Prof. Daniele Ragni
Delft University of Technology

Daniele Ragni graduated in Thermo‑Mechanical Engineering at the Polytechnic University of Marche (2007). Obtained the Ph.D. in 2012 (Faculty of Aerospace Engineering TU Delft) and joined the section of Wind Energy in the AWEP Department in the same year. Associate professor in Aeroacoustics, he worked in the projects NWO-STWs Thames (2016), IPER-MAN (2017), Marie Curie ETN SMART-ANSWER (partner, 2016) and European Project ARTEM (partner, 2016). The research interests cover the development of experimental aeroacoustics (PIV) and its applications to rotors in low/high-speed. His background in wind energy and propulsion is engaging him in the extension of PIV-based pressure reconstruction in wind turbine and aircraft propeller blades for academic and industrial aerodynamics research. He collaborates with many academic institutes and research centres worldwide in the field of experimental fluid mechanics, aeronautics and aerospace.

Experimental techniques for aeroacoustics

The course deals with the preparation of experimental setups meant for the study of full scaled models. By starting with the approach to address a usually difficult problem, the course will then continue presenting the salient aspects of measurement techniques for velocity and pressure quantification. Few details on how to optimize the setup and the measurement techniques together for specific applications in aeroacoustics will be discussed.

The course will be held on 4 & 5 May and will be structured as follows:

Lecture 1 – May, 04 From 09.00 to 11.00 in classroom 1.0.B01 EPS UC3M Leganés

Aeroacoustics fundamentals: what and why to measure

Definition of sound and metrics.

Sources of sound in conventional aerodynamic systems.

Lecture 2.A – May, 04 From 11.30 to 13.30 in classroom 1.0.B01 EPS UC3M Leganés

Measurements for aeroacoustics: microphones for hydrodynamic and far‑field pressures

What is a microphone and how do we use it to isolate far-field acoustic pressure?

Can we adapt a microphone to measure wall pressure fluctuations?

Pressure measurements, in-field versus wind-tunnel measurements, what are the challenges?

Lecture 2.B- May, 04 From 15.00 to 17.00 in classroom 1.0.B01 EPS UC3M Leganés

Laser velocimetry: spatial vs. temporal resolution, how to trade off for large-scale application

How can we use laser velocimetry information for visualization or for integral quantities.

Advanced techniques for saving on costs and increasing high-dynamic spatial resolution.

Lecture 3 – May, 05 From 09.00 to 11.00 in classroom 7.1.J03 EPS UC3M Leganés

Applications in aeroacoustics

Small exercise together, on how to optimize a setup of your choice.

Reference publications for the work of the proposed course:

Review of measurement techniques:

Measurement techniques for aeroacoustics: from aerodynamic comparisons to aeroacoustic assimilations, D Ragni, F Avallone, D Casalino, Measurement Science and Technology 33 (6), 062001

Extension of measurement techniques for aeroacoustic purposes:

Jet noise predictions by time marching of single-snapshot tomographic PIV fields, D Ragni, D Fiscaletti, WJ Baars, Experiments in Fluids 63 (5), 1-18

Benchmarking of high-quality measurements:

Aeroacoustic Benchmarking of Trailing-Edge Noise from NACA Airfoil with Trailing-Edge Serrations, S Luesutthiviboon, LT Lima Pereira, D Ragni, F Avallone, M Snellen, AIAA Journal 61 (1), 329-354

Study of noise reduction technologies:

Noise reduction mechanisms of sawtooth and combed-sawtooth trailing-edge serrations, F Avallone, WCP Van Der Velden, D Ragni, D Casalino, Journal of Fluid Mechanics 848, 560-591

Comparisons of experimental and numerical techniques for rotors:

3D pressure imaging of an aircraft propeller blade-tip flow by phase-locked stereoscopic PIV, D Ragni, BW Van Oudheusden, F Scarano, Experiments in fluids 52 (2), 463-477

The event will be in presence and previous registration is required.