Rapid Compression Machine RCM

  Image of the RCM experiments Copyright: © HGD

Rapid Compression Machine (RCM)

The HGD RCM is a single-stroke, mono-piston machine used for primarily investigating auto-ignition behavior and aid in the development of detailed kinetic models of fuels. Apart from its primary purpose, it is also used for obtaining valuable information on intermediate species when coupled with a rapid sampling system and gas chromatograph mass spectrometer / flame ionization detector (GCMS/FID) system. Investigations on the auto-ignition processes can be extended with the visualization of ignition phenomenon like pre-ignition and also study intrinsic luminescence in the visible spectral range of soot particles. These aspects of the facility help in understanding the different phenomena relevant to oxidation of a fuel and provide key validation targets for kinetic mechanism development.

The key design parameters

Bore x Stroke : 50 x 250 mm

Variable compression ratio : 9 - 32

Design reactor pressure : 1000 bar

Achieved compression pressure : 160 bar

Measurement regime : 4 - 200 ms , low-to-intermediate temperature regime

Functional description

The RCM consists of three mechanically interconnected sections namely, the pneumatic part, the hydraulic part, and the reactor. The premixed fuel-air mixture of a desired stoichiometry is introduced into the heated reaction chamber. The mono-piston is pneumatically compressed and hydraulically locked and released to achieve rapid compression leading to a compression event and an ignition event after a certain delay period. This delay period is defined as ignition delay time which is characteristic for a particular fuel. The data sets obtained from the temperature-dependent ignition delay time for different pressures and stoichiometric ratios serve as a basis for the validation of complex kinetic models of potential target fuels.

The knowledge of species mole fractions as a function of time, provides an intrinsic validation target for mechanism development. A sample from the reaction core can be extracted at any specified point during the ignition delay and analyzed in the Shimadzu GCMS/FID system available at HGD.

Visualization of the ignition process is made possible with the help of a high pressure resistant glass end wall and a high speed camera. This not only provides critical insights to the auto-ignition process but also opens new doors to coupling more diagnostics with the RCM.

*** RCM Video ***