With the increasing demand in air transportation over the past several decades, the aerodynamic noise problem has become a more pressing topic of concern. Airframe noise, mostly generated by the interaction of turbulent flows with aircraft landing gears (LG) and high-lift devices (HLD), is the main contributor to the aircraft noise during approach and landing phases. The development of effective noise reduction techniques (NRT) is thus of paramount importance to the design of next generation quieter business jets and transport aircrafts. The increasing computer power enables computational Aero-Acoustics (CAA) to be an effective approach not only in understanding noise generation mechanisms but also in developing noise reduction techniques. The most commonly used CAA approach is a hybrid method combining Computational Fluid Dynamics (CFD) simulations and acoustic analogies. Among different CFD methods, Detached Eddy Simulation (DES) is considered to be sufficiently accurate and computationally affordable for aeronautical industry, and thus is the best trade-off between predictive accuracy and computational cost. In the presently proposed project, for the LG configuration, numerical simulation and modelling will be carried out to explore LG noise reduction with a perforated fairing. Instead of resolving the detailed flow past the fairing (mesh screen), a novel numerical model will be used, which will be verified against experimental data. For the HLD configuration, CAA analysis will be conducted on noise generation and propagation of a low-noise configuration with Krueger slat. The outcome of the project will be scientific publications as well as novel noise reduction techniques and best practice for airframe noise reduction.