Adjusting Device Design And Bidirectional Dynamic Analysis For A Millimeter-level Test Probe Inside A Flow Channel Of A Gas Turbine Scale Model

For the arrangement of a millimeter-level test probe inside a gas turbine flow channel, a probe adjusting device is designed to achieve the fixation and the adjustment of test points. For the oscillation characteristics of the probe, a bidirectional fluid-structure coupling simulation is conducted to solve the complicated 3D engineering problem. The simulation results show that both the maximum oscillation amplitude and maximum displacement of the probe happen in the X direction, that is, the coming flow direction. The oscillation amplitudes in X, Y, Z direction are 0.049mm,0.017mm and 0.023mm respectively. To verify the influence of O-ring setup on the probe oscillation behavior, an assumed case without O-ring is also conducted to make comparison, which shows that the O-ring setup has obvious damping effects of decreasing the oscillation amplitude, shrinking the oscillation period and accelerating the decay. In order to investigate the influence of the inlet pressure oscillation on the probe oscillation behavior, a sine function with different amplitudes of 0.1 bar,0.5bar and 1bar is applied on the inlet boundary condition. The sine function frequency is set to 5000Hz based on experiment. The results indicate that the probe oscillation amplitude increases with the development of inlet pressure oscillation, however, the probe oscillation increment is very limited compared to the large pressure increment. Therefore, the probe setup is verified numerically with acceptable oscillation amplitude and sufficient safety margin against the real pressure oscillation inside the flow channel.The computational accuracy, convergence and time are balanced in this thesis, which has a guiding significance to the similar engineering problems. By systematic mesh quality check and near-wall remising, the computational accuracy is assured. In order to maintain the convergence during two-way coupling simulation, a set of 3D mesh motion configurations are researched. There are also innovations in the replacement of the O-ring in the FEM settings.In order to estimate the smallest time step in the transient simulation, the vortex shedding frequency is quoted and tested in the computational trial, then the time step is optimized bigger to restart the coupling simulation, then verified by the boundary layer separation theory and the vortex shedding theory. This estimation method is proved efficient and significant for the similar transient simulation case. In addition, the simulation results of different setting show that there are different oscillation mechanisms in different directions, which has reference value for the research of the structural response and oscillation model.