• International Journal of Aeronautical and Space Sciences
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• v.14 no.1
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• pp.99-104
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• 2013

Configuration design, analysis, and wind tunnel test of a vane-type multi-function air data probe (MFP) was described. First, numerical analysis was conducted for the initial configuration of the MFP in order to investigate aerodynamic characteristics. Then, the design was modified to improve static and dynamic stability for better response characteristics. The modified configuration design was verified through wind tunnel tests. The test results are also used to verify the accuracy of the analytical method. The analytically estimated aerodynamic damping provided by the Navier-Stokes equation solver correlated well with the wind tunnel test results. According to the calculation, the damping coefficient estimated from ramp motion analysis yielded a better correlation with the wind tunnel test than pitch oscillation analysis.

• Wind and Structures
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• v.10 no.6
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• pp.543-554
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• 2007

The suspension bridge is situated in an area of complex topography with both open sea and overland turbulence characteristics, and it is subject to frequent typhoon occurrences. This paper investigates experimentally the possible vortex shedding events of the structure under high wind and typhoon conditions. A single-degree-of-freedom model for the vibration of a unit bridge deck section is adopted to determine the amplitude of vibration and to estimate the parameters related to the lifting force in a vortex shedding event. The results of the studies are presented in a companion paper (Law, et al. 2007). In this paper, statistical analysis on the measured responses of the bridge deck shows that the vibration response at the first torsional mode of the structure has a significant increase at and beyond the critical wind speed for vortex shedding as noted in the wind tunnel tests on a section model of the structure.

• Wind and Structures
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• v.8 no.2
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• pp.79-88
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• 2005

This paper deals with a unified way for calculating vortex-induced vibrations (Aeolian vibrations in transmission line parlance) of undamped single overhead conductors. The main objective of the paper is to identify reduced parameters which would unify the predicted vibration response to the largest possible extent. This is actually done by means of a simple mathematical transformation resulting, for a given terrain (associated to a given wind turbulence intensity), into a single, unified response curve that is applicable to any single multi-layered aluminium conductor. In order to further validate the above process, the predicted, unified response curve is compared with measured response curves drawn from tests run on a full-scale test line using several aluminium-conductor-steel-reinforced (ACSR), all-alloy-aluminium-conductor (AAAC) and aluminium-conductor-alloy-reinforced (ACAR) conductors strung at different tensions. On account of the expected scatter in the results from such field tests, the agreement is shown to be good. The final results are expressed by means of only four different curves pertaining to four different terrain characteristics. These curves may then be used to assess the vibration response of any undamped single, multi-layer aluminium conductor of any diameter, strung at any practical tension.

• Wind and Structures
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• v.13 no.3
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• pp.257-273
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• 2010

The aerodynamic and aero-elastic model tests of the China''s highest cooling tower has been carried out in the TJ-3 Boundary Layer Wind Tunnel of Tongji University. By adopting a scanivalve system, the external wind pressure is firstly measured on $12{\times}36$ taps for a single tower, two and four grouped towers under the condition of both smooth flow and the boundary layer due to surrounding geographic and building topography. The measurements of internal wind pressure distribution of $6{\times}36$ taps are taken for a single tower under the various ventilation ratios ranging from 0% to 100% of stuffing layers located at the bottom of the tower. In the last stage, the wind tunnel tests with an aero-elastic model are carefully conducted to determine wind-induced displacements at six levels (each with eight points) with laser displacement sensors. According to the measurement results of wind pressure or vibration response, the extreme aerodynamic loading values of the single or grouped towers are accordingly analyzed based on probability correlation technique.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.260-267
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• 1999

In this paper, We propose the initial shape finding and dynamic analysis of cable dome structure are presented. Cable dome that is consist of three component such as cable, strut and fabric membrane have complex structural characteristics. Main structural system of cable dome is cable-strut tensegric system, and fabric membrane element Is conceived as cladding roof material. One of the important problem of cable dome is shape finding of those subjected to cable and membrane forces, which stabilize the structures. And the other is structural response from external load effect such as snow and wind When cable dome are subjected to dynamic load such as wind load each structural component has many important problem because of their special structural characteristics. One problem is that geometrical nonlinearity should be considered in the dynamic analysis because large deformation is occurred from their flexible characteristic. The other problem is that wrinkling occurs occasionally because cable and membrane elements can not transmit compressive forces. So this paper describe the physical structural response of cable dome structure.

• Wind and Structures
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• v.21 no.1
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• pp.63-84
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• 2015

The shape of a tall building has significant impact on wind force generation and wind-induced dynamic response. To study the effect of recessed cavities, wind excitations on a wind-tunnel model of an H-section tall building were compared with those on a square-section building model. Characteristics of the fluctuating wind pressures on the side faces of the two tall buildings and their role in the generation of crosswind forces on the buildings were investigated with the space-time statistical tool of proper orthogonal decomposition (POD). This paper also compares the use of different pressure data sets for POD analysis in situations where pressures on two different surfaces are responsible for the generation of a wind force. The first POD mode is found to dominate the generation of crosswind excitation on the buildings.

• The KSFM Journal of Fluid Machinery
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• v.15 no.2
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• pp.36-40
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• 2012

Pitch control of wind turbine is activated above rated wind speed for the purpose of rated power regulation. When we design pitch controller, its gain-scheduling is essential due to nonlinear characteristics of aerodynamic torque. In this study, 2-mass model including a vibration mode of drive-train for a 2 MW wind turbine is considered and pitch control with gain-scheduling using a linearization analysis of the nonlinear aerodynamic torque is applied. Some simulation results for the pitch gain-scheduling under step wind speed are presented and investigated. It is shown that gain-scheduling in pitch control is important especially in the region of high wind speeds when there exists a vibration mode of drive-train.

• Wind and Structures
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• v.8 no.2
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• pp.121-134
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• 2005

Wind-induced vibrations measured in the Tsuruga Test Line are characterized in this paper by single-channel data analysis based on piecewise application of Prony's method. Some of events were identified as galloping, while most of events were buffeting responses, which were confirmed partly by the buffeting analysis. Effects of end condition etc. on the response characteristics are also discussed.

• New & Renewable Energy
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• v.5 no.3
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• pp.4-12
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• 2009

The effect of change in DFIG (doubly-fed wind power generator) rotating speed and active power on the grid was analyzed to understand the characteristics of wind power using the wind power simulator connected to the grid at Gochang Power Quality Test Center. Electric power quality improvement devices (DVR, STATCOM, SSTS) and electric power quality disturbance application devices for 22.9 kV grid are equipped at Gochang Power Quality Test Center. Induction motor and VVVF inverter were used to emulate the blade of a wind power generator, and a simulator for Cage wound induction generator and DFIG was developed. The trial line were assumed to be 20 km and 40 km in length, and variable wind speed pattern was set using wind speed data from Ducjeokdo to verify the power characteristics of the wind power generator according to rotating speed.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.1060-1066
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• 1992

One of the undesirable nonlinear phenomenon called 'wind up' occours when the integrator in the controller and the saturated actuator interact. Large overshoot, slow response, instability, limit cycle and jump resonance are the characteristics of wind up phenomenon. Several 'anti-windup' compensators have been developed to prevent some of the aforementioned nonlinear characteristics such as instabilituy and limit cycle, but none has studied the effect of antiwindup compensator on the jump resonance. In this paper, we developed an analyitcal method to design the compensator to prevent not only limit cycle but also jump resonance. An illustrative example is included to show the compensator eliminates jump resonance of effectively.