Advances in combustion and propulsion applications

Over about one hundred years aviation has evolved from an adventurous enterprise of audacious pioneers to a large scale industry providing high performance defense aircraft and world wide transportation. In an even shorter period, initial rocket developments gave rise to a modern industry producing space launchers and satellites allowing space transportation, telecommunications, global positioning, earth observation and space exploration. The technological advances could not have been made without progress in aerospace science and engineering. The Aerodynamics Institute at RWTH has been one important player in this scientific quest. With Theodore Von Kármán as its first director, the institute rapidly became a leader in this field. On its 100th anniversary, it is fit to examine progress accomplished in some key areas. This article focuses on combustion because of its importance for aerospace propulsion. By looking back at some of Kármán’s papers, and other studies of a period situated in the middle of the last century it is interesting to delineate advances. Over the period of 60 years starting from the 1950s where Kármán was writing a set of articles on the fundamentals of aerothermochemistry and on laminar flame propagation, combustion has progressed in a remarkable fashion. Advances on the theoretical level have been accompanied by significant developments in experimentation with new laser diagnostics, high speed imaging and numerical data processing. Advances in computational combustion have had a profound effect on scientific research in this field and on engineering applications. Starting with a list of central issues encountered in combustion, advances are illustrated by examining a selected number of topics of interest to aerospace propulsion: Flame structures and detailed modeling of flames, Turbulent combustion, Cryogenic flames and transcritical combustion, Combustion dynamics, Computational Flame Dynamics.