Running Cool

Mechanical Engineering, May 2008 by Thilmany, Jean

EXPERIMENTS CONDUCTED AT Purdue University's new hydrogen facility aim to help NASA develop rockets faster and less expensively for future missions to Mars and the moon.

A more efficient cooling mechanism could improve performance and reduce the need for costly overhauls, said William Anderson, an associate professor in Purdue's School of Aeronautics and Astronautics in West Lafayette, Ind.

Liquid hydrogen acts as a coolant before it enters the combustion chamber. The frigid liquid hydrogen, about -420°F, circulates through channels in a cooling jacket surrounding the combustor, absorbing heat and raising its temperature before being injected into the combustion chamber.

The Purdue research focuses on accurately measuring the heat flux, which is caused by differences in temperature between the hot combustion gases and the cooled walls of the combustor. Combusted gases in the rocket's chamber reach 6,000°F.

The measurements are used to improve detailed computational models of how propellants mix inside the combustor. The work also aims at better understanding the behavior of coolant inside channels surrounding the combustor, Anderson said.