Noise reduction through Chevron Nozzles via Multi-Point Optimization

Picture: Pressure field of a flow around a NACA0012 airfoil at Ma=0.85 and an angle of attack of α=0. (© SimLab FSE / AIA)

This project aims at reducing the noise of aircrafts during takeoff and landing by finding optimal designs for chevrons, i.e., for crown-like constructions mounted to the engine nozzle. With this approach the demands of the “Flightpath 2050” initiative, which has been established by the Advisory Council for Aeronautical Research in Europe (ACARE) in 2011, is addressed. Therefore, the noise generation that is induced by the geometry and the jet flow is to be reduced to a minimum by adaptively reshaping the chevron geometry.

The optimization process uses local, gradient-based algorithms to find an optimal shape and is constrained by the objective functions that are defined by the engine thrust and the produced noise.

The optimization process evaluates these objective functions based on flow solutions obtained by the Zonal Flow Solver (ZFS) of the Institute of Aerodynamics and Chair of Fluid Mechanics, RWTH Aachen University. The ongoing developments focus is on the direct integration of an optimizer into ZFS to allow for an online optimization during the simulation. To validate the algorithm, a benchmarking case provided by the Aerodynamics Design Optimization Discussion Group (ADODG) of the American Institute of Aeronautics and Astronautics (AIAA) is used. That is, the shape of a NACA 0012 airfoil profile at a Mach number Ma=0.85 and an angle of attack of α=0° in non-viscous Euler flow is subject to an optimization using a SLSQP optimizer.

The pressure field of a flow around the original shape is visualized in the picture. Preliminary results yield a reduction of the drag by about 8.6%.

You can find and overview of all current projects within the SimLab "Highly Scalable Fluids and Solids Engineering" here.