An Exploration of Secondary Fuel Injection as Actuation for Control of Combustion Instabilities in a Laminar Premixed Tube Combustor

Active control of combustion instabilities through secondary fuel injection is a control method that has gained a lot of attention in the past decade. Previous control schemes with acoustic loudspeakers are not practical in full-scale gas turbines due to the extreme temperatures and acoustic power requirements. Much work has gone into controlling these thermoacoustic instabilities with secondary fuel control. Control of a laminar premixed tube combustor through secondary fuel actuation is the concentration of this work. It is the first known published attempt to control a laminar premixed tube combustor through secondary fuel actuation. Due to the low flow rates within the tube combustor an innovative injection technique had to be constructed to perform the secondary fuel actuation. The gaseous fuel is injected only one millimeter above the location of the flame through one, two, or four injectors. These injectors were designed to overcome the serious problem of pulse diffusion. This technique enabled the tube combustor to be controlled through secondary fuel injection. Accompanying the innovative fuel injection technique is a duty cycle modulation technique that was a prime contributor to the success of the control system. This method enabled the system to be controlled at conditions that were uncontrollable with a fixed duty cycle. The overall result was a 35 dB suppression of the limit cycle amplitude with 20% secondary fuel injection.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mechanical Engineering

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2000

Author dc:creator

• Richards, John S.

Chair dc:contributor.committeechair

• Saunders, William R.

Committee members dc:contributor.committeemember

• Vandsburger, Uri
• Robertshaw, Harry H.

• Active Combustion Control
• Secondary Fuel Injection
• Thermoacoustic Instability

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-05022000-16090058

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/32096