scholarly journals AERODYNAMIC ANALYSIS OF A ROLLING WRAPAROUND FIN PROJECTILE IN SUPERSONIC FLOW

2012 ◽  
Vol 19 ◽  
pp. 276-282 ◽  
Author(s):  
JUNG-YOUNG KIM ◽  
SUNG-IN CHO ◽  
IN LEE ◽  
HYOUNG-JIN NA ◽  
SANG-YOUNG JUNG
Keyword(s):  
Supersonic Flow ◽  
Euler Equation ◽  
Three Dimensional ◽  
Numerical Results ◽  
Experimental Results ◽  
Coordinate Frame ◽  
Experiment Data ◽  
Roll Damping ◽  
Time Marching ◽  
Supersonic Region

In this paper, the roll characteristics of a rolling wraparound fin projectile have been investigated in supersonic region. Computation of the flowfield was performed using a time-marching, three-dimensional Euler equation in a body fixed rotating coordinate frame. First, the roll producing moment coefficients of a projectile were obtained from the flowfiled solution at various Mach numbers and compared with the experimental and numerical results. They showed favorable agreement with experimental results in magnitude and sign. Next, the roll damping moment coefficients of a rolling wraparound fin were computed and compared with correlation based on experiment data. The correlation gave a somewhat larger value in magnitude than the present computation. However, the computed values agreed well with correlation in the trend.

Geometric Model and Elastic Constant Prediction of 3D Four-Step Braided Composites Based on the Cubic Spline Curve

2016 ◽  
Vol 08 (02) ◽  
pp. 1650019 ◽  
Author(s):  
Chenbing Ni ◽  
Gaofeng Wei
Keyword(s):  
Geometric Model ◽  
Three Dimensional ◽  
Cubic Spline ◽  
Numerical Results ◽  
Unit Cell ◽  
Experimental Results ◽  
Numerical Calculations ◽  
Braided Composites ◽  
Spline Curve ◽  
Cubic Spline Curve

In this paper, the three-dimensional (3D) four-step ([Formula: see text]) rectangular braided composites are analyzed, the internal yarn spatial topology and mechanical model are determined, a new geometric model, which uses a cubic spline curve to fit yarn trajectory, is presented. The new geometric model can be divided into three types of unit cell models which are the interior, surface and corner unit cell. Based on the new proposed geometric model and the stiffness averaging theory, the corresponding elastic constants are predicted. The predicted numerical results are calculated, and compared with the experimental results. Numerical examples indicate that the numerical calculations well agree with the experimental results. Error values between numerical calculations and experimental results are less than 7.5%. The numerical results verify the validity and accuracy of the new geometrical model.

Prediction of the Aerodynamic Noise Generated by a Centrifugal Fan: Numerical Results and Experimental Validation

2006 ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Sandra Velarde-Sua´rez ◽  
Juan Pablo Hurtado-Cruz ◽  
Bruno Pereiras-Garci´a
Keyword(s):  
Three Dimensional ◽  
Prediction Method ◽  
Numerical Results ◽  
Experimental Results ◽  
Aerodynamic Noise ◽  
Centrifugal Fan ◽  
Fan Noise ◽  
Unsteady Forces ◽  
Model Extension ◽  
Centrifugal Fans

Centrifugal fans are widely used in several applications and, in some cases, the noise generated by these machines has become a serious problem. Usually, the centrifugal fan noise is dominated by tones at the blade passage frequency and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the volute tongue. The purpose of this study is to develop a prediction method for the noise generated by a centrifugal fan. A three-dimensional numerical simulation of the complete unsteady flow on the whole impeller-volute configuration has been carried out using the computational fluid dynamics code FLUENT®. The unsteady forces applied by the fan blades to the fluid are obtained from the data provided by the simulation. The Ffowcs Williams and Hawkings model extension of Lighthill’s analogy predicts the aerodynamic noise generated by the centrifugal fan from these unsteady forces. Also, the noise generated by the fan has been measured experimentally, and the experimental results have been compared to the numerical results in order to validate the aerodynamic noise prediction methodology. A good agreement has been found between the numerical and the experimental results.

Stable and unstable nonlinear resonant response of hanging chains: theory and experiment

1993 ◽  
Vol 440 (1909) ◽  
pp. 345-364 ◽  
Keyword(s):  
Excitation Frequency ◽  
Three Dimensional ◽  
Harmonic Excitation ◽  
Numerical Results ◽  
Experimental Results ◽  
Distinct Region ◽  
Asymptotic Results ◽  
Sensitive Dependence ◽  
Theoretical Predictions ◽  
Hanging Chain

The three-dimensional nonlinear dynamics of a hanging chain, driven by harmonic excitation at the top, are studied first analytically and numerically, and then experimentally. Asymptotic results demonstrate a sensitive dependence on excitation frequency and amplitude. For moderately large excitation amplitudes there are distinct regions of stable two-dimensional and stable three-dimensional response as function of frequency, as well as a distinct region in which all steady-state solutions are unstable. Numerical results were obtained to verify the asymptotic solutions and investigate the dynamics within the irregular response region. Numerical results for even larger excitation amplitudes showed that large impulse-like tension forces cause the chain to lose tension over a region adjacent to its freely hanging end, and then collapse. Following the collapse, the chain configuration intersects itself. Experimental results confirm qualitatively and quantitatively the theoretical predictions. The experimental results also demonstrate the loss of tension and subsequent collapse of the chain at the predicted excitation amplitudes, as well as the intersection of the chain with itself.

Noise Prediction of a Centrifugal Fan: Numerical Results and Experimental Validation

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Sandra Velarde-Suárez ◽  
Juan Pablo Hurtado-Cruz
Keyword(s):  
Three Dimensional ◽  
Cross Flow ◽  
Numerical Results ◽  
Experimental Results ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Noise Prediction ◽  
Centrifugal Fan ◽  
Unsteady Forces ◽  
Centrifugal Fans

Centrifugal fans are widely used in several applications, and in some cases, the noise generated by these machines has become a serious problem. The centrifugal fan noise is frequently dominated by tones at the blade passing frequency as a consequence of the strong interaction between the flow discharged from the impeller and the volute tongue. In this study, a previously published aeroacoustic prediction methodology (Cho, Y., and Moon, Y.J., 2003, “Discrete Noise Prediction of Variable Pitch Cross-Flow Fans by Unsteady Navier-Stokes Computations,” ASME J. Fluids Eng., 125, pp. 543–550) has been extended to three-dimensional turbulent flow in order to predict the noise generated by a centrifugal fan. A three-dimensional numerical simulation of the complete unsteady flow on the whole impeller-volute configuration has been carried out using the computational fluid dynamics code FLUENT®. The unsteady forces applied by the fan blades to the fluid are obtained from the data provided by the simulation. The Ffowcs Williams and Hawkings model extension of Lighthill’s analogy has been used to predict the aerodynamic noise generated by the centrifugal fan from these unsteady forces. Also, the noise generated by the fan has been measured experimentally, and the experimental results have been compared to the numerical results in order to validate the aerodynamic noise prediction methodology. Reasonable agreement has been found between the numerical and the experimental results.

Numerical Simulations of Sloshing in Rectangular Tanks

2006 ◽  
Author(s):  
Samuel R. Ransau ◽  
Ernst W. M. Hansen
Keyword(s):  
Numerical Simulations ◽  
Small Amplitude ◽  
Three Dimensional ◽  
Numerical Results ◽  
Experimental Results ◽  
Non Linear ◽  
Forced Excitation

Simulations of two- and three-dimensional sloshing in rectangular tanks are performed using the commercial CFD code FLOW3D. Small amplitude freely oscillating sloshing and non-linear sloshing due to forced excitation were investigated. The results are compared to both experimental results and other numerical results; and tests are made with different grids. The purpose of this study was the validation of the new VOF algorithm under development at Flow Science and implemented in FLOW3D.

scholarly journals Hydraulic Characteristics and Numerical Simulation of the Entrance Section of Ladder-Shaped Spillway

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
X. B. Gu ◽  
Q. H. Wu ◽  
Y. Wang ◽  
H. X. Zhao
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Dissipation Rate ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Energy Dissipation Rate ◽  
Numerical Results ◽  
Experimental Results ◽  
Flow State ◽  
Hydraulic Characteristics

The ladder-shaped spillway in a certain reservoir junction is set as the engineering background in the paper. The hydraulic similarly model experiment and three-dimensional numerical simulation of hydraulic characteristics of water flow are performed. The outflow capacity, flow state analysis, velocity distribution, water surface line, pressure, and the energy dissipation rate are analyzed, and experimental results are compared with the numerical results. The conclusions demonstrate that the numerical results of the flow characteristics are very proximate to actual experimental results, the changeable law is the same, and their energy dissipation rate is basically consistent; it shows the feasibility of three-dimensional numerical simulation; the conclusions can provide the basis for the optimization about the flow state of the ladder-shaped spillway in the future.

A Note on Three-Dimensional Supercavitating Hydrofoils

1975 ◽  
Vol 19 (03) ◽  
pp. 164-165
Author(s):  
A. J. Acosta ◽  
O. Furuya
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Numerical Results ◽  
Experimental Results ◽  
Surface Theory ◽  
Finite Span ◽  
The Past ◽  
Lifting Surface ◽  
Experimental Findings

The three-dimensional or finite-span effect on supercavitating hydrofoils has received much attention in recent years. Among others may be mentioned the work of Tsen and Gullbaud [1], 3 who give the numerical results of their own fully linearized supercavitating lifting-surface theory together with some experimental data, both their own and from other sources. The numerical results are somewhat different from what one might expect based on existing theories, and some of the experimental findings appear to differ from previously published results. The purpose of this brief note is to compare some of the theoretical and experimental results from reference [1] with other recent works both for fully linearized treatments (valid only for vanishing angles of attack), and nonlinear theories and other experimental data that have been used in the past.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

Conical SNA using fuzzy k-medoids based on user experience

2021 ◽  
pp. 002072092098849
Author(s):  
Poonam Rani ◽  
MPS Bhatia ◽  
Devendra K Tayal
Keyword(s):  
Social Networks ◽  
Social Network ◽  
User Experience ◽  
Three Dimensional ◽  
Experimental Results ◽  
Dynamic Parameters ◽  
Clustering Method ◽  
Cone Model ◽  
Intelligent Approach ◽  
Conical Model

The paper presents an intelligent approach for the comparison of social networks through a cone model by using the fuzzy k-medoids clustering method. It makes use of a geometrical three-dimensional conical model, which astutely represents the user experience views. It uses both the static as well as the dynamic parameters of social networks. In this, we propose an algorithm that investigates which social network is more fruitful. For the experimental results, the proposed work is employed on the data collected from students from different universities through the Google forms, where students are required to rate their experience of using different social networks on different scales.

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