https://backend.orbit.dtu.dk/ws/files/256022566/1_s2.0_S0376042121000427_main.pdf

Turbulent boundary layer trailing-edge noise: Theory, computation, experiment, and application

Cylindrical bodies in uniform flows can be coated with a porous medium as a passive flow and noise control method in an effort to reduce the acoustic effects of vortex shedding. To date, the employed open-cell porous materials typically possess a randomized internal structure. This paper presents the design and validation of a novel 3-D printed structured porous coated cylinder that has significant flexibility, in that the porosity and pores per inch of the porous coating can be modified independently and relatively easily. The performance of the structured porous coating design is compared against porous polyurethane and metal foam with the same coating dimensions and similar pores per inch and porosity via an experimental acoustic investigation, revealing strong similarity in the passive noise control performance of each material type. A numerical comparison illustrates the similarities of the wake structure of the 3-D printed porous coated cylinder to an equivalent Darcy-Forchheimer model simulation that represents a randomized internal porous structure. The performance similarities of these different porous material types indicate that a structured porous geometry can be used to understand the internal flow behavior of the porous medium responsible for reducing the cylinder vortex shedding tone that is otherwise extremely difficult or impossible with typical randomized porous structures. Moreover, significant potential exists for the porous structure to be further optimized or smartly tailored by architectural design for different control purposes, coating geometries and dimensions, and working conditions.

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Structured Porous Material Design for Passive Flow and Noise Control of Cylinders in Uniform Flow

Design, aerodynamic analysis and test flight of a bat-inspired tailless flapping wing unmanned aerial vehicle

Aerodynamic performance assessment of a ducted fan UAV for VTOL applications

Hanru Liu

Papers

Experimental study of a bio-inspired flapping wing MAV by means of force and PIV measurements

Numerical study on reducing aerodynamic drag and noise of circular cylinders with non-uniform porous coatings

Vortex shedding noise and flow mode analysis of cylinder with full/partial porous coating

Passive control of tandem cylinders flow and noise using porous coating

Reduced order model for unsteady aerodynamic performance of compressor cascade based on recursive RBF