Preliminary Experimental Assessment Of The Performance Of Tube-Axial Fans Designed With Different Vortex Criteria (original) (raw)
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Rotor-only axial fans feature rotors designed according to different vortex criteria. Nowadays the literature does not exhaustively clarify when a specific swirl distribution has to be used and which are the advantages/drawbacks in terms of fan performance and efficiency. A review of the experimental performance of rotor-only axial fans designed with different vortex criteria is summarized here in Φ − Ψ and σ − δ (specific speed-specific diameter) graphs to identify the best operating conditions of each design. Four rotor-only axial fans (two free-vortex, a constant-swirl and a rigid-body swirl one) are tested on an ISO-5801-A rig. For two of them, flow velocities at rotor exit are measured with a 5-hole probe. The result is an experimentally based map around the Cordier curve for rotor-only axial fans. Indications on the best Φ − Ψ range for fans designed using different vortex criteria are provided and explained. The effects of increasing the tip clearance on the rotor performance at design duty are investigated as well.
Experimental Thermal and Fluid Science, 2011
The purpose of this work is to study the effects of blade thickness on the performances of an axial-flow fan. Two fans that differ only in the thickness of their blades were studied. The first fan was designed to be part of the cooling system of an automotive vehicle power unit and has very thin blades. The second fan has much thicker blades compatible with the rotomoulding conception process. The overall performances of the fans were measured in a test bench designed according to the ISO-5801 standard. The curve of aerodynamics characteristics (pressure head versus flow-rate) is slightly steeper for the fan with thick blades, and the nominal point is shifted towards lower flow-rates. The efficiency of the thick blades fan is lower than the efficiency of the fan with thin blades but remains high on a wider flow-rate range. The mean velocity fields downstream of the rotors are very similar at nominal points with less centrifugation for the thick blades fan. Moreover, the thick blades fan maintains an axial exit-flow on a wider range of flow-rates. The main differences concern local properties of the flow: Phase-averaged velocities and wall pressure fluctuations strongly differ at the nominal flow-rates. The total level of fluctuations is lower for the thick blades fan that for the thin blades fan and the spectral decomposition of the wall fluctuations and velocity signals reveal more harmonics for the thick blades fan, with less correlation between the different signals. For this kind of turbomachinery, the use of thick blades could lead to a good compromise between aerodynamic and acoustic performances, on a wider operating range.
Experimental and Numerical Investigation onto 1250mm Axial Fan
Applied Mechanics and Materials, 2012
Numerical simulation is of interest for most fan designers to optimize the fan designs. Computational fluid dynamic (CFD) has become an essential tool in almost every branch of fluid dynamics and one of the major tools for fan designs. As the fan designers relying on the numerical simulation, the accuracy of tools such as CFD in predicting the performance has become a subject of interest. This paper validates the CFD modeling of an axial fan design against experimental result. The experimental rig and test procedure are developed with reference to “AMCA standard 210”. The analysis is conducted on 1250mm diameter axial fan with two different blade pitch angle 30° and 40°. Prior to encounter the swirling effect and deflection of velocity vector due to rotor blade, a stator blade with the same profile as rotor blade is used as the outlet guide vanes in opposite direction. The computational model is created according to the experimental condition and applied realistic boundary condition...
Computational characterization of an axial rotor fan
Journal of Energy Systems, 2017
Axial flow fans are broadly applied in numerous industrial applications because of their simplicity, compactness and moderately low cost, such us propulsion machines and cooling systems. Computational fluid dynamics techniques are commonly applied to investigate flow phenomena through the axial fan and the rotor dynamic performance. In the present work, a computational model of an axial fan is presented in the current study. Numerical simulations of a single stage axial fan on variable conditions have been performed to obtain the detailed flow field of the centrifugal fan. The investigation of the current work is focused on the rotor–stator configuration and the modeling of aerodynamic behavior of the blade rows. The precise prediction of axial force and efficiency has essential implication for the optimized operation of axial fan and the choice of thrust bearing. Furthermore, it can act as guide for the geometrical and structural axial fan design and the study of axial force predic...
Axial Flow Fan Design Parameter Affecting the Performance
Material Science Research India
Axial flow fans are employed in heat exchangers and other engineering systems where the flow path around the fan becomes like a duct. The flow takes place along the axis of rotation of the rotor. The flow is essentially symmetrical to the axis. The design calculations are performed with presumption of flow through cascade of blade and it is the main governing factor of the design too. In this paper procedural calculation for an axial flow fan with profiled blade are presented. Calculations are tabulated for different parameter of radius and angles. On profiling, the increase of outlet angle has been shown which gives ultimate angle opening. The small corrections are therefore obtained. Different parameters used in the design are tabulated to get the calculation more accurately.
Aerodynamic Design of Low-Speed Axial-Flow Fans: A Historical Overview
The paper presents a historical overview of the developments of aerodynamic design methods for low-speed axial-flow fans. This historical overview starts from the first fan applications, dating back to the 16th century, and arrives to the modern times of computer-based design techniques, passing through the pioneering times of aerodynamic theories and the times of designing before computers. The overview shows that the major achievements in the axial fan design discipline have actually been related to other technological fields, such as marine and aeronautical propulsion, as well as to the development of wind tunnels. At the end of the paper, the reader will have acquired a complete panorama of how the historical developments of the discipline have brought us to the current state of the art.
The Effect of Tip End-Blade Geometry on the Axial Fans Performance
A numerical study is carried out to investigate the effect of the addition of winglet to the end of blade on the axial fan performance. Validation and assessment of the used computer program FLUENT 6.2, is carried out by comparing its result with previous researcher. Simulation is then carried out to analyze the flow pattern with and without a winglet attached to the fan blade. Velocity distribution produced numerically showed that the winglet suppresses the secondary flow at the tip gap. Pressure distributions also confirmed the winglet advantages. Calculated performance of the fan used showed general increase of the fan efficiency with 3.5% above those without winglet at the optimum efficiency point and with up to 6 % at off design point.. 1. INTRODUCTION Fans demand minimum gaps in order to facilitate operation, this gap tip clearance flow is known to have detrimental effects on the axial fans performance. The static pressure difference between the suction and the pressure side o...
Experimental Investigation on Aerodynamic Characteristics of an Axial Flow Fan
The prime objective of this work is to determine the relationship between the mechanical and aerodynamic characteristics of the fan when the blade position is default and when it is changed and to find out which position gives optimum output at given power and given working conditions and according to the change of environment. In this experiment, the aerodynamic characteristic of an axial flow fan is going to be determined by measuring the static and total pressures in the suction and discharge sides of the fan for various flow rates. In this experiment, for different blade angle, flow velocity is measured and relationship between the change of blade angles and the flow velocity are plotted
International Journal of Rotating Machinery, 2011
The flow field at the rotor exit of a low aspect ratio axial flow fan for different tip geometries and for different flow coefficients is measured in the present study. The following configurations are tested: (1) rotor without partial shroud, designated as rotor (wos), (2) rotor with partial shroud, designated as rotor (ws), and (3) rotor with perforated (perforations in the shape of discrete circular holes) partial shroud, designated as rotor (wps). From steady state measurements, the performance of rotor (wps) is found to be the best. Both the rotors with partial shrouds have stalled at a higher flow coefficient compared to that of rotor (wos). From periodic flow measurements, it is concluded that the low velocity region near the tip section is considerably reduced with the use of partial shrouds with perforations. The extent of this low velocity region for both rotor (wos) and rotor (wps) increases with decreasing flow coefficient due to increased stage loading. This core of low...
EFFECTIVENESS OF BLADE FORWARD SWEEP IN A SMALL INDUSTRIAL TUBE-AXIAL FAN
SUMMARY Forward swept blades in low-speed axial fan rotors allow for appreciable gain in the stall margin and a small percentage gain in the maximum fan efficiency if the rotor blade circulation increases from the hub to tip. However, a reduction of the fan pressure at the design point counteracts these advantages. The paper investigates the effectiveness for small tube-axial fans of a design method suggested to increase the performance of an existing arbitrary vortex design by introducing the span-wise uniform distribution of blade forward sweep. The following three rotors for a 315-mm tube-axial fan have been tested: unswept, forward swept, and forward swept with additional sweep at the blade tip. Experimental data prove the effectiveness of the design method for these small fans.