Aeroacoustic Study of Tonal Noise Generated by Axial Flow Fans

Volume 1 ◽  
2004 ◽  
Author(s):  
T. Belamri ◽  
G. Wang
Keyword(s):  
Experimental Data ◽  
Axial Flow ◽  
Acoustic Analogy ◽  
Noise Levels ◽  
Tonal Noise ◽  
Torque Distribution ◽  
Axial Fans ◽  
Main Input ◽  
Radial Thrust ◽  
Thrust And Torque

SPLNoise is an aeroacoustic program developed to predict tonal noise generated by low speed axial fans. It is based on a generalization of the acoustic analogy of Lowson. The main input to the program are the radial thrust and torque distribution along the blade. This radial distribution is obtained from a CFD calculation. An automatic link to CFX commercial CFD code was made. Noise testing was performed in the anechoic and reverberant room at the Trane Company. Comparison between predicted noise levels and experimental data is very satisfactory.

Control of Axial Flow Fan Noise by Design

1994 ◽  
Vol 1 (4) ◽  
pp. 271-278
Author(s):  
P.J. Hunnaball
Keyword(s):  
Noise Level ◽  
Axial Flow ◽  
Radial Clearance ◽  
Noise Levels ◽  
Tonal Noise ◽  
Axial Flow Fan ◽  
Fan Noise ◽  
Basic Parameters ◽  
Selection Of

This paper discusses the present methods of controlling tonal noise in axial flow fans and puts forward some basic parameters for use in the design and selection of this product. Descriptions are given of the effects of fan casing geometry, the interaction of fixed duct elements and fan rotating parts, the effect of inlet disturbance and changes in noise level with radial clearance. Finally, guidelines are given for users of axial How fans in order to minimise noise levels.

Tonal Noise Generation in an Inlet Vaned Axial Blower at Several Axial Gaps

2006 ◽  
Author(s):  
K. M. Argu¨elles Di´az ◽  
J. M. Ferna´ndez Oro ◽  
C. Santolaria Morros ◽  
R. Ballesteros Tajadura
Keyword(s):  
Source Term ◽  
Noise Source ◽  
Numerical Study ◽  
Axial Flow ◽  
Single Stage ◽  
Axial Distance ◽  
Noise Generation ◽  
Acoustic Analogy ◽  
Tonal Noise ◽  
Specific Contribution

The main objective is the numerical study of the noise generation in a single stage axial flow blower. For the present work, just the discrete noise generation (tonal noise) is dealt with. A numerical methodology based on a generalization of Lighthill’s aero-acoustic analogy, the so-called Ffowcs Williams and Hawkings aero-acoustic analogy (FFWH), is developed. The numerical methodology has been tested with two different operational configurations of the blower: a first one, with a reduced axial gap between the rows of the stage (i.e. 50 mm) and a second one with a higher axial distance (i.e. 70 mm). The specific contribution of every tonal noise source term will be analyzed for both configurations.

scholarly journals Unsteady simulation of tonal noise from isolated centrifugal fan

2020 ◽  
Author(s):  
Martin Ottersten ◽  
Huadong Yao ◽  
Lars Davidson
Keyword(s):  
Experimental Data ◽  
Centrifugal Fan ◽  
Acoustic Analogy ◽  
Tonal Noise ◽  
Aerodynamic Properties ◽  
Trailing Edges ◽  
Recirculating Flows ◽  
Unsteady Simulation ◽  
Inlet Duct

In this study, an isolated centrifugal fan is investigated for the aerodynamic and acoustic performances usingRANS and URANS simulations. The noise is predicted by coupling the URANS and the Ffowcs Williams andHawkings acoustic analogy. The aerodynamic properties obtained from RANS and URANS are consistentwith the experimental data. The magnitudes of the tonal noise at the blade passing frequencies are wellpredicted. Recirculating flows, which are responsible for reducing the fan efficiency and increasing the noisegeneration, are observed between the shroud and the blade trailing edges. It is found that the recirculatingflows are associated with the gap between the shroud and the inlet duct.

Validating Numerical CFD Simulations With Experimental Data for Turbulence Phenomena in Axial Flow Gas Turbine Diffusers

2009 ◽  
Author(s):  
Farrokh Zarifi-Rad ◽  
Hamid Vajihollahi ◽  
James O’Brien
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Axial Flow ◽  
Experimental Results ◽  
Scale Model ◽  
Data Set ◽  
Pressure Profiles ◽  
Scale Models ◽  
Inlet Conditions

Scale models give engineers an excellent understanding of the aerodynamic behavior behind their design; nevertheless, scale models are time consuming and expensive. Therefore computer simulations such as Computational Fluid Dynamics (CFD) are an excellent alternative to scale models. One must ask the question, how close are the CFD results to the actual fluid behavior of the scale model? In order to answer this question the engineering team investigated the performance of a large industrial Gas Turbine (GT) exhaust diffuser scale model with performance predicted by commercially available CFD software. The experimental results were obtained from a 1:12 scale model of a GT exhaust diffuser with a fixed row of blades to simulate the swirl generated by the last row of turbine blades five blade configurations. This work is to validate the effect of the turbulent inlet conditions on an axial diffuser, both on the experimental front and on the numerical analysis approach. The object of this work is to bring forward a better understanding of velocity and static pressure profiles along the gas turbine diffusers and to provide an accurate experimental data set to validate the CFD prediction. For the CFD aspect, ANSYS CFX software was chosen as the solver. Two different types of mesh (hexagonal and tetrahedral) will be compared to the experimental results. It is understood that hexagonal (HEX) meshes are more time consuming and more computationally demanding, they are less prone to mesh sensitivity and have the tendancy to converge at a faster rate than the tetrahedral (TET) mesh. It was found that the HEX mesh was able to generate more consistent results and had less error than TET mesh.

An Implicit Off-Design Deviation Angle Correlation of Axial Flow Compressor Blade Elements

2017 ◽  
Author(s):  
Wu Dong-run ◽  
Teng Jin-fang ◽  
Qiang Xiao-qing ◽  
Feng Jin-zhang
Keyword(s):  
Experimental Data ◽  
Incidence Angle ◽  
High Reliability ◽  
Axial Flow ◽  
Compressor Blade ◽  
Deviation Angle ◽  
Axial Flow Compressor ◽  
New Correlation ◽  
Classical Correlations ◽  
Flow Compressor

This paper applies a new analytical/empirical method to formulate the off-design deviation angle correlation of axial flow compressor blade elements. An implicit function of deviation angle is used to map off-design deviation curves into linear correlations (minimum linear correlation coefficient R = 0.959 in this paper). Solution of the coefficients in the correlation is given through the study of classical theories and statistical analysis of the experimental data. The off-design deviation angle can be calculated numerically. The approach requires only knowledge of the blade element geometry. The comparison among 2 classical correlations and the new correlation proposed in this paper shows the new correlation has minimum error over the entire range of incidence angle while classical correlations show high reliability only in a limited range. Experimental data in this paper is collected from NASA’s open technical reports. Rotors and stators are studied together. Considering there is significant deviation angle variation along spanwise direction, only data at 50% span is studied, if possible. The error among experimental data, statistical regressions of the experimental data, and numerical results based on the new correlation is discussed. It has to be noted that the influence of the flow condition other than incidence angle is only being discussed but with less break through.

ASSESSMENT OF MULTALL AS CFD CODE FOR THE ANALYSIS OF TUBE-AXIAL FANS

2021 ◽  
pp. 1-12
Author(s):  
Piero Danieli ◽  
Massimo Masi ◽  
Giovanni Delibra ◽  
Alessandro Corsini ◽  
Andrea Lazzaretto
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Velocity Distribution ◽  
High Speed ◽  
State Of The Art ◽  
Stable Operation ◽  
Pressure Curve ◽  
Analysis Tool ◽  
Low Speed ◽  
Axial Fans

Abstract This work deals with the application of the open source CFD code MULTALL to the analysis of tube-axial-fans. The code has been widely validated in the literature for high-speed turbomachine flows but not applied yet to low speed tutbomachines. The aim of this work is to assess the degree of reliability of MULTALL as a tool for simulating the internal flow in industrial axial-flow fan rotors. To this end, the predictions of the steady-state air flow field in the annular sector of a 315 mm tube-axial fan obtained by MULTALL 18.3 are compared with those obtained by two state-of-the-art CFD codes and experimental data of the global aerodynamic performance of the fan and the pitch-wise averaged velocity distribution downstream of the rotor. All the steady-state RANS calculations were performed on either fully structured hexahedron or hexa-dominant grids using classical formulations of algebraic turbulence models. The pressure curve and the trend of the aeraulic efficiency in the stable operation range of the fan predicted by MULTALL show very good agreement with both the experimental data and the other CFD results. Although the estimation of the fan efficiency predicted by MULTALL can be noticeably improved by the more sophisticated state-of-the-art CFD codes, the analysis of the velocity distribution at the rotor exit supports the use of MULTALL as a reliable CFD analysis tool for designers of low-speed axial fans.

scholarly journals Bioinspired aerofoil adaptations: the next steps for theoretical models

2019 ◽  
Vol 377 (2159) ◽  
pp. 20190070 ◽  
Author(s):  
Lorna J. Ayton
Keyword(s):  
Experimental Data ◽  
Theoretical Models ◽  
Theoretical Modelling ◽  
Experimental Measurements ◽  
Far Field ◽  
Acoustic Analogy ◽  
Trailing Edge ◽  
Trailing Edge Noise ◽  
Theoretical Predictions ◽  
Field Noise

The extended introduction in this paper reviews the theoretical modelling of leading- and trailing-edge noise, various bioinspired aerofoil adaptations to both the leading and trailing edges of blades, and how these adaptations aid in the reduction of aerofoil–turbulence interaction noise. Attention is given to the agreement between current theoretical predictions and experimental measurements, in particular, for turbulent interactions at the trailing edge of an aerofoil. Where there is a poor agreement between theoretical models and experimental data the features neglected from the theoretical models are discussed. Notably, it is known that theoretical predictions for porous trailing-edge adaptations do not agree well with experimental measurements. Previous works propose the reason for this: theoretical models do not account for surface roughness due to the porous material and thus omit a key noise source. The remainder of this paper, therefore, presents an analytical model, based upon the acoustic analogy, to predict the far-field noise due to a rough surface at the trailing edge of an aerofoil. Unlike previous roughness noise models which focus on roughness over an infinite wall, the model presented here includes diffraction by a sharp edge. The new results are seen to be in better agreement with experimental data than previous models which neglect diffraction by an edge. This new model could then be used to improve theoretical predictions for far-field noise generated by turbulent interactions with a (rough) porous trailing edge. This article is part of the theme issue ‘Frontiers of aeroacoustics research: theory, computation and experiment’.

Theoretical Model of the Spanwise Mixing Caused by Periodic Incoming Wakes

1994 ◽  
Author(s):  
K. Imanari
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Turbulent Diffusion ◽  
Axial Flow ◽  
Single Stage ◽  
Mixing Coefficients ◽  
Predicted Values ◽  
Good Agreement ◽  
Axial Flow Compressors

A theoretical model is proposed for the spanwise mixing caused by periodic incoming wakes in the context of turbulent diffusion in axial-flow compressors prior to repeating-stage conditions. The model was used to predict the spanwise mixing coefficients across a stator of a single-stage compressor without IGVs. The correctness of the theory was demonstrated by the results that the predicted values were in good agreement with the associated experimental data.

An Average-Passage Empirical Closure Model for Centrifugal Compressors

2004 ◽  
Author(s):  
Limin Gao ◽  
Guang Xi ◽  
Shangjin Wang
Keyword(s):  
Experimental Data ◽  
Empirical Model ◽  
Stokes Equations ◽  
Computational Cost ◽  
Axial Flow ◽  
Equation System ◽  
Computational Grids ◽  
Navier Stokes ◽  
Sufficient Information ◽  
Centrifugal Compressors

Applying the novel time- and passage-averaging operators, a reduced average-passage equation system is derived to remove the bodyforce and the blockage factor in Adamczyk’s average-passage equations. Like the Reynolds-averaged Navier-Stokes equations the average-passage flow model does not contain sufficient information to determine its solution. Based on the rich throughflow analysis for axial-flow turbomachinery and numerous studies for centrifugal compressors, a semi-empirical model of the deterministic stress is developed for centrifugal compressors in the present study. Finally, the empirical model coupled with the interface approach is applied to predict the time-averaged flow field in a tested centrifugal compressor stage and the results are compared with experimental data. Using the same computational grids, the computational cost with the empirical model is slightly more than that with the mixing plane model, and a good agreement was obtained between the numerical results and experimental data.

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