Reducing Noise Generated from a Wind Turbine Blade by Pitch Angle Control using CFD and Acoustic Analogy

Mohamed, Mohamed H.; Dizène, Rabah; Mihoubi, Maamoun

doi:10.18869/acadpub.jafm.73.241.27426

Cited by 6 publications

(3 citation statements)

References 13 publications

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“…At present, the method cannot be used to solve aerodynamic noise problems of high-speed trains. Another computation method in Fluent is the Lighthill acoustic analogy which is widely used and can also be called AAA (Aero-Acoustic Analogy) method [22][23][24]. Different from CAA method, "acoustic analogy" method decouples wave equations and flow equations.…”

Section: Acoustic Analogy Theorymentioning

confidence: 99%

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High‐Speed Trains

Sun

Han

2018

Complexity

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Pantographs are important devices on high-speed trains. When a train runs at a high speed, concave and convex parts of the train cause serious airflow disturbances and result in flow separation, eddy shedding, and breakdown. A strong fluctuation pressure field will be caused and transformed into aerodynamic noises. When high-speed trains reach 300 km/h, aerodynamic noises become the main noise source. Aerodynamic noises of pantographs occupy a large proportion in far-field aerodynamic noises of the whole train. Therefore, the problem of aerodynamic noises for pantographs is outstanding among many aerodynamics problems. This paper applies Detached Eddy Simulation (DES) to conducting numerical simulations of flow fields around pantographs of highspeed trains which run in the open air. Time-domain characteristics, frequency-domain characteristics, and unsteady flow fields of aerodynamic noises for pantographs are obtained. The acoustic boundary element method is used to study noise radiation characteristics of pantographs. Results indicate that eddies with different rotation directions and different scales are in regions such as pantograph heads, hinge joints, bottom frames, and insulators, while larger eddies are on pantograph heads and bottom frames. These eddies affect fluctuation pressures of pantographs to form aerodynamic noise sources. Slide plates, pantograph heads, balance rods, insulators, bottom frames, and push rods are the main aerodynamic noise source of pantographs. Radiated energies of pantographs are mainly in mid-frequency and high-frequency bands. In high-frequency bands, the far-field aerodynamic noise of pantographs is mainly contributed by the pantograph head. Single-frequency noises are in the far-field aerodynamic noise of pantographs, where main frequencies are 293 Hz, 586 Hz, 880 Hz, and 1173 Hz. The farther the observed point is from the noise source, the faster the sound pressure attenuation will be. When the distance of two adjacent observed points is increased by double, the attenuation amplitude of sound pressure levels for pantographs is around 6.6 dB.

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Section: Acoustic Analogy Theorymentioning

confidence: 99%

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High‐Speed Trains

Sun

Han

2018

Complexity

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“…Structured grids are generally composed of quadrilaterals in two dimensions and hexahedral in three dimensions. Among Computational Fluid Dynamics (CFD) studies using structural grids, Maizi et al (2017) studied the flow around a wind turbine blade using structured meshes.…”

Section: Many Authors Have Analyzed and Developed Nacelle Anemometry mentioning

confidence: 99%

Effect of Grid Topology on Numerical Simulations of Flow Fields around Wind Turbine Nacelle Anemometer

Tata¹,

Smaili²,

Masson³

2018

JAFM

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In this paper, the effect of mesh topology on the numerical predictions of the immediate near wake region of a horizontal axis wind turbine is investigated. The present work focuses on the nacelle anemometry measurements. Steady Reynolds Averaged Navier-Stokes (RANS) equations are applied to describe the airflow around the wind turbine nacelle. The k-ε turbulence model is used. To model the turbine rotor, the approach based on the actuator disc concept is considered. The computational domain has been meshed with five different configurations of grid; namely, quasi-structured, unstructured and three different hybrid grids constituted of blending of quasi-structured and unstructured grids. The obtained results are compared to the available experimental data. The hybrid mesh with quasi-structured grid in the boundary layer region and unstructured grid in the vicinity of the nacelle is found to be more promising to simulate the near wake generated downstream of the wind turbine nacelle and to predict accurately the nacelle anemometry measurements.

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“…With the development of aviation industry and high demand of environmental protection, the jet noise of aero-engine has become one of the major concerns in the aircraft manufacturing industry (Tam et al 2008). A large number of experimental and numerical studies have been carried out to understand the mechanisms of aero-acoustic noise generation (Tam et al 2008;Freund, 2001;Bahman-Jahromi et al 2019;Zuo et al 2019) and its reduction (Henderson 2010;Maizi et al 2017;Zhao et al 2018;Semlitsch et al 2019). For the simplicity and the effectivity for noise reduction, chevron nozzles (Bastos et al 2017;Xia et al 2009) are one of the most popular noise reduction strategies.…”

Section: Introductionmentioning

confidence: 99%

Compressibility Modified RANS Simulations for Noise Prediction of Jet Exhausts with Chevron

2021

JAFM

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The impact of compressibility modified RANS turbulence closures is investigated for high subsonic round and chevron jet flows with Mach = 0.9 and Re = 1.03×10 6 , including the predicted acoustic noise generation. The well-documented chevron jet flow and noise cases, namely NASA SMC000 and SMC006 are selected as the simulation configurations. Two compressibility RANS closures are considered, which are based on the k-ε turbulence model. The first type only considers the compressibility dissipation rate, and the second type accounts for three modifications of compressibility dissipation rate, pressure dilation and production limiter. The acoustic noise is calculated employing the SNGR (Stochastic Noise Generation and Radiation) method using the flow prediction of the three-dimensional RANS simulations. The results show that both of the two types of compressibility modified RANS models improve the accuracy of the mean flow and turbulence quantities. This results in more accurate jet noise predictions than with the standard RANS model. The first type modification is found to be moderate and the second type is remarkable. The noise results by the second type model, i.e. Sarkar2 model, agree with the experimental data quite well. For the mean flow field, the compressibility modified model (Sarkar2 model) estimates a shorter potential jet core, and improved predictions of the velocity in the downstream region are observed. The study demonstrates the importance of considering the compressibility modified RANS closure for the noise prediction of high-speed jets via the comparison to experimental data. Hence, the SNGR method is found to be cost effective for jet noise prediction, when compared to other approaches.

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Reducing Noise Generated from a Wind Turbine Blade by Pitch Angle Control using CFD and Acoustic Analogy

Cited by 6 publications

References 13 publications

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High‐Speed Trains

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High‐Speed Trains

Effect of Grid Topology on Numerical Simulations of Flow Fields around Wind Turbine Nacelle Anemometer

Compressibility Modified RANS Simulations for Noise Prediction of Jet Exhausts with Chevron

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