AERODYNAMIC CHARACTERISTICS OF FLOW OVER BOAT-TAIL MODELS AT SUBSONIC AND SUPERSONIC CONDITIONS

2021 ◽  
pp. 60-69
Author(s):  
Tran The Hung
Keyword(s):  
Shock Waves ◽  
Velocity Distribution ◽  
Pressure Distribution ◽  
Flow Behavior ◽  
Numerical Approach ◽  
Aerodynamic Characteristics ◽  
Numerical Results ◽  
Experimental Results ◽  
Axisymmetric Model

In this study, the flow behavior and drag of the axisymmetric model at subsonic and supersonic speeds were investigated by a numerical approach. The numerical results were validated with previous experimental results to determine the model's accuracy. The numerical results showed that the optimal angles reduce from 14° at subsonic conditions to 6° ÷ 8° at supersonic conditions. At the supersonic speeds, shock waves occur at the head and boat-tail of the model, which leads to changes in the pressure distribution and drag of the model. The flow behavior and velocity distribution around the model were investigated and presented in detail in this study. 

scholarly journals Experiments and numerical calculation to determine aerodynamic characteristics of flows around 3D wings

2014 ◽  
Vol 36 (2) ◽  
pp. 133-143 ◽  
Author(s):  
Nguyen Hong Son ◽  
Hoang Thi Bich Ngoc ◽  
Dinh Van Phong ◽  
Nguyen Manh Hung
Keyword(s):  
Numerical Calculation ◽  
Wind Tunnel ◽  
Pressure Distribution ◽  
Numerical Method ◽  
Aerodynamic Characteristics ◽  
Numerical Results ◽  
Computational Method ◽  
Wing Surface ◽  
Thickness Profile

The report presents method and results of experiments in wind tunnel to determine aerodynamic characteristics of 3D wings by measuring pressure distribution on the wing surfaces. Simultaneously, a numerical method by using sources and doublets distributed on panel elements of wing surface also is carried out to calculate flows around 3D wings. This computational method allows solving inviscid problems for wings with thickness profile. The experimental and numerical results are compared to each other to verify the built program that permits to extend the range of applications with the variation of wing profiles, wing planforms, and incidence angles.

scholarly journals Experimental and Numerical Study on Pressure Distribution of 90° Elbow for Flow Measurement

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Beibei Feng ◽  
Shiming Wang ◽  
Shengqiang Li ◽  
Xingtuan Yang ◽  
Shengyao Jiang
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Pressure Distribution ◽  
Flow Measurement ◽  
Static Pressure ◽  
Numerical Study ◽  
Numerical Approach ◽  
Test System ◽  
Numerical Results ◽  
Helium Gas

Numerical simulation is performed to investigate the pressure distribution of helium gas under high pressure and high temperature for 10 MW High Temperature Gas-Cooled Reactor (HTGR-10). Experimental studies are first conducted on a self-built test system to investigate the static pressure distribution of a 90° elbow and validate the credibility of the computational approach. The 90° elbow is designed and manufactured geometrically the same as HTGR-10. Based on the experimental data, comparison of static pressure of inner wall and outer wall of 90° elbow with numerical results is carried out to verify the numerical approach. With high agreement between experimental results and numerical results of water flowing through 90° elbow, flow characteristics of helium gas under high pressure and high temperature are investigated on the confirmed numerical approach for flow measurement. And wall pressure distribution of eight cross sections of 90° elbow is given in detail to represent the entire region of the elbow.

A Linear Theory of Springing

1980 ◽  
Vol 24 (02) ◽  
pp. 74-84
Author(s):  
Svein O. Skjørdal ◽  
Odd M. Faltinsen
Keyword(s):  
Pressure Distribution ◽  
Linear Theory ◽  
Short Wavelength ◽  
Numerical Results ◽  
Experimental Results ◽  
Function Approach ◽  
Wave Excitation ◽  
Slender Body Theory ◽  
Forced Motion ◽  
Body Theory

A linear slender-body theory of springing is derived. The wave excitation loads are calculated by a generalization of the short-wavelength theory of Faltinsen. A Green's function approach is used to find the pressure distribution. Numerical results are compared with experimental results of Wereldsma and Moeyes. The "forced-motion loads" are obtained by a generalization of the Ogilvie and Tuck approach for forced heave and pitch motions. Discrepancies with other methods are discussed. Numerical results of springing are presented.

scholarly journals Numerical and Experimental Investigations on a Three-Dimensional Rod-Plate Impact

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Jianyao Wang ◽  
Zhuyong Liu ◽  
Jiazhen Hong
Keyword(s):  
Finite Element ◽  
Rigid Motion ◽  
Mesh Size ◽  
Numerical Approach ◽  
Numerical Results ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Element Mesh ◽  
Simulation Accuracy ◽  
Oblique Impacts

There are a few numerical simulation methods available for impact problems. However, most numerical results are not validated experimentally. The goal of this paper is to examine how well the simulation results correspond to the physical reality. In this work, normal and oblique impacts of a hemispherical-tip rod on a square plate are investigated both numerically and experimentally. In the numerical approach, finite element method is used to discretize the contact bodies to describe the deformation precisely combined with the floating reference frame method to describe the rigid motion. In the experimental study, strain gauges and Laser Doppler Vibrometers are employed to measure the high-frequency impact responses. Detailed comparative studies between numerical and experimental results are performed. In the case of normal impact, great attention is given to investigate the influence of finite element mesh size on the simulation accuracy and a “Prediction-Refinement” discretization strategy is proposed for obtaining a mesh which is optimal for impact dynamics. In the case of oblique impact, the influence of Coulomb’s friction coefficient is investigated additionally. It shows that the numerical results are in good agreement with the experimental results for both normal and oblique impacts.

Experimental Study and Numerical Simulation of Domes Under Wind Load

2009 ◽  
Author(s):  
H. Al-Hashimi ◽  
A. C. Seibi ◽  
A. Molki
Keyword(s):  
Numerical Simulation ◽  
Experimental Study ◽  
Wind Speed ◽  
Pressure Distribution ◽  
Structural Integrity ◽  
Material Selection ◽  
Flow Behavior ◽  
Air Flow ◽  
Pressure Vessels ◽  
Experimental Results

Dome structures are of architectural significance in many applications ranging from building decorations to fluid confinement usage such as pressure vessels and storage tanks in the petrochemical industry. Most domes are subjected to severe external loads caused by wind flow. Therefore, careful material selection and structural design of domes is imperative to avoid any unexpected failure. This paper presents the design of an experimental set-up to study the flow behavior around ABS dome models of hemispherical and elliptical shapes and their structural integrity under wind loads. The objective of this paper is to determine the dome’s wall thickness for various geometrical shapes. The domes were placed inside a wind tunnel where the wind speed was varied from 60 to 100 km/hr and pressure distribution on the surface of the dome roof was measured. Pressure measurements were carried out for various attack angles with respect to its centerline using a data acquisition system programmed in LabVIEW™. In addition, flow visualization of the air flow around the dome was carried out using a smoke generator. The experimental study was supplemented by a numerical simulation of the air flow around domes to mimic experiments using Computational Fluid Dynamics (CFD) techniques. The effect of wind on the dome structural integrity was studied using finite element analysis. The experimental results were used to validate the CFD models from which pressure distribution around domes were obtained. Results related to the pressure distribution around domes obtained from the CFD analysis were used as loading conditions to study the structural integrity of the domes using ANSYS™. Preliminary experimental results of wind speed effect on a hemispherical/elliptical dome revealed pressure variations for various angles of attack and height inclination along the dome roof surface.

scholarly journals CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3934
Author(s):  
Federico Lluesma-Rodríguez ◽  
Temoatzin González ◽  
Sergio Hoyas
Keyword(s):  
Shock Waves ◽  
Power Consumption ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Flow Behavior ◽  
Critical Conditions ◽  
Vehicle Speed ◽  
Blockage Ratio ◽  
The Cost

One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.

scholarly journals Quantitative Experimental and Theoretical Investigations on the Interaction of Shock Waves with Magnetic Fields

1969 ◽  
Vol 24 (10) ◽  
pp. 1449-1457
Author(s):  
H. Klingenberg ◽  
F. Sardei ◽  
W. Zimmermann
Keyword(s):  
Magnetic Fields ◽  
Shock Waves ◽  
Physical Model ◽  
Spectroscopic Method ◽  
Experimental Results ◽  
Dimensional Theory ◽  
One Dimensional ◽  
Theoretical Investigations ◽  
Theoretical Predictions ◽  
Interaction Of Shock Waves

Abstract In continuation of the work on interaction between shock waves and magnetic fields 1,2 the experiments reported here measured the atomic and electron densities in the interaction region by means of an interferometric and a spectroscopic method. The transient atomic density was also calculated using a one-dimensional theory based on the work of Johnson3 , but modified to give an improved physical model. The experimental results were compared with the theoretical predictions.

scholarly journals Infrasound and the Avian Navigational Map

2001 ◽  
Vol 54 (3) ◽  
pp. 377-391 ◽  
Author(s):  
Jonathan T. Hagstrum
Keyword(s):  
Shock Waves ◽  
Magnetic Compass ◽  
Experimental Results ◽  
Supersonic Transport ◽  
Atmospheric Processes ◽  
Topographic Features ◽  
Navigational Map ◽  
The North ◽  
North Eastern ◽  
Eastern Usa

Birds can accurately navigate over hundreds to thousands of kilometres, and use celestial and magnetic compass senses to orient their flight. How birds determine their location in order to select the correct homeward bearing (map sense) remains controversial, and has been attributed to their olfactory or magnetic senses. Pigeons can hear infrasound down to 0·05 Hz, and an acoustic avian map is proposed consisting of infrasonic cues radiated from steep-sided topographic features. The source of these infrasonic signals is microseisms continuously generated by interfering oceanic waves. Atmospheric processes affecting the infrasonic map cues can explain perplexing experimental results from pigeon releases. Moreover, four recent disrupted pigeon races in Europe and the north-eastern USA intersected infrasonic shock waves from the Concorde supersonic transport. Having an acoustic map might also allow clock-shifted birds to test their homeward progress and select between their magnetic and solar compasses.

Simulation of a Free Standing Riser Model and Validation With Experimental Results

2014 ◽  
Author(s):  
Marcio Yamamoto ◽  
Sotaro Masanobu ◽  
Satoru Takano ◽  
Shigeo Kanada ◽  
Tomo Fujiwara ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Previous Experiment ◽  
Numerical Results ◽  
Experimental Results ◽  
Previous Article ◽  
Scale Model ◽  
Analysis Software ◽  
Free Standing ◽  
Reduced Scale

In this article, we present the numerical analysis of a Free Standing Riser. The numerical simulation was carried out using a commercial riser analysis software suit. The numerical model’s dimensions were the same of a 1/70 reduced scale model deployed in a previous experiment. The numerical results were compared with experimental results presented in a previous article [1]. Discussion about the model and limitations of the numerical analysis is included.

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