H10
Acoustics 1

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08:35
conference time (CEST, Berlin)
Study on the Aerodynamic Noise Source of the Concept Designed Air Taxi
27/10/2021 08:35 conference time (CEST, Berlin)
Room: H
W. Jeon (MSC Software, KOR); K-K. Lee, J. Sim (CEDIC Co. Ltd., KOR); C. Lee, T-G. Lim (MSC Software, KOR)
W. Jeon (MSC Software, KOR); K-K. Lee, J. Sim (CEDIC Co. Ltd., KOR); C. Lee, T-G. Lim (MSC Software, KOR)
The flow-induced noise generated from the rotor in the operation of air taxis will be one of the issues that we will face. In this paper, the flow noise generated by rotors on the shape of the air taxi designed conceptually was numerically analyzed as the first step to reduce the flow noise of air taxis. The commercial code, Cradle CFD, was introduced to solve the three-dimensional Reynolds-Averaged Navier-Stokes analysis in the steady-state analysis and the LES model in the unsteady-state analysis, respectively. Also, the commercial code, Actran, was used to predict the flow-induced noise. To predict the flow-induced noise of the UAM, we need unsteady CFD results. The CFD analysis has been conducted by the following process: Step 1. steady-state analysis, Step 2. the first unsteady-state analysis, and Step 3. the second unsteady-state analysis. The steady-state analysis was performed to obtain roughly and quickly the flow field in the computational domain, and then the first unsteady-state analysis was carried out to enough develop the unsteadiness in the flow field during three rotations of the rotors. After the first unsteady-state analysis, the second unsteady-state analysis during four rotations of the rotors was performed to obtain the flow field data required for analyzing the flow-induced noise. The flow-induced noise was predicted through the terms of dipole and quadrupole in the FW-H(Ffowcs Williams and Hawkings) equation using the wall pressure fluctuations about the time obtained in the flow field of the second unsteady-state analysis as an input value. Through the flow-induced noise analysis, the mechanism generating the noise was found, and the noise sources were identified differently according to the installation position of each rotor on the air taxi. For the development of low noise air taxis, it is necessary to reduce the noise generated by the main rotor as well as to consider the noise source depending on the location of each rotor.
CFD(Computational Fluid Dynamics), CAA(Computational Aero-Acoustics), UAM(Urban Air Mobility), Noise
08:55
conference time (CEST, Berlin)
Experimental and Numerical Investigation of Aerodynamic Noise Generated By Subsonic Axial Fan Using Hybrid Approach
27/10/2021 08:55 conference time (CEST, Berlin)
Room: H
S. Hangargekar (Trane Technologies, IND); S. Reddy (Trane Technologies, IND); G. Wang, J. S. Hausmann (Trane Technologies, USA)
S. Hangargekar (Trane Technologies, IND); S. Reddy (Trane Technologies, IND); G. Wang, J. S. Hausmann (Trane Technologies, USA)
This research work reports the study and investigation of aerodynamically generated noise characteristics of the fan using hybrid numerical approach. Experimental work is also reported and validated with numerical simulation results. The experiment is conducted for determination of sound power radiated by the fan. This experiment is carried out in the reverberant and anechoic chambers as a test environment. The axial subsonic fan is considered for the study. Detailed experimental work is reported in the first section, in the second section numerical simulation and analysis is reported. Flow analysis is carried out using unsteady Navier Stokes based equations with Large Eddy Simulation scale resolving turbulence model in commercial solver Ansys Fluent. Fluctuating components of velocity and density are computed for further calculation of Acoustics. Flow results from the simulation are compared with flow results measured in the experiment, As the aerodynamic performance of the fan is validated, then followed by aeroacoustics analysis performed in MSC Actran Acoustics solver. Lighthills analogy is used to compute the flow noise generation and propagation terms. Sound power characteristics is studied with the help of one third octave band and Narrow band analysis. Overall sound power is computed in MSC Actran is compared with experiment. Also, the sound power computed in Ansys Fluent is compared with experiment. This work also reports the detailed computational methodology for fan noise prediction for any type of fan applications.
Turbulence, Aerodynamics, Aeroacoustics, Large Eddy Simulation, Lighthills Analogy
09:15
conference time (CEST, Berlin)
Using Data Science’s Methods in Analyzing Frequency Filtering in Grids
27/10/2021 09:15 conference time (CEST, Berlin)
Room: H
I. Podpruzhnikov, A. Vershinin, V. Levin (Lomonosov Moscow State University, RUS); K. Zingerman (Tver State University, RUS)
I. Podpruzhnikov, A. Vershinin, V. Levin (Lomonosov Moscow State University, RUS); K. Zingerman (Tver State University, RUS)
The report examines the effects that occur when acoustic waves (the Berlage pulse) are applied to linearly elastic solids formed by a periodic structure. For a series of numerical experiments based on the finite element method, various types of lattice structures were modeled in the Fidesys strength analysis package. In these lattice structures, the parameters of the undulation of the bars forming the lattice structure, as well as the frequency of the applied pulse and the distance at which the sound insulation level was measured, were varied. The number of points forming cells of the lattice structure was also varied. For the calculation using the finite element method, grid convergence is established and a formula is found that allows predicting the level of accuracy for a given grid refinement. In the course of direct calculations, the presence of frequency filtering was established for some of the specified variable parameters. The analysis of dependences of variable parameters and sound insulation level is made. Also, based on a series of virtual experiments, a model predicting the level of sound insulation is built based on combining the following machine learning methods: Gradient Boosting, Random Forest, Gaussian Process. This algorithm was configured using the Python programming language and the scikit-learn library. The use of this algorithm allowed to reduce the time for calculating the sound insulation level by several hundred times, as well as to solve the inverse problem: specifying the necessary parameters of the lattice structure at a fixed level of sound insulation. As a development of the idea, further research of three-dimensional lattices, layered lattices, lattices with viscoelastic filler, lattices with artificially introduced deformations in the path of acoustic wave propagation, and variation of a larger number of lattice parameters is proposed. It is also possible to use high-order beam spectral elements to improve the accuracy of calculations instead of additional refinement of the finite element method grid.
Lattice structure, frequency filtering of waves, Data Science, CAE Fidesys.
09:35
conference time (CEST, Berlin)
Optimizing Noise Performance in Cooktop Extractors for an Enhanced User Experience
27/10/2021 09:35 conference time (CEST, Berlin)
Room: H
J. Laguna, F. Cuzzola (Dassault Systemes, DEU ); A. Rafidiarisoa (Dassault Systèmes, FRA)
J. Laguna, F. Cuzzola (Dassault Systemes, DEU ); A. Rafidiarisoa (Dassault Systèmes, FRA)
Among the common spaces of a house or an apartment, the kitchen has traditionally been a place where families and friends gather and share while cooking, eagerly spending time in this space. Several renowned home appliance manufacturers have identified this tendency. As such, they have developed and set new benchmarks for kitchen device aesthetics, quality and functionality. Nowadays, home appliance manufacturers promote a clear integration of their offered devices within the kitchen architecture with focus on high quality materials, simple cleaning, operation effectiveness, flexibility of installation and most relevant, quiet operation for the best possible user experience. A quiet operation is especially relevant for cooktop extractors. Conventional as well as integrated cooktop extractors from premium manufacturers reach high sound pressure levels during operation. Especially at the maximum extraction level, this can heavily affect user acoustic comfort and diminish the user satisfaction towards the device. The key component of the cooktop extractor affecting the acoustic comfort is the blower fan unit, which represents the dominant noise source while providing the required airflow performance for a correct system operation. In this regard, we present within the scope of this publication, a Lattice-Boltzmann based transient flow simulation able to assess the acoustic comfort level of the user in terms of the noise levels emitted by a conventional cooktop extractor. The simulated device is equipped with a blower fan unit as the main component to achieve the required airflow performance. The proprietary FIND module (Flow-Induced Noise Sources and Detection) is implemented to identity the dominant noise sources. These results are used to modify the system and reduce the noise levels emitted by the conventional cooktop extractor. The improved system acoustic performance leads to an enhanced user experience while providing the required airflow for the optimal performance of the device.
Computational Aeroacoustics (CAA), Computational Fluid Dynamics (CFD), Blower fan noise, Lattice-Boltzmann Method
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