Fan system for a boundary layer ingesting jet engine

This project sets out to combine a well-known theoretical ideal with a new practical approach to achieving it. The ingestion of slow moving boundary layer fluid for the efficient propulsion of a vehicle is a well-established objective (used in ships and submarines), but so far this principal has not been successfully applied to aircraft propulsion. The new approach proposed here becomes timely and practical as a consequence of recent efforts to design more efficient, and less noisy, aircraft. The favoured layout of the new aircraft makes use of a large lifting surface, the so called 'blended wing body', in conjunction with surface mounted engines ingesting boundary layer fluid. The engines would be mounted above the wing to reduce noise on the ground.The fundamental challenge for engines ingesting boundary layer fluid is the non-uniform, or distorted, velocity profile of the air entering the engine. Conventional fan engines will not accept distorted inlet flow without serious loss of operability. A possible way around this problem is to mix the slow moving air adjacent to the wing surface with free stream air taken from further above the wing. The mixing process is inefficient and so the theoretical advantage of boundary layer ingestion is reduced. However, a new approach is proposed here in which the fan of a conventional aero-engine can be modified to accept distorted boundary layer flow without the need for pre-mixing. This project plans to test and develop the new fan design using both calculations and experiments. The ultimate aim is to develop a novel aero-engine fan that will accept a distorted inlet velocity profile, without significant loss of operability or efficiency, whilst delivering a near normal flow distribution to the remainder of the engine.