Discrete Frequency Noise and Its Reduction in Small Axial‐Flow Fans

1982 ◽  
Vol 72 (4) ◽  
pp. 1333-1333
Author(s):  
James Mitchael Fitzgerald
Keyword(s):  
Axial Flow ◽  
Frequency Noise ◽  
Discrete Frequency

Experimental Investigation of Discrete Frequency Noise Generated by Unsteady Blade Forces

1970 ◽  
Vol 92 (1) ◽  
pp. 155-164 ◽  
Author(s):  
N. J. Lipstein ◽  
R. Mani
Keyword(s):  
Axial Flow ◽  
Small Scale ◽  
Frequency Noise ◽  
Unsteady Forces ◽  
Discrete Frequency ◽  
Acoustic Modes ◽  
Compressor Rotor ◽  
Critical Experiment ◽  
Flow Compressor ◽  
Good Agreement

A critical experiment was designed and carried out to study discrete frequency noise generation from an axial flow compressor row. The experiments were carried out in a small-scale Freon loop. Two arrays of rods were introduced upstream of a single compressor rotor so as to cause acoustic modes oriented approximately normal and parallel to the blade force. R. Mani’s analysis of the coupling of unsteady forces to acoustic modes was applied to these experimental results. Good agreement was obtained.

Discrete Frequency Noise Generation From an Axial Flow Fan Blade Row

1970 ◽  
Vol 92 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Ramani Mani
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Acoustic Energy ◽  
Frequency Noise ◽  
Noise Generation ◽  
Two Dimensional ◽  
Axial Flow Fan ◽  
Fan Noise ◽  
Blade Row ◽  
Fan Blade

An analysis is presented which treats the noise generation from an axial flow fan row by given forces including the effects of a moving medium. The linearization of Euler’s equations to yield tractable problems for fan noise is discussed. The three-dimensional problem is decomposed into several two-dimensional problems. Finally, full details are given of a two-dimensional analysis to predict the amounts of acoustic energy, at the blade passing frequency and its harmonics, radiated up and downstream of a blade row due to its interaction with a neighboring row.

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