Purdue University researchers were part of an award-winning team honored by the NASA Engineering & Safety Center (NESC).

Timothee Pourpoint, Hilkka Kenttämaa and Swanand Sardeshmukh were among an 11-member team given the NESC Group Achievement Award.

The Transient Combustion Modeling for Hypergolic Engines Assessment Team was selected in “recognition of a unique and insightful combination of modeling, testing and analysis to determine the sources of ZOTs and pressure spikes in hypergolic engines,” the NESC release said. Chuck Pierce, an aerospace engineer at NASA Marshall Space Flight Center, will accept the award on behalf of the team at a ceremony at the Langley Research Center at a later date.

A still frame as a drop of MMH touches a drop of NTO. A flash of light is visible in the background as a timed laser pulse ionizes the reaction intermediates. The field of view is about 1/8th-inch wide.

Liquid hypergolic propellants are highly reactive with one another and provide very rapid control of space thrusters. Under some conditions, however, that reactivity can induce a “ZOT” phenomenon — a combustion detonation in the oxidizer manifold producing a pressure spike that can damage hardware.

“The exact source of those ZOT events has eluded rocket scientists for decades but must be better understood ahead of upcoming missions in Cislunar space,” said Pourpoint, a professor in the School of Aeronautics and Astronautics and co-chair of Purdue’s Cislunar Initiative.

One of the team’s goals was to identify and characterize early reactions that occur between monomethylhydrazine (MMH) fuel and dinitrogen tetroxide (NTO) oxidizer in the liquid and gas phases to improve the understanding of the root causes of ZOT and other combustion pressure spikes identified in current space thrusters. That work involved a joint effort with experiments and modeling work.

Pourpoint and Kenttämaa, a professor in the Department of Chemistry, focused on developing a highly controlled experiment bringing minute quantities of propellants into contact and analyzing their reaction products by using photo-ionization mass spectrometry. Sardeshmukh, a research scientist in mechanical engineering, used the state-of-the-art kinetics mechanisms and solvers to model the ignition and flame propagation of the propellants.

The results of the experiments and modeling conducted by the NESC assessment team will augment modeling capabilities with the objective of improving combustion instability predictions for existing and future hypergolic propellant engines, according to NESC’s 2020 Technical Update.  

The Group Achievement Award honors teams of employees comprising government and non-government personnel. The award is in recognition of outstanding accomplishment through the coordination of individual efforts that have contributed substantially to the success of the NESC mission, its website said.

The NESC Honor Awards are given each year to NASA Center employees, industry representatives and other stakeholders for their efforts and achievements in the areas of engineering, leadership, teamwork and communication. The award, part of NESC’s incentive and recognition program, formally identify individuals and groups who have made outstanding contributions to NESC’s mission and who demonstrate engineering and technical excellence, and foster an open environment.