Investigation of The Effects Of Various Parameters On A Subsonic Axial Flow Fan Performance And Tonal Noise PDF Download
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Author: Racheet Matai
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This work was aimed at improving the efficiency and decrease the noise generated by a cooling fan used by GE transportation to cool a row of resistor networks which dissipate excess energy generated by regenerative power in an inverter application. The first part of study focused on determining the effect of various parameters on the performance of the fan quantitatively by using FLUENT, a general purpose CFD code. The effects of parameters such as hub to tip ratio, chord length/thickness and solidity/number of blades was studied. Once the effect of these parameters was found a new fan was designed which increased the efficiency at the operating point from 73% to 77%. This new fan had a longer blade (increased by 0.75 inches), less number of blades (24 reduced to 18) and a larger chord length (the airfoil scaled by 1.5 time). The hub shape was also modified to reduce separation at the hub. Although a more efficient design, this new fan was found to make more noise with the peak dB levels increasing from 89dB to 110dB due to a higher rate of change of axial force on blades which is proportional to the sound pressure level. Thus a different approach was adopted, an inlet guide vane (IGV) with different lean angles were experimented with. It was seen that a 6 degree lean angle eliminated the peak at the first harmonic of the blade pass frequency (2400Hz) and a 15 degree lean angle eliminated the first and the second harmonic of the blade pass frequency (2400Hz and 3600Hz). The first peak at the blade passing frequency remained approximately the same (~89dB) with the IGV lean.
Author: Racheet Matai
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This work was aimed at improving the efficiency and decrease the noise generated by a cooling fan used by GE transportation to cool a row of resistor networks which dissipate excess energy generated by regenerative power in an inverter application. The first part of study focused on determining the effect of various parameters on the performance of the fan quantitatively by using FLUENT, a general purpose CFD code. The effects of parameters such as hub to tip ratio, chord length/thickness and solidity/number of blades was studied. Once the effect of these parameters was found a new fan was designed which increased the efficiency at the operating point from 73% to 77%. This new fan had a longer blade (increased by 0.75 inches), less number of blades (24 reduced to 18) and a larger chord length (the airfoil scaled by 1.5 time). The hub shape was also modified to reduce separation at the hub. Although a more efficient design, this new fan was found to make more noise with the peak dB levels increasing from 89dB to 110dB due to a higher rate of change of axial force on blades which is proportional to the sound pressure level. Thus a different approach was adopted, an inlet guide vane (IGV) with different lean angles were experimented with. It was seen that a 6 degree lean angle eliminated the peak at the first harmonic of the blade pass frequency (2400Hz) and a 15 degree lean angle eliminated the first and the second harmonic of the blade pass frequency (2400Hz and 3600Hz). The first peak at the blade passing frequency remained approximately the same (~89dB) with the IGV lean.
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 480
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Author: Juan Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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ABSTRACT : The counter rotating subsonic axial flow fans could be a good solution for applications where the highly improved static pressure and efficiency are required without the increase of rotational speed and fan diameter. However, the mechanisms of high performance CRS and parameters influences are not well understood nowadays. This thesis is an experimental investigation of the performance and parameter studies of two counter rotatingaxial flow ducted fans. The design and measurement methods are based on the previous research work in Laboratory Dynfluid (Arts et Métiers ParisTech). Three Counter Rotating Stages (CRS) (named JW1, JW2 and JW3) are developed and tested on a normalized test bench (AERO2FANS). These systems have same design point and differ by the distribution of loading as well as the ratio of angular velocity between the Front Rotor (FR) and Rear Rotor (RR). The first part of results focus on the JW1. The overall performance is obtained by the experimental results of the static pressure rise and static efficiency, as well as the wall pressure fluctuations recorded by a microphone on the casing wall. The parameter study is conducted to investigate the effects of the axial distance and the ratio of angular velocity between the FR and RR on the global performance and flow fields measured by Laser Doppler Velocimetry (LDV).The last part of the work is devoted to analyze the differences of the three CRS with different distribution of work, in terms of the global performance and flow features.
Author:
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ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 892
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Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 492
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Author:
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ISBN:
Category : Noise control
Languages : en
Pages : 994
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Author: K. B. Washburn
Publisher:
ISBN:
Category :
Languages : en
Pages : 149
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Book Description
Discrete frequency acoustic radiation is generated by subsonic axial flow fans through both steady and unsteady blade loading. Steady loading is a function of pumping requirement, and unsteady loading is generated by spatially periodic inflow distortions. The latter effect is the dominant generation mechanism when small fans are used to cool electronic equipment. Fans mounted to exhaust out of a device ingest distortions created by all objects within the unit. This work represents an empirical survey of noise generated by small axial flow cooling fans in the presence of upstream obstructions and various inlet configurations. the obstructions include a cylinder, a thin rectangle, a thick rectangle, and an electronic card gate model. Each of these represents obstructions found in a typical installation. Simple and modified inlet baffles, finger guards, and honeycomb flow straighteners are investigated. Design recommendations are offered to minimize discrete tone generation. These include aerodynamic shaping of unaviodable obstructions, a minimum axial distance of 0.3 fan radii for obstructions in the inlet, the avoidance of blockage in lateral inflow and the use of an inlet baffle to smooth inlet distortions. Account is taken of the spatial restictions of typical installations.
Author: Lewis Research Center
Publisher:
ISBN:
Category : Technology
Languages : en
Pages : 356
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Book Description
This compilation of abstracts describes and indexes over 780 technical reports resulting from the scientific and engineering work performed and managed by the Lewis Research Center in 1977. All the publications were announced in the 1977 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Documents cited include research reports, journal articles, conference presentations, patents and patent applications, and theses.
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 974
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Author: Emanuel Boxer
Publisher:
ISBN:
Category : Axial flow
Languages : en
Pages : 28
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An experimental investigation has been conducted to determine the effects of the wall boundary layer upon the performance of an axial-flow fan rotor. Tests were conducted at low Mach numbers and at one blade angle on a fan designed to have uniform downstream tangential velocity. The maximum disturbed-flow region of the six boundary-layer configurations tested exceeded one-half of the annular width of the duct and the peak efficiency was reduced 2 1/2 percent for this condition. The over-all loss in efficiency may possibly be reduced by decreasing the blade pitch angle in the boundary-layer region to conform to the upstream velocity profile.
