To achieve the goals of energy saving and emission reduction, enhancing compression ratio and better combustion organization are required. The main obstacle to further improving the power and efficiency of internal combustion engines (ICEs) is knock or deto-knock. The suppression of detonation consists of many scientific issues, including chemical kinetics, shockwave, turbulence, and the interaction of those factors.
The Rapid Compression Machine (RCM) laboratory is affiliated to the State Key Laboratory of Automotive Safety and Energy at Tsinghua University. The THU-RCM is able to decouple the complex factors in ICEs, i.e. turbulence and inlet temperature, thus providing resolution to practical problems under engine-relevant conditions. Meanwhile, THU-RCM can adapt to wide temperature and pressure range. Apart from multiple existing measurement methods, including pressure trace, visualization access, and intermediate species sampling, it provides even broader test range with the connection to one-dimensional detonation cavity and time of flight mass spectrometer (TOF-MS). Main fundamental studies in our lab are
1) Development and validation of chemical kinetics mechanisms;
2) Dynamics of deflagration-detonation transition inside confined space;
3) Evaporation and combustion of a single droplet.
Besides, research focused on practical problems include:
1) 3-D CFD simulation coupled with detailed chemical kinetics;
2) Prediction and suppression of engine knock;
3) Mechanism of pre-ignition that originates from particles and oil droplets;
4) Fuel design and novel combustion modes development.
Since established in 2013, many projects have been assigned and completed in THU-RCM, including National Natural Science Foundation programs, 863 and 973 projects. International cooperation was also carried out with famous enterprises like GM, Commins and Afton. Up to now, about 20s SCI and 10s EI papers have been published. As recognized, THU-RCM attributes much to the studies about engine knock and reveals the essence of deto-knock in ICEs as detonation for the first time. The principal investigator of our lab, Professor Zhi Wang, was invited by Progress of Energy and Combustion Science to write a review named ''Knocking combustion in spark-ignition engines'', published in 2017. With such efforts, the works of RCM Lab provide solutions to engine knock in practical applications and give more insights into the mechanism of detonation initiation.
Occurrence of sporadic super-knock is the main obstacle in the development of advanced gasoline engines. By utilizing a rapid compression machine, events of pre-ignition and super-knock in a closed system under high temperature and high pressure were captured by synchronous high-speed direct photography and pressure measurement. Two different types of engine super-knock could exist. The first type is the super-knock induced by pre-ignition followed by deflagration of the end-gas. This type of...