Search

We had already obtained the analytical solutions for the compression wave and steady-state oscillating flow in a pipe with a circular cross section [Sato Y, Kanki H. Formulas for compression wave and oscillating flow in circular pipe. To be published in Appl Acoust [accepted 11 Sept. 2006]]. This work contains three key-components. The first key is to simplify the formulas using the unique mathematic technique without losing the accuracy. Simplifying the formulas is the one of the most important factors for formulas used in engineering use. The results will enable us to greatly reduce the work and computation costs. The second is to verify the flow distribution calculated by our formulas. The third is to study the possibility of application of our method to the analysis in turbulent flow region. Kawata et al. have represented the validity of one-dimensional quasi-analysis in turbulent flow region, using the method of D’Souza et al. and the shear viscosity. Therefore, in this paper the validity of the analysis in a turbulence region was verified by proving theoretically that the methods of D’Souza et al. and ours are intrinsically equivalent. The proof of equivalence was accomplished using the formulas simplified in this paper.

Turbine blades are subjected to high static and dynamic loads. In order to reduce the vibration amplitude means of friction damping devices have been developed, e.g. damping wires, interblade friction dampers and shrouds. This paper presents both numerical and experimental results for investigating the dynamical behavior of shrouded turbine blades. The studies are focused on the lowest family of the bladed disk. The aspect of experimental studies, the effect of the shroud contact force on the resonance frequency of the blade was examined by using the simplified blade test stand. Based on the result of the simplified blade studies, the shroud contact force of the real blade was determined in order to stabilize the resonance frequencies of the bladed disk system. The resonance frequencies and mode shapes of the real bladed disk assembly were measured in no rotation and room temperature condition. Finally, the dynamic strains were measured in the actual engine operations by using a telemetry system. The aspect of analytical studies, a non-linear vibration analysis code named DATES was applied to predict vibration behavior of a shrouded blade model which includes contact friction surfaces. The DATES code is a forced response analysis code that employs a 3-dimensional friction contact model. The Harmonic Balance Method (HBM) is applied to solve resulting nonlinear equations of motion in frequency domain. The simulated results show a good agreement with the experimental results.