the 96h LC50 value of diazinon was 0.4 mgl^-1 and that the maximum allowable concentration (MAC) value of this toxin was 0.04 mgl^-1. The second stage of experiments consisted of four treatments: LC0: 0 as blank, treatment A with a concentration of LC1: 0.107 mgl^-1, treatment B with a concentration of LC5: 0.157 mgl^-1, treatment C with a concentration of MAC value: 0.04 mgl^-1. Male brood stocks of R. frisii were treated with these concentrations for 45 days. The results showed that long-term exposure to diazinon causes a decrease in the erythrocyte count (RBC), haemoglobin (Hb), haematocrit (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), leucocyte count (WBC), lymphocyte, testosterone, iron (Fe), sodium (Na), lactate dehydrogenase (LDH) and cholinesterase (CHeS) (P0.05). The results showed that long-term exposure to low concentrations of diazinon causes changes in some haematological and biochemical parameters of R. frisii male brood stocks