scholarly journals Low-pressure reversible axial fan designed with different specific work of elementary stages

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 605-615 ◽  
Author(s):  
Bozidar Bogdanovic ◽  
Zivan Spasic ◽  
Jasmina Bogdanovic-Jovanovic
Keyword(s):  
Suction Side ◽  
Low Pressure ◽  
Standard Test ◽  
Specific Work ◽  
Spatial Curvature ◽  
Operating Characteristics ◽  
Test Rig ◽  
Axial Fan ◽  
Air Intake ◽  
Axial Fans

Low-pressure axial fan impellers designed according to the principle of equal specific work of all elementary stages have blades whose profile near the fan hub is under a significantly larger inclination angle than at the impeller periphery. In order to minimize the spatial curvature of the fan blades and the fan hub length, impeller blades of low-pressure axial fans can be designed with different specific work of elementary stages, so that the specific work of elementary stages is smaller at the hub than at the periphery. This paper presents the operating characteristics of a low-pressure reversible axial fan with straight blade profiles, designed with different specific work of elementary stages. The fan was tested on a standard test rig, with air intake loading on the suction side of the fan.

scholarly journals Low-pressure reversible axial fan with straight profile blades and relatively high efficiency

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 593-603 ◽  
Author(s):  
Zivan Spasic ◽  
Sasa Milanovic ◽  
Vanja Sustersic ◽  
Boban Nikolic
Keyword(s):  
Numerical Simulations ◽  
High Efficiency ◽  
Suction Side ◽  
Standard Test ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Blade Profile ◽  
Operating Characteristics ◽  
Axial Fan ◽  
Increase Energy Efficiency

The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.

Computational Modeling of Low-Pressure Fan Flows

2000 ◽  
Author(s):  
Siddharth Thakur ◽  
Wanlai Lin ◽  
Jeffrey Wright ◽  
Wei Shyy ◽  
Ron Lievens
Keyword(s):  
Pressure Rise ◽  
Low Pressure ◽  
Flow Fields ◽  
Numerical Dissipation ◽  
Computational Tool ◽  
Axial Fan ◽  
Static Efficiency ◽  
Blade Shape ◽  
Axial Fans ◽  
Mass Flow Rates

A CFD-based computational tool is used to analyze flows in axial fans. Computed results for an axial fan flow field for one particular blade shape are presented; certain global quantities such as the mass-averaged pressure rise and the static efficiency available from test data for different mass flow rates are used to evaluate the trends predicted by the CFD results. The characteristic feature of the fan flow fields presented here is a very low pressure rise; due care is exercised to ensure that grid dependence and numerical dissipation do not smear out the key features of the computed flow fields.

Experimental Investigation of Ambient Wind Influence on the Performance of Axial Fans

2014 ◽  
Author(s):  
Till Heinemann ◽  
Stefan Becker
Keyword(s):  
Wind Tunnel ◽  
Operating Mode ◽  
Positive Influence ◽  
Test Rig ◽  
Axial Fan ◽  
Axial Fans ◽  
Wind Velocities ◽  
Wind Influence ◽  
Water Scarce ◽  
The University

The EU-funded MACCSol project is developing a new modular air-cooled condenser design for power plant applications in water scarce regions. In that scope, this work is to examine the influence ambient winds may have on an axial ventilator’s performance. An axial fan test rig was built inside a wind tunnel environment at the University of Erlangen to realize different wind velocities and angles. Total fan pressure was captured using an array of 81 Kiel probes. The validity of the test rig adaptations to the wind tunnel restrictions was shown in comparison to results from ISO 5801 standard fan test rigs. Two different fan geometries were examined in their characteristic fan curves’ reactions to wind influence at the free fan inlet. The two fans’ characteristic curves showed effects differing in magnitude, but similar in their tendency. While frontal winds tended to improve fan performance, cross winds reduced it. In reverse operating mode, the effect of wind at the fan outlet demonstrated little but positive influence on the fan curve. In order to reduce negative cross wind influence at the fan inlet, different conical and cylindrical inlet extensions were tested. Short conical shrouds performed best.

scholarly journals COMPARISON OF AXIAL FAN ROTOR EXPERIMENTAL DATA WITH CFD SIMULATION

2016 ◽  
Vol 56 (1) ◽  
pp. 62 ◽  
Author(s):  
Aleš Prachař
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Cfd Simulation ◽  
Free Stream ◽  
Calculated Data ◽  
Experimental Simulation ◽  
Test Rig ◽  
Axial Fan ◽  
Axial Fans ◽  
Adequate Agreement

Data obtained from an experimental simulation on a new test rig for axial fans are compared to a CFD simulation. The Edge solver is used and the development needed for the simulation (boundary conditions, free stream consistency) is described. Adequate agreement between the measured and calculated data is observed.

Cross Wind Influence on Noise Emission and Computed Vibrational Noise of an Axial Fan

2015 ◽  
Author(s):  
Till Heinemann ◽  
Sven Münsterjohann ◽  
Florian Zenger ◽  
Stefan Becker
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Laser Scanning ◽  
Sound Pressure ◽  
Cross Flow ◽  
Test Rig ◽  
Axial Fan ◽  
Noise Emission ◽  
Axial Fans ◽  
Operating Points

The total noise emissions of two commercial axial fans were measured in a semi-anechoic fan test rig in comparison. The total sound pressure levels and the respective spectra were found to change with the fans’ operating points. Increasing fan flow rates lowered the total acoustic pressure, with a broadband shift towards higher frequencies, keeping perceived (A-weighted) sound pressure levels approximately constant over a wide range of operating points. In a second step, Laser Scanning Vibrometry measurements of the fan blades’ axial motion were conducted in comparison inside a wind tunnel fan test rig. Rotating blade surface vibration data was used as sole input to a Ffowcs Williams and Hawkings algorithm, to estimate noise emission from vibration. The computed noise from surface vibration was found to be hardly affected by the change of fan flow rate. In the application of an axial fan subject to natural wind or induced cross flow at its inlet, the flow field and possible noise emission of the fan changes. Microphone measurements of the cross flow influence inside a semi-anechoic wind tunnel revealed increasing broadband noise with ambient flow field velocity, and an amplification of the sound at the blade passing frequency harmonics. Similar excitations of the blade passing frequency harmonics under cross flow influence were also found in sound pressure spectra computations based on the Laser Scanning Vibrometry measurement data captured in the wind tunnel fan test rig. Blade vibration is considered to contribute to the low frequency tonal noise emission of axial fans operating under cross flow conditions.

Inverse Analytical and Computational Design Method Applied to a Low Pressure Axial Fan

2010 ◽  
Author(s):  
Mihai Miclea-Bleiziffer ◽  
Philipp Epple ◽  
Antonio Delgado
Keyword(s):  
Design Method ◽  
Computational Design ◽  
Integrated Approach ◽  
Low Pressure ◽  
Inverse Design ◽  
Axial Fan ◽  
Rotating Speed ◽  
Design And Optimization ◽  
Research Fields ◽  
Axial Fans

Nowadays precise and reliable tools for designing and optimizing turbomachines have a high impact on industrial and research fields. The design methods of turbomachines follow usually two main paths: direct design, where performances are achieved by iteratively modifying a given geometry, and inverse design where performance characteristics are prescribed and the proper geometry for reaching them is found (usually using analytical methods). Both of these methods are used today in research and development and they are coupled with numerical simulations (CFD) for shorter design cycles. This paper proposes an inverse design approach for low pressure axial fans based upon performance equations, namely the equations for total-to-static pressure and efficiency. To validate our approach we use numerical simulation of the axial fan in a virtual test rig. Combining inverse design with the CFD for its validation offers an integrated approach for improving the design in the development phase. In the first step analytical energy equations are derived for a blade cascade section and then integrated over the blade surface, i.e. from hub to tip radii, providing a dependency of the theoretical performances characteristics such as for the pressure and the efficiency, as a function of the flow-rate, rotating speed and the outer dimensions and blade angles of the machine. The next step computes inversely the main outer dimensions and blade angles of the geometry required for reaching the performance. In the final design step the blade shape is computed inversely using a NACA 4 Digit camber as it will be shown in the paper upon the required blade angles and other constrains of the cascade. The final shape is generated in CAD software-program and then a proper computational grid is generated so that it can be finally simulated with a commercial Navier-Stokes solver for the complete pressure and efficiency characteristics. The aim of this study is to offer general conclusions about the analytical influence of certain geometry parameters on the design and optimization of axial fans of this type. The last step for the proposed design method is typically the experimental validation with prototypes which will be not covered in this study.

scholarly journals Temperature rise in induction motor windings as the cause of variation in rotational speed of an axial fan

2016 ◽  
Vol 20 (suppl. 5) ◽  
pp. 1449-1459
Author(s):  
Zivan Spasic ◽  
Milan Radic ◽  
Dragana Dimitrijevic
Keyword(s):  
Induction Motor ◽  
Temperature Rise ◽  
Rotational Speed ◽  
Theoretical Background ◽  
Standard Test ◽  
Test Rig ◽  
Axial Fan ◽  
Specific Behavior ◽  
Experimental Procedure ◽  
Three Phase

The paper presents results of an experimental investigation performed under controlled laboratory conditions, in order to identify real causes of variation in the rotational speed of an axial fan that can be noticed after a certain period following the start of operation. The theoretical background important for understanding the observed phenomenon is given and the hypothesis is proposed which states that the temperature rise in motor windings and a consequential rise of their resistances are responsible for such specific behavior of the axial fan. The experiment was performed on a standard test rig with a small industrial axial fan, driven by a three-phase induction motor with the rated power of 1.5 kW. The experimental procedure is described in details, measured and calculated results are presented and appropriate conclusions are given. The obtained experimental results confirm the proposed hypothesis.

scholarly journals Approbation of the Laser Doppler Anemometer Lad-08 on the Secondary Standard Test Rig for Air Flow Speed

2020 ◽  
Vol 1675 ◽  
pp. 012082
Author(s):  
I K Kabardin ◽  
V G Meledin ◽  
S V Dvoinishnikov ◽  
V A Pavlov ◽  
G V Bakakin ◽  
...  
Keyword(s):  
Air Flow ◽  
Flow Speed ◽  
Standard Test ◽  
Laser Doppler Anemometer ◽  
Laser Doppler ◽  
Secondary Standard ◽  
Test Rig

The Effect of Pulsed Blowing on the Boundary Layer of a Highly Loaded Low Pressure Turbine Blade

2013 ◽  
Author(s):  
Marion Mack ◽  
Roland Brachmanski ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Mach Number ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Trailing Edge ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Highly Loaded

The performance of the low pressure turbine (LPT) can vary appreciably, because this component operates under a wide range of Reynolds numbers. At higher Reynolds numbers, mid and aft loaded profiles have the advantage that transition of suction side boundary layer happens further downstream than at front loaded profiles, resulting in lower profile loss. At lower Reynolds numbers, aft loading of the blade can mean that if a suction side separation exists, it may remain open up to the trailing edge. This is especially the case when blade lift is increased via increased pitch to chord ratio. There is a trend in research towards exploring the effect of coupling boundary layer control with highly loaded turbine blades, in order to maximize performance over the full relevant Reynolds number range. In an earlier work, pulsed blowing with fluidic oscillators was shown to be effective in reducing the extent of the separated flow region and to significantly decrease the profile losses caused by separation over a wide range of Reynolds numbers. These experiments were carried out in the High-Speed Cascade Wind Tunnel of the German Federal Armed Forces University Munich, Germany, which allows to capture the effects of pulsed blowing at engine relevant conditions. The assumed control mechanism was the triggering of boundary layer transition by excitation of the Tollmien-Schlichting waves. The current work aims to gain further insight into the effects of pulsed blowing. It investigates the effect of a highly efficient configuration of pulsed blowing at a frequency of 9.5 kHz on the boundary layer at a Reynolds number of 70000 and exit Mach number of 0.6. The boundary layer profiles were measured at five positions between peak Mach number and the trailing edge with hot wire anemometry and pneumatic probes. Experiments were conducted with and without actuation under steady as well as periodically unsteady inflow conditions. The results show the development of the boundary layer and its interaction with incoming wakes. It is shown that pulsed blowing accelerates transition over the separation bubble and drastically reduces the boundary layer thickness.

scholarly journals Innovative Test Rig for Jet Fuels Thermal Stability Testing / Innowacyjne Stanowisko Badawcze Do Określania Stabilności Termicznej Paliw Lotniczych

2014 ◽  
Vol 29 (1) ◽  
pp. 15-22
Author(s):  
Jarosław Sarnecki
Keyword(s):  
Thermal Stability ◽  
Laboratory Test ◽  
Thermal Conditions ◽  
Standard Test ◽  
Test Method ◽  
Jet Fuels ◽  
Stability Testing ◽  
Test Rig ◽  
Standard Test Method ◽  
Laboratory Test Method

Abstract The article deals with laboratory test method for jet fuels thermal stability testing. Author described the reasons that led to test rig preparation, its construction and operation principles. Innovative test rig for jet fuels thermal stability testing enables research in wide thermal conditions and different pressures. Testing capabilities and advantages compared with currently used standard test method of jet fuels thermal stability testing according to ASTM D3241 have been also presented

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