Brillouin scattering based fiber optic strain sensor
In this study, stress-induced Brillouin scattering was experimentally analyzed by the weight applied to a specific point of the classical single mode fiber cable. A Brillouin optical time domain analysis (BOTDA) test system was developed for frequency shifts according to different weights applied. For different weights, the frequency values of the scattered light are obtained from the specific point of the fiber cable.
Structural health monitoring based on strain distributions measured by fiber-optic distributed sensors
Highly-dense information in a structure can be useful to identify deformation, applied loads, or some kind of existing damages in implementation of structural health monitoring (SHM). Fiber-optic distributed strain sensors return a value of strain as a function of the linear position along an optical fiber, as they are having useful characteristics of optical fiber sensors for SHM, such as immunity of electromagnetic interference, durability and capability to be embedded into composite materials. It has been confirmed that the applicability of the distributed sensor to SHM could be improved as making the spatial resolution higher. In this paper, the principle of the developed fiber-optic distributed sensor is shown. The simulation technique considering both structural and optical effects seamlessly in strain measurements and the measurement technique enabling simultaneous distributed strain and temperature measurements will be shown in the conference.
Turbine blade temperature calculation and life estimation - a sensitivity analysis
Abstract The overall operating cost of the modern gas turbines is greatly influenced by the durability of hot section components operating at high temperatures. In turbine operating conditions, some defects may occur which can decrease hot section life. In the present paper, methods used for calculating blade temperature and life are demonstrated and validated. Using these methods, a set of sensitivity analyses on the parameters affecting temperature and life of a high pressure, high temperature turbine first stage blade is carried out. Investigated uncertainties are: (1) blade coating thickness, (2) coolant inlet pressure and temperature (as a result of secondary air system), and (3) gas turbine load variation. Results show that increasing thermal barrier coating thickness by 3 times, leads to rise in the blade life by 9 times. In addition, considering inlet cooling temperature and pressure, deviation in temperature has greater effect on blade life. One of the interesting points that can be realized from the results is that 300 hours operation at 70% load can be equal to one hour operation at base load.