# Project B1

### From MACwiki

## Contents |

# Aeroacoustic Tailoring

**Principal Investigators:**

Prof. Dr.-Ing. Nikolaus A. Adams (coordination) | Aerodynamics |

Prof. Gudrun Klinker, Ph.D. | Augmented Reality |

Prof. Dr. Helmut Krcmar | Information Systems |

Prof. Dr.-Ing. habil. Michael Manhart | Hydromechanics |

Prof. Dr. Peter Rentrop | Numerical Analysis |

Prof. Dr. Michael Ulbrich | Mathematical Optimisation |

**Project Members:**

Eva Artinger |

Dr. Patrick Maier |

Jithendra Tirakala |

# Background

Noise emissions from high-lift devices of airplanes or helicopter rotors and noise transmission into passenger compartments of automobiles are examples for areas where passive and active measures for reducing noise impact are topical issues. Noise is generated in unsteady and turbulent flow fields with or without heat release, from oscillating propulsion elements, or by stimulated structure vibrations. The original objective of noise suppression is to reduce noise generation. Other measures, such as damping by acoustic confinement, are necessarily inferior. Similarly as with aeroelastic tailoring, the aeroacoustic tailoring is a multi-physics problem, frequently called a three-field (flow, structure, sound) problem. Reducing noise emissions amounts to solving this coupled three-field problem in an inverse fashion. The objective of aeroacoustic tailoring is to design structures in such a way that (i) a flow through or over the structure is affected in such a way that noise emitted from flow sources does not exceed certain limits, and (ii) that noise emitted from structure vibrations (which again can have aeroelastic or aeroacoustic origin) does not exceed certain limits in the near or the far field. The inverse solution of the three-field problem above requires the most detailed available flow-field modelling and an enormous amount on computational resources. Modelling and computational limitations require concurrent verification with physical experiments, which is available by wind tunnel experimentation within an augmented virtual flow lab.

# Objectives

The objectives are three-fold: (i) accurate and detailed prediction of unsteady turbulent complex flow fields for reliable extraction of noise sources; (ii) solution to the first inverse problem of designing the large-scale flow under given boundary and geometric constraints such that noise emissions are minimised; (iii) solution to the second inverse problem of designing surface material properties for damping sound generation from small-scale flow disturbances.

# Research Focus

As generic cases relevant for the objectives we will address (i) a slat-wing configuration and (ii) a generic helicopter-passenger compartment for which experimental flow-field data are available. Large-Eddy Simulations and unsteady Reynolds-averaged simulations will be performed for these configurations for obtaining detailed flow-field information and sound sources. Automatic optimisation will be used for investigating the effect of compliant material and for optimising the geometry. Flow simulations and sound source extraction will be performed based on available experiments by Adams and Manhart. Geometry and material-property optimisation based on the computational flow models will be contributed by Ulbrich. Further development of employed discretisation methods will be done in cooperation with Rentrop. The evaluation of the experimental data will be based on augmented and virtual reality (Klinker), and the project will be empirically observed to derive patterns for CSE requirements engineering methods (Krcmar).

# Publications

- P. Maier,
, Dissertation, 2014**Augmented Chemical Reactions - Research on 3D Selection and Confirmation Methods**