Numerical and Experimental Design of a radial displaceable Inlet Distortion Device

Abstract

The engine embedded in the aircraft fuselage is a promising future engine concept to achieve the aimed reduction of the flight mission fuel consumption. Due to high degree of integration, a part of the fuselage boundary layer enters the engines, which reaccelerate the fluid. The benefit is due to a reduced engine inlet momentum whereby less necessary power input for thrust production is necessary to produce the same amount of thrust, compared to non-distorted and is the main idea of the Boundary Layer Ingestion concept (BLI). This concept requires a well-adapted Fan - resistance against the inhomogeneous inflow condition over the whole flight mission. Design of this kind of Fan or more over an efficient and reliable thrust generator system requires a deep knowledge of the flow phenomena governing this area. This paper presentsthe development of an Inlet distortion device (IDD) dedicated for a test setup with a newly designed counter rotating fan. The basis is the design of a device, which is able to generate the BLI-distortion in the test rig and the target is to achieve a calculated BLI pressure distribution, which comes from a CFD simulation of an aircraft with embedded engines. Since the counter-rotating rotor blades are made of carbon-fiber reinforced plastic material and were designed without inlet distortion, the mechanical behaviour of the blades is assumed to be critical at distorted inflow conditions. The inlet distortion device (IDD) should be able to be removed completely from the flow channel, so undistorted flow will be achieved quickly in the case of critical vibrations or amplitudes. One important parameter of the perforation is the opening ratio. This parameter will be applied as a design parameter to achieve the desired total pressure distribution. The validation of the numerical CFD simulations is done by experimental measurement data at a pre-examination test bench. The perforation pattern is optimized at a Mach number condition of test rig applying the validated numerical setup. Through the optimization of the opening ratio the choking of the IDD could be prevented. The influence of the immersion depth of the IDD is investigated by 3D-RANS CFD calculations to achieve different BLI distributions.