Welcome to the Lynch Laboratory Homepage.
We are interested in a variety of combustion and chemically reacting flow phenomena. We primarily work on providing reaction rates and other details for modelers in support of cleaner more efficient combustion processes.
We are currently focused on:
- The rates and products of combustion relevant chemical reactions, principally radical reactions.
- Ignition, especially in new fuels, especially in in rapidly changing environments.
- Advancing and expanding diagnostic techniques, particularly at high pressure.
For more information on our current projects, please consult the Research Page.
Most of the experimental work in the laboratory involves using a 12.7 mm bore miniature high repetition rate shock tube (HRRST). In a shock tube, shock waves are used to generate high temperature, high pressure, controlled environment conditions. It is in those conditions that we study combustion phenomena. Miniature shock tubes use the opening of a fast acting solenoid valve separating the driver and driven section in order to generate the incident shock. The whole process is automated, (usually 1 experiment every 2-4 seconds) and includes filling the test gas, performing the experiment, and purging the residual gases in preparation for the next experiment.
The main advantages are in the ability to quickly sweep out a wide range of experimental conditions and to repeatedly access conditions. One approach to measure weak signals is to employ signal averaging (this is very hard for conventional shock tubes because of large differences shot-to-shot). This repeatability permits experiments otherwise impossible to perform. The disadvantages include a short test time, short path length for single pass diagnostics, and less than perfect gas conditions following the reflected shock. Some of these can be overcome with modelling.
For more information on the miniature shock tube, its operation, schematics, etc. consult:
- P.T. Lynch, “Note: An Improved Solenoid Driver Valve For Miniature Shock Tubes” Review of Scientific Instruments 87 2016 056110. doi:10.1063/1.4953115
- P. T. Lynch, G. Wang “Chemical Thermometry in Miniature HRRST using 1,1,1-Trifluoroethane Dissociation” Proceedings of the Combustion Institute 36 2017, 307-314. doi:10.1016/j.proci.2016.05.057
- R. S. Tranter, P. T. Lynch, “A Miniature High Repetition Rate Shock Tube,” Review of Scientific Instruments, 84(9) 2013, 094102. doi:10.1063/1.4820917
Other techniques currently being developed involve similar miniaturization and automation applied to other high pressure reactors, including rapid compression machines.
The HRRST is used for a variety of experimental measurements including high temperature ignition delay, time-resolved species concentrations measured with tunable diode laser spectroscopy, and even high temperature fluid mechanic measurements using synchrotron sourced techniques.
There are a number of diagnostic tools available to provide information to measure reaction rates and constrain reactive models. These are a few that we are using.
Diagnostic Equipment and Capabilities:
- Tunable diode lasers: 2x CO, CH2O, H2O, I, HF, and suitable detectors.
- Optical spectrum analyzer
- Custom spectrometer with high speed line detectors and ccd cameras, and various light sources.
- Product gas sampling
The Other Stuff
Despite the experimental focus, many of the problems we solve require extensive computational supporting efforts including: chemically reactive modeling, computational fluid mechanics, custom data acquisition, and large data handling and processing.