Reacting Flows Laboratory / Virginia Active Combustion Control Group
The Reacting Flows Lab and the Virginia Active Combustion Control Group (RFL/VACCG) coexist with the joint purpose of better understanding combustion and flow phenomena.
Presently, the RFL/VACCG is active in the following R&D areas:
- ultra lean premixed combustion stability
- fuel-air mixing and flow control
- combustor emissions control
- reduction of soot formation in combustion processes
- fuel variability
- multiple fuel combustors
- transport of poisonous combustion byproducts in building fires
- halon replacement methods for fire suppression
Any R&D program attempting to address the issues listed above is by definition multidisciplinary, incorporating at least the fields of fluid mechanics, combustion, chemistry, acoustics, dynamic systems, controls, sensors, actuators, and optics.
Dr. Uri Vandsburger formed the RFL in 1991 when he arrived at the Virginia Tech Department of Mechanical Engineering, and presently works with flow, mixing, soot formation in combustion systems, compartment fires, and fire suppression. By 1996 Vandsburger, Dr. William Saunders, and Dr. Bill Baumann formed a collaborative team made up of combustion, fluids and dynamic systems and controls faculty, all under the name of VACCG. This group offered a fresh, fundamental approach to modern combustion problems such as combustion instabilities and active combustion control.
The closing days of the 20th Century and the birth of the 21st Century can be characterized by many technological symbols. However, above all, is the societal dependency on fossil fuels conversion also known as combustion. Combustion is used for electrical power generation, propulsion (land, sea, and air) and industrial heat/refrigeration. A key difference between the dawn of the 21st Century and 20th Century is the external constraint on the combustion process existing today, namely, the demand to reduce pollutants, such as NOx, CO, soot, UHC (unburned hydrocarbons) and PAH (polycyclic aromatic hydrocarbons), as well as the clean combustion product CO2, known as a "greenhouse gas".
In the case of gas turbines, the combustor as a whole acts as a complex dynamic system, which in turn couples with systems upstream and downstream. The combustion process, its coupling with the fluid flow, and the flow train acoustics, must each be treated as a dynamic subsystem.
The group has been awarded several contracts, and the Department of Mechanical Engineering and the College of Engineering assisted in erecting a new active combustion control lab. The lab is almost completed and is fully equipped to be able to test combustion dynamics in a single nozzle, full-scale combustor under realistic conditions, with an inlet air temperature of 1200° F, pressure up to 500 psi, and a flow rate of 1000 scfm and for various types of fuels both liquid and gaseous.
Fires occurring in occupancies such as hospitals, dormitories, and nursing homes pose a serious threat to their occupants. Poisoning due to carbon monoxide is an issue that affects not only the occupants present in the rooms containing the fire, but also to those located at remote locations away from the fire.
The building fire research laboratory has been active in this area since1989 and has been collaborating with the Building Fire Research Laboratory of the National Institute of Standards and Technology (BFRL/NIST). The goal of this research is to the develop tools that can be used by the fire protection engineering community to predict the transport of poisonous combustion products through rooms, doors, windows, and hallways. These tools can vary between simple hand calculations, algorithms, or complex computer models. Tests at the building fire research lab are conducted in a ½-scaled ISO 9705 compartment using liquid n-hexane pool fires or gaseous propane fires; the facility is capable of supporting fires ranging in size from 20 kilowatts to 2.3 megawatts.