scholarly journals Wind-induced Stresses on Water Surfaces: A Wind-tunnel Study

1963 ◽  
Vol 16 (4) ◽  
pp. 475 ◽  
Author(s):  
LM Fitzgerald
Keyword(s):  
Wind Tunnel ◽  
Surface Stress ◽  
Water Surface ◽  
Surface Films ◽  
Surface Slope ◽  
Wind Speeds ◽  
Induced Stresses ◽  
Set Up ◽  
Wind Tunnel Study ◽  
Good Agreement

A laboratory wind tunnel has been used to study the effect of wind on a water surface. The surface shearing stress 7'0 and the slope of the surface induced by wind have been measured. Values of the surface stress, in good agreement with each other, have been obtained from: (a) the velocity profile of the wind above the water surface, (b) the measured values of surface slope or set-up, and (c) the spreading characteristics of surface films. The drag coefficient, Cn = TO/ pu2n, was found to be constant for wind speeds up to about 412 cm/s and then to rise gradually for higher wind speeds.

Experimental Study of Airflow Around the Syracuse CoE Building

2009 ◽  
Author(s):  
Joshua Kehs ◽  
Dougal Bohl ◽  
Goodarz Ahmadi ◽  
Behtash Tavakoli
Keyword(s):  
Wind Tunnel ◽  
Physical Model ◽  
Wind Tunnel Experiments ◽  
Computer Simulation Study ◽  
Exterior Surface ◽  
Piv Measurements ◽  
3D Cad ◽  
Wind Speeds ◽  
Under Construction ◽  
Good Agreement

The Center of Excellence (CoE) in Environmental and Energy Building in Syracuse is currently under construction and is planned for completion in 2009. In this study, wind tunnel experiments of the CoE Building were performed. A 3D CAD model was created from architectural blueprints and was used to create a scale (1/16th inch = 1 foot) physical model using the stereo-lithography techniques. The details of the building structure were captured in the model for features with characteristic lengths greater than 1% of the building height. The physical model included 54 surface pressure taps located over the model’s exterior surface. The model was installed on a turntable built into the floor of the wind tunnel. Pressure measurements were taken at several wind speeds for different wind directions. PIV measurements were performed in 2 planes for the same wind directions and speeds. From the PIV measurements, 2D mean and root-mean square (RMS) velocities mean and RMS vorticity were calculated. The experimental data was compared with the computer simulation study and good agreement was found.

scholarly journals Comparative Study of Ram Air Turbines based on Wind Tunnel Study for Specific Air Borne Energy Extraction

2021 ◽  
Vol 71 (5) ◽  
pp. 588-593
Author(s):  
A. Arunachaleswaran ◽  
Muralidhar Madhusudan ◽  
A. Ramya ◽  
S. Elangovan ◽  
M. Sundararaj
Keyword(s):  
Power Generation ◽  
Wind Tunnel ◽  
Comparative Study ◽  
Electrical Energy ◽  
Energy Extraction ◽  
Specific Requirement ◽  
Hydraulic Power ◽  
Wind Speeds ◽  
Emergency Power ◽  
Wind Tunnel Study

Ram Air Turbines (RAT) are used for emergency on-board power generation on aircraft and associated systems. Many studies on usage of RATs have shown promising results in terms of using RATs as a source of emergency on-board power generation. Many external podded systems on aircraft utilise RATs for self-sufficient adaptation. These pods generate their own power using RATs for their power requirements instead of depending on the mother aircraft power. Commercial cargo planes use RATs for generating emergency hydraulic power. A RAT was suggested to be used for emergency power, during failure of main alternator on a prototype aircraft. A specific requirement of the RAT was also to produce high drag for aerodynamic braking when deployed and concurrently generate electrical energy. Three models with different solidity were studied in wind tunnel at different wind speeds for suitability of this drag-energy combination. This paper presents the results of the study. Based on the results, a suitable RAT was selected for further analysis and ground trials.

scholarly journals Laboratory Measurements of Light Scattering by Dust Particles

1996 ◽  
Vol 150 ◽  
pp. 409-413
Author(s):  
Patrick P. Combet ◽  
Philippe L. Lamy
Keyword(s):  
Light Scattering ◽  
Laser Beam ◽  
Mie Theory ◽  
Spherical Particles ◽  
Dust Particles ◽  
Laboratory Measurements ◽  
Scattering Function ◽  
Hene Laser ◽  
Set Up ◽  
Good Agreement

AbstractWe have set up an experimental device to optically study the scattering properties of dust particles. Measurements over the 8 — 174° interval of scattering angles are performed on a continuously flowing dust loaded jet illuminated by a polarized red HeNe laser beam. The scattering is averaged over the population of the dust particles in the jet, which can be determined independently, and give the “volume scattering function” for the two directions of polarization directly. While results for spherical particles are in good agreement with Mie theory, those for arbitrary particles show conspicuous deviations.

scholarly journals Galloping Stability and Wind Tunnel Test of Iced Quad Bundled Conductors considering Wake Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xiaohui Liu ◽  
Ming Zou ◽  
Chuan Wu ◽  
Mengqi Cai ◽  
Guangyun Min ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Transmission Lines ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Aerodynamic Coefficients ◽  
Wake Effect ◽  
Aerodynamic Coefficient ◽  
Set Up ◽  
The Stability ◽  
Three Degrees Of Freedom

A new quad bundle conductor galloping model considering wake effect is proposed to solve the problem of different aerodynamic coefficients of each subconductor of iced quad bundle conductor. Based on the quasistatic theory, a new 3-DOF (three degrees of freedom) galloping model of iced quad bundle conductors is established, which can accurately reflect the energy transfer and galloping of quad bundle conductor in three directions. After a series of formula derivations, the conductor stability judgment formula is obtained. In the wind tunnel test, according to the actual engineering situation, different variables are set up to accurately simulate the galloping of iced quad bundle conductor under the wind, and the aerodynamic coefficient is obtained. Finally, according to the stability judgment formula of this paper, calculate the critical wind speed of conductor galloping through programming. The dates of wind tunnel test and calculation in this paper can be used in the antigalloping design of transmission lines.

Simulation Study on Dynamic Reactive Power Compensation of Grid-Connected Wind Farms

2013 ◽  
Vol 756-759 ◽  
pp. 4171-4174 ◽  
Author(s):  
Xiao Ming Wang ◽  
Xing Xing Mu
Keyword(s):  
Voltage Stability ◽  
Wind Farm ◽  
Reactive Power ◽  
Wind Farms ◽  
Reactive Power Compensation ◽  
Wind Speeds ◽  
Wind Generators ◽  
Reactive Compensation ◽  
Farm Model ◽  
Set Up

With the Asynchronous wind generators as research object, this paper analyzes the problems of the voltage stability and the generation mechanism of the reactive power compensation during the wind farms connected operation. For paralleling capacitor bank has shown obvious defects, therefore this paper employs dynamic reactive power compensation to improve reactive characteristics of grid-connected wind farms. With the influences of different wind disturbances and grid faults on wind farms, wind farm model is set up and dynamic reactive power compensation system and wind speeds are built in the Matlab/Simulink software, The simulation result shows that they can provide reactive power compensation to ensure the voltage stability of the wind farms. But STATCOM needs less reactive compensation capacity to make sure the voltage and active power approaching steady state before the faults more quickly, Therefore STATCOM is more suitable for wind farms connected dynamic reactive power compensation.

The Reduction of Bias Error in Transfer Function Estimates Using FFT-Based Analyzers

1984 ◽  
Vol 106 (1) ◽  
pp. 29-35 ◽  
Author(s):  
P. Cawley
Keyword(s):  
Transfer Function ◽  
Random Excitation ◽  
Analogue Computer ◽  
Bias Error ◽  
Testing Time ◽  
Theoretical Predictions ◽  
Set Up ◽  
Modal Mass ◽  
Time Required ◽  
Good Agreement

The susceptibility to bias error of two methods for computing transfer (frequency response) functions from spectra produced by FFT-based analyzers using random excitation has been investigated. Results from tests with an FFT analyzer on a single degree-of-freedom system set up on an analogue computer show good agreement with the theoretical predictions. It has been shown that, around resonance, the bias error in the transfer function estimate H2 (Syy/Sxy*) is considerably less than that in the more commonly used estimate, H1 (Sxy/Sxx). The record length, and hence the testing time, required for a given accuracy is reduced by over 50 percent if the H2 calculation procedure is used. The analysis has also shown that if shaker excitation is used on lightly damped structures with low modal mass, it is important to minimize the mass of the force gage and the moving element of the shaker.

Sign in / Sign up

Export Citation Format

Share Document