Boundary Layer Ingesting Fan Rig

The rig is a single stage low speed fan designed to be representative of modern civil engine fans.

The rig is a single stage, low-speed fan designed for zero swirl at stage inlet and stage exit, purpose built to study fan-distortion interaction. The stator was designed to resemble the bypass OGV form a civil fan while the core section is not modelled. The low hub-to-tip radius ratio and spinner upstream of the rotor are similar to those in modern civil engines. This is important to ensure a representative interaction with distortion.

 

BLI fan rig with traverse gear

BLI distortion is generated by a non-uniform gauze in the inlet. A method was developed to build a gauze with a 3D printer to cover the full rig intake. The porosity of the gauze is varied to reproduce velocity gradients smoothly and precisely. No modification to the rig is required. The gauze is coupled to a flow straightener.

BLI rig fan and inlet with undistorted inflow

Full-annulus flow field measurements are performed at each measurement station. Area traverse measurements can be performed by mounting a five-hole pressure probe on a computer-controlled, motorised traverse system. Probe’s radial and circumferential coordinates can be controlled independently. Access to the rig working section is through thin slots at the casing.

The rotor is driven by a motor at a constant shaft speed. The flow coefficient can be controlled using a variable-area throttle downstream of the stage. In clean flow the flow coefficient can be monitored using a pitot-static rake in the intake. These rake measurements are essentially meaningless when inlet distortion is present and area traversing is necessary in order to determine the operating point.