
In study year 20222023 this course will be given through selfstudy with assistance
 Understand the concept of sound waves and analyze the effect of different sound fields and the diffraction and refraction phenomena in practical applications;
 Understand the concept of Sound Power, Acoustic Power, and Sound Pressure Level and evaluate the mathematical addition of those before mentioned levels;
 Understand the concept of directivity, analyze how different idealized sound sources produce distinct directivity patterns;
 Evaluate the Doppler Effect in complex sound propagation fields;
 Analyze the sound propagation based on the continuity, Euler and Poisonâ€™s equations;
 Apply the order of magnitude analysis to evaluate the sound propagation in complex environments;
 Understand the physics and mathematics involved in the computation of the speed of sound;
 Analyze the elementary noise sources: monopoles, dipoles, and quadrupoles;
 Analyze the compactness, nearfield and farfield concepts in a complex sound field;
 Understand the beamforming technique and create and validate a beamforming code;
 Analyze the aeroacoustic noise production using the aeroacoustic analogies formal theoretical basis;
 Use the previous knowledge to analyze the noise produced in a highlift device and an airfoil. Evaluate the effect of the fundamental aeroacoustic sources in these application problems;



Aeroacoustics studies the aerodynamic noise production. Aeroacoustics noise is produced, for example, by the turbulent flow motion in the jet of an airplane or by the turbulent boundary layer reaching the trailing edge of a wind turbine blade. The aeroacoustic noise is present even though the surface interacting with the flow is free of vibrations. The aeroacoustic noise generally represents the ultimate noise reduction barrier commonly defining the minimum noise production of an application.
This course discusses the fundamental theory and concepts related to the aeroacoustic noise production. It starts introducing fundamental concepts of acoustics and aerodynamics. In a next stage, those fundaments are merged, and the aeroacoustics noise sources are formalized by the introduction of the aeroacoustic analogies.
The student will apply the theoretical knowledge acquired in this course developing a beamforming (aka acoustic camera) code able to localize and quantify sound sources with the help of a microphone array. The student will then perform an aeroacoustic test in the UTwente Aeroacoustic wind tunnel. In this test, the student applies the previously developed beamforming code and evaluate the aeroacoustic noise production in an aeronautical and in a wind energy application.
The evaluation consists of a report and an oral presentation of the results of the aeroacoustic wind tunnel measurements in addition to an oral exam.




 Assumed previous knowledgeMandatory: 201700127 Fluid Mechanics & Heat Transfer
Recommended: 201500136 Fluid Mechanics II 
Master Mechanical Engineering 
  Required materialsBookProf. Dr.Ing. Jan Delfs, “Basics of Aeroacoustics”, Technische Universitat Braunschweig 
 BookStewart Glegg and William Devenport, Aeroacoustics of Low Mach Number Flows, Elsevier Science, 2017 
 Book"Sound and Sources of Sound" (A.P.Dowling and J.E.Ffowcs Williams, Ellis Horwood, Chichester,UK (1983).) 

 Recommended materialsInstructional modesAssignmentPresence duty   Yes 
 Q&APresence duty   Yes 

 TestsOral Exam


 