Evaluating structural properties of new ceramic candle filters using the dynamic characterization method

This paper presents an interpretation of dynamic characterization tests aim ed at identifying the structural stiffness of ceramic candle filters. The c andle filter is a hollow cylindrical structure made of a porous material th at protects the gas turbine component in advanced, coal fired power generat ion systems. A total of 59 ceramic candle filters have been tested nondestr uctively. All filters were subjected to an excitation force and the respons e was picked up by an accelerometer in a free-free boundary condition. The experimental results were evaluated using digital signal analysis to obtain the frequency response function and vibration mode shape of each filter. F inite element models were built to calculate the filter's dynamic response. Results from this study indicate that the vibration signatures can be used as an index to quantify the structural properties of ceramic candle filter s. The influence of Poisson's ratio on the vibration frequency is minimal. The results also show that the average Young's modulus values obtained far the Coors, Schumacher TF-20 and Refractron 326 filters are about 29.6 x 10( 9) Pa (4.3 x 10(6) psi), 42.7 x 10(9) Pa (6.2 x 10(6) psi) and 51 x 10(9) P a (7.4 x 10(6) psi), respectively.