Numerical aerodynamic performance assessment of HLFC wing configurations using far-field drag analysis

Abstract

This paper presents the aerodynamic performance analysis of realistic large passenger aircraft equipped with a Hybrid Laminar Flow Control (HLFC) system. To this purpose, the design of two HLFC aircraft geometries is first outlined, both designed by DLR based on an Airbus HLFC variant of the XRF-1 geometry. Numerical simulations were performed with the TAU RANS solver of DLR, using an extension of its LST-based automatic transition prediction capability for cases with boundary layer suction. Aerodynamic performance assessment was then performed using the ONERA ffd72 far-field drag analysis software, allowing comparisons between configurations in terms of phenomenological drag components. The overall assessment of the different configurations considers both the laminarization benefit using HLFC technology compared to a fully turbulent reference aircraft and the performance penalty when the HLFC wing is operated under fully turbulent conditions. Results of the analysis are consistent with the geometry modifications and the flow physics, highlighting an overall HLFC benefit via the reduction of friction and viscous pressure drag components. A wave drag penalty, inherent to the laminarization of the outer wing upper surface, is identified in the original HLFC geometry designed by DLR and reduced in its further improved version.