Evaluation of Inlet Conditions of an AFT Mounted BLI Design in a Sub-Scale Test Rig

Abstract

Abstract A unique sub-scale rig for studying boundary layer ingestion (BLI) propulsion has been developed by National Research Council of Canada (NRC). The rig is capable of varying the operating pressure levels and Mach numbers independently. It consists of a boundary layer generator to simulate boundary layer development over an aircraft fuselage. The boundary layer thickness upstream of the fan blades is controlled independent of other parameters using air injected through a perforated plate. The purpose is to demonstrate the advantages of BLI in reducing the power required for a given thrust and to evaluate varying inlet conditions on BLI fan performance. This paper provides details on set-up and procedure for testing an aft-mounted, distortion-tolerant fan tested at a number of different operating conditions. The results shows how the fan speed can affect the boundary layer thickness at the nacelle inlet. Different strategies for probe traversing are evaluated to find suitable procedures for obtaining valid data. Considering that there are 24 vanes, the 36° intervals give a better representation of the average compared to 45° intervals, since the clocking relative to the stator wakes significantly affects the total pressure. The traversing has to be done individually in order to avoid that the downstream probes data be affected by the upstream probes. The numerical results are compared with the experimental data and show reasonably good agreement.