An altitude capable rig for studying engine inlet velocity profile effects: Boundary layer generator

Abstract

A new aerodynamic open-circuit test rig for studying boundary layer ingestion (BLI) propulsion has been developed by National Research Council of Canada. The purpose is to demonstrate the advantages of BLI in reducing the power required for a given thrust and to validate the performance of BLI fan concepts. The rig consists of a boundary layer generator to simulate boundary layer development over an aircraft fuselage. The boundary layer generator can be used to create a natural boundary layer due to skin friction but also comprises an array of perforated plates through which pressurised air can be blown to manipulate the boundary layer thickness. The size of the boundary layer thickness can be controlled upstream of the fan blades. Parametric studies of boundary layer thickness were then feasible. The test calibration was conducted to validate the concept.

Effects of distortion on a BLI fan

“…A common way of defining the circumferential distortion level is to use a distortion index normalised the dynamic pressure in front of the fan rotor. A common such index is DC60 defined in Equation (11).…”

“…An upstream centrebody allows different levels and patterns of distortion to be generated for building knowledge and validation. The design of the rig is described in more detail in (11) and the design of the test fan for use in the rig in [12]. The BLI distortion pattern used for this study includes both an axisymmetric radial variation as well as circumferential features.…”

Design of a sub-scale fan for a boundary layer ingestion test with by-pass flow

“…The fan design will therefore need to be mechanically robust as well as aerodynamically tolerant to variations in operating conditions. Design conditions for the sub-scale fan are derived from the BLI fan integrated with a Fokker 100 aircraft as described in [14] and [12].…”

“…Data for this are taken from the CFD analysis of the whole Fokker 100 aircraft including the TCT. Figure 2 shows the distribution over the fan face (b) and the circumferentially averaged radial profile (a) derived from the same data set as used in [12]. In addition to providing good performance at ADP, the TCT is required to operate while the aircraft is on the ground where an absence of ram pressure pushes the fan working line towards stall.…”

“…The present study aims at designing and analysing a fan serving as a test object for a BLI research test rig. The broader purpose of the rig built by The National Research Council of Canada (NRC) is to gain an understanding of whether BLI is advantageous in reducing the power required for a given thrust as discussed in [12]. Integrating the fan with the aircraft in order to gain the improvements of BLI, increases the complexity of the fan design, as each possible installation will generate a unique distortion pattern that the fan needs to cope with.…”