Rapid Compression Machines are used to study auto-ignition of fuels for low temperature and high pressure conditions. Typical test times in an RCM are much longer than those in shock tubes and the conditions are highly controllable and repeatable. RCMs simulate a single compression stroke of a piston engine to produce the desired post-compression conditions.
It has a dual opposed piston configuration which gives significantly reduced compression times compared with a single piston arrangement. The characteristic time for the final 50% of the pressure rise is approximately 2 ms. It has a 50 mm chamber bore and can be used to achieve post compression conditions within the range of 10-40 bar and 600-1000 K. A heating jacket is used to increase initial chamber temperature up to 400 K. The piston heads are creviced to preserve temperature homogeneity within the combustion chamber and avoid boundary layer mixing with the core gas.