Session: 01-06 Inlet Distortion and Engine Operability

Paper Number: 100561

100561 - Evaluation of Axisymmetric Bli Design Using an Altitude Capable Test Rig 

Recent advances in aerospace propulsion seek to minimise emissions and noise of aircraft propulsion systems via electric hybridisation. Unfortunately, aircraft are poorly suited to electrical propulsion as the energy storage requires significant weight increases, making these systems considerably less efficient than liquid hydrocarbon fuel-powered propulsion systems. Benefits due to hybridisation can only be realised if coupled with other energy saving technologies such as distributed propulsion or integrated propulsion-airframe systems. One such energy saving technology getting attention is boundary layer ingestion (BLI), in which the aircraft propulsors ingest the aircraft boundary layer and consequently require less energy to create the same amount of thrust. Preliminary studies on the benefits of boundary layer ingestion predict about a 10% reduction in energy consumption.
There are several architectures which allow the ingestion of the boundary layer. Theoretical estimations have shown the architecture with the propulsor mounted on the tail of the aircraft and powered by the main engines has a substantial potential improvement in fuel efficiency. However, a challenge with BLI is that it creates a non-uniform engine inlet flow which may reduce engine performance, create unsteady blade forces and vibrations, combustion instabilities (for gas turbine engines) and reduced engine stall margin.
Limited experimental results evaluating boundary layer performance have been published compared to the considerable number of analytical and numerical studies. A new aerodynamic open-circuit test rig for studying BLI propulsion has therefore been developed by National Research Council of Canada (NRC). 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 test 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. The boundary layer rig is unique compared to most known BLI projects in that it is capable of varying the operating pressure levels and Mach numbers, while most other known studies have been performed atmospheric inlet pressure and lower speeds. This paper provides details on test set-up, procedure and results for the sub-scale distortion tolerant fan tested at a number of off-design operating conditions. 

Presenting Author: Faezeh Rasimarzabadi National Research Council Canada

Presenting Author Biography: Dr. Faezeh Rasimarzabadi completed her Ph.D. in Aerospace engineering and received a Post-Doctoral from University of Alberta in Mechanical Engineering. Prior to joining NRC she spent a year working with Bombardier as a project manager. She currently works at the NRC Aerospace, National Research Council Canada as an Associate Research Officer in the Engine Performance and Icing group in the Gas Turbine Laboratory. Her interests include propulsion and aerodynamics and heat transfer. She currently leads a project on development of a boundary layer ingestion rig. She also works proactively towards the challenges of thermal management systems of hybrid-electric aircrafts.

Authors:

Faezeh Rasimarzabadi National Research Council Canada
Hans Martensson GKN Aerospace Engine Systems
Catherine Clark National Research Council Canada
Martin Neuteboom National Research Council Canada