Internal Flow Conditions of Contra-Rotating Small-Sized Axial Fan

Small-sized axial fans are used as air cooler for electric equipments. But there is a strong demand for higher power of fans according to the increase of quantity of heat from electric devices. Therefore, higher rotational speed design is conducted, although, it causes the deterioration of efficiency and the increase of noise. Then the adoption of contra-rotating rotors for the small-sized axial fan is proposed for the improvement of performance. In the present paper, the performance curves of the contra-rotating small-sized axial fan with 100mm diameter are shown and the velocity distributions at a partial flow rate at the inlet and the outlet of each front and rear rotor are clarified with experimental results. Furthermore, the flow conditions between front and rear rotors of the contra-rotating small-sized axial fan are investigated by numerical analysis results and causes of the performance deterioration of the contra-rotating small-sized axial fan at the partial flow rate is discussed.

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Performance and Flow Conditions of Contra-Rotating Small-Sized Axial Fan

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1, Symposia – Parts A, B, and C ◽

10.1115/fedsm-icnmm2010-30418 ◽

2010 ◽

Cited By ~ 2

Author(s):

Toru Shigemitsu ◽

Junichiro Fukutomi ◽

Yuki Okabe ◽

Kazuhiro Iuchi

Keyword(s):

Numerical Analysis ◽

Flow Rate ◽

Rotational Speed ◽

Flow Conditions ◽

Axial Fan ◽

Higher Power ◽

Performance Curves ◽

Air Cooler ◽

Axial Fans ◽

Quantity Of Heat

Small-sized axial fans are used as air cooler for electric equipments. But there is a strong demand for higher power of fans according to the increase of quantity of heat from electric devices. Therefore, higher rotational speed design is conducted although, it causes the deterioration of efficiency and the increase of noise. Then the adoption of contra-rotating rotors for the small-sized axial fan is proposed for the improvement of performance. In the present paper, the performance curves of the contra-rotating small-sized axial fan with 100mm diameter are shown and the velocity distributions for a designed flow rate at the inlet and the outlet of each front and rear rotor are clarified with experimental results. Furthermore, the flow conditions between front and rear rotors of the contra-rotating small-sized axial fan are investigated by numerical analysis results and higher performance design of the contra-rotating small-sized axial fan is discussed.

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Numerical analysis of axial fan characteristics

Mechanik ◽

10.17814/mechanik.2018.7.98 ◽

2018 ◽

Vol 91 (7) ◽

pp. 606-608

Author(s):

Stanisław Wrzesień ◽

Michał Frant ◽

Maciej Majcher

Keyword(s):

Numerical Analysis ◽

Numerical Methods ◽

Flow Rate ◽

Total Pressure ◽

Volumetric Flow Rate ◽

Total Efficiency ◽

Axial Fan ◽

Axial Fans ◽

Basic Characteristics

The paper presents an analysis and comparison of basic characteristics of axial fans, both analytically and numerically. Such characteristics are: the characteristics of the total pressure, power and total efficiency as a function of the volumetric flow rate. The presented results showed significant quantitative and qualitative differences in the characteristics obtained by two methods. The usefulness of numerical methods in relation to the results of the initial analytical project was confirmed.

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The best efficiency point of an axial fan at low-pressure conditions

Advances in Mechanical Engineering ◽

10.1177/16878140211001188 ◽

2021 ◽

Vol 13 (3) ◽

pp. 168781402110011

Author(s):

Jose J Corona ◽

Osama Mesalhy ◽

Louis Chow ◽

Quinn Leland ◽

John P Kizito

Keyword(s):

Optimal Design ◽

Performance Measures ◽

Flow Rate ◽

Rotational Speed ◽

Ambient Pressure ◽

Axial Flow ◽

Axial Fan ◽

Electromechanical Actuators ◽

Aerospace Applications ◽

Axial Fans

In the current work, the objective is to determine the best efficiency point (BEP) of an axial fan using CFD. Analyzing the performance of the fan based upon the parameters chosen can lead to the optimal design of an axial flow fan for aerospace applications where the ambient pressure varies rapidly. The 2-bladed fan chosen for the study is the Propimax 2L which is considered the base fan used for comparison of all the results of the work. The set of parameters tested were fan rotational speed, ambient pressure conditions, blade count, and the airfoil design. All the performance measures were based on overall fan efficiency. The results yield the following: an increased rotational speed led to higher efficiencies, the most efficient ambient pressure of which the fan can perform is 0.7 atm, a 5-bladed fan configuration produced the highest efficiency, and airfoil selection is critical for fan efficiency enhancements. The results demonstrated that at 0.7 atm the fan efficiency is the highest due to the changes in power consumption to the density effect. A key finding in the work is that higher blade counts do not necessarily lead to higher performing axial fans. A high cambered airfoil provided a higher flow rate at free delivery than that of the Propimax 2L design, but the rotorcraft airfoil did not yield favorable results. The analysis is focused on the fan design of cooling of the electromechanical actuators (EMAs).

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Numerical Prediction and Performance Experiment in an Engine Cooling Water Pump with Different Blade Outlet Widths

Mathematical Problems in Engineering ◽

10.1155/2017/8945712 ◽

2017 ◽

Vol 2017 ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Wei Li ◽

Xiaofan Zhao ◽

Weiqiang Li ◽

Weidong Shi ◽

Leilei Ji ◽

...

Keyword(s):

Flow Rate ◽

High Efficiency ◽

Static Pressure ◽

Cooling Water ◽

Internal Flow ◽

Water Pump ◽

Centrifugal Pumps ◽

Suction Surface ◽

Engine Cooling ◽

Performance Curves

Changing the blade outlet width is an important method to adjust the performance curves of centrifugal pumps. In this study, three impellers with different blade outlet widths in an engine cooling water pump (ECWP) were numerically simulated based on ANSYS-CFX software. Numerical calculation reliability was validated based on the comparison between simulation results and experimental datum. As the blade outlet width increases, from the performance curves, the investigated ECWP head increases gradually; and the best efficiency point (BEP) offsets to larger flow rate; and the high efficiency region (HER) is becoming larger; and the critical cavitation pressure of the investigated ECWP at BEP increases, which indicates that the cavitation performance at BEP became worse. Compared with the internal flow field, we find vortex appears mainly in the blade passage near the tongue and volute outlet, and the region of the low static pressure is located in the blade inlet suction surface, and impeller inlet and outlet are the regions of high turbulence kinetic energy. Meanwhile, at the same flow rate, with the increase of blade outlet width, the areas of vortex and low static pressure become obvious and bigger.

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Modification of Axial Fan Flow by Trailing Edge Self-Induced Blowing

Journal of Fluids Engineering ◽

10.1115/1.4000345 ◽

2009 ◽

Vol 131 (11) ◽

Cited By ~ 4

Author(s):

Matjaž Eberlinc ◽

Brane Širok ◽

Matevž Dular ◽

Marko Hočevar

Keyword(s):

Standardized Test ◽

Flow Direction ◽

Performance Testing ◽

Internal Flow ◽

Suction Side ◽

Flow Conditions ◽

Axial Fan ◽

Trailing Edge ◽

Local Characteristics ◽

Hollow Blade

Axial fans often show adverse flow conditions at the fan hub and at the tip of the blade. The modification of conventional axial fan blade is presented. Hollow blade was manufactured from the hub to the tip. It enables the formation of self-induced internal flow through internal passages. The internal flow enters the passage of the hollow blade through the opening near the fan hub and exits through the trailing edge slots at the tip of the hollow blade. The study of the influence of internal flow on the flow field of axial fan and modifications of axial fan aerodynamic characteristics is presented. The characteristics of the axial fan with the internal flow were compared to characteristics of a geometrically equivalent fan without internal flow. The results show integral measurements of performance testing using standardized test rig and the measurements of local characteristics. The measurements of local characteristics were performed with a hot-wire anemometry and a five-hole probe. Reduction in adverse flow conditions near the trailing edge at the tip of the hollow blade, boundary-layer reduction in the hollow blade suction side, and reduction in flow separation were attained. The introduction of the self-induced blowing led to the preservation of external flow direction defined by the blade geometry, which enabled maximal local energy conversion. The integral characteristic reached a higher degree of efficiency.

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Internal Flow Condition between Front and Rear Rotor of Contra-Rotating Small-Sized Axial Fan at Low Flow Rate

Open Journal of Fluid Dynamics ◽

10.4236/ojfd.2017.74046 ◽

2017 ◽

Vol 07 (04) ◽

pp. 709-723 ◽

Cited By ~ 1

Author(s):

Toru Shigemitsu ◽

Kensuke Tanaka ◽

Katsuhiko Hirosawa ◽

Keisuke Miyazaki

Keyword(s):

Flow Rate ◽

Flow Condition ◽

Internal Flow ◽

Low Flow ◽

Axial Fan ◽

Low Flow Rate

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Axial fan blade vibration under inlet cross-flow

10.20944/preprints201707.0007.v1 ◽

2017 ◽

Author(s):

Till Heinemann ◽

Stefan Becker

Keyword(s):

Flow Rate ◽

Power Plants ◽

Thermal Power ◽

Amplitude Spectrum ◽

Cross Flow ◽

Flow Conditions ◽

Axial Fan ◽

Blade Vibration ◽

Fan Blade ◽

Operating Points

In thermal power plants equipped with air-cooled condensers, axial cooling fans operate under the influence of ambient flow fields. Under inlet cross-flow conditions, the resultant asymmetric flow field is known to introduce additional harmonic forces to the fan blades. This effect has previously been studied only numerically or using blade mounted strain gauges. For this study, Laser Scanning Vibrometry was used to assess fan blade vibration under inlet cross-flow conditions in an adapted fan test rig inside a wind tunnel test section. Two co-rotating laser beams scanned a low pressure axial fan, resulting in spectral, phase resolved surface vibration patterns of the fan blades. Two distinct operating points were examined, with and without inlet cross-flow influence. While almost identical fan vibration patterns were found for both reference operating points, overall blade vibration increased by 100% at low fan flow rate due to cross-flow, and by 20% at high fan flow rate. While numerically predicted natural frequency modes could be confirmed from experimental data as minor peaks in the vibration amplitude spectrum, they were not excited significantly by cross-flow. Instead, primarily higher rotation rate harmonics were amplified, i.a. a synchronous blade tip flapping was strongly excited at the blade pass frequency.

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