Method for reducing the noise level of a turbomachine fan

Patent metadata

Field	Value
Publication number	US-10054133-B2
Application number	US-201514958175-A
Country	US
Kind code	B2
Filing date	Dec 3, 2015
Priority date	Dec 4, 2014
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

A method for reducing the noise level generated by a fan of a turbomachine including a plurality of vanes, said method further including, when the turbomachine is operating and under given flight conditions, the following steps measuring an operational pitch angle for each of the vanes, calculating an offset between the operational pitch angle of each of the vanes and a predetermined reference pitch angle for the given flight conditions so as to produce a controlled noise level at multiple rotation frequencies of the fan, correcting the orientation of the vanes so as to compensate their operational pitch angles depending on the offsets thus calculated.

First claim

The invention claimed is:

1. A method for reducing the noise level generated by a fan of a turbomachine comprising a plurality of vanes, said method comprising, when the turbomachine is operating and in given flight conditions:
measuring an operational pitch angle for each of the vanes;
calculating an offset between the operational pitch angle of each of the vanes and a predetermined reference pitch angle for the given flight conditions, at which the vanes produce a controlled noise level at rotation multiple frequencies of the fan; and
correcting an orientation of the vanes so as to compensate the operational pitch angles of the vanes depending on the calculated offsets.

2. The method according to claim 1 , wherein the operational pitch angle is corrected individually for each vane.

3. The method according to claim 1 , wherein the operational pitch angle is measured at the tip of each vane.

4. The method according to claim 1 , wherein the operational pitch angle is measured at the tip of each vane,
wherein each vane comprises a leading edge and a trailing edge, and
wherein the operational pitch angle of each of the vanes is measured according to the following operations comprising:
detecting in real time the passage of the leading edge of each vane,
detecting in real time the passage of the trailing edge of each vane, and
measuring of the engine speed of the turbomachine.

5. The method according to claim 1 , wherein the operational pitch angle of each vane is compensated when the offset is greater than a threshold of 0.05 degrees.

6. The method according to claim 1 , wherein the controlled noise level at the rotation multiple frequencies corresponds to a generally reduced noise level at said rotation multiple frequencies compared to the noise level at said rotation multiple frequencies without a controlled noise level at said rotation multiple frequencies.

7. The method according to claim 1 , wherein the controlled noise level at rotation multiple frequencies corresponds to a generally equalized noise level at said rotation multiple frequencies compared to the noise level at said rotation multiple frequencies without a controlled noise level at said rotation multiple frequencies.

8. A fan of a turbomachine comprising:
a plurality of vanes; and
a device comprising:
a measuring device configured to measure an operational pitch angle for each of the vanes, when the turbomachine is operating and in given flight conditions,
a calculator configured to calculate an offset between the operational pitch angle of each of the vanes and a predetermined reference pitch angle for said given flight conditions, at which the vanes produce a controlled noise level at rotation multiple frequencies of the fan, and
an angular adjustment device configured to correct an orientation of the vanes so as to compensate the operational pitch angles of the vanes depending on the calculated offsets.

9. A turbomachine comprising a fan comprising:
a plurality of vanes; and
a device comprising:
a measuring device configured to measure an operational pitch angle for each of the vanes, when the turbomachine is operating and in given flight conditions,
a calculator configured to calculate an offset between the operational pitch angle of each of the vanes and a predetermined reference pitch angle for said given flight conditions, at which the vanes produce a controlled noise level at rotation multiple frequencies of the fan, and
an angular adjustment device configured to correct an orientation of the vanes so as to compensate the operational pitch angles of the vanes depending on the calculated offsets.

Assignees

• Snecma

Inventors

• Julienne Francois
• Courtiade Nicolas
• Roux Jean-Michel

Classifications

• F05D2260/96

  Preventing, counteracting or reducing vibration or noise · CPC title

• F05D2260/74

  by turning around an axis perpendicular the rotor centre line · CPC title

• F04D29/325

  for axial flow fans (blade mountings F04D29/34, blades F04D29/38) · CPC title

• F04D27/0246

  by varying geometry within the pumps, e.g. by adjusting vanes · CPC title

• F04D29/666

  by means of rotor construction or layout, e.g. unequal distribution of blades or vanes · CPC title