Numerical Modelling of Flow around a Turbine Blade
In this lab we used Fluent package to analyse the flow around a turbine blade profile. The blade is one of a cascade of periodically arranged blades, which means the pitch between the blades is constant. Therefore, the flow around one blade assumed to be identical to flow around any other blade. Hence, it is only necessary to compute the flow through an area which covers the passage between two consecutive blades. The flow around the blade depends on several parameters where the most important one is the inlet angle of the flow relative to the chord of the blade.
In real blade application the inlet conditions obviously depend on the preceding turbine stages which is why they are unknown and the performance of the blade needs to be investigated for a range of inlet conditions to determine the sensitivity to off-design conditions.
In this experiment simulations are run on three different kinds of grids. The highest grid densities are generally close to the blade surfaces, where the highest gradients of flow quantities are expected to occur.
Initially similar boundary conditions were used for each grid and then boundary conditions were changed for the third grid to analyse the effects of changing inlet angle and changing inlet velocity (i.e higher Reynolds number). The details of the grids are given below.
First Grid: Relatively coarse grid of approximately 8300 cells, with fine near-wall grid spacing.
Second Grid: Finer grid of approximately 16500 cells, with fine near-wall grid spacing.
Third Grid: Approximately 6500 cells. Grid density in the outer flow region was similar to the coarser grid above but with coarse near-wall grid spacing, designed for use with the wall function near-wall modelling approach.
Initially the simulations run on each grid...