Analysis and Uncertainty Quantification of a Hybrid Laminar Flow Control System

Abstract

This study aims to quantify suction velocities for hybrid laminar flow control of a vertical fin by taking data and model uncertainties into account. Because suction velocities cannot be measured directly, they are calculated using the Darcy–Forchheimer model, which needs the pressure distribution and porosity characteristics as input. Uncertainties in the pressure distribution are characterized using a novel data fusion method incorporating wind-tunnel and numerical data. Furthermore, geometrical uncertainties of the airfoil that alter the pressure distribution are considered. Two methods are proposed to model the porosity characteristics of the surface: one of which uses a local representation, and the other a global representation. In addition, the modeling error of the Darcy–Forchheimer model is estimated. These input uncertainties are quantified and propagated by Monte Carlo sampling through the Darcy–Forchheimer model. It reveals that local information on the porosity characteristics is essential for accurate suction velocity estimates for this specific application. A sensitivity study shows that the most influential contribution to the variance of suction velocities is the uncertainty in the porosity characteristics, followed by uncertainties in the pressure distribution. The model error and uncertainties in the reference pressure are shown to have a negligible influence.