Simulation of Suction Chambers with Variable Pressure Distribution for HLFC Applications

Abstract

For a simplified but effective chamber concept of boundary-layer suction for hybrid laminar flow control, different velocity distributions inside suction chambers under consideration of pressure gradients are simulated. The flow inside these chambers is calculated by 2D and 3D grids to predict suction velocity as well as the wall pressure distribution at different suction pressures. The classical ALTTA concept of a microporous metal with a substructure of stringers and single chambers for adapted inner pressure will be investigated, as well as modern chamberless applications with TSSD surfaces and micro etched metal foils at varying porosity for each surface part. By the latter approach, extensively long suction regions result in non negligible pressure gradients inside the porous sheet and the pressure distribution on the outside wall, which is also taken into account. These effects require an additional pressure gradient boundary condition, which was added and successfully evaluated by comparison with experimental data, allowing the future prediction of suction distribution for an optimal transition suppression.