Numerical and Experimental Analyses for the Aerodynamic Design of High Performance Counter-Rotating Axial Flow Fans

2009 ◽  
Author(s):  
Leesang Cho ◽  
Hyunmin Choi ◽  
Seawook Lee ◽  
Jinsoo Cho
Keyword(s):  
High Performance ◽  
Incidence Angle ◽  
Flow Analysis ◽  
Axial Flow ◽  
Flow Fields ◽  
Rotor Blades ◽  
Design Parameters ◽  
Aerodynamic Design ◽  
Axial Fan ◽  
Experimental Analyses

A study was done on the numerical and experimental analyses for the aerodynamic design of high performance of the counter rotating axial fan (CRF). Front rotor and rear rotor blades of a counter rotating axial fan are designed using the simplified meridional flow analysis method with the radial equilibrium equation and the free vortex design condition, according to design requirements. The through-flow fields and the aerodynamic characteristics of the designed rotor blades are analyzed by the matrix method and the frequency domain panel method. Fan performance curves are measured by following the standard fan testing method, KS B 6311. Three-dimensional flow fields in the CRF are analyzed by using the prism type five-hole probe. Performance characteristics of a counter-rotating axial flow fan are estimated for the variation of design parameters such as the hub to tip ratio, the taper ratio and the solidity. The effect of the hub to tip ratio on the fan efficiency is significant compared with the effects of other design parameters such as the solidity and the taper ratio. The fan efficiency is peak at the hub to tip ratio of 0.4, which is almost same point for the front rotor efficiency and rear rotor efficiency. The magnitudes of the meridional and relative velocities on the front and rear rotors are increased with the radial direction from hub to tip. This results in the reverse pressure gradient at the blade leading edges of both the front rotor and the rear rotor. Axial velocities of the CRF, which are measured by the prism type five-hole probe, are gradually increased at the mean radius due to the flow contraction effect. At the hub region, axial velocity is gradually decreased due to the flow separation and the hub vortex compare with design results. This result induces the increment of the incidence angle and the diffusion factor of the front rotor and the rear rotor.

scholarly journals Flow Analysis through Collector Well Laterals: A Case Study from Sonoma County Water Agency, California

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1848
Author(s):  
Matteo D’Alessio ◽  
John Lucio ◽  
Ernest Williams ◽  
James Warner ◽  
Donald Seymour ◽  
...  
Keyword(s):  
Optimal Design ◽  
Visual Inspection ◽  
Flow Analysis ◽  
Axial Flow ◽  
Design Parameters ◽  
Sonoma County ◽  
Russian River ◽  
North Western ◽  
Entrance Velocity

The Sonoma County Water Agency (SWCA) uses six radial collector wells along the Russian River west of Santa Rosa, to provide water for several municipalities and water districts in north-western California. Three collector wells (1, 2, and 6) are located in the Wohler area, and three collector wells (3, 4, and 5) are located in the Mirabel area. The objective of this paper is to highlight the performance of the three collector wells located in the Mirabel area since their construction. The 2015 investigation showed a lower performance of Collectors 3 and 4 compared to their original performances after construction in 1975, while the performance of Collector 5 was relatively stable since 1982. The potential change in capacity could be due to the increase in encrustation observed during the visual inspection of laterals in all three collector wells. Overall, the three collectors are still within the optimal design parameters (screen entrance velocity < 0.305 m min−1 and axial flow velocity of lateral screens < 1.524 m s−1).

OVERVIEW OF THE BEST 2020 AXIAL-FLOW FAN DATA AND INCLUSION IN SIMILARITY CHARTS FOR THE SEARCH OF THE BEST DESIGN

2022 ◽  
pp. 1-19
Author(s):  
Massimo Masi ◽  
Piero Danieli ◽  
Andrea Lazzaretto
Keyword(s):  
Axial Flow ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Axial Fan ◽  
Axial Flow Fan ◽  
General Picture ◽  
Fan Performance ◽  
Global Performance ◽  
Present Design ◽  
Statistical Survey

Abstract The paper deals with the aerodynamic performance of ducted axial-flow fans available in the 2020 market and aims to create a general picture of the best designs and design trends, as a tool for fan designers. To this end, the paper first presents the general formulation of the similarity approach to the fan performance analysis, including the effects of rotational speed (which affects the validity of the Reynolds similarity) and turbomachine size (which can hinder the perfect geometrical similarity of some shape details). The second part reports a statistical survey of the axial-flow fan performance based on data from catalogues of major manufacturers, and compares the resulting Cordier-lines with optimum fan designs from empirical or CFD-based models available in the literature. In addition to the global performance at maximum aeraulic and total-to-static efficiencies, this survey uses the form of dimensionless Balje-Cordier charts to identify the trends and values of other design parameters, such as hub-to-tip ratio, blade count, and blade positioning angle. As a result, a summary of the aerodynamic performance of year 2020 best designs, the improvements achieved during the last forty years, and the present design trends in contra-rotating, vane-axial, and tube-axial fan types are made available to fan designers.

Experimental and Numerical Study of Blade Profiles for Axial Flow Fans

1998 ◽  
Author(s):  
Veronique Henry
Keyword(s):  
Optimization Design ◽  
Numerical Study ◽  
Axial Flow ◽  
Leading Edge ◽  
Design Parameters ◽  
Blade Design ◽  
Aerodynamic Design ◽  
Design And Optimization ◽  
Expected Performance ◽  
Ventilation Fan

Abstract An experimental and numerical investigation is presented for blade profiles in axial flow fans. In order to improve the aerodynamic design of the blades, first numerical simulations with a two dimensional cascade oriented code have been performed in the rotor passage of a single-stage axial flow ventilation fan. The optimization design has been performed involving statistics. The influence of four design parameters have been investigated: rate of curvature, leading edge shape, chordwise location of the maximum camber and chordwise location of the maximum thickness. The new profile produced has been tested in wind-tunnel with a well-known C4 profile to validate the expected performance level. Next step has consisted in performing Navier-Stockes computations. Results demonstrate that the use of a coupled viscous-inviscid approach is appropriate for blade design and optimization. The Navier-Stockes code can be seen as a complementary tool as it leads to a complete description of the flow.

Performance of the Wells Turbine With Variable Pitch Rotor Blades

1991 ◽  
Vol 113 (3) ◽  
pp. 141-146 ◽  
Author(s):  
L. M. C. Gato ◽  
L. R. C. Ec¸a ◽  
A. F. de O. Falca˜o
Keyword(s):  
Flow Analysis ◽  
Three Dimensional ◽  
Axial Flow ◽  
Ocean Waves ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Computational Method ◽  
Wells Turbine ◽  
Predicted Values ◽  
Energy Absorbing

The Wells turbine is an axial-flow air-turbine designed to extract energy from the ocean waves. The turbine is self-rectifying, i.e., produces an unidirectional time-averaged torque from a reciprocating flow. The paper describes an experimental investigation on the aerodynamic performance of a modified version of the Wells turbine, whose rotor blades can be set at varying angle (as in a Kaplan turbine) while the turbine is in motion. The purpose of the work is to investigate whether, and to what extent, the modification to the turbine can enable it to achieve phase control—a method of tuning the energy-absorbing device to the incident waves—and avoid aerodynamic stall on the turbine rotor blades at peaks of air flow rate under conditions of real irregular ocean waves. Experimental results obtained with a model turbine are compared with predicted values from a quasi-three-dimensional computational method of flow analysis.

scholarly journals Study of Sweep and Induced Dihedral Effects in Subsonic Axial Flow Compressor Passages—Part I: Design Considerations—Changes in Incidence, Deflection, and Streamline Curvature

2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
P. V. Ramakrishna ◽  
M. Govardhan
Keyword(s):  
Axial Compressor ◽  
Axial Flow ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Design Parameters ◽  
Tip Leakage Flow ◽  
Efficient Energy Transfer ◽  
Compressor Rotor ◽  
Mass Flow Rates ◽  
Flow Compressor

This article presents the study of Tip Chordline Sweeping (TCS) and Axial Sweeping (AXS) of low-speed axial compressor rotor blades against the performance of baseline unswept rotor (UNS) for different tip clearance levels. The first part of the paper discusses the changes in design parameters when the blades are swept, while the second part throws light on the effect of sweep on tip leakage flow-related phenomena. 15 domains are studied with 5 sweep configurations (, TCS, TCS, AXS, and AXS) and for 3 tip clearances (0.0%, 0.7%, and 2.7% of the blade chord). A commercial CFD package is employed for the flow simulations and analysis. Results are well validated with experimental data. Forward sweep reduced the flow incidences. This is true all over the span with axial sweeping while little higher incidences below the mid span are observed with tip chordline sweeping. Sweeping is observed to lessen the flow turning. AXS rotors demonstrated more efficient energy transfer among the rotors. Tip chordline sweep deflected the flow towards the hub while effective positive dihedral induced with axial sweeping resulted in outward deflection of flow streamlines. These deflections are more at lower mass flow rates.

scholarly journals 3-D Viscous Flow Analysis of an Axial Flow Pump Impeller

1997 ◽  
Vol 3 (3) ◽  
pp. 153-161 ◽  
Author(s):  
Steven M. Miner
Keyword(s):  
Stokes Equations ◽  
Flow Analysis ◽  
Axial Flow ◽  
Flow Coefficient ◽  
Navier Stokes ◽  
Design Parameters ◽  
Pump Impeller ◽  
Flow Angle ◽  
Axial Flow Pump ◽  
Flow Pump

A commercial CFD code is used to compute the flow field within the first stage impeller of a two stage axial flow pump. The code solves the 3-D Reynolds Averaged Navier Stokes equations in a rotating cylindrical coordinate system using a standardk−εturbulence model. Stage design parameters are, rotational speed 870 rpm, flow coefficientφ=0.12, head coefficientψ=0.06, and specific speed 2.86 (8070 US). Results from the study include relative and absolute velocities, flow angles, and static and total pressures. Comparison is made to measured data available for the same impeller at two planes, one upstream of the impeller and the other downstream. The comparisons are for circumferentially averaged results and include axial and tangential velocities, impeller exit flow angle, static pressure, and total pressure. Results of this study show that the computational results closely match the shapes and magnitudes of the measured profiles, indicating that CFD can be used to accurately predict performance.

Unsteady Flow Analysis of the Stator-Rotor Interaction in an Axial Flow Fan

2003 ◽  
Author(s):  
J. Ferna´ndez Oro ◽  
K. Argu¨elles Di´az ◽  
C. Santolaria Morros ◽  
R. Ballesteros Tajadura
Keyword(s):  
Unsteady Flow ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Axial Flow ◽  
3D Models ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Axial Flow Fan ◽  
Rotating Blade ◽  
Flow Phenomena

In the usual operation of turbomachinery, some unsteady flow phenomena appear due to the non uniformity of the flow inside the rotor, when observed in the fixed reference frame. These phenomena are often related to the unsteady character of the pressure and velocity fields, which produce oscillating forces on the blades, superimposed to the steady force. These oscillating forces are the main mechanism of noise generation, which appear even at a constant rotational speed and at flow rates where the performance curves are stable. In axial turbomachines, the interaction is due to relative motion between the static and rotating blade rows. Considering the case of a fixed blade row (stator) placed upstream of the rotor, the non uniform flow leaving those blades (usually referred as IGV blades) is observed as an unsteady flow by the rotor blades. The effect of this interaction is the generation of unsteady forces on the rotor blades, which generate vibrations (risk of fatigue failure) and noise, and non-uniformity and unsteadiness of the pressure field, that propagates as an acoustic wave. The first part of this work is a brief description of a URANS numerical modeling of the unsteady flow characteristics of a one-stage subsonic axial flow fan with a reaction degree greater than 1. The focus is placed on the statorrotor interaction performance. Both 2D and 3D models of the fan, with 13 IGV’s and 9 rotor blades, were developed and an unsteady simulation was achieved to carry out the main characteristics of the flow inside the turbomachine. Once the actuating forces are determined, the influence of the radial position, the operating conditions and the distance of the fixed and the rotating blade rows is also analyzed. The final part of the paper is focused over the identification, through the definition of deterministic stresses — related to the characteristic blade-passage frequency of every row — that provoke the interaction between fixed and rotating blade rows and its evolution through time. The object is to obtain, in a stress tensor form, the contribution of the velocity field, that is changing because of the sucessive relative positions between blade rows, to the pressure distribution over the blade surfaces in the interior of the stage. Finally, a map of deterministic stresses and even, deterministic kinetic energy, can be obtained to show the influence of the blade rows in the interaction, unsteady phenomena.

Experimental Investigation of Stall Inception and its Propagation in a Contra Rotating Axial Fan Under Radial Inflow Distortion

2017 ◽  
Author(s):  
Tegegn Dejene Toge ◽  
A. M. Pradeep
Keyword(s):  
Wavelet Transform ◽  
Mass Flow ◽  
Wavelet Transforms ◽  
Fourier Transforms ◽  
Incidence Angle ◽  
Axial Flow ◽  
Pressure Data ◽  
Axial Fan ◽  
Stall Inception ◽  
Unsteady Pressure

Radial inflow distortion is encountered by any turbomachine in some form or the other. Radial inflow distortion alters the design blade loading distribution by redistributing the velocity along the blade span. The present experimental study is aimed to understand the influence of radially distorted inflow on the stall inception and propagation in a low speed contra rotating axial flow fan (CRAF). The study is carried out near-stall and at stall mass flow conditions for the design speed and off-design rotational speed combinations of the rotors. Total pressure rakes and Kiel probe rakes are used for flow characterization at the inlet of rotor-1 and rotor-2. Data from seven-hole probe measurement is also used to calculate the incidence angle at rotors inlet and the total press loss at relative frame of reference. Unsteady pressure data from the casing wall mounted sensors is used to understand the stall inception mechanism. The unsteady pressure data is analyzed using wavelet transforms and Fast Fourier Transforms (FFT). Wavelet transform is used to identify the stall inception mechanism, whereas FFT is used for quantification of the stall parameters. The study reveals that the performance and the stability of the CRAF stage is highly affected in case of hub covered radial distorted inflow condition and the stall incepts at a higher mass flow compared with the undistorted flow. However, the effect of tip covered radial distorted inflow on the performance and stability is negligible, and the stall incepts at nearly the same mass flow rate as that of the undistorted flow. Moreover, the CRAF stage gives better performance at higher mass flow for tip radially distorted inflow compared with the undistorted case. The wavelet transform clearly indicates that stall inception occurs mainly through long length-scale disturbances (LLSDs) for both the rotors. It is also observed that in some cases, spikes are embedded within LLSDs. The combined effect of stall initiated due to inflow distortion and direct interaction of the wake and the tip leakage vortex from rotor-1 with rotor-2 made the LLSDs and spikes type disturbances much stronger for rotor-2 compared with rotor-1.

Overview of the Best 2020 Axial-Flow Fan Data and Inclusion in Similarity Charts for the Search of the Best Design

2021 ◽  
Author(s):  
Massimo Masi ◽  
Piero Danieli ◽  
Andrea Lazzaretto
Keyword(s):  
Axial Flow ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Axial Fan ◽  
Axial Flow Fan ◽  
General Picture ◽  
Fan Performance ◽  
Global Performance ◽  
Present Design ◽  
Statistical Survey

Abstract The paper deals with the aerodynamic performance of ducted axial-flow fans available in the 2020 market and aims to create a general picture of the best designs and design trends, as a tool for fan designers. To this end, the paper first presents the general formulation of the similarity approach to the fan performance analysis, including the effects of rotational speed (which affects the validity of the Reynolds similarity) and turbomachine size (which can hinder the perfect geometrical similarity of some shape details). The second part reports a statistical survey of the axial-flow fan performance based on data from catalogues of major manufacturers, and compares the resulting Cordier-lines with optimum fan designs from empirical or CFD-based models available in the literature. In addition to the global performance at maximum aeraulic and total-to-static efficiencies, this survey uses the form of dimensionless Balje-Cordier charts to identify the trends and values of other design parameters, such as hub-to-tip ratio, blade count, and blade positioning angle. As a result, a summary of the aerodynamic performance of year 2020 best designs, the improvements achieved during the last forty years, and the present design trends in contra-rotating, vane-axial, and tube-axial fan types are made available to fan designers.

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