scholarly journals Flow and Noise Characteristics of Centrifugal Fan under Different Stall Conditions

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Lei Zhang ◽  
Shoufang Liang ◽  
Chenxing Hu
Keyword(s):  
Flow Field ◽  
Power Level ◽  
Aerodynamic Characteristics ◽  
Rotating Stall ◽  
Field Analysis ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Implicit Time ◽  
Centrifugal Fan ◽  
Noise Characteristics

An implicit, time-accurate 3D Reynolds-averaged Navier-Stokes (RANS) solver is used to simulate the rotating stall phenomenon in a centrifugal fan. The goal of the present work is to shed light on the flow field and particularly the aerodynamic noise at different stall conditions. Aerodynamic characteristics, frequency domain characteristics, and the contours of sound power level under two different stall conditions are discussed in this paper. The results show that, with the decrease of valve opening, the amplitude of full pressure and flow fluctuations tends to be larger and the stall frequency remains the same. The flow field analysis indicates that the area occupied by stall cells expands with the decrease of flow rate. The noise calculation based on the simulation underlines the role of vortex noise after the occurrence of rotating stall, showing that the high noise area rotates along with the stall cell in the circumferential direction.

Aerothermal Investigation of a Rib-Roughened Trailing Edge Channel With Crossing-Jets—Part I: Flow Field Analysis

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Alessandro Armellini ◽  
Filippo Coletti ◽  
Tony Arts ◽  
Christophe Scholtes
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Side Wall ◽  
Field Analysis ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Present Contribution ◽  
Cross Sectional ◽  
Numerical Predictions ◽  
Rib Roughened

The present contribution addresses the aerothermal, experimental, and computational studies of a trapezoidal cross-sectional model simulating a trailing edge cooling cavity with one rib-roughened wall. The flow is fed through tilted slots on one side wall and exits through straight slots on the opposite side wall. The flow field aerodynamics is investigated in Part I of the paper. The reference Reynolds number is defined at the entrance of the test section and set at 67,500 for all the experiments. A qualitative flow model is deduced from surface-streamline flow visualizations. Two-dimensional particle image velocimetry measurements are performed in several planes around midspan of the channel and recombined to visualize and quantify three-dimensional flow features. The crossing-jets issued from the tilted slots are characterized and the jet-rib interaction is analyzed. Attention is drawn to the motion of the flow deflected by the rib-roughened wall and impinging on the opposite smooth wall. The experimental results are compared with the numerical predictions obtained from the finite volume Reynolds-averaged Navier–Stokes solver, CEDRE.

Numerical Modeling of Radiative and Reactive Flow Field Around a Blunt Body at Hypersonic Regimes

2010 ◽  
Author(s):  
Morteza Rahmanpour ◽  
Reza Ebrahimi ◽  
Mehrzad Shams
Keyword(s):  
Flow Field ◽  
Differential Equations ◽  
Heat Fluxes ◽  
Transitional Flow ◽  
Navier Stokes ◽  
Implicit Time ◽  
Discrete Ordinates ◽  
Two Dimensional ◽  
Fully Implicit ◽  
Time Marching

A numerical method for calculation of strong radiation for two-dimensional reactive air flow field is developed. The governing equations are taken to be two dimensional, compressible Reynolds-average Navier-Stokes and species transport equations. Also, radiation heat flux in energy equation is evaluated using a model of discrete ordinate method. The model used S4 approximation to reduce the governing system of integro-differential equations to coupled set of partial differential equations. A multiband model is used to construct absorption coefficients. Tangent slab approximation is assumed to determine the characteristic parameters needed in the Discrete Ordinates Method. The turbulent diffusion and heat fluxes are modeled by Baldwin and Lomax method. The flow solution is obtained with a fully implicit time marching method. A thermochemical nonequilibrium formulation appropriate to hypersonic transitional flow of air is presented. The method is compared with existing experimental results and good agreement is observed.

scholarly journals Prediction and Reduction of Aerodynamic Noise of the Multiblade Centrifugal Fan

2014 ◽  
Vol 6 ◽  
pp. 712421 ◽  
Author(s):  
Shuiqing Zhou ◽  
Jun Wang
Keyword(s):  
Flow Field ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Low Noise ◽  
Aerodynamic Noise ◽  
Hybrid Technique ◽  
Field Calculation ◽  
Pressure Amplitude ◽  
Centrifugal Fan ◽  
Hybrid Techniques

An aerodynamic and aeroacoustic investigation of the multiblade centrifugal fan is proposed in this paper, and a hybrid technique of combining flow field calculation and acoustic analysis is applied to solve the aeroacoustic problem of multiblade centrifugal fan. The unsteady flow field of the multiblade centrifugal fan is predicted by solving the incompressible Reynolds-averaged Navier-Stokes (RANS) equations with conventional computing techniques for fluid dynamics. The principal noise source induced is extracted from the calculation of the flow field by using acoustic principles, and the modeled sources on inner and outer surfaces of the volute are calculated with multiregional boundary element method (BEM). Through qualitative analysis, the sound pressure amplitude distribution of the multiblade centrifugal fan in near field is given and the sound pressure level (SPL) spectrum diagram of monitoring points in far field is obtained. Based on the analysis results, the volute tongue structure is adjusted and then a low-noise design for the centrifugal fan is proposed. The comparison of noise tests shows the noise reduction of improved fan model is more obvious, which is in good agreement with the prediction using the hybrid techniques.

2703 High Performance Computing of Flow Field and Aerodynamic Noise for Centrifugal Fan of Air-conditioner

2013 ◽  
Vol 2013.26 (0) ◽  
pp. _2703-1_-_2703-2_
Author(s):  
Taku IWASE ◽  
Isao HAGIYA ◽  
Hideshi OBARA ◽  
Hiroyasu YONEYAMA ◽  
Yoshinobu YAMADE ◽  
...  
Keyword(s):  
Flow Field ◽  
High Performance Computing ◽  
High Performance ◽  
Aerodynamic Noise ◽  
Centrifugal Fan ◽  
Air Conditioner ◽  
Performance Computing

Flow Field Analysis of Inlet Distortion in a Transonic Fan With Straight and Bowed Stator Blade

2007 ◽  
Author(s):  
Peng Sun ◽  
Jingjun Zhong ◽  
Guotai Feng
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Three Dimensional ◽  
Field Analysis ◽  
Navier Stokes ◽  
Fan Performance ◽  
Inlet Distortion ◽  
Flow Loss ◽  
Stator Blade ◽  
Transonic Fan

The performance and stability of a fan in clean and distorted inlet flow can be improved through the use of bowed stator blades. Measurements between the blade rows in transonic and supersonic flow are too complex to provide any useful insights, so 3D flow simulations are required. In this paper, a time-accurate three-dimensional Navier-Stokes solver of the unsteady flow field in a transonic fan is carried out using “Fluent-parallel” in a parallel supercomputer. Two sets of simulations are performed. The first simulation focuses on a better understanding of inlet total pressure distortion effects on a transonic fan. The second set of numerical simulation aims at studying the improvements of fan performance made by bowed stator blades. Three aspects are contained in this paper. The first is about the distortion effects on characteristics of the fan stage with straight stator. The effects of bowed stator on fan performance with inlet distortion are demonstrated secondly. One hand bowed stator increases the loss in rotor. On the other hand, it reduces the flow loss in stator. Finally, the patterns of flow loss caused by total pressure distortion with straight/bowed stator are compared. The scale of vortex in stator induced by inlet total pressure distortion is weakened by bowed blades, which decreases the stator loss.

Velocity Measurements Downstream of the Impellers in a Multistage Centrifugal Blower

1994 ◽  
Author(s):  
G. L. Amulfi ◽  
D. Micheli ◽  
P. Pinamonti
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Flow Rate ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Field Analysis ◽  
Test Plant ◽  
Hot Wire ◽  
Centrifugal Blower ◽  
Ensemble Averaging

The paper presents the results of an experimental investigation on a four-stage centrifugal blower, having the aim of obtaining an accurate description of the flow field behind the impellers in several operative conditions and for different geometrical configurations. Actually, the test plant allows to change the turbomachinery characteristics assembling one, two, three or four stages and three different types of diffusers. In this first research step, the blower has been tested in the four-stage vaneless diffuser configuration. The unsteady flow field behind the impellers and in the diffusers has been measured by means of a hot-wire anemometer. A Phase Locked Ensemble Averaging Technique has been utilised to obtain the relative flow field from the instantaneous signals of the stationary hot-wire probes. Several detailed measurements sets have been performed using both single and crossed hot-wire probe, to obtain the velocity vectors and turbulence trends, just behind the blower impellers and in several radial positions of the vaneless diffusers. These measurements have been done at different flow rate conditions, covering unsteady flow rate phenomena (rotating stall) too. The results obtained allowed to get a detailed flow field analysis in the multistage centrifugal blower, in relation to the geometrical configuration and to the differing operating conditions.

scholarly journals AERODYNAMIC CHARACTERISTIC OF THE ACTIVE COMPLIANT TRAILING EDGE CONCEPT

2016 ◽  
Vol 42 ◽  
pp. 1660173
Author(s):  
RUI NIE ◽  
JINHAO QIU ◽  
HONGLI JI ◽  
DAWEI LI
Keyword(s):  
Flow Separation ◽  
Aerodynamic Characteristic ◽  
High Strength ◽  
Aerodynamic Characteristics ◽  
Structure Design ◽  
Field Analysis ◽  
Design Parameters ◽  
Morphing Wing ◽  
Trailing Edge ◽  
Noise Characteristics

This paper introduces a novel Morphing Wing structure known as the Active Compliant Trailing Edge (ACTE). ACTE structures are designed using the concept of “distributed compliance” and wing skins of ACTE are fabricated from high-strength fiberglass composites laminates. Through the relative sliding between upper and lower wing skins which are connected by a linear guide pairs, the wing is able to achieve a large continuous deformation. In order to present an investigation about aerodynamics and noise characteristics of ACTE, a series of 2D airfoil analyses are established. The aerodynamic characteristics between ACTE and conventional deflection airfoil are analyzed and compared, and the impacts of different ACTE structure design parameters on aerodynamic characteristics are discussed. The airfoils mentioned above include two types (NACA0012 and NACA64A005.92). The computing results demonstrate that: compared with the conventional plane flap airfoil, the morphing wing using ACTE structures has the capability to improve aerodynamic characteristic and flow separation characteristic. In order to study the noise level of ACTE, flow field analysis using LES model is done to provide noise source data, and then the FW-H method is used to get the far field noise levels. The simulation results show that: compared with the conventional flap/aileron airfoil, the ACTE configuration is better to suppress the flow separation and lower the overall sound pressure level.

scholarly journals Constrained Shape Optimization of Airfoil Cascades Using a Navier-Stokes Solver and a Genetic/SQP Algorithm

1999 ◽  
Author(s):  
Brian H. Dennis ◽  
George S. Dulikravich ◽  
Zhen-Xue Han
Keyword(s):  
Flow Field ◽  
Shape Optimization ◽  
Pressure Loss ◽  
Total Pressure ◽  
Total Pressure Loss ◽  
Field Analysis ◽  
Navier Stokes ◽  
Conic Section ◽  
Aerodynamic Shape ◽  
Flow Field Analysis

The objective in this aerodynamic shape design effort is to minimize total pressure loss across the two-dimensional linear airfoil cascade row while satisfying a number of constraints. They included fixed axial chord, total torque, inlet and exit flow angles, and blade cross-section area, while maintaining thickness distribution greater than a minimum specified value. The aerodynamic shape optimization can be performed by using any available flow-field analysis code. For the analysis of the performance of intermediate cascade shapes we used an unstructured grid based compressible Navier-Stokes flow-field analysis code with k-e turbulence model. A robust genetic optimization algorithm was used for optimization and a constrained sequential quadratic programming was used enforcement of certain constraints. The airfoil geometry was parameterized using conic section parameters and B-splines thus keeping the number of geometric design variables to a minimum while achieving a high degree of geometric flexibility and robustness. Significant reductions of the total pressure loss were achieved using this constrained method for a supersonic exit flow axial turbine cascade.

Numerical Analysis of a Centrifugal Fan for a Road Sweeper

2017 ◽  
Author(s):  
Xiaoxuan Chen ◽  
Mingyang Yang ◽  
Kangyao Deng ◽  
Yunlong Bai
Keyword(s):  
Flow Field ◽  
Field Analysis ◽  
Centrifugal Fan ◽  
Suction Force ◽  
Flow Loss ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Field Analysis ◽  
Cfd Method ◽  
Original Configuration ◽  
Inlet Duct

Road sweeper is the widely-employed machine to clear up garbage and dust on streets. Its performance has profound influence on the reduction of fuel consumption and hence CO2 emission. The key component of a road sweeper is a centrifugal fan which produces suction force for clearing. Therefore, the performance of this device has direct impact on fuel economy of the machine. This paper targets at the performance analysis of a centrifugal fan in a commercial road sweeper. Firstly, the performance and flow field of the centrifugal fan are analyzed by computational fluid dynamics (CFD) method. The breakdown of the flow loss in the fan shows that the volute and the impeller are major components contributing to flow loss in the fan. The flow at the inlet of the impeller is highly distorted due the interaction among the asymmetrical inlet duct, the leakage and the volute tongue. Because of the interaction, flow passages near the tongue are the ones with the highest flow loss. Moreover, the flow velocity entering the volute is considerably high which thus results in high flow loss in the volute. Finally, based on the flow field analysis, an inlet duct with round shape is designed preliminarily and simulated together with the centrifugal fan. The results show that the efficiency can be improved by more than 4% compared with the original configuration due to the alleviation of the interaction.

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