Operating noise of fans is reduced by adding part span vanes to vane row of stator, reducing the number of full span vanes and maintaining a vane-to-blade ratio of about 2 to 1

Volk, L. J.

English

NASA Technical Reports Server

SDecember 1971	 Brief 71-10528 
NASA TECH BRIEF 
Ames Research Center 	
_4V 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a aubscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Split Stator Vane Row for Fans and Compressors 
The problem: 
To reduce the operating noise of fans by reducing 
the interaction that takes place between a rotating 
blade row and the stationary vanes of compressors 
or turbines.
tribution of acoustic energy in the annulus of most 
fans or compressors, and the majority of noise is 
generated in the outer annulus region near the tip, 
a high vane-to-blade ratio need be applied only in 
this region. 
The solution: 
Add part-span vanes to the vane row of the stator, 
reduce the number of full-span vanes, and maintain 
a vane-to-blade ratio of about 2 to 1. 
How it's done: 
A unique feature of this design is that additional 
vanes need be added only to the outer annulus 
region. Because there is a nonuniform radial dis-
The length of the added vanes does not affect the 
concept, nor does the addition of a stiffening ring. 
The stiffening ring can also be an acoustic splitter, 
a ring structure incorporating acoustic material on 
each side. Moreover, a reduction in the number of 
full-span stator vanes reduces the performance and 
weight penalties imposed by stiffening rings (part-
span shrouds) or other structures that are incorpo-
rated to ensure adequate strength of the vane row. 
(continued overleaf) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000520 2020-03-17T02:27:04+00:00Z
Notes: 
1. The following documentation may be obtained 
from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: 
NASA CR-1493 (N70-22699), Study Pro-
gram for Lift Fan Noise Reduction and 
Suppression.
2. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: B71-10528 
Patent status: 
No patent action is contemplated by NASA. 
Source: Lawrence J
.
 Volk of
General Electric Company/Aircraft Engine Group
under contract to

Ames Research Center 
(ARC-10288)
. 
.. 
Brief 71-10528	 Category 06


Split stator vane row for fans and compressors

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