A method is derived to detect and localize linear damage in a structure using the measured modal vibration parameters. This method is applicable when the vibration strain energy is stored in the axial or torsional modes, which differentiates it from previously derived strain-energy-based methods. The new method is compared to the previously derived flexibility-change method for comparison. Both methods are verified by application to an analytical eight degree of freedom model. Experimental validation for both methods is also presented by application to an experimental eight degree of freedom spring-mass structure.

a b s t r a c tThis paper discusses the procedure of a blockage effect correction method involving small-scale wind turbine rotor experimental data. To simulate the aerodynamic performance of full-scale rotors in the field, however, measured data from scaled model experiments need to be analyzed appropriately. One of the most important elements of such an analysis is a procedure to remove the blockage effect of the wind tunnel wall from the measured power data. In this paper, a correction algorithm proposed as part of Glauert's blockage effect correction method is used to process the data from a wind turbine rotor tested with three different wind tunnel sizes. Also, this study considered the modified blockage effect correction method, which has been used to process the rotor thrust data in closed-circuit wind tunnels and open-circuit wind tunnels. A small-scale rotor was tested under the same operating conditions, i.e., the same advance ratio, rotating speed, rotor torque and speed of the wind tunnel. The small-scale wind turbine rotor has a diameter of 1.408 m and a rotating speed according to the tip speed ratio. In each case, the effect of the blockage ratio and aerodynamic characteristics are determined using wind tunnel test results and with a simple analytical correction method. The results of the modified correction method show that the aerodynamic performance levels during a wind tunnel test are cleared by the blockage effect.

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As considerable interests in noise emission from a ship have been increased, the need for localization of noise sources of the marine propeller generating cavitation and singing noise is looming large. In many practical cases, cavitation and singing noise occur on a particular position of the certain blade of the propeller. It is so important to know the position of noise source correctly in order to eliminate or suppress unwanted noise. In this study, we develop "noise source localization technology" using TDOA method.Experimental measurements carried out at the circulating water channel and towing tank show that noise source can be clearly identified and localized using TDOA method.