Moon mission

Researchers at Purdue University are conducting NASA-funded research to develop rockets faster and less expensively for missions to Mars and the moon. The work will focus on liquid-fuelled rockets and in particular understanding how fuel and a component called the oxidiser interact inside the rocket engine’s fuel injectors to cause unstable combustion.

This instability is a complex phenomenon which has continually plagued rocket development as it causes extreme bursts of heat and pressure fluctuations that could lead to accidents and hardware damage. Therefore more knowledge is needed before future engines can be developed and used for space flight.

Heat from combustion naturally fluctuates inside the combustion chamber. At the same time, the combustion chamber generates resonant sound waves that cause ‘acoustic pressure’ which also fluctuates. When heat and pressure fluctuations coincide, the combined result can be devastating, causing accidents and damage to rocket engines.

A paper published by the university demonstrated that an experiment can be designed to study instabilities occurring simultaneously, something which has been virtually impossible in the past. Engineers used a carefully designed injector and varied the length of the combustion chamber to see how changing acoustics affected the heat-driven pressure fluctuations.