Laser Velocimeter Measurements of Axial Velocity Field in the NASA Supersonic Fan Rotor

An analysis of laser Doppler velocimeter (LDV) data for the axial velocity flowfield in the rotor of the Mach 2 inlet flow supersonic throughflow fan (SSTF) is presented in this paper. The paper starts with a short description of the SSTF test package to highlight the specifics of the SSTF operation. It is followed by a detailed description of a dedicated LDV system for measurement in a supersonic throughflow fan and the experience gained. Most of the experimental data presented were acquired in a low supersonic throughflow regime (inlet Mach number of 1.4). The results and conclusions presented are based mainly on the experimental data only. A limited amount of computational fluid dynamics (CFD) predictions were used for comparison with the experimental results. The CFD methods, however, are not discussed in this paper. As shown in this paper, a reasonably good agreement between the LDV data and the CFD predictions was found for the low supersonic throughflow regime. The design point data (inlet Mach number of 2.0) exhibited an unexpectedly high noise in the velocity data in comparison with the data for low supersonic throughflow operating conditions. For the off-design supersonic regime (shock in rotor), substantial differences exist between the experimental and computational data.