Analysis of High Load Turbine Blades at Low Re Numbers with CFXBladeGen+
Gas turbine blades, especially those with high camber, exhibit flow separation in the suction side at partload conditions. These conditions may arise due to reduced power demand in stationary applications, or due to flight at high altitudes. In the latter case, the reduced density compounds the lower operating velocities required to enhance range, and small trough-flows result in separation. When the inlet velocity is reduced to the point that the flow is laminar, the flow in the suction side does not embody enough kinetic energy to prevent flow reversal. Hence, a separation bubble takes place. The ensuing reduced blade effectiveness results in losses that increase fuel consumption. It has been shown experimentally in cascades that the inception and extent of separation are respectively a weak and strong function of the flow Reynolds no. Also, cascade experimental data are available in the form of pressure and loss coefficients. The flow around a highly loaded blade is modeled with CFX-BladeGen Plus. The insights thus gained regarding wake flow and surface pressures are discussed in relation to data and conclusions afforded from other experimental and analytical work. The experience with the predictive possibilities of numerical techniques regarding this difficult problem, along with the benefits accrued via simulation are addressed.