Final Activity Report Summary - FLUISTCOM (Fluid-structure interaction for combustion systems)
The research activities in the FLUISTCOM were targeted towards the improved understanding of transient combustion and its coupling with combustor wall vibration. The overall objective was to provide well-validated numerical models of transient combustion and wall vibration. Indeed, these studies aimed at leading to design rules of combustors that are extremely robust even in combustion oscillatory situations. In order to reach these ambitious goals, in the frame of FLUISTCOM a total of 5 research fellows have been recruited.
The most significant research achievements were the development of wall-law based boundary conditions for unsteady Large Eddy Simulation (LES) methods, as well as the one-way coupling and investigations made on "1.5-coupling" methods. In order to validate the numerical methods developed in frame of the FLUISTCOM project, experimental investigations were conducted in the academic test rig. A lab-scale burner has been built for reactive flow measurements.
The thermal fluid-structure interaction at liner walls was investigated mainly by employing the unsteady U-RANS approach. These research activities focused on the thermal boundary layer response and the effects of unsteady flow. The numerical results showed that the low-Reynolds turbulence model was in good agreement with the experimental data especially in the high-amplitude pulsation regime and for pulsation frequencies above the quasi-steady limit. Similar limitations were observed in LES simulation when the boundary layer was not resolved and the wall-function approach was used. Low-Reynolds turbulence models seem to be more accurate but are unable to predict the experimental dependence of the overall heat transfer on pulsation frequency.
The research on mechanical fluid-structure interaction concentrated on the vibration analysis caused by oscillating flames in combustion chambers. One-way coupling (fluid-to-wall) was obtained by first recording the position of the internal surface nodes in the structural mesh. Then fluid simulations were performed and the values of fluctuating flow pressure were obtained at these locations. The obtained pressure quantities were used as the input for the structural code and the non-linear dynamic computation was performed.
Overall, the research conducted in FLUISTCOM demonstrated the feasibility of investigations on fluid-structure interaction. Only very small wall displacements were observed as consequence of the reacting flow instabilities or wall heat flux. Thus, in the context of the present configuration, there was no need for two-way coupling, i.e. the insignificant wall displacements had no impact on the fluid flow.
The training and mobility activities are summarised by 5 workshops organised by the research partners (one of them in the frame of an international conference), in total 10 exchanges and secondments to the industry partner of duration between one week and three months took place. Beyond project end several long lasting collaborations have been established between the research fellows.
The most significant research achievements were the development of wall-law based boundary conditions for unsteady Large Eddy Simulation (LES) methods, as well as the one-way coupling and investigations made on "1.5-coupling" methods. In order to validate the numerical methods developed in frame of the FLUISTCOM project, experimental investigations were conducted in the academic test rig. A lab-scale burner has been built for reactive flow measurements.
The thermal fluid-structure interaction at liner walls was investigated mainly by employing the unsteady U-RANS approach. These research activities focused on the thermal boundary layer response and the effects of unsteady flow. The numerical results showed that the low-Reynolds turbulence model was in good agreement with the experimental data especially in the high-amplitude pulsation regime and for pulsation frequencies above the quasi-steady limit. Similar limitations were observed in LES simulation when the boundary layer was not resolved and the wall-function approach was used. Low-Reynolds turbulence models seem to be more accurate but are unable to predict the experimental dependence of the overall heat transfer on pulsation frequency.
The research on mechanical fluid-structure interaction concentrated on the vibration analysis caused by oscillating flames in combustion chambers. One-way coupling (fluid-to-wall) was obtained by first recording the position of the internal surface nodes in the structural mesh. Then fluid simulations were performed and the values of fluctuating flow pressure were obtained at these locations. The obtained pressure quantities were used as the input for the structural code and the non-linear dynamic computation was performed.
Overall, the research conducted in FLUISTCOM demonstrated the feasibility of investigations on fluid-structure interaction. Only very small wall displacements were observed as consequence of the reacting flow instabilities or wall heat flux. Thus, in the context of the present configuration, there was no need for two-way coupling, i.e. the insignificant wall displacements had no impact on the fluid flow.
The training and mobility activities are summarised by 5 workshops organised by the research partners (one of them in the frame of an international conference), in total 10 exchanges and secondments to the industry partner of duration between one week and three months took place. Beyond project end several long lasting collaborations have been established between the research fellows.