Rapid Compression Machine

The two twin opposed-pistons rapid compression machines now operated in NUI Galway are used to simulate conditions similar to those reached in internal combustion engines and in gas turbines. The rapid compression machine is capable of compressing a premixed gaseous fuel in air to 40 atm in less than 20 milliseconds over a range of temperatures from 600–1050 K. The auto-ignition event can then be followed by monitoring the pressure change within the chamber and/or the light emitted as the fuel ignites.

A rapid sampling system has been added to the rapid compression machine which enables the acquisition of samples prior to ignition for later chemical analysis in our own gas chromatograph with mass spectrometer detection. Using this we can report fuel, intermediate, and product species concentration profiles as a function of time. This data can then be used, in addition to ignition data, to validate the chemical kinetic mechanism, understanding the formation of toxic chemical species and emissions as well as paths leading to soot production.

Rapid Compression Machine, Combustion Chamber and Pistons

Shock Tubes

High-Pressure Shock Tube: We have built a heated high-pressure shock tube capable of operating at pressures of up to 70 atm to study auto-ignition events under engine-like conditions. This 12 metre long tube is used to study the ignition behaviour of a large range of fuels. Since the installation of a heating system that covers the entire tube we have extended the range of fuels we can investigate to include fuels of low vapour pressure and large molecular weight.

Data recorded in the two shock tubes and in the RCMs will be complementary and will provide a cross validation of experimental results.

Instrumented Shock Tube: The shock tube has a 5.8 m driven section with an inner diameter of 10.24 cm. There are 5 PCB Piezotronics 113A21 transducers embedded on the sidewall of the tube. The end-wall has a Kistler 603CAB piezoelectric sensor connected to a Kistler 5018 charge amplifier. The driver section is rather unique and is barrel shaped with a diameter of 52 cm and a length of 53 cm.  To operate the system in single pulse mode, a 200L dump tank is connected to the driven section via a pneumatic valve.  A sampling system is connected to the end wall of the shock tube, allowing online sampling with a 6890/5975 GC-MS system.

Low-pressure Shock Tube and High-pressure Shock Tube