| Popis: |
Four low-pressure turbine blade geometries designated L1A, L1M, L2A, and L2F were analyzed at low Reynolds numbers to evaluate the effects of flow separation. The F, M, and A suffixes correspond to front-, mid-, and aft-loading, respectively, to denote the relative chordwise location of peak loading and minimum pressure. The four research blade profiles were designed to allow for higher blade loading and, consequently, fewer blades to reduce the overall weight of the low-pressure turbine stage. The present research performs a parametric numerical study of the L1A, L1M, L2A, and L2F low-pressure turbine blade geometries for 24 baseline flow cases using a sixth-order implicit large eddy simulation (ILES) approach. The flow regimes of interest include Reynolds numbers of 10x10^3, 20x10^3, 25x10^3, 30x10^3, 40x10^3, and 50x10^3. The present analysis indicates the L2F airfoil outperforms L1A, L1M, and L2A in the criterion of smallest separation losses at the Reynolds numbers of interest. L2F has the lowest wake pressure loss downstream of the blade and, therefore, exhibits the most preferable Reynolds lapse characteristic of the four high-lift geometries. As the name indicates, L2F is shown to have the forward-most location of peak pressure as well as the forward-most location of separation in comparison to the other three geometries. Furthermore, L2F features the largest distance between the location of minimum pressure and location of separation, indicating L2F has the longest chordwise region of adverse pressure gradient where flow remains attached. |
