scholarly journals A study of aerodynamic noise in air duct systems with turning vanes

2021 ◽  
Vol 49 (2) ◽  
pp. 308-314
Author(s):  
Boško Rašuo ◽  
Mirko Dinulović ◽  
Marta Trninić ◽  
Marina Stamenović ◽  
Novak Milošević ◽  
...  
Keyword(s):  
Acoustic Analysis ◽  
Acoustic Noise ◽  
Health Hazard ◽  
Industrial Applications ◽  
Noise Model ◽  
Aerodynamic Noise ◽  
Acoustic Analogy ◽  
Industrial Systems ◽  
Analysis And Design ◽  
Duct Systems

Noise is becoming one of the problems in many industrial applications. In this paper the aerodynamic noise in air duct system that arises from air flow passing over a surface of turning vanes is investigated. Based on Proudman's formula using Lighthill's acoustic analogy broadband acoustic noise model can be predicted. To model the turbulent flow in an air duct k - e turbulent model is used and required constants are obtained experimentally in a low speed wind tunnel followed by noise measurement in the vicinity of deflected airfoil. Several designs are investigated: Inner airfoil in the duct elbow, center positioned air foil, outer positioned and the overall combination of all previous cases. It was found that in order to satisfy all noise requirements and regulation, which are becoming more strict nowadays, the acoustic analysis and design must be performed in most industrial systems since the noise levels arising from the operating industrial equipment may represent occupational and health hazard.

Acoustic Analysis of the NREL Phase VI Wind Turbine

2010 ◽  
Author(s):  
Kirsten Ranft ◽  
Ali A. Ameri ◽  
J. Iwan D. Alexander ◽  
Edmane Envia
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Acoustic Analysis ◽  
Near Field ◽  
Accurate Solution ◽  
Broadband Noise ◽  
Aerodynamic Noise ◽  
Acoustic Analogy ◽  
Flow Equations ◽  
Nrel Phase Vi

The aim of this work is to predict the aerodynamic noise emitted from the NREL Phase VI Wind Turbine [1]. Specifically rotational noise and broadband noise of the blade have been investigated. The approach to predict aeroacoustic noise is based on the acoustic analogy [2]. In acoustic analogy, the sources of aerodynamic noise are derived from the flow equations and the resulting radiated noise is calculated using the Ffowcs Williams and Hawkings equation [3]. Thus, the prediction of aerodynamic noise requires an accurate solution of the flow field. In this work the flow field around the blade has been modeled using FLUENT’s k-ω SST turbulence model. A hybrid grid containing approximately 1.5 × 106 tetrahedral and prismatic elements has been created. The near field around the blade is a structured O-grid with 100 cells along the chord and 50 cells normal to the blade surface. To obtain the resolution of the viscous sublayer, a y+ of approximately unity has been chosen. For the flow computation a simple scheme is used with a second order upwind method and wind speeds of 7m/s, 10m/s and 25 m/s, respectively and a rotor rotation speed of 72 rpm.

Anti-noise model-free adaptive control and its application in the circulating fluidized bed boiler

2020 ◽  
pp. 095965182097937
Author(s):  
Na Dong ◽  
Wenjin Lv ◽  
Shuo Zhu ◽  
Donghui Li
Keyword(s):  
Adaptive Control ◽  
Complete Convergence ◽  
Circulating Fluidized Bed ◽  
Control Method ◽  
Noise Model ◽  
Good Resistance ◽  
Industrial Systems ◽  
Noise Interference ◽  
Model Free ◽  
Tracking Differentiator

Model-free adaptive control has been developed greatly since it was proposed. Up to now, model-free adaptive control theory has become mature and tends to be an effective solution for complex unmodeled industrial systems. In practical industrial processes, most control systems are inevitably accompanied by noise that will result in indelible error and may further cause inaccurate feedback to the output. In order to solve this kind of problem with model-free technique, this article incorporates an improved tracking differentiator into model-free adaptive control. After that, the anti-noise model-free adaptive control method with complete convergence analysis is proposed. Meanwhile, numerical simulation proves that the improved control method can quickly track a given signal with good resistance to noise interference. Finally, the effectiveness and practicability of the proposed algorithm are verified by experiments through the control of drum water level of circulating fluidized.

scholarly journals Present and Future of Supercapacitor Technology Applied to Powertrains, Renewable Generation and Grid Connection Applications

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3060
Author(s):  
Gustavo Navarro ◽  
Jorge Torres ◽  
Marcos Blanco ◽  
Jorge Nájera ◽  
Miguel Santos-Herran ◽  
...  
Keyword(s):  
Energy Storage ◽  
Control Strategies ◽  
Industrial Applications ◽  
Frequency Regulation ◽  
Scientific Publications ◽  
Industrial Systems ◽  
Grid Connection ◽  
Huge Impact ◽  
Traction Drives ◽  
Electric Traction

Energy storage systems (ESS) are becoming essential as a solution for troublesome industrial systems. This study focuses on the application of a type of ESS, a high-power technology known in the literature as supercapacitors or electric double layer capacitors (EDLC). This technology has had a huge impact during the last decade on research related to the electric traction drives, renewable sources and powergrids. Related to this aspect, this paper summarizes the most relevant scientific publications in the last five years that study the use of supercapacitor technology (SCs) in electric traction applications (drives for rail vehicles and drives for road vehicles), generation systems for renewable energy (wind, solar and wave energy), and connection systems to the electric grid (voltage and frequency regulation and microgrids). The technology based on EDLC and the practical aspects that must be taken into account in the op-eration of these systems in industrial applications are briefly described. For each of the aforementioned applications, it is described how the problems are solved by using the energy storage technology, drawing the solutions proposed by different authors. Special attention is paid to the control strategies when combining SCs with other technologies, such as batteries. As a summary, some conclusions are collected drawn from the publications analyzed, evaluating the aspects in which it is necessary to conduct further research in order to facilitate the integration of EDLC technology.

A study of sound sources and unsteady surface pressure in an axial fan

2021 ◽  
pp. 2150267
Author(s):  
Bo Luo ◽  
Wuli Chu ◽  
Song Yan ◽  
Zhengjing Shen ◽  
Haoguang Zhang
Keyword(s):  
Leading Edge ◽  
Noise Spectrum ◽  
Industrial Applications ◽  
Acoustic Analogy ◽  
Dynamics Modeling ◽  
Axial Fan ◽  
Sound Sources ◽  
Recirculating Flow ◽  
Aerodynamic Interaction ◽  
Blade Tip

The noise emitted from an axial fan has become one of the primary concerns for many industrial applications. This paper presents the work to predict the noise generation and investigate sound sources in a low speed axial fan. Computational fluid dynamics modeling is conducted using Scale Adaptive Simulation for the unsteady flow field. The sound predictions by the acoustic analogy are in good agreement with the experimental data. The results from this study show that the aerodynamic interaction between the blades and outlet vanes has a major contribution to the radiated noise spectrum. Two types of sources of narrowband humps are identified in the axial fan. The first is found at the leading edge of the blade tip, which is related to the interaction of coherent flow structures in the blade tip region. The second is found in the vicinity of the blade hub, which can be attributed to the recirculating flow and hub vortex. The noise below the frequency of 1500 Hz is mainly due to the blade-outlet vane aerodynamic interaction, manifested as the tonal sound at BPF and its harmonics, whereas above 1500 Hz the broadband component of sound is mainly related to the turbulent boundary layers.

A REVIEW OF METHODS FOR HYDRO-ACOUSTIC ANALYSIS OF NON-CAVITATING MARINE PROPELLERS

2021 ◽  
Vol 161 (A3) ◽  
Author(s):  
Abhishek Kumar Tewari ◽  
R Vijayakumar
Keyword(s):  
Marine Mammals ◽  
Acoustic Analysis ◽  
Open Water ◽  
Acoustic Analogy ◽  
Hydrodynamic Analysis ◽  
Radiated Noise ◽  
Acoustic Performance ◽  
Marine Propellers ◽  
Potential Contributor ◽  
Ocean Environment

Underwater Radiated Noise (URN) emanating from surface and underwater marine platforms has become a significant concern for all the Nations in view of the global requirement to minimise the increasing adverse impact on marine mammals and fishes and maintain ecological balance in the ‘Silent’ ocean environment. Ambient noise level in the sea, in 10 to 300 Hz frequency band, has increased by 20 to 30 dB due to shipping (Wittekind, 2009). Marine propeller (in non- cavitating and cavitating regime) is a potential contributor to the ships noise and a lot of scientific research has been undertaken and considerable progress has been achieved in estimating the hydro-acoustic performance of marine propellers. In light of this, the scope of this paper is to review and critically examine the various methods used for estimating the hydro-acoustic performance of marine propellers, particularly in the non-cavitating regime, over the past many years. This review paper brings out the details, applicability, merits and demerits of various methods, extrapolation laws to obtain full scale results, scientific conclusion of all the know-how on this subject and the scope of further research as perceived by the authors. This paper also presents a numerical methodology to estimate the noise radiated by a DTMB 4119 model propeller in the non-cavitating regime in open water condition. The hydrodynamic analysis of the propeller was performed using commercial CFD software STARCCM+, closure was achieved using standard k-ε turbulence model and hydro-acoustic predictions have been performed using FWH acoustic analogy. The results compare very well with the published literature.

Experimental Study of Aerodynamic Noise From the Trailing Edge and Leading Edge of Blades in a Coaxial-Double Shaft Fan

2013 ◽  
Author(s):  
Jafar Madadnia ◽  
Mustafa Shekeb ◽  
Thimantha Ulluwishewa
Keyword(s):  
Wind Turbines ◽  
Acoustic Noise ◽  
Residential Building ◽  
Leading Edge ◽  
Noise Pollution ◽  
Aerodynamic Noise ◽  
Trailing Edge ◽  
Double Row ◽  
Positive Effects ◽  
Spacing Variation

Proactive acoustic noise control technologies in wind turbines and blowers have in recent years been the focus of intensive research to integrate wind turbines in residential building and to address public concerns on noise pollution. However efforts to understand the mechanics has been inconclusive, mainly due to the complexity and commercial confidentiality of the topic. The paper reports on the experimental investigation on two methods in controlling aerodynamic noise. A counter-rotating-double-row-turbine with variable gap/spacing (s) was designed, built and tested. Serrations were designed and attached on the leading edge and the trailing edge of the blades to proactively control aerodynamic noise. The model was operated in fan-mode and air velocity, shaft-revolution; electric-fan-power, acoustic noise amplitude (dB) and Centre frequency (CF in Hz) were measured for a number of spacing and serrations. Coefficients of Performance (COP), dB, CF were plotted against tip speed (TS). It was noticed that: • The double-shaft-fan has operated quieter than the single shaft fan especially as TS decreases. Acoustic noise (dB) dropped 20% at TS = 4m/s to less than 2% at TS = 10m/s. Efficiency and CF increased in the double-shaft fan as TS increased. Spacing variation between blade-rows had insignificant effect on the dB, Cf, and efficiency. • Serrations on single-shaft fan have also reduced dB (up to 10%), increased efficiency and CF with more positive effects with the serrations on the leading edge than the trailing edge. Serrations are more effective at higher TS range. • Serrations on a double-shaft fan with an optimum spacing, reduced acoustic noise (dB) only allow speeds [at TS <4m/s]. However minor improvement was noticed in efficiency or noise frequency.

Simulation of acoustic noise in duct systems.

2010 ◽  
Vol 127 (3) ◽  
pp. 1799-1799
Author(s):  
M.G. Prasad ◽  
B. Rajavel
Keyword(s):  
Acoustic Noise ◽  
Duct Systems

scholarly journals Validating Aircraft Noise Models

Proceedings ◽  
2020 ◽  
Vol 59 (1) ◽  
pp. 12
Author(s):  
Ran Giladi ◽  
Eliav Menachi
Keyword(s):  
Noise Level ◽  
Health Hazard ◽  
Aircraft Noise ◽  
Noise Model ◽  
Aviation Industry ◽  
Noise Abatement ◽  
Statistical Variation ◽  
Huge Impact ◽  
Aircraft Type ◽  
Noise Models

Aircraft noise, especially at takeoffs and landings, became a major environmental nuisance and a health hazard for the population around metropolitan airports. In the battle for a better quality of life, wellbeing, and health, aircraft noise models are essential for noise abatement, control, enforcement, evaluation, policy-making, and shaping the entire aviation industry. Aircraft noise models calculate noise and exposure levels based on aircraft types, engines and airframes, aircraft flight paths, environment factors, and more. Validating the aircraft noise model is a mandatory step towards the model credibility, especially when these models play such a key role with a huge impact on society, economy, and public health. Yet, no validation procedure was offered, and it turns out to be a challenging task. The actual, measured, aircraft noise level is known to be subject to statistical variation, even for the same aircraft type at the same situation and flight phase, executing the same flight procedure, with similar environmental factors and at the same place. This study tries to validate the FAA’s AEDT aircraft noise model, by trying to correlate the specific flight path of an aircraft with its measured noise level. The results show that the AEDT noise model underestimates the actual noise level, and four validation steps should be performed to correct or tune aircraft noise databases and flight profiles.

Combustion Dynamics in a Gas Turbine Single Annular Combustor Sector

2010 ◽  
Author(s):  
Fumitaka Ichihashi ◽  
Jun Cai ◽  
Y. H. Kao ◽  
A. A. Syed ◽  
S. M. Jeng
Keyword(s):  
Gas Turbine ◽  
Acoustic Impedance ◽  
Acoustic Analysis ◽  
Industrial Applications ◽  
Propagation Model ◽  
Future Research ◽  
Test Rig ◽  
Combustion Dynamics ◽  
Resonance Modes ◽  
Impedance Characteristics

The occurrence of combustion instability dynamics known, as “screech, howl and growl,” in the combustors of gas turbine engines is a very difficult challenge for engineers. The very high amplitude pressure oscillations caused by combustion dynamics, are not only detrimental to the operation of the engine and combustor, but the difficulty in predicting and remedying these problems can lead to significant costs and delays in engine development. The coupling of the unsteady heat release in the flame with the natural acoustic resonance modes of the combustor duct causes the phenomena of combustion dynamics. To improve our understanding of stability characteristics in such complex systems, encountered in many industrial applications, the flame structure of an atmospheric swirl-stabilized burner, containing dilution and cooling air holes and fed with natural gas fuel, was systematically investigated for various inlet temperatures, pressure drops and air-fuel ratios. Experiments were also designed and conducted with the goal to understand better the phenomena of combustion dynamics that were experienced. More specifically, six acoustic pressure transducers were incorporated in the combustor and in the upstream duct to measure the acoustic field and the acoustic impedance characteristics at specified locations of interest. A one-dimensional wave propagation model is presented to predict the acoustic frequencies and damping of resonance modes, based on the geometry of the test rig, the flow conditions, and the acoustic impedance characteristics of the terminations of the combustor. This paper will present the acoustic analysis of the test data in the light of the above-mentioned theoretical modeling. The limitations of the current test rig are pointed out and changes in the rig design are discussed for future research.

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