Flow in a Centrifugal Fan Impeller at Off-Design Conditions

1984 ◽  
Vol 106 (4) ◽  
pp. 913-919 ◽  
Author(s):  
T. Wright ◽  
K. T. S. Tzou ◽  
S. Madhavan

Predicted and measured surface velocity and pressure distributions in the internal flow channels of a centrifugal fan impeller are presented for volume flow rates between 80 and 125 percent of design flow rate. Predictions are based on a fully three-dimensional, finite element analysis of the inviscid, incompressible blade channel flow. Additional predictions using a conventional quasi-three-dimensional analysis are presented for comparison. Experimental results were developed using extensive blade and sidewall surface pressure taps installed in a scale model of an airfoil-bladed centrifugal fan impeller designed for heavy industrial and power generation applications. The results illustrate the ability of both flow analyses to predict the dominant features of the impeller flow field, including peak blade surface velocities and adverse gradients at flows far from the design point. In addition, the experimental results provide valuable insight into the limiting channel diffusion values for typical centrifugal cascade performance, and the influence of viscous effects as seen in deviations from the ideal flow predictions.

Author(s):  
D Pan ◽  
A Whitfield ◽  
M Wilson

The initial conceptual design of centrifugal fan and compressor volutes is considered and extended to accommodate overhung volute designs often used in process and turbocharger compressors. The initial passage design is then developed through the application of a commercial computational fluid dynamics (CFD) code.’ Based on the experimental data of a turbocharger compressor volute, three-dimensional, compressible, steady flow computations were carried out for alternative volute designs. Detailed internal flow data in both a conventional and a modified volute design, at both design and off-design flow conditions, are presented. The design investigation showed that enlarging the flow passage area near the tongue region, but without changing the exit-inlet area ratio of the volute, led to an improvement in the internal flow distribution at off-design flow conditions.


Author(s):  
Jian-Cheng Cai ◽  
Da-Tong Qi ◽  
Fu-An Lu

This paper presents a method for predicting casing vibration and noise radiation of a centrifugal fan due to internal fluctuating pressure fields at the blade passing frequency (BPF). Using computational fluid dynamics (CFD) technique based on the finite volume method (FVM), a three-dimensional unsteady simulation of internal flow was carried out by solving the Reynolds averaged Navier-Stokes equations. The oscillating pressure distribution at the volute casing was taken as the excitation of the finite element analysis (FEA) model of the casing structure. Time-domain nodal forces on the casing were obtained by integrating the pressure and viscous stress over the element surfaces. Fast Fourier transform (FFT) was applied to these time series of nodal forces in order to extract the BPF components. Harmonic response analysis was carried out to the casing structure. Sound radiation was finally calculated by the indirect boundary element method (IBEM) with the vibration results as velocity boundary condition. This study shows that it is feasible to use fluid-structure weakly coupled simulations for the prediction of flow-induced casing vibration and noise radiation of centrifugal turbomachinary.


Author(s):  
M. B. Flathers ◽  
G. E. Bache ◽  
R. Rainsberger

The flowfield of a complex three dimensional radial inlet for an industrial pipeline centrifugal compressor has been experimentally determined on a half scale model. Based on the experimental results, inlet guide vanes have been designed to correct pressure and swirl angle distribution deficiencies. The unvaned and vaned inlets are analyzed with a commercially available fully 3D viscous Navier-Stokes code. Since experimental results were available prior to the numerical study, the unvaned analysis is considered a postdiction while the vaned analysis is considered a prediction. The computational results of the unvaned inlet have been compared to the previously obtained experimental results. The experimental method utilized for the unvaned inlet is repeated for the vaned inlet and the data has been used to verify the computational results. The paper will discuss experimental, design and computational procedures, grid generation, boundary conditions, and experimental versus computational methods. Agreement between experimental and computational results is very good, both in prediction and postdiction modes. The results of this investigation indicate that CFD offers a measurable advantage in design, schedule and cost and can be applied to complex, three dimensional radial inlets.


2005 ◽  
Vol 128 (2) ◽  
pp. 359-369 ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Sandra Velarde-Suárez ◽  
Juan Pablo Hurtado-Cruz ◽  
Carlos Santolaria-Morros

In this work, a numerical model has been applied in order to obtain the wall pressure fluctuations at the volute of an industrial centrifugal fan. The numerical results have been compared to experimental results obtained in the same machine. A three-dimensional numerical simulation of the complete unsteady flow on the whole impeller-volute configuration has been carried out using the computational fluid dynamics code FLUENT®. This code has been employed to calculate the time-dependent pressure both in the impeller and in the volute. In this way, the pressure fluctuations in some locations over the volute wall have been obtained. The power spectra of these fluctuations have been obtained, showing an important peak at the blade passing frequency. The amplitude of this peak presents the highest values near the volute tongue, but the spatial pattern over the volute extension is different depending on the operating conditions. A good agreement has been found between the numerical and the experimental results.


Author(s):  
Qiang Kang ◽  
Shuguang Zuo ◽  
Kaijun Wei

The regenerative flow compressor used in fuel-cell cars generates high aerodynamic noise, which is the main source of noise. Compared with the research on centrifugal or axial turbomachinery, research on the noise of regenerative flow compressors is far from adequate. This paper presents the on-going work on it at Tongji University based on both experimental and computational works. In this study, a three-dimensional unsteady computational fluid dynamic model of the compressor was constructed with the large eddy approach. The pressure fluctuation, vortex noise source and Ffowcs William-Hawkings (FW-H) method were used to analyze the characteristics of the aerodynamic noise sources. Additionally, the far-field aerodynamic noise generated by the internal flow of the compressor was predicted using the aeroacoustic finite element method. The simulation results were validated with the experimental data. It was found that combining the fluid dynamic model and aeroacoustic finite element analysis promising results for aerodynamic noise prediction of compressors could be produced. The effects of the impeller parameters on the aerodynamic noise of the compressor were also studied.


2013 ◽  
Vol 284-287 ◽  
pp. 996-1000 ◽  
Author(s):  
Jong Boon Ooi ◽  
Xin Wang ◽  
Ying Pio Lim ◽  
Ching Seong Tan ◽  
Jee Hou Ho ◽  
...  

Portal axle unit is a gearbox unit installed on every end axles of the vehicle. It is installed to the vehicle to give higher ground clearance to enable vehicle to go over large obstacle when driving in off-road conditions. Shafts must be exceptionally tough and lightweight to improve the overall performance of the portal axle unit. In this paper, the shaft is analyzed in three-dimensional model and the stress of the shaft model is analyzed using finite element analysis (FEA). The FEA result is compared with experimental results.


Author(s):  
Alex P. Cocco ◽  
Kyle N. Grew

Abstract The analytical transport network (ATN) model for flow through microstructural networks is extended to linearly coupled flows subject to Onsager reciprocity. Electrokinetic flow is used as an example system. Through the extension, we gain an improved understanding of if, and how, morphology and topology influence coupled flow systems differently than un-coupled flows. In Part 1, a channel-scale model is developed to describe electrokinetic flow through a channel of arbitrary morphology. The analytical model agrees well with finite element analysis (FEA), but is significantly less expensive in terms of computational resources, and, furthermore, offers general insight into morphology's additional influence on coupled flows relative to uncoupled flows. In Part 2, we exploit these savings to develop a computationally economical, network-scale model and associated algorithm for its implementation to voxel-based three-dimensional images. Included in the algorithm is a means for rapidly calculating a structure's tortuosity factor. This modeling effort represents an important initial step in extending the ATN approach to coupled flow phenomena relevant to emerging technologies that rely on heterogeneous, hierarchical materials.


1996 ◽  
Vol 118 (2) ◽  
pp. 371-384 ◽  
Author(s):  
M. B. Flathers ◽  
G. E. Bache ◽  
R. Rainsberger

The flow field of a complex three-dimensional radial inlet for an industrial pipeline centrifugal compressor has been experimentally determined on a half-scale model. Based on the experimental results, inlet guide vanes have been designed to correct pressure and swirl angle distribution deficiencies. The unvaned and vaned inlets are analyzed with a commercially available fully three-dimensional viscous Navier–Stokes code. Since experimental results were available prior to the numerical study, the unvaned analysis is considered a postdiction while the vaned analysis is considered a prediction. The computational results of the unvaned inlet have been compared to the previously obtained experimental results. The experimental method utilized for the unvaned inlet is repeated for the vaned inlet and the data have been used to verify the computational results. The paper will discuss experimental, design, and computational procedures, grid generation, boundary conditions, and experimental versus computational methods. Agreement between experimental and computational results is very good, both in prediction and postdiction modes. The results of this investigation indicate that CFD offers a measurable advantage in design, schedule, and cost and can be applied to complex, three-dimensional radial inlets.


Author(s):  
Seoung-Jin Seo ◽  
Kwang-Yong Kim

This paper presents the response surface optimization method using three-dimensional Navier-Stokes analysis to optimize the shape of a forward-curved blades centrifugal fan. For numerical analysis, Reynolds-averaged Navier-Stokes equations with k-ε turbulence model are discretized with finite volume approximations. In order to reduce huge computing time due to a large number of blades in forward-curved blades centrifugal fan, the flow inside of the fan is regarded as steady flow by introducing the impeller force models. Three geometric variables, i.e., location of cut off, radius of cut off, and width of impeller, and one operating variable, i.e., flow rate, were selected as design variables. As a main result of the optimization, the efficiency was successfully improved. And, optimum design flow rate was found by using flow rate as one of design variables. It was found that the optimization process provides reliable design of this kind of fans with reasonable computing time.


2012 ◽  
Vol 538-541 ◽  
pp. 686-689
Author(s):  
Yu Kun Lv ◽  
Bao Jun Song ◽  
Tong Chang Lu

Taking the G4-73№8D centrifugal fan as research object and utilizing the software of NUMECA to simulate flow fields of volute with different widths, the parameters of width are optimized through contrastive analysis of the effects on internal flow characteristics and performance. Results show that the optimized scheme can improve the uniformity of internal flow field, full pressure and efficiency seperatly increase by 0.52% and 0.48% under the design flow. For the needs of variable fan load operation, this paper puts forward the optimization principle of width parameter.


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