scholarly journals Features of subsonic air flow around perforated plates

2020 ◽  
Author(s):  
A.G. Golubev ◽  
E.G. Stolyarova ◽  
M.D. Kalugina
Keyword(s):  
Normal Force ◽  
Air Flow ◽  
Angle Of Attack ◽  
Vertical Plane ◽  
Perforated Plate ◽  
Aerodynamic Characteristics ◽  
Perforated Plates ◽  
Subsonic Speed ◽  
Solid Plate ◽  
Zero Degree

The paper considers the process of flow around a flat plate with rounded front and side edges at various degrees of surface perforation. The flow patterns were studied both near the plate with zero degree of perforation, and at the surface of plates with a perforation degree of more than 20%. The features of air flow directly inside the holes at various values of the angle of attack are considered. Isobars of pressure distribution in the vertical plane of the flow over a solid plate are given. A simulation of the flow around a perforated plate at subsonic speed of the incoming air flow is performed, aerodynamic characteristics are obtained and graphical dependencies of the aerodynamic coefficients of longitudinal and normal force on the angle of attack are presented. Special attention is paid to the comparative analysis of aerodynamic characteristics for solid (with zero degree of perforation) and perforated plates.

Study on Equivalent Stress to Control Average Inelastic Behavior of Perforated Plates

2014 ◽  
Author(s):  
Yeldos Kultayev ◽  
Naoto Kasahara
Keyword(s):  
Stress Ratio ◽  
Elevated Temperatures ◽  
Equivalent Stress ◽  
Perforated Plate ◽  
Estimation Method ◽  
Inelastic Behavior ◽  
Perforated Plates ◽  
Inelastic Analysis ◽  
Solid Plate ◽  
Simple Models

Next generation reactors which are subjected to elevated temperatures must be designed to account for inelastic deformation along with elastic one. In order to simplify design analysis of perforated portions, conventionally axisymmetric models with equivalent elastic materials are employed. To extend to inelastic analysis, a method of Effective Stress Ratio (ESR) has been studied in recent years. Previous studies have shown that perforated plates have their own ESR and it is a function of geometry and is independent from their materials. In this study the only geometry dependence and physical meaning of ESR were clarified. ESR results were compared with Reference Stress Method (RSM) results for unit-ligaments with various ligament efficiencies. It was revealed that RSM results coincide with ESR. First meaning of ESR is stress ratio between solid plate and perforated plate at the same reference stresses. Second meaning of this ratio is how plasticity properties of equivalent solid plate have to be changed to give the same steady state deformation rate at the same mean boundary stress. Moreover, to clarify stress redistribution control mechanism at different ligament efficiencies, simple models were developed and an estimation method based on simple models was proposed for engineering use.

Resonant frequencies of perforated plates with rectangular slots

2016 ◽  
Vol 232 (7) ◽  
pp. 1247-1254 ◽  
Author(s):  
Oumar R Barry ◽  
Emadeddin Y Tanbour
Keyword(s):  
Elastic Properties ◽  
Material Properties ◽  
Natural Frequencies ◽  
Perforated Plate ◽  
Free Vibrations ◽  
Equivalent Material ◽  
Resonant Frequencies ◽  
Perforated Plates ◽  
Rectangular Slot ◽  
Solid Plate

Most previous work on perforated plates employed elasticity theory to determine equivalent material properties that make the deflection of the solid plate identical to that of the perforated plate. However, it will be inaccurate to utilize the proposed elastic properties to predict the natural frequencies of a perforated plate. In this paper, the free vibrations of perforated plates with rectangular slots and rectangular slot-patterns are examined using theoretical and finite-element methods. The natural frequencies are obtained for various cases of perforations. An explicit expression is obtained for the equivalent elastic properties using the regression analysis method. These effective material properties are used in a solid-plate model to predict the natural frequencies of the corresponding perforated plate. To validate the theoretical analysis, the effective resonant frequencies are compared with the exact natural frequencies of the perforated plates. Parametric studies are conducted to examine the effect of both parallel and perpendicular ligament efficiencies on the resonant frequencies.

Subsonic Wing-Body Interference for Missile Configurations at Large Angles of Attack

1977 ◽  
Vol 28 (3) ◽  
pp. 163-175 ◽  
Author(s):  
K D Thomson
Keyword(s):  
Normal Force ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Supporting Evidence ◽  
Pitching Moment ◽  
Aerodynamic Properties ◽  
Moment Estimates ◽  
Effective Angle ◽  
Series Of Experiments

SummaryAn approximate method is presented for estimating the normal-force and pitching-moment characteristics (including the effects of wing-body interference) of wings mounted on bodies. A pair of wings placed side by side can be specified which, when operating at a certain angle of attack different from the geometrical angle of attack, have the same aerodynamic properties as the wings in the presence of the body. The equivalent wings and effective angle of attack are determined, and these enable the wing-body normal force and pitching moment to be estimated for wing-body combinations at angles of attack up to 90°. Comparisons made with the results of a specially conducted series of experiments on rectangular and delta planform wing-body combinations have provided gratifying supporting evidence for the theory.Estimates are also made of the normal force and pitching moment produced by two cone-cylinder bodies over the angle of attack range 0° to 90°. These estimates, when added to the wing-body normal-force and pitching-moment estimates, have resulted in a set of longitudinal aerodynamic characteristics which are generally close to those found experimentally. The method appears to have application in the preliminary design phase for slewing missiles.

Determining the aerodynamic characteristics of the colorado potato beetle collection device

10.12737/2438 ◽  
2014 ◽  
Vol 8 (4) ◽  
pp. 87-91
Author(s):  
Хазиахметов ◽  
Rustem Khaziakhmetov ◽  
Хасанов ◽  
Ilmer Khasanov ◽  
Валиев ◽  
...  
Keyword(s):  
Colorado Potato Beetle ◽  
Air Flow ◽  
Vertical Plane ◽  
Aerodynamic Characteristics ◽  
Technological Parameters ◽  
Fall Velocity ◽  
Rational Form ◽  
Potato Beetle ◽  
The Right ◽  
The Impact

In this paper we examined the rotor aerodynamic characteristics of some devices for collection of the Colorado potato beetle and its larvae, consisting of a casing in the form of an oval, separated at the top, and a device, through which the casing arranged inside the airflow. The executed theoretical studies devoted to determining the necessary speed-fall of larvae and beetles, computer modeling of air flow inside the device to identify a rational form of housing and assess the impact of the presence of bushes on the velocity field. According to studies the authors prepared a formula and fall velocity values, depending on the orientation and size of insects in space. It was established that the rate of upflow of υ> 35 m/s provides puffing as adults and larvae, irrespective of their orientation in the housing. In the simulation of air flow within the enclosure, the system of hydrodynamic equations were solved by finite element method using the members of the software packages Salome and OpenFoam of freeware CAE-Linux distribution. It was established that the first in the center upward flow with the velocity of 35m/s is implemented, that blows bush. After that, the flow “leaves” to the right, because the bush creates a drag not symmetrical about a vertical plane, passing through the horizontal axis of the housing. Further in the device a stable motion flow counterclockwise was formed. The obtained results allow to further substantiate the rational form of housing and basic structural and technological parameters of rotor device for collecting the Colorado potato beetle and its larvae.

Influence of a rough surface on the aerodynamic characteristics of a rotating cylinder

2021 ◽  
Vol 103 (3) ◽  
pp. 52-59
Author(s):  
N.K. Tanasheva ◽  
◽  
A.R. Bakhtybekova ◽  
A.Zh. Tleubergenova ◽  
L.L. Minkov ◽  
...  
Keyword(s):  
Rough Surface ◽  
Drag Force ◽  
Air Flow ◽  
Angle Of Attack ◽  
Experimental Studies ◽  
Rotating Cylinder ◽  
Aerodynamic Characteristics ◽  
Magnus Force ◽  
Lifting Force ◽  
Relative Roughness

The article considers the influence of the relative roughness of a cylindrical blade on aerodynamic characteristics. It is known that the operation basis of blades under consideration is the Magnus effect, which is characterized by appearance of a lifting force (Magnus force), when the cylinders rotate in a transverse flow. This force is used to rotate the wind wheel, similar to lifting force, but can have a much larger value when selecting optimal conditions, both geometric and aerodynamic. The authors conducted a comparative analysis of cylinder layout with a relative roughness (0.005 ÷ 0.02). Experimental studies of aerodynamics process of rotating cylinders were carried out in the aerodynamic laboratory using the T-1-M wind tunnel at an air flow value of 5 to 15 m/s. Graphs of dependences of rotating cylinder's lifting force and drag force on the changing air flow velocity and on relative roughness, k/d, are obtained. For further study experimental cylinder layout’s aerodynamic parameters, the most optimal is the variant with a relative roughness value of 0.02, which had high indicators, was selected. In the course of experimental studies, graphs of the dependence of the values of lift and drag force on the angles of attack of a single rotating cylinder with a rough surface on the speed and angle of attack of the wind flow (0°, 30° and 60°) were obtained. It is established that the effective angle of attack is 0°, at which aerodynamic characteristics’s maximum values were obtained.

scholarly journals Influence of Holes Manufacture Technology on Perforated Plate Aerodynamics

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6624
Author(s):  
Joanna Grzelak ◽  
Ryszard Szwaba
Keyword(s):  
Gas Turbines ◽  
Perforated Plate ◽  
Flow Characteristics ◽  
Aerodynamic Characteristics ◽  
Physical Models ◽  
Experimental Investigations ◽  
Perforated Plates ◽  
Flow Losses ◽  
Large Numbers

Transpiration flow is a very important and still open subject in many technical applications. Perforated walls are useful for the purpose of “flow control”, as well as for the cooling of walls and blades (effusive cooling) in gas turbines. We are still not able to include large numbers of holes in the numerical calculations and therefore we need physical models. Problems are related also to the quality of the holes in perforated plates. The present transpiration analysis concerns with experimental investigations of the air flow through perforated plates with microholes of 125 and 300 µm diameters. A good accordance of the results with other experiments, simulations and theory was obtained. The received results very clearly show that technology manufacturing of plate holes influences on their aerodynamic characteristics. It turned out that the quality of the plate microholes using laser technology and, consequently, the shape of the hole, can affect the flow losses. Therefore, this effect was investigated and the flow characteristics in both directions were measured, i.e., for two plate settings.

Aerodynamic characteristics of a dual-spin projectile with canards

2019 ◽  
Vol 233 (12) ◽  
pp. 4541-4553
Author(s):  
Xiaodong Liu ◽  
Xiaosheng Wu ◽  
Jintao Yin
Keyword(s):  
Mach Number ◽  
Normal Force ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Lateral Force ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Force Coefficient ◽  
Sliding Mesh ◽  
Flow Mechanisms

Based on the three-dimensional Navier–Stokes (N–S) equations, using unsteady numerical technology, flow over a dual-spin projectile was simulated to investigate its aerodynamic characteristics during flight. Spin was achieved via the sliding mesh method. The influence laws of the aftbody spin rate, Mach number, and angle of attack on the aerodynamic characteristics of the projectile are presented, and the flow mechanisms for the laws are revealed. The results demonstrate that the influence of the aftbody spin rate on the normal force coefficient is very small, whereas, on the lateral force coefficient, it is larger. With the increase in the Mach number, the time-averaged normal force coefficient and lateral force coefficient increase, while the fluctuation quantities of the normal force coefficient and the lateral force coefficient decrease. The variation of angle of attack will influence the size, distribution, and interference effect of the shedding vortices.

scholarly journals Numerical Study of Air Flow Induced by Shock Impact on an Array of Perforated Plates

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 1051
Author(s):  
Lite Zhang ◽  
Zilong Feng ◽  
Mengyu Sun ◽  
Haozhe Jin ◽  
Honghui Shi
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Air Flow ◽  
Perforated Plate ◽  
Incident Shock ◽  
Reflected Shock Wave ◽  
Perforated Plates ◽  
Reflected Shock ◽  
Shock Mach Number ◽  
Dynamic Wave

This study is focused on the propagation behavior and attenuation characteristics of a planar incident shock wave when propagating through an array of perforated plates. Based on a density-based coupled explicit algorithm, combined with a third-order MUSCL scheme and the Roe averaged flux difference splitting method, the Navier–Stokes equations and the realizable k-ε turbulence model equations describing the air flow are numerically solved. The evolution of the dynamic wave and ring vortex systems is effectively captured and analyzed. The influence of incident shock Mach number, perforated-plate porosity, and plate number on the propagation and attenuation of the shock wave was studied by using pressure- and entropy-based attenuation rates. The results indicate that the reflection, diffraction, transmission, and interference behaviors of the leading shock wave and the superimposed effects due to the trailing secondary shock wave are the main reasons that cause the intensity of the leading shock wave to experience a complex process consisting of attenuation, local enhancement, attenuation, enhancement, and attenuation. The reflected shock interactions with transmitted shock induced ring vortices and jets lead to the deformation and local intensification of the shock wave. The formation of nearly steady jets following the array of perforated plates is attributed to the generation of an oscillation chamber for the inside dynamic wave system between two perforated plates. The vorticity diffusion, merging and splitting of vortex cores dissipate the wave energy. Furthermore, the leading transmitted shock wave attenuates more significantly whereas the reflected shock wave from the first plate of the array attenuates less significantly as the shock Mach number increases. The increase in the porosity weakens the suppression effects on the leading shock wave while increases the attenuation rate of the reflected shock wave. The first perforated plate in the array plays a major role in the attenuation of the shock wave.

Elasto-Plastic Analysis of Perforated Plates Containing Triangular Penetration Patterns of 10 Percent Ligament Efficiency

1979 ◽  
Vol 101 (3) ◽  
pp. 210-215 ◽  
Author(s):  
D. P. Jones ◽  
J. L. Gordon
Keyword(s):  
Work Hardening ◽  
Pure Shear ◽  
Perforated Plate ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Hardening Material ◽  
Perforated Plates ◽  
Solid Plate ◽  
Deformation Plasticity ◽  
Concentration Factors

The finite element method is utilized to obtain the elasto-plastic stress and strain fields in a perforated plate made of a work-hardening material. The perforated plate contains penetrations arranged in a triangular pattern with a ligament efficiency of 10 percent and is considered to be in a state of plane stress. Stress distributions as well as strain concentration factors are presented for the two orthogonal uniaxial and the pure shear load cases. Effective elasto-plastic equivalent solid plate properties are presented in terms of Hill’s anisotropic deformation plasticity theory. The localized stress and plastic strain distributions are discussed in terms of the work-hardening characteristics of the material. Conclusions are drawn relevant to the plastic design and analysis of perforated plates.

High Speed Flow through Perforated Plates

1960 ◽  
Vol 64 (590) ◽  
pp. 103-105
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Perforated Plate ◽  
Wire Mesh ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Perforated Plates ◽  
Speed Flow ◽  
Flow Through ◽  
Points Of View

The flow through porous screens has been widely studied from both the theoretical and experimental points of view. The most widely used types of screen are the wire mesh and the perforated plate, and the majority of the literature has been concerned with the former. Several attempts have been made to correlate the parameters governing the flow through such screens, i.e. the pressure drop, the flow conditions and the geometry of the mesh.

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